Icosahedral carbonyl clusters [Ni10Sb2(μ 12-Ni)Ni(CO)32-(CO)18] n- (n = 2, 3 or 4); synthesis, spectroscopic, electrochemical and bonding analysis. Crystal structures of [Ni10Sb2(μ 12-Ni)Ni(CO)32(CO)18] n- (n = 2 or 3)

The new [Ni13Sb2(CO)24]n- (n = 2, 3 or 4) cluster anions have been isolated from the reaction of [Ni 6(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 P1̄, 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.