Coordination chemistry of arylphosphanes : binding and interligand interactions in chromium, molybdenum and tungsten carbonyl complexes

Abstract

The first part of this work consisted of a study of the coordination chemistry of aromatic (P,S) and (P,O) heterodonor phosphanes with Cr(CO)₆, Mo(CO)₆ and W(CO)₆. The (P,S) donor ligands having one or two o-thiomethoxyphenyl groups, preferred bidentate coordination mode, while the (P,O) donor ligands, having one, two or three o-methoxyphenyls, formed monodentate phosphorus bound complexes. Steric and electronic parameters affecting the coordination chemistry of the phosphanes are discussed for the monodentate complexes.

In the second part, triphenylphosphane and 2- and 4-pyridyldiphenylphosphane substituted tungsten tetracarbonyl derivatives was prepared, and attractive intramolecular interactions between the phosphane ligands were studied for both the neutral and the protonated complexes. Hydrogen bonding, π-stacking and cation-π bonding interactions were established, and observed to influence the cis/trans isomerism of the complexes. Cis/trans isomerism could be tuned by protonation, and deprotonation of the pyridyldiphenylphosphane derivatives.

All the complexes were characterised by ¹H, ¹³C-{¹H} and ³¹P-{¹H} NMR spectroscopy, X-ray crystallography, IR spectroscopy, and either elemental analysis or mass spectroscopy.