Electron-Sink Behaviour of the Carbonylnickel Clusters [Ni32C6(CO)36]6– and [Ni38C6(CO)42]6–: Synthesis and Characterization 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] · 4 MeCN

Abstract

The hexacarbide clusters [H6–nNi38C6(CO)42]n− (n = 3, 4, 5, or 6) have been directly obtained from the reaction of [Ni6(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 °C of [Ni10C2(CO)16]2– salts. The compound [PPh3Me]6[Ni32C6(CO)36] ·4 MeCN is triclinic, space group P&1macr; (No 2), with a = 15.974(3), b = 17.474(3), c = 18.200(4) Å, α = 61.37(2), β = 69.31(2), γ = 72.35(2)° and Z = 1; final R = 0.033. The structure of [Ni32C6(CO)36]6– has an idealised Oh 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 1H‐NMR spectroscopy.

From Small Metal Clusters to Molecular Nanoarchitectures with a Core–Shell Structure: The Synthesis, Redox Fingerprint, Theoretical Analysis, and Solid-State Structure of [Co38As12(CO)50]4–

“…First, these redox potentials are regularly spaced, and the Δ E rev difference between two consecutive waves is constantly 280 mV. This behavior strongly resembles that observed for large nickel carbides, which also display several reversible redox waves …”

Rh–Sb Nanoclusters: Synthesis, Structure, and Electrochemical Studies of the Atomically Precise [Rh20Sb3(CO)36]3– and [Rh21Sb2(CO)38]5– Carbonyl Compounds

“…Nonetheless, it has been experimentally demonstrated that clusters may show interesting electronic properties, for instance multivalent behaviors, when they possess some ad hoc features that enhance their stability under redox conditions . The presence of heteroatoms reinforcing the metal skeleton is one of them, as in the case of the cationic [Au 24 Pd­(PPh 3 ) 10 (SC 2 H 4 Ph) 5 Cl 2 ] + heteroleptic compound or in the [H 6– n Ni 31 P 4 (CO) 39 ] n − ( n = 4 and 5) and [Ni 32 C 6 (CO) 36 ] n − ( n = 5–10) homoleptic carbonyl species. , The latter two clusters present the additional synergy arising from the shielding of the carbonyl shell and the presence of interstitial metal atoms.…”