Preparation, crystal structure and extended-Hückel molecular-orbital study of the free-radical complex [Ni2(cp)2(PhCN2S2)](cp =η-C5H5)

Abstract

Dimeric 4-phenyl-1,2,3,5-dithiadiazole (PhCN₂S₂)₂ reacted with [{Ni(cp)(CO)}₂] to give [Ni₂(cp)₂-(PhCN₂S₂)](cp =η-C₅H₅). The X-ray structure was found to be based on an Ni₂S₂ tetrahedral core with Ni–Ni 2.441(1), S ⋯ S 2.905(2) and average Ni–S 2.172(1)Å. The relatively short nickel–nickel distance, indicating formally 19-electron nickel centres, and other structural features are discussed in relation to similar dinickel complexes and by means of extended-Hückel calculations.