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-BPh 4 and Ni(COD) 2 afforded the compound [(CDC)Ni(η 1 -C 8 H 13 )][BPh 4 ] (2-BPh 4 ) 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 NiCl 2 or CoCl 2 in the presence of triethylamine. For the synthesis of the iron coordination complex of CDC ligand 1, Fe 2 Mes 4 was used to produce [(CDC)Fe-Mes][BPh 4 ] (5), an intermediate-spin Fe(II) compound. Complexes 3−7 were characterized by spectroscopic methods and X-ray single-crystal diffraction analysis.

γ-Agostic interactions in (MesCCC)Fe–Mes(L) complexes

“…8 These characteristics make it a powerful reagent, and consequently, it has seen increasing application in the deprotonation and metalation of NHC-based ligands. 9 The addition of in situ generated FeMes 2 (Py) 2 (Mes = mesityl and Py = pyridine) to a mixture of the ligand salt [H 3 ( Mes CCC)]Cl 2 and 2 equiv. of LiN(SiMe 3 ) 2 in toluene resulted in the formation of the product ( Mes CCC)FeMes(Py) ( 1-Py ), which was isolated as a purple powder after workup in 94% yield (Scheme 1).…”