OLIGOPHOSPHANE LIGANDS .42. CARBONYL(CYCL OPENTADIENYL)RHENIUM(I) COMPLEXES ETA(1)-C5H5RE(CO)(3)L(2) WITH FLUCTUATING SP(3)-BONDED AND RIGID SP(2)-BONDED COORDINATION OF C5H5 RINGS

Combination of the halo rhenium(I) complexes fac-Re(CO)(3)L(2)X (L/X = PMe(3)/Br (1), PPh(3)/Cl (2), PCy(3)/Br (3)), fac-Re(CO)(3)(Ph(2)PCH( 2)PPh(2))Br, 4, fac-Re(CO)(3)[R(2)P(CH2)(2)PR(2)]Br (R = Me (5), Ph (6 ), Cy (7)), fac-Re(CO)(3)[Ph(2)P(CH2)(3)PPh(2)]Cl, 8, and fac-Re(CO)(3 )[C5H8(PCy(2))(2)]Br, 9 (C5H8(PCy(2))(2) = -cyclopentan-1,2-diyl-bis(d icyclohexyl)phosphine), with Ag[O3SCF3] yielded fac-Re(CO)(3)(PR(3))(2 )OSO2CF3 (R = Me (10), Ph (11), Cy (12)), fac-Re(CO)(3)[R(2)P(CH2)(n)P R(2)]OSO2CF3 (n = 1: R = Ph (13); n = 2: R = Me (14), Ph (15), Cy (16) ; n = 3: R = Ph (17)), and fac-Re(CO)(3)[C5H8(PCy(2))(2)]OSO2CF3, 18. Triflates 10, 11, and 14-17 were converted into cyclopentadienyl deriv atives containing fluxional sp(3)-bonded C5H5 rings, fac-eta(1)-C5H5Re (CO)(3)(PMe(3))(2), 19, fac-eta(1)-C5H5Re(CO)(3)[R(2)P(CH2)(n)PR(2)] ( n = 2: R = Me (20), Ph (21), Cy (22); n = 3: R = Ph (23)), and mer,tra ns-eta(1)-C5H5Re(CO)(3)(PPh(3))(2), 24, when allowed to interact with Na[C5H5] in THF. Treatment of 18 with Na[C5H5] produced fac-eta(1)-C5H 5Re(CO)(3)[C5H8(PCy(2))(2)] as a mixture of three isomers with the rhe nium atom in the allylic position of a fluxional sp(3)-bonded ring (25 a) or in the two vinylic sites of an sp(2)-bonded rigid C5H5 system, w here the CH2 group is either alpha or beta to the metalated carbon ato m (25b, 25c). eta(5)-C5H5Re(CO)(3) and )(Ph(2)PCH(2)PPh(2)-P,P')(Ph(2) PCH(2)PPh(2)-P)](+) were identified as the only organometallic complex es resulting from interaction of triflates 12 and 13 with Na[C5H5]. Th e structure of fac-eta(1)-C5H5Re(CO)(3)[Ph(2)P(CH2)(2)PPh(2)] . 2CH(2) Cl(2) was determined by single-crystal X-ray diffractometry.