Gehinderte Ligandbewegungen in Übergangsmetallkomplexen, XLIII [1]: Photoreaktionen von Hexacarbonyl-μ-η5:5-fulvalen-dimolybdän und -diwolfram mit konjugierten Cyclodienen / Hindered Ligand Movements in Transition Metal Complexes, XLIII [1]: Photoreactions of Hexacarbonyl-μ-η5:5-fulvalene-dimolybdenum and -ditungsten with Conjugated Cyclodienes

Abstract

Abstract Hexacarbonyl-μ-η5:5-fulvalene-dimolybdenum (1) reacts photochemically with 1,3-cyclopentadiene (a), and 1,3-cyclohexadiene (b) to yield the corresponding tetracarbonyl-η4-1,3-cyclodiene-μ-η5:5-fulvalene-dimolybdenum complexes 4a, 4b. With a also mixed valent tricarbonyl-η5-cyclopentadienyl-μ-η5:5-fulvalene-hydrido-dimolybdenum (3) is formed. Hexacarbonyl-μ-η5:5-fulvalene-ditungsten (2) yields with a only tricarbonyl-η5-cyclopentadienyl-μ-η5:5-fulvalene-hydrido-ditungsten (5). The η4-1,3-cyclodiene ligands in 4a, 4b are u-oriented towards fulvalene. The complexes 4a, 4b show hindered inversions with energy barriers of ΔG# 273 = 59.9 ± 2 kJ/mol (4a) and ΔG# 293, = 62.7 ± 2 kJ/mol (4b).