High versatility of 3,4-dimethyl-1-phenyl-phosphole and 3-methyl-1-phenyl-phosphole as ligands in the reaction with [Re2(CO)8(CH3CN)2] and [Ru3(CO)12]: X-ray structures of [Re2(CO)7(η1:η2:η2-PhPC4H2Me2)], [Re2(CO)7(η1:η2:η2-PhPC4H3Me)] and [Ru2(CO)4(PhPC4

The reaction of [Re2(CO)8(CH3CN)2] with 3,4-dimethyl-1-phenylphosphole affords three chromatographically inseparable isomers of [Re2(CO)8(PhPC4H2Me2)2] (1) identified by means of spectroscopic methods, in which the phosphole ligand acts as a tertiary phosphine bonded through the phosphorus atom, and the σ–π complex [Re2(CO)7(η1:η2:η2-PhPC4H2Me2)] (2) obtained in low yields. Thermolysis of the mixture of isomers gives (2) in good yields, while photolysis in dichloromethane at room temperature causes metal–metal bond cleavage to give [Re(CO)4(PhPC4H2Me2)Cl] (3) and [Re(CO)5Cl] (4). The reaction with 3-methyl-1-phenyl-phosphole gives only the σ–π complex [Re2(CO)7(η1:η2:η2-PhPC4H3Me)] (5). Furthermore, the main product of the reaction of [Ru3(CO)12] with 3-methyl-1-phenyl-phosphole was [Ru2(CO)4(PhPC4H3Me)2] (6) a sandwich type complex without metal–metal bond.