Correlations of carbonyl stretching frequencies and 31P and 95Mo NMR parameters for FAC-[Mo(CO) 3(bipy)(PR 3)] complexes

Abstract

Several complexes of the type [Mo(CO) 3(bipy)(PR 3)] [where bipy = 2,2′-dipyridine, R = n-Bu, Me, p-C 6H 4-X; X = F, Cl, H, CH 3, OCH 3, N(CH 3) 2] were synthesized and characterized by 31P NMR, 95Mo NMR and IR spectroscopy. Relationships are drawn between the bonding nature of the ligands and the 95Mo and 31P NMR chemical shifts and the v(CO) values. Correlations of δ( 95Mo), Δδ( 31P) and v(CO) to various parameters such as ligand p K a, ligand cone angle θ, and the Kabachnik parameter (σσø) are discussed and indicate the interrelationship of the donor abilities of CO, dipy and the phosphine ligands. The importance of steric effects in influencing net metal electron density is demonstrated by the results.