Icosahedral carbonyl clusters [Ni10Sb2(µ12-Ni){Ni(CO)3}2-(CO)18]n–(n= 2, 3 or 4); synthesis, spectroscopic, electrochemical and bonding analysis. Crystal structures of [Ni10Sb2(µ12-Ni){Ni(CO)3}2(CO)18]n–(n= 2 or 3)

Abstract

The new [Ni₁₃Sb₂(CO)₂₄]^n–(n= 2, 3 or 4) cluster anions have been isolated from the reaction of [Ni₆(CO)₁₂]^2– with SbCl₃ and have been characterized spectroscopically and electrochemically. Their structures (n= 2 or 3), elucidated by X-ray diffraction studies, consist in Ni-centred icosahedral [Ni₁₁Sb₂(CO)₁₈]^n– moieties which display an unexpected electron count and formally behave as ‘exotic’ distibine bridging ligands. The compound [N(PPh₃)₂]₂[Ni₁₃Sb₂(CO)₂₄] is triclinic, space group P, with a 13.134(3), b 13.546(2), c 15.416(2)Å, α= 109.54(1), β= 91.47(2), γ= 101.68(1)° and Z= 1; final R 0.030. Compound [NMe₃(CH₂Ph)]₄[Ni₁₃Sb₂(CO)₂₄]Cl is monoclinic, space group C2/c, with a 20.615(4), b 15.508(3), c 25.805(19)Å, β= 99.21(4)° and Z= 4; final R 0.034. A bonding analysis of icosahedral nickel carbonyl clusters centred by a transition or a main group element, as well as non-centred, has been carried out. This indicates the relevance of both the cavity occupation and the number of ligands and the associated stereogeometry in determining the number of cluster valence electrons.