Abstract
The title compound, [Fe(C(21)H(13)N(3)S)(CO)(PMe(3))(2)] (2), bearing a 3-(dibenzo[b,d]thio-phen-4-yl)-6-(pyridin-2-yl)pyridazine ligand was obtained by the reaction of [Fe(C(21)H(13)N(3)S)(CO)(3)] (1) with [Fe(PMe(3))(4)]. Crystal structure analysis of 2 revealed that the N,N-bidentate and three monodentate ligands form a five-coordinate square-pyramidal geometry around Fe, which differs from the trigonal-bipyramidal geometry observed in 1. The steric and electronic factors were investigated by combining crystal structure and density functional theory (DFT) calculations. Compared with CO, the better σ donor properties of PMe(3) induce the square-pyramidal geometry of 2, and a significant π-back-bonding inter-action was confirmed between Fe and the pyridazine moiety.