Homoleptic Diphosphacyclobutadiene Complexes [M(η4-P2C2R2)2]x (M=Fe, Co; x=0, 1)

Authors

  • Dr. Robert Wolf,

    Corresponding author
    1. Institute of Inorganic and Analytical Chemistry, University of Münster, Corrensstrasse 30, 48149 Münster (Germany), Fax: (+49) 251-833-6610
    2. Department of Organic and Inorganic Chemistry, Faculty of Sciences, VU University Amsterdam, De Boelelaan 1083, 1081 HV, Amsterdam (The Netherlands), Fax: (+31) 20-5987488
    • Institute of Inorganic and Analytical Chemistry, University of Münster, Corrensstrasse 30, 48149 Münster (Germany), Fax: (+49) 251-833-6610
    Search for more papers by this author
  • Dr. Andreas W. Ehlers,

    1. Department of Organic and Inorganic Chemistry, Faculty of Sciences, VU University Amsterdam, De Boelelaan 1083, 1081 HV, Amsterdam (The Netherlands), Fax: (+31) 20-5987488
    Search for more papers by this author
  • Dr. Marat M. Khusniyarov,

    1. Department of Chemistry and Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstrasse 1, 91058 Erlangen (Germany)
    Search for more papers by this author
  • Prof. Dr. František Hartl,

    1. Homogeneous and Supramolecular Catalysis, Van't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam (The Netherlands)
    2. Department of Chemistry, University of Reading, Whiteknights, Reading, RG6 6AD (UK)
    Search for more papers by this author
  • Dr. Bas de Bruin,

    1. Homogeneous and Supramolecular Catalysis, Van't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam (The Netherlands)
    Search for more papers by this author
  • Prof. Dr. Gary J. Long,

    1. Department of Chemistry, Missouri University of Science and Technology, University of Missouri, Rolla, MO 65409-0010 (USA)
    Search for more papers by this author
  • Prof. Dr. Fernande Grandjean,

    1. Department of Physics, B5, University of Liège, 4000 Sart-Tilman (Belgium)
    Search for more papers by this author
  • Dr. Falko M. Schappacher,

    1. Institute of Inorganic and Analytical Chemistry, University of Münster, Corrensstrasse 30, 48149 Münster (Germany), Fax: (+49) 251-833-6610
    Search for more papers by this author
  • Prof. Dr. Rainer Pöttgen,

    1. Institute of Inorganic and Analytical Chemistry, University of Münster, Corrensstrasse 30, 48149 Münster (Germany), Fax: (+49) 251-833-6610
    Search for more papers by this author
  • Dr. J. Chris Slootweg,

    1. Department of Organic and Inorganic Chemistry, Faculty of Sciences, VU University Amsterdam, De Boelelaan 1083, 1081 HV, Amsterdam (The Netherlands), Fax: (+31) 20-5987488
    Search for more papers by this author
  • Dr. Martin Lutz,

    1. Bijvoet Center for Biomolecular Research, Crystal and Structural Chemistry, Utrecht University, Padualaan 8, 3584 CH, Utrecht (The Netherlands)
    Search for more papers by this author
  • Prof. Dr. Anthony L. Spek,

    1. Bijvoet Center for Biomolecular Research, Crystal and Structural Chemistry, Utrecht University, Padualaan 8, 3584 CH, Utrecht (The Netherlands)
    Search for more papers by this author
  • Prof. Dr. Koop Lammertsma

    Corresponding author
    1. Department of Organic and Inorganic Chemistry, Faculty of Sciences, VU University Amsterdam, De Boelelaan 1083, 1081 HV, Amsterdam (The Netherlands), Fax: (+31) 20-5987488
    • Department of Organic and Inorganic Chemistry, Faculty of Sciences, VU University Amsterdam, De Boelelaan 1083, 1081 HV, Amsterdam (The Netherlands), Fax: (+31) 20-5987488
    Search for more papers by this author

Abstract

The preparation and comprehensive characterization of a series of homoleptic sandwich complexes containing diphosphacyclobutadiene ligands are reported. Compounds [K([18]crown-6)(thf)2][Fe(η4-P2C2tBu2)2] (K1), [K([18]crown-6)(thf)2][Co(η4-P2C2tBu2)2] (K2), and [K([18]crown-6)(thf)2][Co(η4-P2C2Ad2)2] (K3, Ad=adamantyl) were obtained from reactions of [K([18]crown-6)(thf)2][M(η4-C14H10)2] (M=Fe, Co) with tBuC[TRIPLE BOND]P (1, 2), or with AdC[TRIPLE BOND]P (3). Neutral sandwiches [M(η4-P2C2tBu2)2] (4: M=Fe 5: M=Co) were obtained by oxidizing 1 and 2 with [Cp2Fe]PF6. Cyclic voltammetry and spectro-electrochemistry indicate that the two [M(η4-P2C2tBu2)2]/[M(η4-P2C2tBu2)2] moieties can be reversibly interconverted by one electron oxidation and reduction, respectively. Complexes 15 were characterized by multinuclear NMR, EPR (1 and 5), UV/Vis, and Mössbauer spectroscopies (1 and 4), mass spectrometry (4 and 5), and microanalysis (13). The molecular structures of 15 were determined by using X-ray crystallography. Essentially D2d-symmetric structures were found for all five complexes, which show the two 1,3-diphosphacyclobutadiene rings in a staggered orientation. Density functional theory calculations revealed the importance of covalent metal–ligand π bonding in 15. Possible oxidation state assignments for the metal ions are discussed.

Ancillary