The hexacarbide clusters [H 6-n Ni 38 C 6 (CO) 42 ] n-(n = 3, 4, 5, found previously in [HNi 38 C 6 (CO) 42 ] 5-, and shows very close interatomic separations. Both [Ni 32 C 6 (CO) 36 ] 6-and [H 6- or 6) have been directly obtained from the reaction of [Ni 6 -(CO) 12 ] 2-with C 3 Cl 6 , whereas the related anions, [H 6-nn Ni 38 C 6 (CO) 42 ] n-(n = 5 or 6) display electron-sink behaviour. Thus, they have been chemically and electrochemically Ni 32 C 6 (CO) 36 ] n-(n = 5 or 6), have been obtained by degradation under carbon monoxide of [Ni 38 C 6 (CO) 42 ] 6-, or reduced to their corresponding [Ni 32 C 6 (CO) 36 ] n-(n = 7-10), [Ni 38 C 6 (CO) 42 ] n-(n = 7-9) and [HNi 38 C 6 (CO) 42 ] n-(n = 6-8) upon thermal treatment at ca. 110 °C of [Ni 10 C 2 (CO) 16 ] 2- salts. The compound [PPh 3 Me] 6 [Ni 32 C 6 (CO) 36 ] • 4 MeCN is derivatives, and several of the involved redox changes show features of electrochemical reversibility. In contrast, both triclinic, space group P1 ¯(No 2), with a = 15.974(3), b = 17.474(3), c = 18.200(4) A ˚, α = 61.37(2), β = 69.31(2), γ = [Ni 32 C 6 (CO) 36 ] 6-and [H 6-n Ni 38 C 6 (CO) 42 ] n-(n = 5 or 6) support only one partially reversible oxidation step. Their 72.35(2)°and Z = 1; final R = 0.033. The structure of [Ni 32 C 6 (CO) 36 ] 6-has an idealised O h symmetry and is based different behaviour upon protonation or oxidation is an indirect, but unambiguous, proof of the hydride nature of on a truncated octahedral Ni 32 C 6 framework, with all edges spanned by bridging carbonyl groups. The six interstitial [HNi 32 C 6 (CO) 36 ] 5-and [H 6-n Ni 38 C 6 (CO) 42 ] n-(n = 3, 4, or 5), which could not be validated by 1 H-NMR spectroscopy. carbide atoms are lodged in square-antiprismatic cavities. The overall geometry of the Ni 32 C 6 core is very similar to that low-lying delocalised orbital, non-bonding or slightly anti-F. Dahl as 'experimental quantomechanics'). Secondly, the