Einkernige derivate der hexacarbonylmetalle, M(CO)6 (M = Cr, Mo, W), mit dem mehrzähnigen liganden tri(1-cyclohepta-2,4,6-trienyl)phosphan, P(C7H7)3

The reactions of THF-stabilized pentacarbonylmetal fragments, [M(CO)5], with P(C7H7)3 (1) at room temperature lead to normal phosphane complexes, M(CO)5[P(C7H7)3] (M = Cr (3a), Mo (3b), W (3c)). Upon irradiation in ethereal solution, 3a-c are converted to tetracarbonylmetal derivatives, M(CO)4[P(C7H7)2(η2-C7H7)] (M = Cr (4a), Mo (4b), W (4c)) in which one of the three cyclohepta-trienyl substituents of the ligand 1 is symmetrically coordinated as a mono-olefinic side-chain. On the other hand, the reactions of donor-stabilized tricarbonylmetal fragments, [M(CO)3], with 1 give complexes of the type M(CO)3[P(C7H7)2(η4-C7H7)] (M = Cr (5a), Mo (5b), W (5c)) which contain one of the three ring substituents of 1 coordinated in the η4-norcaradiene form. In the case of 5a, subsequent irradiation in ether solution led to compound Cr(CO)2[P(C7H7)(η2-C7H7)(η4-C7H7)] (6a) where 1 is acting as an eight-electron ligand. Displacement of the acetonitrile ligands from the tropylium half-sandwich [(η7-C7H7)Mo(CH3CN)3]BF4 by P(C7H7)3 (1) gave {(η7-C7H7)Mo[P(C7H7)2(η4-C7H7)]}BF4 (7b) The new complexes were characterized by their 1H, 13C and 31P NMR spectra, and the molecular structure of 5a has been confirmed by an X-ray crystal structure analysis.