[Ni(30)S(16)(PEt(3))(11)]: an open-shell nickel sulfide nanocluster with a “metal-like” core

Reaction of [Ni(1,5-cod)(2)] (30 equiv.) with PEt(3) (46 equiv.) and S(8) (1.9 equiv.) in toluene, followed by heating at 115 °C for 16 h, results in the formation of the atomically precise nanocluster (APNC), [Ni(30)S(16)(PEt(3))(11)] (1), in 14% isolated yield. Complex 1 represents the largest open-shell Ni APNC yet isolated. In the solid state, 1 features a compact “metal-like” core indicative of a high degree of Ni–Ni bonding. Additionally, SQUID magnetometry suggests that 1 possesses a manifold of closely-spaced electronic states near the HOMO–LUMO gap. In situ monitoring by ESI-MS and (31)P{(1)H} NMR spectroscopy reveal that 1 forms via the intermediacy of smaller APNCs, including [Ni(8)S(5)(PEt(3))(7)] and [Ni(26)S(14)(PEt(3))(10)] (2). The latter APNC was also characterized by X-ray crystallography and features a nearly identical core structure to that found in 1. This work demonstrates that large APNCs with a high degree of metal–metal bonding are isolable for nickel, and not just the noble metals.