Gehinderte Ligandenbewegungen in Übergangsmetallkomplexen, X1 Carbonyl-donorligand-η-1.3.5-cycloheptatrien-chrom(0)-Komplexe / Hindered Ligand Motions in Transition Metal Complexes, X1 Carbonyl-donorligand-η-1,3,5-cycloheptatriene-chromium(0) Complexes

Abstract

Tricarbonyl-η-1,3,5-cycloheptatriene-chromium(0) (1) reacts photochemically with trimethyl-phosphine, -arsine, or -phosphite respectively to form the complexes CrC7H8(CO)2L (2-4) (L = P(CH3)3, As(CH3)3, P(OCH3)3) and CrC7H8(CO)[P(OCH3)3]2 (5) The 1H, 13C and 31P NMR spectra of these complexes are temperature dependent as a result of a hindered motion of the C7H8 ligand. By this motion the dissimilar stereoisomers of the complexes, which are present, partly in very different concentrations, are interconverted. The energy barriers of the isomerisations were determined.