Synthesis, characterisation, crystal structures and electrochemistry of triosmium nitrite carbonyl clusters containing ferrocenyl phosphines

The triosmium nitrite carbonyl cluster [Os-3(mu -H)(CO)(10)(mu-eta (2)-NO2)] (1) was allowed to react with 1,1'-bis(diphenylphosphino)ferrocene (dppf) and N,N-dimethyl-1-[(S)-2-(diphenylphosphino)ferrocenyl]ethylamine (ppfa) in the presence of Me3NO in CH2Cl2, and clusters [Os-3(mu -H)(CO)(8)(mu-eta (2)-NO2)(mu -dppf)] (2) and [Os-3(mu -H)(CO)(8)(mu-eta (2)-NO2)(mu -ppfa)] (3) were afforded in moderate yields. Clusters 2 and 3 were fully characterised by spectroscopic techniques and X-ray crystallography. The nitrite, hydride and the ferrocenyl phosphine ligands are all bridged across the same Os-Os edge. The amine group of the ppfa ligand shows a preference to coordinate with the Os atom with a a-bonded nitrite O atom. The redox properties of the nitrite complexes were investigated using cyclic voltammetry. (C) 2001 Elsevier Science B.V. All rights reserved.