metal-organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

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ISSN: 2053-2296

Di­aqua­iodido­tetra­sarcosine­potassium: an overview of sarcosine metal halogenide structures

aInstitut für Mineralogie und Kristallographie, Universität Wien–Geozentrum, Althanstrasse 14, A-1090 Wien, Austria, and bInstitute of Applied Problems of Physics, National Academy of Science of Armenia, 25 Nersessyan Street, 0014 Yerevan, Armenia
*Correspondence e-mail: michel.fleck@univie.ac.at

(Received 10 October 2012; accepted 26 November 2012; online 13 December 2012)

The monoclinic crystal structure of tetra­sarcosine potassium iodide dihydrate {or catena-poly[[potassium-tetra-μ-sarcosine-κ4O:O′;κ4O:O] iodide dihydrate]}, {[K(C3H7NO2)4]I·2H2O}n or Sar4·KI·2H2O (space group C2/c), comprises two crystallographically different sarcosine mol­ecules and one water mol­ecule on general positions, and one K+ cation and one I anion located on twofold axes. The irregular eight-coordinated K+ polyhedra are connected into infinite chains along [001] via sarcosine mol­ecules. This compound is the first sarcosine metal halogenide salt with a 4:1 ratio. A short overview of other sarcosine metal halogenide salts is presented and relationships to similar glycine salts are discussed.

Comment

In recent years, there has been considerable interest in the study of the crystal structures of amino acid salts, as they are of inter­est from several points of view, e.g. as candidates for nonlinear optical crystals (Fleck, Becker et al., 2008[Fleck, M., Becker, P., Bayarjargal, L., Ochrombel, R. & Bohatý, L. (2008). Cryst. Res. Technol. 43, 127-134.]; Kaminskii et al., 2009[Kaminskii, A. A., Bohatý, L., Becker, P., Eichler, H. J., Rhee, H. & Hanuza, J. (2009). Laser Phys. Lett. 6, 872-885.], and references therein). Within these salts, the amino acids can act as cationic, anionic or zwitterionic units. The most extensive data are found for salts of glycine (see, for example, Fleck, Held et al., 2008[Fleck, M., Held, P., Schwendtner, K. & Bohatý, L. (2008). Z. Kristallogr. 223, 212-221.]; Fleck, 2008[Fleck, M. (2008). Z. Kristallogr. 223, 223-232.], and references therein), but many other amino acid salts have been reported (e.g. Ghazaryan et al., 2011a[Ghazaryan, V. V., Fleck, M. & Petrosyan, A. M. (2011a). Proc. Soc. Photo-Opt. Instrum. Eng. 7998, 79980F.]). Apart from the 20 `standard' amino acids, several others have been utilized in the design of crystalline salts, e.g. β-alanine (Sridhar et al., 2001[Sridhar, B., Srinivasan, N. & Rajaram, R. K. (2001). Acta Cryst. E57, o1004-o1006.]; Baran et al., 1995[Baran, J., Drozd, M., Lis, T. & Ratajczak, H. (1995). J. Mol. Struct. 372, 151-159.]), betaine (e.g. Wiehl et al., 2008[Wiehl, L., Schreuer, J., Haussuhl, E. & Hofmann, P. (2008). Z. Kristallogr. New Cryst. Struct. 485, 223.]; Kocadag et al., 2008[Kocadag, M., Fleck, M. & Bohatý, L. (2008). Acta Cryst. E64, m1273-m1274.]) and ornithine (Via et al., 2006[Via, L. D., Gia, O., Magno, S. M., Dolmella, A., Marton, D. & Di Noto, V. (2006). Inorg. Chim. Acta, 359, 4197-4206.]; Ghazaryan et al., 2011b[Ghazaryan, V. V., Fleck, M. & Petrosyan, A. M. (2011b). J. Cryst. Phys. Chem. 2, 7-16.]). Our group has been studying sarcosine (Sar) in recent years and investigating its mol­ecular and crystal structures, vibrational spectra and thermal expansion. This work has mainly concerned sarco­sinium salts, i.e. compounds comprising sar­co­sine as cations combined with inorganic anions (see Table 1[link], and references therein), although there are also several structures of sarcosine as a zwitterion combined with neutral salts (see Table 2[link], and references therein). As can be seen, most of these salts represent combinations of sarcosine and metal halogenides. In addition, two salts are known in which sarcosine acts as an anion in combination with metal cations, namely bis(sarcosinato)copper dihydrate (space group P21/n; Krishnakumar et al., 1994[Krishnakumar, R. V., Natarajan, S., Bahadur, S. A. & Cameron, T. S. (1994). Z. Kristallogr. 209, 443-444.]) and bis­(sarcosinato)nickel dihydrate (space group P[\overline{1}]; Guha, 1973[Guha, S. (1973). Acta Cryst. B29, 2167-2170.]). In this work, we focus on the structure of the title compound, (I)[link], formed from sarcosine and a neutral salt (Sar4·KI·2H2O).

[Scheme 1]

In (I)[link], there are two crystallographically different sarcosine moieties (labelled A and B) located on general positions, and one K+ cation and one I anion, both of which are located on twofold axes (Wyckoff position 4e). Additionally, there is one water mol­ecule on a general position, which participates in an extensive hydrogen-bond network stabilizing the structure (Table 3[link]). The sarcosine mol­ecules are zwitterions and their geometry agrees well with the usual values (Fig. 1[link]). However, one feature deserves attention, namely the C—O bond lengths within the two carboxyl­ate groups, which show some variation; in the deprotonated mesomeric state one would expect more or less identical distances. These differences between the somewhat longer C1—O1 bonds [1.2640 (19) and 1.2624 (17) Å] and the shorter C1—O2 bonds [1.2379 (18) and 1.2348 (17) Å] are due to the fact that both atoms O1A and O1B are acceptors of hydrogen bonds extending from the N atoms and the water mol­ecule (Table 3[link]), whereas atoms O2A and O2B are not. The sarcosinate anions act as both O:O′- and O:O-bidentate–bridging ligands, thus connecting adjacent irregular eight-coordinated K+ cations into infinite chains along [001]. Hydrogen bonding provides further intra-chain connections, except for the hydrogen bonds involving the water mol­ecules, which connect adjacent chains into a three-dimensional framework. A packing diagram is shown in Fig. 2[link] and a detailed view of one polyhedron as part of the chain is shown in Fig. 3[link].

The IR and Raman spectra of (I)[link] are shown in Fig. 4[link]. As expected, they show the characteristic vibrations of zwitterionic sarcosine and solvent water mol­ecules. Comparison of the spectra of pure sarcosine with those shown in Fig. 4[link] allows the assignment of the IR absorption band with peaks at 3477 and 3425 cm−1 and the Raman band at 3441 cm−1 to O—H stretching vibrations of the water mol­ecule. The characteristic intense Raman lines at 3025–2939 cm−1 and the respective IR peaks at 3022–2938 cm−1 are caused by C—H stretching vibrations of the CH2 and CH3 groups. These peaks are superimposed on a broad band caused by stretching N—H vibrations of the NH2+ groups and possibly by combination bands. In the region near 1600 cm−1, there is a strong IR absorption band with peaks at 1640, 1621 and 1586 cm−1. In the IR spectrum of sarcosine, there are two peaks at 1642 and 1600 cm−1 in this region. On this basis, we assign the peaks at 1640 and 1621 cm−1 to an asymmetric stretching vibration of the COO group and a deformation vibration of the NH2+ groups, and the peak at 1585 cm−1 to a deformation vibration of the water mol­ecule. The IR absorption band with peaks at 1401 and 1379 cm−1 is assigned to a symmetric stretching vibration of the COO group, and the peaks at 648 and 598 cm−1 (and the respective Raman line at 601 cm−1) are assigned to a deformation vibration of the same group. We assign the peaks at 1485 and 1462 cm−1 (and the respective Raman lines at 1470 and 1418 cm−1) to an asymmetric deformation vibration of CH3 and a deformation vibration of CH2 groups, while the peaks at 1306, 1298 and 1289 cm−1 and the Raman line at 1298 cm−1 are assigned to the wagging vibration of the CH2 group. The IR peaks at 1167 and 1145 cm−1, and the respective lines at 1173 and 1140 cm−1, are assigned to a rocking vibration of the CH3 group, in contrast with the peak at 695 cm−1 and the Raman lines at 708 and 697 cm−1 which are assigned to the rocking vibration of the CH2 group. The position of the absorption peak at 1061 cm−1 (the respective Raman line is at 1062 cm−1) is characteristic of stretching vibrations of a C—N bond. The deformation vibration δ(CC=O) is reflected by the presence of an absorption peak at 499 cm−1 (and Raman lines at 507 and 487 cm−1), while the vibration δ(CNC) is expressed at 377 cm−1 in the Raman spectrum. The Raman lines at 970, 926 and 900 cm−1 and the respective IR absorption peaks are assigned to skeleton vibrations. These spectroscopic data are in excellent agreement with the structural data elucidated from the X-ray diffraction experiment.

As stated above, (I)[link] belongs to the group of sarcosine metal halogenides, which represent the majority of the compounds of sarcosine with neutral salts (Table 2[link]). A comparison of these sarcosine metal halogenide structures shows that, as found previously for similar compounds with glycine, the structural diversity is high, i.e. each salt represents a unique structure type (for a detailed classification, see Fleck, 2008[Fleck, M. (2008). Z. Kristallogr. 223, 223-232.]). These can be arranged into groups according to the connectivity of the building units. In doing so, it becomes apparent that there are many striking similarities with the respective compounds of glycine. There are examples of isolated units, as found in Sar2·ZnCl2 (Subha Nandhini et al., 2001[Subha Nandhini, M., Krishnakumar, R. V. & Natarajan, S. (2001). Acta Cryst. E57, m435-m437.]) and Sar+·ZnCl3 (Krishnakumar et al., 2001[Krishnakumar, R. V., Subha Nandhini, M. & Natarajan, S. (2001). Acta Cryst. E57, m192-m194.]), which comprise tetra­hedral four-coordinate Zn2+ cations with monodentate sarcosine ligands. The structure of the former is closely related to that of Gly3·ZnCl2 (Hariharan et al., 1989[Hariharan, M., Rajan, S. S., Srinivasan, R. & Natarajan, S. (1989). Z. Kristallogr. 188, 217-222.]), which is of inter­est because of its physical properties (e.g. Fleck, Becker et al., 2008[Fleck, M., Becker, P., Bayarjargal, L., Ochrombel, R. & Bohatý, L. (2008). Cryst. Res. Technol. 43, 127-134.]; Kaminskii et al., 2009[Kaminskii, A. A., Bohatý, L., Becker, P., Eichler, H. J., Rhee, H. & Hanuza, J. (2009). Laser Phys. Lett. 6, 872-885.]), and that of the latter bears a close similarity to Gly·ZnCl2·H2O (Fleck, Held et al., 2008[Fleck, M., Held, P., Schwendtner, K. & Bohatý, L. (2008). Z. Kristallogr. 223, 212-221.]). Another example of a structure comprising isolated units is that of Sar2·PtBr2 (Sabo et al., 2005[Sabo, T. J., Dinovic, V. M., Kaluderovic, G. N., Stanojkovic, T. P., Bogdanovic, G. A. & Juranic, Z. D. (2005). Inorg. Chim. Acta, 358, 2239-2245.]), which also has a glycine analogue, namely trans-(Gly)2·PtIVCl22+ (Davies et al., 1995[Davies, H. O., Brown, D. A., Yanovsky, A. I. & Nolan, K. B. (1995). Inorg. Chim. Acta, 237, 71-77.]). Fig. 5[link] shows the similarities of the respective parts of these structures.

Nevertheless, most sarcosine metal halogenide crystal structures can be described as chains [as is the case for (I)[link]], the majority of which have glycine analogues as well. Among the chains, there are two subtypes: (i) isolated polyhedra connected to chains via bridging sarcosine ligands and (ii) polyhedral chains with the ligands attached (Fig. 6[link]). Examples of the first subtype are Sar2·MnCl2·2H2O (Rzaczynska et al., 2002[Rzaczynska, Z., Mrozek, R. & Sikorska-Iwan, M. (2002). Pol. J. Chem. 76, 29-35.]) (an analogue of Gly2·MnCl2; Narayanan & Venkataraman, 1975[Narayanan, P. & Venkataraman, S. (1975). Z. Kristallogr. 142, 52-81.]), Sar·MnCl2·2H2O (Silva et al., 2001[Silva, M. R., Beja, A. M., Paixão, J. A. & de Veiga, L. A. (2001). Z. Kristallogr. New Cryst. Struct. 216, 419.]) [an analogue of Gly·NiCl2·2H2O (Fleck & Bohatý, 2004[Fleck, M. & Bohatý, L. (2004). Acta Cryst. C60, m291-m295.]) and Gly·MnCl2·2H2O (Clegg et al., 1987[Clegg, W., Lacy, O. M. & Straughan, B. P. (1987). Acta Cryst. C43, 794-797.])] and Sar3·CaCl2 (Mishima et al., 1984[Mishima, N., Itoh, K. & Nakamura, E. (1984). Acta Cryst. C40, 1824-1827.]) (similar to Gly3·CeCl3; Fleck, Held et al., 2008[Fleck, M., Held, P., Schwendtner, K. & Bohatý, L. (2008). Z. Kristallogr. 223, 212-221.]). It is noteworthy that the structures of Sar·MnCl2·2H2O and Gly·MnCl2·2H2O are so closely related that even the unit-cell parameters agree reasonably well (allowing for the additional CH3 group of sarcosine), confirming that the crystal structures are not merely topologically similar.

Naturally, larger cations tend to form structures of the second subtype, i.e. polyhedral chains. These chains can be formed by edge-sharing polyhedra, as in Sar·CdCl2 (Yamada et al., 1994[Yamada, J., Hashimoto, H., Inomata, Y. & Takeuchi, T. (1994). Bull. Chem. Soc. Jpn, 67, 3224-3230.]) (similar to Gly·NaI·H2O; Verbist et al., 1971[Verbist, J. J., Putzeys, J.-P., Piret, P. & Van Meerssche, M. (1971). Acta Cryst. B27, 1190-1194.]), or face-sharing polyhedra, as in Sar·BaCl2·4H2O (Krishnakumar & Natarajan, 1995[Krishnakumar, R. V. & Natarajan, S. (1995). Cryst. Res. Technol. 30, 825-830.]) or Sar3·BaBr2 (Trzebiatowska-Gusowska et al., 2009[Trzebiatowska-Gusowska, M., Gagor, A., Baran, J. & Drozd, M. (2009). J. Raman Spectrosc. 40, 315-322.]), both of which are roughly similar to Gly2·BaCl2·H2O and Gly2·SrCl2·3H2O (Narayanan & Venkataraman, 1975[Narayanan, P. & Venkataraman, S. (1975). Z. Kristallogr. 142, 52-81.]). It is inter­esting to note that analogues of glycine and sarcosine exist for all these examples. Compound (I)[link] is a notable exception, as it is the first instance (for both sarcosine and glycine) with an amino acid–metal ratio of 4:1. Nevertheless, as far as connectivity is concerned, the structure is related to those of salts with large cations (compare Figs. 6[link]e, 6[link]f and 6[link]k).

In conclusion, it has been shown that there are several sarcosine metal halogenide structures, most of which can be characterized by infinite chains as the building units, and all of which have analogues with similar glycine compounds (if the connectivity of polyhedra via organic mol­ecules is considered). The title compound, Sar4·KI·2H2O, is exceptional in that no similar glycine compound exists, as the amino acid–metal ratio of 4:1 has not been observed so far in any reported glycine or sarcosine metal halogenide compound.

[Figure 1]
Figure 1
The mol­ecular structure of tetra­sarcosine potassium iodide dihydrate, (I)[link], showing the atom-numbering scheme. Atoms K1 and I1 are located on twofold axes (Wyckoff position 4e). Displacement ellipsoids are drawn at the 50% probability level.
[Figure 2]
Figure 2
A packing diagram for (I)[link]. Note the chains oriented horizontally (in the [001] direction). H atoms have been omitted for clarity.
[Figure 3]
Figure 3
Detail of the chain in (I)[link], viewed along [010]. [Symmetry codes: (i) −x, −y, −z + [{3\over 2}]; (ii) −x, −y, −z + 1; (iii) x, −y, z − [{1\over 2}]; (iv) −x, −y, −z + 2; (v) x, −y, z + [{1\over 2}].]
[Figure 4]
Figure 4
Vibrational spectra of (I)[link].
[Figure 5]
Figure 5
The similarity of isolated units in (top) sarcosine compounds and (bottom) glycine compounds, shown for (a) Sar2·ZnCl2, (b) Sar+·ZnCl3 and (c) Sar2·PtBr2, compared with (d) Gly3·ZnCl2, (e) Gly·ZnCl2·H2O and (f) trans-(Gly)2·PtIVCl22+; for references, see Comment.
[Figure 6]
Figure 6
The chains in (top) sarcosine metal salts and (bottom) glycine metal halogenide salts. (a) Sar2·MnCl2·2H2O, (b) Sar·MnCl2·2H2O, (c) Sar3·CaCl2, (d) Sar·CdCl2, (e) Sar·BaCl2·4H2O, (f) Sar4·KI2·2H2O, (g) Gly2·MnCl2, (h) Gly·NiCl2·2H2O, (i) Gly3·CeCl3, (j) Gly·NaI·H2O and (k) Gly2·BaCl2·H2O; for references, see Comment.

Experimental

The initial reagents were sarcosine (Sigma) and chemically pure KI (Reakhim). The title compound, (I)[link], was obtained from an aqueous solution containing sarcosine and KI in a stoichiometric 4:1 molar ratio by slow evaporation at room temperature. However, crystals of (I)[link] were obtained initially from a solution containing an equimolar ratio of sarcosine and KI. A 2:1 molar ratio leads to crystals with the same composition.

Fourier-transform Raman spectra were recorded using an NXR FT–Raman module on a Nicolet 5700 spectrometer (number of scans 512, power at the sample 0.15 W, resolution 4 cm−1) at room temperature. The same spectrometer was used for measuring atten­uated total reflection Fourier transform IR spectra (FT–IR ATR) (ZnSe prism, 4000–500 cm−1, Happ–Genzel apodization, ATR distortion corrected; number of scans 32, resolution 4 cm−1). Part of the IR spectrum in the region 500–400 cm−1 was taken from FT–IR spectra recorded with a Nujol mull (4000–400 cm−1; number of scans 32, resolution 2 cm−1).

Crystal data
  • [K(C3H7NO2)4]I·2H2O

  • Mr = 558.42

  • Monoclinic, C 2/c

  • a = 13.714 (1) Å

  • b = 22.799 (2) Å

  • c = 8.0786 (5) Å

  • β = 111.940 (4)°

  • V = 2343.0 (3) Å3

  • Z = 4

  • Mo Kα radiation

  • μ = 1.60 mm−1

  • T = 296 K

  • 0.08 × 0.05 × 0.05 mm

Data collection
  • Bruker APEXII CCD area-detector diffractometer

  • Absorption correction: multi-scan (APEX2; Bruker, 2004[Bruker (2004). APEX2. Bruker AXS Inc., Madison, Wisconsin, USA.]) Tmin = 0.883, Tmax = 0.925

  • 14485 measured reflections

  • 4036 independent reflections

  • 2993 reflections with I > 2σ(I)

  • Rint = 0.035

Refinement
  • R[F2 > 2σ(F2)] = 0.033

  • wR(F2) = 0.073

  • S = 1.02

  • 4036 reflections

  • 152 parameters

  • 6 restraints

  • H atoms treated by a mixture of independent and constrained refinement

  • Δρmax = 0.44 e Å−3

  • Δρmin = −0.72 e Å−3

Table 1
Salts of sarcosine I: sarcosinium–anion compounds

CompoundSpace groupa (Å)b (Å)c (Å)α (°)β (°)γ (°)Reference
SarH·Sar·NO3P[\overline{1}]5.3206.57815.95795.44895.94493.410(a)
SarH·Sar·ClPca2123.5146.06115.270909090(b)
SarH·Sar·BrPca2123.7716.18715.405909090(b)
SarH·IP215.5876.4519.8659097.0490(c)
SarH·Sar·IP21/c9.5176.26120.30190100.93100(c)
SarH·Sar·BF4P2121216.0089.76420.582909090(d)
SarH·Sar·ClO4P2121216.0419.80120.788909090(d)
SarH2·SiF6P21/n5.7166.33517.4479091.9390(e)
SarH2·Sar·SiF6·2H2OPnma11.70514.70911.113909090(e)
SarH2·Sar2·SiF6P21/c11.48510.6069.76890114.6390(e)
References: (a) Fleck et al. (2012a[Fleck, M., Ghazaryan, V. V. & Petrosyan, A. M. (2012a). Z. Kristallogr. 227, 819-824.]); (b) Ghazaryan et al. (2012a[Ghazaryan, V. V., Fleck, M. & Petrosyan, A. M. (2012a). J. Mol. Struct. 1020, 160-166.]); (c) Ghazaryan et al. (2012b[Ghazaryan, V. V., Fleck, M. & Petrosyan, A. M. (2012b). J. Mol. Struct. 1032, 35-40.]); (d) Ghazaryan et al. (2012c[Ghazaryan, V. V., Fleck, M. & Petrosyan, A. M. (2012c). J. Mol. Struct. 1021, 130-137.]); (e) Fleck et al. (2012b[Fleck, M., Ghazaryan, V. V. & Petrosyan, A. M. (2012b). Solid State Sci. 14, 952-963.]).
†Phase transition at 180 K to a noncentrosymmetric structure (space group P212121).

Table 2
Salts of sarcosine II: sarcosine–neutral salt compounds

CrystalSpace groupa (Å)b (Å)c (Å)α (°)β (°)γ (°)Reference
Sar3·CaCl2Pnma9.12217.40810.228909090(a)
Sar2·MnCl2·2H2OP[\overline{1}]4.8225.37913.78383.7680.5587.58(b)
Sar·MnCl2·2H2OP21/c8.3145.77718.6809095.8390(c)
Sar2·ZnCl2Pbca14.19110.65515.917909090(d)
SarH·ZnCl3P216.6187.4999.9009092.6290(e)
Sar·BaCl2·4H2OP2121217.23510.66815.686909090(f)
Sar·CdCl2P21/n7.96013.8446.9179092.4290(g)
Sar2·PtBr2P21/a10.9219.5626.89090125.4690(h)
Sar3·BaBr2P21/c18.34510.6688.9219091.8690(i)
Sar4·KI·2H2OC2/c13.71422.7998.07990111.9490(j)
Sar3·Eu(ClO4)3·2H2OP19.14611.04214.696100.42104.56109.24(k)
References: (a) Mishima et al. (1984[Mishima, N., Itoh, K. & Nakamura, E. (1984). Acta Cryst. C40, 1824-1827.]) and Ashida et al. (1972[Ashida, T., Bando, S. & Kakudo, M. (1972). Acta Cryst. B28, 1560-1565.]); (b) Rzaczynska et al. (2002[Rzaczynska, Z., Mrozek, R. & Sikorska-Iwan, M. (2002). Pol. J. Chem. 76, 29-35.]); (c) Silva et al. (2001[Silva, M. R., Beja, A. M., Paixão, J. A. & de Veiga, L. A. (2001). Z. Kristallogr. New Cryst. Struct. 216, 419.]); (d) Subha Nandhini et al. (2001[Subha Nandhini, M., Krishnakumar, R. V. & Natarajan, S. (2001). Acta Cryst. E57, m435-m437.]); (e) Krishnakumar et al. (2001[Krishnakumar, R. V., Subha Nandhini, M. & Natarajan, S. (2001). Acta Cryst. E57, m192-m194.]); (f) Krishnakumar & Natarajan (1995[Krishnakumar, R. V. & Natarajan, S. (1995). Cryst. Res. Technol. 30, 825-830.]); (g) Yamada et al. (1994[Yamada, J., Hashimoto, H., Inomata, Y. & Takeuchi, T. (1994). Bull. Chem. Soc. Jpn, 67, 3224-3230.]); (h) Sabo et al. (2005[Sabo, T. J., Dinovic, V. M., Kaluderovic, G. N., Stanojkovic, T. P., Bogdanovic, G. A. & Juranic, Z. D. (2005). Inorg. Chim. Acta, 358, 2239-2245.]); (i) Trzebiatowska-Gusowska et al. (2009[Trzebiatowska-Gusowska, M., Gagor, A., Baran, J. & Drozd, M. (2009). J. Raman Spectrosc. 40, 315-322.]); (j) this work; (k) Gawryszewska et al. (2000[Gawryszewska, P. P., Jerzykiewicz, L., Sobota, P. & Legendziewicz, J. (2000). J. Alloys Compd, 300, 275-282.]).
†Phase transition at 127 K to a noncentrosymmetric structure (space group Pn21a).
‡This species actually comprises cationic sarcosinium, but as metal cations and halogenide anions are present, it is included here.

Table 3
Hydrogen-bond geometry (Å, °)

D—H⋯AD—HH⋯ADAD—H⋯A
N1A—H11A⋯O1Bi0.87 (1)1.92 (2)2.7538 (17)162 (2)
N1A—H12A⋯O1Bii0.87 (1)1.93 (1)2.7911 (17)176 (2)
N1B—H12B⋯O1A0.88 (2)2.34 (2)3.0117 (19)133 (2)
N1B—H11B⋯O1Aiii0.89 (2)1.88 (2)2.750 (2)164 (2)
O1W—H1W⋯O1Aiv0.84 (2)2.04 (2)2.870 (2)169 (4)
O1W—H2W⋯I1v0.84 (2)2.82 (2)3.6280 (19)163 (4)
Symmetry codes: (i) [x, -y, z+{\script{1\over 2}}]; (ii) x, y, z+1; (iii) [-x, y, -z+{\script{3\over 2}}]; (iv) [-x+{\script{1\over 2}}], [-y+{\script{1\over 2}}, -z+2]; (v) [-x+{\script{1\over 2}}, -y+{\script{1\over 2}}, -z+1].

H atoms bonded to C atoms were refined using the riding model, with C—H = 0.96–0.97 Å. The positions of the H atoms bonded to O and N atoms were refined with bond-length restraints of 0.89 (2) and 0.82 (2) Å for N—H and O—H, respectively. For methyl and water H atoms, Uiso(H) = 1.5Ueq(C,O), and for methylene H atoms, Uiso(H) = 1.2Ueq(C), while for the amine H atoms, their Uiso(H) values were refined freely.

Data collection: APEX2 (Bruker, 2004[Bruker (2004). APEX2. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: APEX2; data reduction: APEX2; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: DIAMOND (Bergerhoff et al., 1996[Bergerhoff, G., Berndt, M. & Brandenburg, K. (1996). J. Res. Natl Inst. Stand. Technol. 101, 221-225.]); software used to prepare material for publication: SHELXL97.

Supporting information


Comment top

In recent years, there has been considerable activity in the study of the crystal structures of amino acid salts, as they are of interest from several points of view, e.g. as candidates for nonlinear optical crystals (Fleck, Becker et al., 2008; Kaminskii et al.,2009, and references therein). Within these salts, amino acids can act as cationic, anionic or zwitterionic units. The most extensive data are found for salts of glycine (see e.g. Fleck, Held et al., 2008; Fleck, 2008, and references therein), but many other amino acid salts have been reported (e.g. Ghazaryan et al., 2011a). Apart from the 20 `standard' amino acids, several others have been utilized in the design of crystalline salts, e.g. β-alanine (Sridhar et al., 2001; Baran et al., 1995), betaine (e.g. Wiehl et al., 2008; Kocadag et al., 2008) and ornithine (Via et al., 2006; Ghazaryan et al., 2011b). Our group has been studying sarcosine (Sar) in recent years, investigating its molecular and crystal structures, vibrational spectra and thermal expansion. This work has mainly concerned sarcosinium salts, i.e. compounds comprising sarcosine as cations combined with inorganic anions (see Table 1 and references therein), although there are also several structures of sarcosine as a zwitterion combined with neutral salts (see Table 2 and references therein). As can be seen, most of these salts represent combinations of sarcosine and metal halogenides. In addition, two salts are known in which sarcosine acts as an anion in combination with metal cations, namely bis(sarcosinato)copper dihydrate (space group P21/n; Krishnakumar et al., 1994) and bis(sarcosinato)nickel dihydrate (space group P1; Guha, 1973). In this work, we focus on the structure of the title compound, (I), formed from sarcosine and a neutral salt (Sar4.KI.2H2O).

In compound (I), there are two crystallographically different sarcosine moieties (labelled A and B) located on general positions, and one K+ cation and one I- anion, both of which are located on special positions, i.e. on twofold axes (Wyckoff 4e). Additionally, there is one water molecule on a general position, which participates in an extensive hydrogen-bond network stabilizing the structure (Table 3). The sarcosine molecules are zwitterions and their geometry agrees well with the usual values (Fig. 1). However, one feature deserves attention, namely the C—O bond lengths within the two carboxylate groups, which show some variation; in the deprotonated mesomeric state one would expect more or less identical distances. These differences between the somewhat longer C1—O1 bonds and the shorter C1—O2 bonds are due to the fact that both atoms O1A and O1B are acceptors of hydrogen bonds extending from the N atoms and the water molecule (Table 3), whereas atoms O2A and O2B are not. The sarcosinate anions act as both O,O'-bidentate and O,O-bridging ligands, thus connecting adjacent irregular eight-coordinated K+ cations into infinite chains along [001]. Hydrogen bonding provides further intra-chain connections, except for the hydrogen bonds involving the water molecules, which connect adjacent chains into a three-dimensional framework. A packing diagram is shown in Fig. 2 and a detailed view of one polyhedron as part of the chain is shown in Fig. 3.

The IR and Raman spectra of (I) are shown in Fig. 4. As expected, they show the characteristic vibrations of zwitterionic sarcosine and solvent water molecules. A comparison of the spectra of pure sarcosine with those shown in Fig. 4 allows the assignment of the absorption band with peaks at 3477 and 3425 cm-1 and the Raman band at 3441 cm-1 to O—H stretching vibrations of the water molecule. The characteristic intensive Raman lines at 3025–2939 cm-1 and the respective peaks at 3022–2938 cm-1 are caused by C—H stretching vibrations of the CH2 and CH3 groups. These peaks are superimposed on a broad band caused by stretching N—H vibrations of the NH2+ groups and possibly by combination bands. In the region near 1600 cm-1, there is a strong absorption band with peaks at 1640, 1621 and 1586 cm-1. In the spectrum of sarcosine, there are two peaks at 1642 and 1600 cm-1 in this region. On this basis, we assign the peaks at 1640 and 1621 cm-1 to an asymmetric stretching vibration of the COO- group and a deformation vibration of the NH2+ groups, and the peak at 1585 cm-1 to a deformation vibration of the water molecule. The absorption band with peaks at 1401 and 1379 cm-1 is assigned to a symmetric stretching vibration of the COO- group, and the peaks at 648 and 598 cm-1 and the respective Raman line at 601 cm-1 are assigned to a deformation vibration of the same group. We assign the peaks at 1485 and 1462 cm-1 (and the respective Raman lines at 1470 and 1418 cm-1) to an asymmetric deformation vibration of CH3 and a deformation vibration of CH2 groups, while the peaks at 1306, 1298 and 1289 cm-1 and the Raman line at 1298 cm-1 are assigned to the wagging vibration of the CH2 group. The peaks at 1167 and 1145 cm-1, and the respective lines at 1173 and 1140 cm-1, are assigned to a rocking vibration of the CH3 group, in contrast with the peak at 695 cm-1 and the Raman lines at 708 and 697 cm-1 which are assigned to the rocking vibration of the CH2 group. The position of the absorption peak at 1061 cm-1 (the respective Raman line is at 1062 cm-1) is characteristic of stretching vibrations of a C—N bond. The deformation vibration δ(CCO) is reflected in the presence of an absorption peak at 499 cm-1 (and Raman lines at 507 and 487 cm-1), while the vibration δ(CNC) is expressed at 377 cm-1 in the Raman spectrum. The Raman lines at 970, 926 and 900 cm-1 and the respective absorption peaks are assigned to skeletal vibrations. These spectroscopic data are in excellent agreement with the structural data elucidated from the X-ray diffraction experiment.

As stated above, (I) belongs to the group of sarcosine metal halogenides, which represent the majority of the compounds of sarcosine with neutral salts (Table 3). A comparison of these sarcosine metal halogenide structures shows that, as found previously for similar compounds with glycine, the structural diversity is high, i.e. each salt represents a unique structure type (for a detailed classification, see Fleck, 2008). These can be arranged into groups according to the connectivity of the building units. In doing so, it becomes apparent that there are many striking similarities with the respective compounds of glycine. There are examples of isolated units, as found in Sar2.ZnCl2 (Subha Nandhini et al., 2001) and SarH.ZnCl3 (Krishnakumar et al., 2001), which comprise tetrahedral four-coordinate Zn2+ cations with monodentate sarcosine ligands. The structure of the former is closely related to that of Gly3.ZnCl2 (Hariharan et al., 1989), which is of interest because of its physical properties (e.g. Fleck, Becker et al., 2008; Kaminskii et al., 2009), and that of the latter bears a close similarity to Gly.ZnCl2.H2O (Fleck, Held et al., 2008). Another example of a structure comprising isolated units is that of Sar2.PtBr2 (Sabo et al., 2005), which also has a glycine analogue, namely trans-(Gly-)2.PtIVCl2 (Davies et al., 1995). Fig. 5 shows the similarities of the respective parts of these structures.

Nevertheless, most sarcosine metal halogenide crystal structures can be described as chains [as is the case for (I)], the majority of which have glycine analogues as well. Among the chains, there are two subtypes: (i) isolated polyhedra connected to chains via bridging sarcosine ligands, and (ii) polyhedral chains with the ligands attached (Fig. 6). Examples of the first subtype are Sar2.MnCl2.2H2O (Rzaczynska et al., 2002) [an analogue of Gly2.MnCl2 (Narayanan & Venkataraman, 1975)], Sar.MnCl2.2H2O (Silva et al., 2001) [an analogue of Gly.NiCl2.2H2O (Fleck & Bohatý, 2004) and Gly.MnCl2.2H2O (Clegg et al., 1987)] and Sar3.CaCl2 (Mishima et al., 1984) [similar to Gly3.CeCl3 (Fleck, Held et al., 2008)]. It is noteworthy that the structures of Sar.MnCl2.2H2O and Gly.MnCl2.2H2O are so closely related that even the unit-cell parameters agree reasonably well (allowing for the additional CH3 group of sarcosine), confirming that the crystal structures are not merely topologically similar.

Naturally, larger cations tend to form structures of the second subtype, i.e. polyhedral chains. These chains can be formed by edge-sharing polyhedra, as in Sar.CdCl2 (Yamada et al., 1994) [similar to Gly.NaI.H2O (Verbist et al., 1971)], or face-sharing polyhedra, as in Sar.BaCl2.4H2O (Krishnakumar & Natarajan, 1995) or Sar3.BaBr2 (Trzebiatowska-Gusowska et al., 2009), both of which are roughly similar to Gly2.BaCl2.H2O and Gly2.SrCl2.3H2O (Narayanan & Venkataraman, 1975). It is interesting to note that, for all these examples, analogues of glycine and sarcosine exist. Compound (I) is a notable exception, as it is the first instance (for both sarcosine and glycine) with an amino acid–metal ratio of 4:1. Nevertheless, as far as connectivity is concerned, the structure is related to those of salts with large cations (compare Figs. 6e, 6f and 6k).

In conclusion, it has been shown that there are several sarcosine metal halogenide structures, most of which can be characterized by infinite chains as the building units, and all of which have analogues with similar glycine compounds (if the connectivity of polyhedra via organic molecules is considered). The title compound, Sar4.KI.2H2O, is exceptional in that no similar glycine compound exists, as the amino acid–metal ratio of 4:1 has not been reported in any glycine or sarcosine metal halogenide compound.

Related literature top

For related literature, see: Baran et al. (1995); Clegg et al. (1987); Davies et al. (1995); Fleck (2008); Fleck & Bohatý (2004); Fleck, Becker, Bayarjargal, Ochrombel & Bohatý (2008); Fleck, Held, Schwendtner & Bohatý (2008); Ghazaryan et al. (2011a, 2011b); Guha (1973); Hariharan et al. (1989); Kaminskii et al. (2009); Kocadag et al. (2008); Krishnakumar & Natarajan (1995); Krishnakumar et al. (1994, 2001); Mishima et al. (1984); Narayanan & Venkataraman (1975); Rzaczynska et al. (2002); Sabo et al. (2005); Silva et al. (2001); Sridhar et al. (2001); Subha Nandhini, Krishnakumar & Natarajan (2001); Trzebiatowska-Gusowska, Gagor, Baran & Drozd (2009); Verbist et al. (1971); Via et al. (2006); Wiehl et al. (2008); Yamada et al. (1994).

Experimental top

As initial reagent, we used sarcosine (Sigma) and chemically pure KI (Reakhim). The title compound was obtained from an aqueous solution containing sarcosine and KI in a stoichiometric 4:1 molar ratio by slow evaporation at room temperature. However, we initially obtained Sar4.KI.2H2O out of a solution containing an equimolar ratio of sarcosine and KI. A 2:1 molar ratio leads to crystals with the same composition.

Fourier transform Raman spectra were recorded using an NXR FT–Raman module on a Nicolet 5700 spectrometer (number of scans 512, power at the sample 0.15 W, resolution 4 cm-1) at room temperature. The same spectrometer was used for measuring attenuated total reflection Fourier transform IR spectra (FT–IR ATR) (ZnSe prism, 4000–500 cm-1, Happ–Genzel apodization, ATR distortion corrected; number of scans 32, resolution 4 cm-1). Part of the IR spectrum in the region 500–400 cm-1 was taken from FT–IR spectra registered with a Nujol mull (4000–400 cm-1; number of scans 32, resolution 2 cm-1).

Refinement top

H atoms bonded to C atoms were refined using the riding model, with C—H = 0.96–0.97 Å [Please check added text]. H atoms bonded to O and N atoms were refined semi-freely, with the distances restrained to 0.89 and 0.82 Å for N—H and O—H, respectively. For methyl and water H atoms, Uiso(H) = 1.5Ueq(C,O), and for all other H atoms, Uiso(H) = 1.2Ueq(C,N).

Computing details top

Data collection: APEX2 (Bruker, 2004); cell refinement: APEX2 (Bruker, 2004); data reduction: APEX2 (Bruker, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Bergerhoff et al., 1996); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top
Fig. 1. The molecular structure of tetrasarcosine potassium iodide dihydrate, (I), showing the atom-numbering scheme. Atoms K1 and I1 are located on special positions (twofold axes, Wyckoff position 4e). Displacement ellipsoids are drawn at the 50% probability level.

Fig. 2. A packing diagram for (I). Note the chains oriented horizontally (in the [001] direction). H atoms have been omitted for clarity.

Fig. 3. Detail of the chain in (I), viewed along [010]. [Symmetry codes: (i) -x, -y, -z + 3/2; (ii) -x, -y, -z + 1; (iii) x, -y, z - 1/2; (iv) -x, -y, -z + 2; (v) x, -y, z + 1/2.]

Fig. 4. Vibrational spectra of (I).

Fig. 5. The similarity of isolated units in (top) sarcosine compounds and (bottom) glycine compounds, shown for (a) Sar2.ZnCl2, (b) Sar+.ZnCl3 and (c) Sar2.PtBr2, compared with (d) Gly3.ZnCl2, (e) Gly.ZnCl2.H2O and (f) trans-Gly-2.PtIVCl2; for references, see Comment.

Fig. 6. The chains in (top) sarcosine–metal salts and (bottom) glycine–metal halogenide salts. (a) Sar2.MnCl2.2H2O, (b) Sar.MnCl2.2H2O, (c) Sar3.CaCl2, (d) Sar.CdCl2, (e) Sar.BaCl2.4H2O, (f) Sar4.KI2.2H2O, (g) Gly2.MnCl2, (h) Gly.NiCl2.2H2O, (i) Gly3.CeCl3, (j) Gly.NaI.H2O and (k) Gly2.BaCl2.H2O; for references, see Comment.
catena-Poly[[potassium-tetra-µ-sarcosine- κ4O:O';κ4O:O] iodide dihydrate] top
Crystal data top
[K(C3H7NO2)4]I·2H2OF(000) = 1136
Mr = 558.42Dx = 1.583 Mg m3
Monoclinic, C2/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2ycCell parameters from 14498 reflections
a = 13.714 (1) Åθ = 3.1–32.1°
b = 22.799 (2) ŵ = 1.60 mm1
c = 8.0786 (5) ÅT = 296 K
β = 111.940 (4)°Prism, colourless
V = 2343.0 (3) Å30.08 × 0.05 × 0.05 mm
Z = 4
Data collection top
Bruker APEXII CCD area-detector
diffractometer
4036 independent reflections
Radiation source: fine-focus sealed tube2993 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.035
Detector resolution: 0.1 pixels mm-1θmax = 32.1°, θmin = 3.1°
ϕ and ω scansh = 2013
Absorption correction: multi-scan
(APEX2; Bruker, 2004)
k = 3233
Tmin = 0.883, Tmax = 0.925l = 1212
14485 measured reflections
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.033Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.073H atoms treated by a mixture of independent and constrained refinement
S = 1.01 w = 1/[σ2(Fo2) + (0.0305P)2 + 0.960P]
where P = (Fo2 + 2Fc2)/3
4036 reflections(Δ/σ)max = 0.002
152 parametersΔρmax = 0.44 e Å3
6 restraintsΔρmin = 0.72 e Å3
Crystal data top
[K(C3H7NO2)4]I·2H2OV = 2343.0 (3) Å3
Mr = 558.42Z = 4
Monoclinic, C2/cMo Kα radiation
a = 13.714 (1) ŵ = 1.60 mm1
b = 22.799 (2) ÅT = 296 K
c = 8.0786 (5) Å0.08 × 0.05 × 0.05 mm
β = 111.940 (4)°
Data collection top
Bruker APEXII CCD area-detector
diffractometer
4036 independent reflections
Absorption correction: multi-scan
(APEX2; Bruker, 2004)
2993 reflections with I > 2σ(I)
Tmin = 0.883, Tmax = 0.925Rint = 0.035
14485 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0336 restraints
wR(F2) = 0.073H atoms treated by a mixture of independent and constrained refinement
S = 1.01Δρmax = 0.44 e Å3
4036 reflectionsΔρmin = 0.72 e Å3
152 parameters
Special details top

Experimental. A single crystal was selected manually and mounted on a glass needle with laboratory grease. The suitability for XRD was checked via three short sets of omega scans (measuring time per frame 10 s).

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Single-crystal X-ray intensity data were collected at 296 K on a Bruker APEXII diffractometer with CCD area detector, using 926 frames with ϕ and ω increments of 0.5° and a counting time of 60 s per frame. The crystal-to-detector distance was 30 mm. The reflection data were processed with Bruker APEX2 software and corrected for Lorentz, polarization, background and absorption effects (Bruker, 2004). The crystal structure was determined by direct methods (SHELXS97; Sheldrick, 2008) and subsequent Fourier and difference Fourier syntheses, followed by full-matrix least-squares refinements on F2 (SHELXL97; Sheldrick, 2008).

Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
K10.00000.005247 (19)0.75000.02595 (9)
I10.00000.369835 (8)0.25000.05337 (8)
O1A0.09405 (11)0.17168 (5)0.99381 (19)0.0451 (3)
O2A0.06104 (8)0.08076 (5)1.06001 (15)0.0343 (2)
C1A0.12116 (13)0.12139 (6)1.0611 (2)0.0289 (3)
C2A0.23862 (12)0.11119 (6)1.1478 (2)0.0292 (3)
H21A0.27050.11771.06050.035*
H22A0.26880.13911.24400.035*
N1A0.26259 (10)0.05119 (6)1.21911 (17)0.0277 (3)
H11A0.2283 (14)0.0260 (7)1.137 (2)0.034 (5)*
H12A0.2386 (14)0.0477 (8)1.304 (2)0.034 (5)*
C3A0.37537 (14)0.03614 (9)1.2851 (3)0.0503 (5)
H31A0.40160.04211.19160.076*
H32A0.38460.00421.32180.076*
H33A0.41330.06071.38490.076*
O1B0.19050 (9)0.04452 (5)0.49915 (14)0.0304 (2)
O2B0.17396 (9)0.07178 (5)0.75227 (14)0.0336 (2)
C1B0.17711 (11)0.08184 (6)0.60416 (18)0.0242 (3)
C2B0.16609 (13)0.14499 (6)0.5392 (2)0.0294 (3)
H21B0.23460.16000.55110.035*
H22B0.12100.14630.41390.035*
N1B0.12123 (12)0.18248 (5)0.64197 (19)0.0319 (3)
H11B0.0537 (13)0.1733 (9)0.613 (3)0.046 (6)*
H12B0.1529 (16)0.1766 (9)0.757 (2)0.045 (6)*
C3B0.12226 (18)0.24562 (8)0.6033 (3)0.0548 (5)
H31B0.19360.25860.63580.082*
H32B0.08940.26710.67070.082*
H33B0.08450.25230.47820.082*
O1W0.33341 (15)0.20953 (8)0.9319 (3)0.0760 (5)
H1W0.354 (3)0.2445 (9)0.939 (5)0.114*
H2W0.383 (2)0.1932 (14)0.913 (5)0.114*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
K10.0275 (2)0.0245 (2)0.0271 (2)0.0000.01170 (16)0.000
I10.06073 (14)0.03628 (10)0.06179 (13)0.0000.02140 (10)0.000
O1A0.0471 (7)0.0262 (6)0.0653 (8)0.0054 (5)0.0246 (6)0.0092 (5)
O2A0.0291 (6)0.0334 (6)0.0411 (6)0.0037 (4)0.0141 (5)0.0050 (5)
C1A0.0344 (8)0.0265 (7)0.0297 (7)0.0006 (6)0.0163 (6)0.0024 (5)
C2A0.0310 (8)0.0254 (7)0.0327 (7)0.0072 (6)0.0135 (6)0.0021 (6)
N1A0.0261 (6)0.0274 (6)0.0305 (6)0.0023 (5)0.0114 (5)0.0035 (5)
C3A0.0273 (9)0.0561 (12)0.0599 (12)0.0056 (8)0.0074 (8)0.0107 (9)
O1B0.0405 (6)0.0243 (5)0.0295 (5)0.0015 (4)0.0165 (4)0.0028 (4)
O2B0.0496 (7)0.0265 (5)0.0291 (5)0.0006 (5)0.0200 (5)0.0027 (4)
C1B0.0250 (7)0.0207 (6)0.0273 (6)0.0025 (5)0.0103 (5)0.0006 (5)
C2B0.0387 (8)0.0228 (7)0.0324 (7)0.0006 (6)0.0198 (6)0.0026 (5)
N1B0.0445 (8)0.0204 (6)0.0348 (7)0.0014 (5)0.0193 (6)0.0014 (5)
C3B0.0667 (14)0.0208 (8)0.0852 (15)0.0021 (8)0.0379 (12)0.0054 (9)
O1W0.0695 (12)0.0551 (10)0.1153 (15)0.0180 (9)0.0481 (11)0.0204 (10)
Geometric parameters (Å, º) top
K1—O2Ai2.8039 (11)N1A—H11A0.869 (14)
K1—O2Aii2.8039 (11)N1A—H12A0.865 (14)
K1—O2B2.8214 (12)C3A—H31A0.9600
K1—O2Biii2.8214 (12)C3A—H32A0.9600
K1—O1Biv2.8696 (11)C3A—H33A0.9600
K1—O1Bv2.8696 (11)O1B—C1B1.2624 (17)
K1—O2A2.8932 (12)O1B—K1iv2.8696 (11)
K1—O2Aiii2.8932 (12)O2B—C1B1.2348 (17)
K1—C1B3.5321 (14)C1B—C2B1.5205 (19)
K1—C1Biii3.5321 (14)C2B—N1B1.477 (2)
K1—K1iv4.0464 (3)C2B—H21B0.9700
K1—K1ii4.0464 (3)C2B—H22B0.9700
O1A—C1A1.2640 (19)N1B—C3B1.474 (2)
O2A—C1A1.2379 (18)N1B—H11B0.892 (15)
O2A—K1ii2.8039 (11)N1B—H12B0.875 (15)
C1A—C2A1.515 (2)C3B—H31B0.9600
C2A—N1A1.4730 (19)C3B—H32B0.9600
C2A—H21A0.9700C3B—H33B0.9600
C2A—H22A0.9700O1W—H1W0.839 (18)
N1A—C3A1.476 (2)O1W—H2W0.835 (18)
O2Ai—K1—O2Aii91.25 (5)O1Biv—K1—K1ii109.71 (2)
O2Ai—K1—O2B87.42 (3)O1Bv—K1—K1ii67.42 (2)
O2Aii—K1—O2B142.85 (3)O2A—K1—K1ii43.86 (2)
O2Ai—K1—O2Biii142.85 (3)O2Aiii—K1—K1ii142.32 (3)
O2Aii—K1—O2Biii87.42 (3)C1B—K1—K1ii128.22 (2)
O2B—K1—O2Biii114.95 (5)C1Biii—K1—K1ii55.93 (2)
O2Ai—K1—O1Biv73.70 (3)K1iv—K1—K1ii173.22 (2)
O2Aii—K1—O1Biv74.20 (3)C1A—O2A—K1ii148.61 (10)
O2B—K1—O1Biv139.74 (3)C1A—O2A—K1115.35 (9)
O2Biii—K1—O1Biv70.25 (3)K1ii—O2A—K190.50 (3)
O2Ai—K1—O1Bv74.20 (3)O2A—C1A—O1A125.99 (16)
O2Aii—K1—O1Bv73.70 (3)O2A—C1A—C2A118.59 (13)
O2B—K1—O1Bv70.25 (3)O1A—C1A—C2A115.41 (14)
O2Biii—K1—O1Bv139.74 (3)N1A—C2A—C1A111.51 (12)
O1Biv—K1—O1Bv133.42 (4)N1A—C2A—H21A109.3
O2Ai—K1—O2A147.25 (4)C1A—C2A—H21A109.3
O2Aii—K1—O2A89.50 (3)N1A—C2A—H22A109.3
O2B—K1—O2A72.78 (3)C1A—C2A—H22A109.3
O2Biii—K1—O2A69.89 (3)H21A—C2A—H22A108.0
O1Biv—K1—O2A137.36 (3)C2A—N1A—C3A114.07 (14)
O1Bv—K1—O2A74.63 (3)C2A—N1A—H11A109.7 (12)
O2Ai—K1—O2Aiii89.50 (3)C3A—N1A—H11A108.5 (12)
O2Aii—K1—O2Aiii147.25 (4)C2A—N1A—H12A107.3 (12)
O2B—K1—O2Aiii69.89 (3)C3A—N1A—H12A110.5 (12)
O2Biii—K1—O2Aiii72.78 (3)H11A—N1A—H12A106.4 (17)
O1Biv—K1—O2Aiii74.63 (3)N1A—C3A—H31A109.5
O1Bv—K1—O2Aiii137.36 (3)N1A—C3A—H32A109.5
O2A—K1—O2Aiii106.96 (5)H31A—C3A—H32A109.5
O2Ai—K1—C1B77.29 (3)N1A—C3A—H33A109.5
O2Aii—K1—C1B155.71 (3)H31A—C3A—H33A109.5
O2B—K1—C1B18.41 (3)H32A—C3A—H33A109.5
O2Biii—K1—C1B114.66 (3)C1B—O1B—K1iv114.51 (9)
O1Biv—K1—C1B121.39 (3)C1B—O2B—K1115.41 (9)
O1Bv—K1—C1B82.54 (3)O2B—C1B—O1B126.34 (13)
O2A—K1—C1B88.97 (3)O2B—C1B—C2B118.37 (12)
O2Aiii—K1—C1B55.22 (3)O1B—C1B—C2B115.28 (12)
O2Ai—K1—C1Biii155.71 (3)O2B—C1B—K146.18 (8)
O2Aii—K1—C1Biii77.29 (3)O1B—C1B—K1100.47 (9)
O2B—K1—C1Biii114.66 (3)C2B—C1B—K1126.24 (9)
O2Biii—K1—C1Biii18.41 (3)N1B—C2B—C1B111.28 (12)
O1Biv—K1—C1Biii82.54 (3)N1B—C2B—H21B109.4
O1Bv—K1—C1Biii121.39 (3)C1B—C2B—H21B109.4
O2A—K1—C1Biii55.22 (3)N1B—C2B—H22B109.4
O2Aiii—K1—C1Biii88.97 (3)C1B—C2B—H22B109.4
C1B—K1—C1Biii120.74 (5)H21B—C2B—H22B108.0
O2Ai—K1—K1iv45.64 (2)C3B—N1B—C2B114.03 (14)
O2Aii—K1—K1iv128.06 (3)C3B—N1B—H11B105.4 (13)
O2B—K1—K1iv73.91 (2)C2B—N1B—H11B109.0 (13)
O2Biii—K1—K1iv109.92 (2)C3B—N1B—H12B109.5 (13)
O1Biv—K1—K1iv67.42 (2)C2B—N1B—H12B111.2 (14)
O1Bv—K1—K1iv109.71 (2)H11B—N1B—H12B107.4 (19)
O2A—K1—K1iv142.32 (3)N1B—C3B—H31B109.5
O2Aiii—K1—K1iv43.86 (2)N1B—C3B—H32B109.5
C1B—K1—K1iv55.93 (2)H31B—C3B—H32B109.5
C1Biii—K1—K1iv128.22 (2)N1B—C3B—H33B109.5
O2Ai—K1—K1ii128.06 (3)H31B—C3B—H33B109.5
O2Aii—K1—K1ii45.64 (2)H32B—C3B—H33B109.5
O2B—K1—K1ii109.92 (2)H1W—O1W—H2W100 (3)
O2Biii—K1—K1ii73.91 (2)
Symmetry codes: (i) x, y, z1/2; (ii) x, y, z+2; (iii) x, y, z+3/2; (iv) x, y, z+1; (v) x, y, z+1/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1A—H11A···O1Bv0.87 (1)1.92 (2)2.7538 (17)162 (2)
N1A—H12A···O1Bvi0.87 (1)1.93 (1)2.7911 (17)176 (2)
N1B—H12B···O1A0.88 (2)2.34 (2)3.0117 (19)133 (2)
N1B—H11B···O1Aiii0.89 (2)1.88 (2)2.750 (2)164 (2)
O1W—H1W···O1Avii0.84 (2)2.04 (2)2.870 (2)169 (4)
O1W—H2W···I1viii0.84 (2)2.82 (2)3.6280 (19)163 (4)
Symmetry codes: (iii) x, y, z+3/2; (v) x, y, z+1/2; (vi) x, y, z+1; (vii) x+1/2, y+1/2, z+2; (viii) x+1/2, y+1/2, z+1.

Experimental details

Crystal data
Chemical formula[K(C3H7NO2)4]I·2H2O
Mr558.42
Crystal system, space groupMonoclinic, C2/c
Temperature (K)296
a, b, c (Å)13.714 (1), 22.799 (2), 8.0786 (5)
β (°) 111.940 (4)
V3)2343.0 (3)
Z4
Radiation typeMo Kα
µ (mm1)1.60
Crystal size (mm)0.08 × 0.05 × 0.05
Data collection
DiffractometerBruker APEXII CCD area-detector
diffractometer
Absorption correctionMulti-scan
(APEX2; Bruker, 2004)
Tmin, Tmax0.883, 0.925
No. of measured, independent and
observed [I > 2σ(I)] reflections
14485, 4036, 2993
Rint0.035
(sin θ/λ)max1)0.747
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.033, 0.073, 1.01
No. of reflections4036
No. of parameters152
No. of restraints6
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.44, 0.72

Computer programs: APEX2 (Bruker, 2004), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), DIAMOND (Bergerhoff et al., 1996).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1A—H11A···O1Bi0.869 (14)1.915 (15)2.7538 (17)161.7 (17)
N1A—H12A···O1Bii0.865 (14)1.927 (14)2.7911 (17)176.2 (18)
N1B—H12B···O1A0.875 (15)2.342 (19)3.0117 (19)133.4 (18)
N1B—H11B···O1Aiii0.892 (15)1.882 (16)2.750 (2)164 (2)
O1W—H1W···O1Aiv0.839 (18)2.042 (19)2.870 (2)169 (4)
O1W—H2W···I1v0.835 (18)2.82 (2)3.6280 (19)163 (4)
Symmetry codes: (i) x, y, z+1/2; (ii) x, y, z+1; (iii) x, y, z+3/2; (iv) x+1/2, y+1/2, z+2; (v) x+1/2, y+1/2, z+1.
Salts of sarcosine I: sarcosinium–anion compounds top
CompoundSpace groupabcαβγReference
SarH.Sar.NO3P15.3206.57815.95795.44895.94493.410a
SarH.Sar.ClPca2123.5146.06115.270909090b
SarH.Sar.BrPca2123.7716.18715.405909090b
SarH.IP215.5876.4519.8659097.0490c
SarH.Sar.IP21/c9.5176.26120.30190100.93100c
SarH.Sar.BF4P2121216.0089.76420.582909090d
SarH.Sar.ClO4P2121216.0419.80120.788909090d
SarH2.SiF6P21/n5.7166.33517.4479091.9390e
SarH2.Sar.SiF6.2H2OPnma*11.70514.70911.113909090e
SarH2.Sar2.SiF6P21/c11.48510.6069.76890114.6390e
Notes: (*) phase transition at 180 K to a noncentrosymmetric structure (space group P212121). References: (a) Fleck et al. (2012a); (b) Ghazaryan et al. (2012a); (c) Ghazaryan et al. (2012b); (d) Ghazaryan et al. (2012c); (e) Fleck et al. (2012b).
Salts of sarcosine II: sarcosine–neutral salt compounds top
CrystalSpace groupabcαβγReference
Sar3.CaCl2Pnma*9.12217.40810.228909090a
Sar2.MnCl2.2H2OP14.8225.37913.78383.7680.5587.58b
Sar.MnCl2.2H2OP21/c8.3145.77718.6809095.8390c
Sar2.ZnCl2Pbca14.19110.65515.917909090d
SarH.ZnCl3**P216.6187.4999.9009092.6290e
Sar.BaCl2.4H2OP2121217.23510.66815.686909090f
Sar.CdCl2P21/n7.96013.8446.9179092.4290g
Sar2.PtBr2P21/a10.9219.5626.89090125.4690h
Sar3.BaBr2P21/c18.34510.6688.9219091.8690i
Sar4.KI.2H2OC2/c13.71422.7998.07990111.9490j
Sar3.Eu(ClO4)3.2H2OP19.14611.04214.696100.42104.56109.24k
Notes: (*) phase transition at 127 K to a noncentrosymmetric structure (space group Pn21a). (**) This species actually comprises cationic sarcosinium, but as metal cations and halogenide anions are present, it is included here. References: (a) Mishima et al. (1984) and Ashida et al. (1972); (b) Rzaczynska et al. (2002); (c) Silva et al. (2001); (d) Subha Nandhini et al. (2001); (e) Krishnakumar et al. (2001); (f) Krishnakumar & Natarajan (1995); (g) Yamada et al. (1994); (h) Sabo et al. (2005); (i) Trzebiatowska-Gusowska et al. (2009); (j) this work; (k) Gawryszewska et al. (2000).
 

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