[Ni30S16(PEt3)11]: an open-shell nickel sulfide nanocluster with a metal-like core

Reaction of [Ni(1,5-cod)(2)] (30 equiv.) with PEt3 (46 equiv.) and S-8 (1.9 equiv.) in toluene, followed by heating at 115 degrees C for 16 h, results in the formation of the atomically precise nanocluster (APNC), [Ni30S16(PEt3)(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 P-31{H-1} NMR spectroscopy reveal that 1 forms via the intermediacy of smaller APNCs, including [Ni8S5(PEt3)(7)] and [Ni26S14(PEt3)(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.

Automated summary

This study successfully isolated a nickel-based atomically precise nanocluster (APNC), which is the largest open-shell nickel APNC to date. SQUID magnetometry reveals that this nanocluster possesses a manifold of closely-spaced electronic states near the HOMO-LUMO gap. In situ monitoring by ESI-MS and P-31{H-1} NMR spectroscopy shows that the nanocluster forms via the intermediacy of smaller APNCs.