Transition metal chemistry : VII. Calculation of CO stretching force constants and separation of mesomeric and inductive effects for LM(CO) 5 complexes

Abstract

Refined values of the CO stretching force constants for monosubstituted metal pentacarbonyl complexes have been obtained by rigorous direct methods of calculation. The following compounds have been treated by this method: manganese carbonyl complexes, halogenometal pentacarbonyls, some recently prepared aminocarbene complexes [RHN(Me)C]Cr(CO) 5, carbene pentacarbonyl compounds [R(OC 2H 5)C]M(CO) 5 (R = CH 3, n-C 4H 9 and M = Cr, W), phosphacarborane metal carbonyls of general formula (CH 3) 4N[B 9H 10CHE M(CO) 5] with E = P, As and M = Mo, W, Cr and arsine pentacarbonyl complexes of Cr, Mo and W. Using the more exact carbonyl stretching force constants obtainable from such calculations, relative σ and π Graham parameters for a series of LMn(CO) 5 compounds have been derived. The relative importance of σ and π bonding in some organotin derivatives is discussed.