Synthesis and Characterization of Bis(phosphine)carbodicarbene Complexes of Iron, Cobalt, and Nickel

Abstract

The synthesis and characterization of nickel, cobalt, and iron complexes of the bis(phosphine)carbodicarbene (CDC) ligand 1 is described. The square-planar complexes can be synthesized without the isolation of the deprotonated carbodicarbene ligand, and three different synthetic methods were used to make these first-row transition-metal compounds. The reaction between ligand 1-BPh4 and Ni(COD)2 afforded the compound [(CDC)Ni(η1-C8H13)][BPh4] (2-BPh4) via the insertion of COD into the Ni–H bond produced by cyclometalation. The complexes [(CDC)MCl]+ for nickel and cobalt were synthesized from the reaction of carbodicarbene ligand 1 with NiCl2 or CoCl2 in the presence of triethylamine. For the synthesis of the iron coordination complex of CDC ligand 1, Fe2Mes4 was used to produce [(CDC)Fe-Mes][BPh4] (5), an intermediate-spin Fe(II) compound. Complexes 3–7 were characterized by spectroscopic methods and X-ray single-crystal diffraction analysis.