86372-96-5Relevant academic research and scientific papers
Metal cluster nitrile derivatives
Kouba,Muetterties,Thompson,Day
, p. 1065 - 1073 (1983)
Thermal and photochemical activation of Fe3(μ3-PC6H5) 2(CO)9 and Co4(μ4-PC6H5) 2(CO)10, in acetonitrile or propionitrile solutions, provided the reactive nitrile clusters: Fe3(μ3-PC6H5) 2(CO)8(NCR), Fe3(μ3-PC6H5) 2(CO)7(NCR)2, and Co4(μ4-PC6H5) 2(CO)9(NCR). Using these nitrile derivatives, a series of substitution derivatives with PF3, P(OR)3, PR3, and AsR3 ligands were prepared in high yield. Interestingly, the bis(acetonitrile) derivative of the iron cluster had both nitrile groups on the same (basal) iron atom. X-ray crystallographic studies for single crystals of Fe3(μ3-PC6H5) 2(CO)7(NCCH3)2 established that they utilize the centrosymmetric orthorhombic space group Pnma - C2h16 with a = 13.103 (2) A?, 6 = 16.972 (2) A?, c = 25.038 (5) A?, and Z = 8. The asymmetric unit contains two crystallographically independent molecules both of which possess rigorous Cs-m symmetry. The molecular structure of Fe3(μ3-PC6H5) 2(CO)7(NCCH3)2 is related to that of the parent Fe3(μ3-PC6H5) 2(CO)9 with two of the equatorial carbonyl ligands on a single basal Fe atom replaced by acetonitrile ligands. Basically, the stereochemistry of the phosphorus- and arsenic-based ligand derivatives of the iron cluster were analogous to that of the parent nitrile derivatives from which they were obtained. Conformationally, there were differences that can be rationalized in terms of steric and electronic factors and of fluxional features of the molecules. Studies of the temperature-dependent 13C spectra of the parent ion cluster and its derivatives established certain dominant mechanistic pathways for ligand site exchange in the cluster.
