Molybdenum(0) Fischer ethoxycarbene complexes : synthesis, x-ray crystal structures and DFT study

Abstract

The synthesis and structural investigations are presented of molybdenum(0) Fischer carbene complexes with general formula [L(CO)4MoC(OEt)(Ar)] with L = CO, PPh3, AsPh3 and Ar = 2-thienyl, 2-furyl, 2-(N-methyl)pyrrolyl, 2,2’-bithienyl. The X-ray crystal structures, along with NMR and IR spectroscopy, revealed a cis-orientation of the carbene and pnictogen ligands (PPh3 or AsPh3) for all the substituted complexes. A density functional theory study of all possible conformers indicated, in agreement with experimental results, that the cis-isomers (PPh3 or AsPh3 cis relative to the carbene ligand) are more stable than the corresponding trans-isomers, and that most stable conformers have the aryl group syn to the ethoxy group for Ar = 2-thienyl, 2-(N-methyl)pyrrolyl, 2,2’-bithienyl and anti to the ethoxygroup for Ar = 2-furyl.