Gehinderte Ligandbewegungen in übergangsmetallkomplexen: XL. Synthese und dynamisches Verhalten von Tricarbonyl-η 4-tricyclo[6.3.0.0 2,7]undeca-3,5-dien-trimethylphosphit-metall(0)-und Dicarbonyl-η 4-tricyclo[6.3.0.0 2,7]undeca-3,5-dien-bis(trimethylphosphit)metall(0)-Komplexen der Elemente Chrom, Molybdän und Wolfram

Abstract

Tricarbonyl-η 4-tricyclo[6.3.0.0 2,7]undeca-3,5-diene-trimethylphosphite-metal(0) and cis-dicarbonyl-η 4-tricyclo[6.3.0.0 2,7]undeca-3,5-diene-bis(trimethylphosphite)metal(0) complexes of chromium ( 1, 4), molybdenum ( 2, 5) and tungsten ( 3, 6) have been prepared photochemically in high yields from the corresponding pentacarbonyl-trimethylphosphite-metal(0) or tetracarbonyl-bis (trimethylphosphite) metal(0) complexes, respectively, with tricyclo[6.3.0.0 2,7]undeca-3,5-diene. The stereochemistry of 1– 6 was determined by IR and NMR spectroscopy. In the case of tricarbonyl-η 4-tricyclo[6.3.0.0 2,7]undeca-3,5-diene-trimethylphosphite-tungsten (0) ( 3), X-ray crystal and molecular structure analysis confirm the conclusions drawn from the spectroscopic data. The distorted pseudo-octahedral complexes 1– 3 are obtained exclusively as f-isomers, and 4– 6 as af-isomers. All of them show hindered ligand movements, according to their temperature-dependent NMR spectra. For 1– 3 a carbonyl scrambling, and for 4– 6 a rotation of the diene ligand is observed.