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Keywords:

  • Nickel;
  • Rhodium;
  • Cluster compounds;
  • Carbonyl ligands;
  • Carbides

Abstract

The reaction of [Ni9C(CO)17]2– (1) with [Rh(cod)Cl]2 (2) results in the formation of the new hetero-bimetallic [Ni10Rh2C(CO)20]2– (3) and [Ni9Rh3C(CO)20]3– (4) clusters, which have been separated by differential solubility. Degradation of 3 under a carbon monoxide atmosphere leads to the formation of the first bis-acetylide Ni-Rh cluster, i.e. [Ni6Rh8(C2)2(CO)24]4– (5). These new compounds have been characterised by X-ray crystallography, elemental analysis, ESI-MS, IR and 13C NMR spectroscopy (on 13C-carbido-enriched samples). The 13C NMR spectra indicate that 3 exists as a mixture of two isomers in a 4:1 ratio, as also inferable from partial Ni/Rh disorder in the solid-state structure. More interestingly, coordination of Rh atoms to the interstitial carbide atom seems to be very effective in shortening its longitudinal relaxation time (T1) by ca. two orders of magnitude compared to homometallic Ni carbido clusters. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)