Synthesis, Structure, and Reactions of a Three-Coordinate Nickel-Carbene Complex, {1,2-Bis(di-<i>tert</i>-butylphosphino)ethane}NiCPh₂

The three-coordinate nickel-carbene complex (dtbpe)NiCPh2 (3) was prepared from the thermolysis of the diphenyldiazoalkane complex (dtbpe)Ni(N,N‘:η2-N2CPh2) (2) (dtbpe = 1,2-bis(di-tert-butylphosphino)ethane). Complex 3 was structurally characterized by single-crystal X-ray diffraction methods (Ni−C = 1.836(2) Å). Complex 3 reacts with 2 equiv of CO2 to afford (dtbpe)Ni{OC(O)CPh2C(O)O} (4), with diphenylketene to give (dtbpe)Ni{OC(CPh2)CPh2} (5), with excess CO to transfer the carbene fragment and generate diphenylketene and (dtbpe)Ni(CO)2 (6), with sulfur dioxide to give the metallasulfone (dtbpe)Ni{C,S:η2-S(O)2CPh2} (7), and with the Brønsted acid [HNMe2Ph][B(C6F5)4] to give the alkyl cation [(dtbpe)Ni(CHPh2)][B(C6F5)4] (8). Complexes 4, 5, and 7 have also been characterized by single-crystal X-ray diffraction methods.