MONONUCLEAR DERIVATIVES OF HEXACARBONYL M ETALLATES, M(CO)(6) (M=CR, MO, W), WITH THE MULTIDENTATE LIGAND TRI-(1-CYCLOHEPTA-2,4,6-TRIENYL)PHOSPHANE, 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 c omplexes, M(CO)(5)[P(C7H7)(3)] (M = Cr (3a), Mo (3b), W (3c)). Upon ir radiation in ethereal solution, 3a-c are converted to tetracarbonylmet al derivatives, M(CO)(4)[P(C7H7)(2)(eta(2)-C7H7)] (M = Cr (4a), Mo (4b ), W (4c)) in which one of the three cycloheptatrienyl substituents of the ligand 1 is symmetrically coordinated as a mono-olefinic side-cha in. On the other hand, the reactions of donor-stabilized tricarbonylme tal fragments, [M(CO)(3)], with 1 give complexes of the type M(CO)(3)[ P(C7H7)(2)(eta(4)-C7H7)] (M = Cr (5a), Mo (5b), W (5c)) which contain one of the three ring substituents of 1 coordinated in the eta(4)-norc aradiene form. In the case of 5a, subsequent irradiation in ether solu tion led to compound Cr(CO)(2)[P(C7H7)(eta(2)-C7H7)(eta(4)-C7H7)] (6a) where 1 is acting as an eight-electron ligand. Displacement of the ac etonitrile ligands from the tropylium half-sandwich [(eta(7)-C7H7)MO(C H3CN)(3)]BF4 by P(C7H7)(3) (1) gave {(eta(7)-C7H7)Mo[P(C7H7)(2)(eta(4) -C7H7)]}BF4 (7b). The new complexes were characterized by their H-1, C -13 and P-31 NMR spectra, and the molecular structure of 5a has been c onfirmed by an X-ray crystal structure analysis.