Diphosphorus Release and Heterocumulene Oligomerisation by Nickel Complexes

The generation of diphosphorus molecules P(2) under mild conditions in solution is a useful strategy to generate diphosphines via [4+2] cycloadditions. We recently described the release of P(2) units from the nickel butterfly complex [{(IMes)Ni(CO)}(2)(μ(2),η(2):η(2)‐P(2))] (IMes=1,3‐bis(2,4,6‐trimethylphenyl)imidazolin‐2‐ylidene) upon addition of CO gas. Herein, we developed an alternative protocol for the same process using heterocumulenes. In addition to formation of P(4) (the dimerisation product of P(2)), the reactions afford nickel complexes of novel pincer‐type ligands. Aryl isothiocyanates undergo a trimerisation within the coordination sphere of nickel and afford square planar nickel complexes with S−C−S pincer‐ligand frameworks. Carbon disulfide coordinates to the [(IMes)Ni]‐fragment in an η(2)‐fashion, affording a dinuclear complex. Similar products are formed when the N‐heterocyclic carbene nickel(0) complex [(IMes)Ni(vtms)(2)] is used as a precursor (vtms=vinyltrimethylsilane).