Synthesis and Reactivity of Side-Arm Phosphine Functionalized Amidinatosilylene- and Amidinatogermylene-Supported Nickel(0) Complexes

Reactions of [PhC­(N t Bu)2]­ECl (E = Si, Ge) with Li­[(3,5-Me2-C6H3)­NP i Pr2] afforded the mixed donor ligands [PhC­(N t Bu)2]­E­[(3,5-Me2-C6H3)­NP i Pr2] (1, E = Si; 2, E = Ge) in high yields. Further reaction of these ligands 1 and 2 with the complex Ni­(cod)2 readily generated their corresponding phosphine-functionalized silylene or germylene nickel(0) complexes 3 and 4, respectively. Treatment of these complexes 3 and 4 with Ad–CP afforded 1,3-diphosphacyclobutadiene complexes 5 and 6, respectively, via selective head-to-tail cyclization of two phosphaalkynes. The reaction of 4 with 2,4,6-tri-tert-butyl-1-nitrosobenzene (Ar*NO) formed complex 7 as the first example of a mixed donor ligand stabilized Ni nitrosoarene complex.