Chemie des η1‐Rhenium‐koordinierten Triphenylcyclopropenyl‐Liganden

Abstract

Chemistry of the η1‐Rhenium‐Coordinated Triphenylcyclopropenyl LigandThe s̀‐coordinated pentacarbonyl[η1‐1,2,3‐triphenylcyclopropenyl)rhenium complex 1 is transformed into the green tetracarbonyl(η2‐1,2,3‐triphenylpropenetriyl)rhenium compound 2 with loss of CO by heating or irradiation. In addition, tetracarbonyl(η3‐4‐oxo‐1,2,3‐triphenylcyclobutenyl)rhenium (3a) and Tricarbonyl(η5‐1,2,3,4,5,6‐hexaphenylcyclohexadienyl)‐rhenium (4) were obtained from this reaction. Treatment of 1 with trimethylamine N‐oxide leads under oxygen transfer to tetracarbonyl(η2‐3‐oxo‐1,2,3‐triphenyl‐1‐propenyl)rhenium (5) and tricarbonyl(trimethylamine)(η2‐3‐oxo‐1,2,3‐triphenyl‐1‐propenyl)rhenium (6). The NMe3 ligand in 6 can be substituted either by CO or trimethyl phosphite to yield 5 or tricarbonyl‐(trimethyl phosphite)(η2‐oxo‐1,2,3‐triphenyl‐1‐propenyl)‐rhenium (7), respectively. Complex 1 reacts with trimethyl‐phosphane or trimethyl phosphite to give tetracarbonyl(phosphorus donor)(η1‐4‐oxo‐1,2,3‐triphenyl‐2‐cyclobuten‐1‐yl)rhenium 8b [L = PMe3] or 8c [L = P(OMe)3]. The derivatives Re(CO)3L2‐η1‐C3Ph3CO [L = CO, 8a; L = PMe3, 8d; L = P(O‐Me)3 8e] were obtained by treatment of 3a with CO or two equivalents of PMe3 or P(OMe)3. The formation of 8d and 8e proceeded via the tricarbonyl(phosphorus donor)(η3‐4‐oxo‐1,2,3‐triphenylcyclobutenyl)rhenium compounds 3b and 3c. The unusual η1‐coordination of the cyclobutenone system in 8 was established by an X‐ray structure analysis of 8c. Furthermore, 4 and 5 were characterized by single‐crystal X‐ray diffraction. Reactions of 2 with alkynes led to substituted tricarbonyl(cyclopentadienyl)rhenium derivatives Re(η5‐C5Ph3RR')(CO)3 9 (R = R' = Ph, 9a; R = R' = CO2Me, 9b; R = R' = CO2Et, 9c; R = Ph, R' = H, 9d).