Electron-sink behaviour of the carbonylnickel clusters [Ni32C6(CO)(36)](6-) and [Ni38C6(CO)(42)](6-): Synthesis and characteriztion of the anions [Ni32C6(CO)(36)](n-) (n = 5-10) and [Ni38C6(CO)(42)](n-) (n = 5-9) and crystal structure of [PPh3Me](6)[Ni32C6(CO)(36)]center dot 4 MeCN

The hexacarbide clusters [H6-nNi38C6(CO)(42)](n-) (n = 3, 4, 5, or 6) have been directly obtained from the reaction of [Ni-6(CO)(12)](2-) with C3Cl6, whereas the related anions, [H6-nNi32C6(CO)(36)](n-) (n = 5 or 6), have been obtained by degradation under carbon monoxide of [Ni38C6(CO)(42)](6-), or upon thermal treatment at ca. 110 degrees C of [Ni10C2(CO)(42)](2-) salts. The compound [PPh3Me](6)[Ni32C6(CO)(36)] . 4 MeCN is triclinic, space group P (1) over bar (No 2), with a = 15.974(3), b = 17.474(3), c = 18.200(4) Angstrom, alpha = 61.37(2), beta = 69.31(2), gamma = 72.35(2)degrees and Z = 1; final R = 0.033. The structure of [Ni32C6(CO)(36)](6-) has an idealised O-h symmetry and is based on a truncated octahedral Ni32C6 framework, with all edges spanned by bridging carbonyl groups. The six interstitial carbide atoms are lodged in square-antiprismatic cavities, The overall geometry of the Ni32C6 core is very similar to that found previously in [HNi38C6(CO)(42)](5-), and shows very close interatomic separations. Both [Ni32C6(CO)(36)](6-) and [H6-nNi38C6(CO)(42)](n-) (n = 5 or 6) display electron-sink behaviour. Thus, they have been chemically and electrochemically reduced to their corresponding [Ni32C6(CO)(36)](n-) (n = 7-10), [Ni38C6(CO)(42)](n-) (n = 7-9) and [HNi38C6(CO)(42)](n-) (n = 6-8) derivatives, and several of the involved redox changes show features of electrochemical reversibility. In contrast, both [Ni32C6(CO)(36)](6-) and [H6-nNi38C6(CO)(42)](n-) (n = 5 or 6) support only one partially reversible oxidation step. Their different behaviour upon protonation or oxidation is an indirect, but unambiguous, proof of the hydride nature of [HNi32C6(CO)(36)](5-) and [H6-nNi38C6(CO)(42)](n-) (n = 3, 4, or 5), which could not be validated by IH-NMR spectroscopy

alpha,omega-diferrocenyl cumulene molecular wires. Synthesis, spectroscopy, structure, and electrochemistry

8Cumulene sp-carbon molecular wires C2 [Fc(Ph)CC(Ph)Fc] up to C7 [Fc(Ph)CCCCCCC(Ph)Fc] endcapped by two electroactive ferrocenyl groups are presented in this report. Synthetically, ferrocenyl cumulenes can be built-up by a modular strategy using C1 synthon ferrocenyl(phenyl)ketone as starting material with various acetylenic/propargylic/homopropargylic C2−C5 reagents, taking into account and exploiting the efficient stabilization of an electron-deficient carbenium center by an adjacent ferrocenyl moiety. With increasing cumulene chain length the reactivity of cumulenes increases considerably, indicating steric protection as the main requirement for bulk stability. Even cumulenes C2, C4, and C6 are conjugated “molecular wires” effecting electronic communication between the terminal ferrocenyl substituents, whereas odd cumulenes C3, C5, and C7 are nonconjugated and electronically decoupled due to their orthogonal terminal π-systems. Electrochemically, separate redox waves can be detected up to a C6 cumulene spacer, but the electronic communication between the endcapping redox-active ferrocenyl substituents decreases with increasing cumulene length.nonenoneSkibar, W.; Kopacka, H.; Wurst, K.; Salzmann, C.; Ongania, K. H.; FABRIZI DE BIANI, Fabrizia; Zanello, Piero; Bildstein, B.Skibar, W.; Kopacka, H.; Wurst, K.; Salzmann, C.; Ongania, K. H.; FABRIZI DE BIANI, Fabrizia; Zanello, Piero; Bildstein, B