SYNTHESIS AND NUCLEAR-MAGNETIC-RESONANCE STUDIES OF MOLYBDENUM AND TUNGSTEN THIOLATE COMPLEXES

Reactions of [WCl3(CO)(2)(eta(5)-C5H5)] with Tl[SC6F4H-4] and [WBr3(CO )(2)(eta(5)-C5H5)] with Tl[SR] (R = Ph or C(6)H(4)Me-4) in dichloromet hane gave tungsten(IV) compounds [W(SPh)(3)(CO)(eta(5)-C5H5)]. 0.25CH( 2)Cl(2) 1a, [W(SC(6)H(4)Me-4)(3)(CO)(eta(5)-C5H5)] 1b and [W(SC6F4H-4) (3)(CO)(eta(5)-C5H5)] 1c, respectively. Reaction of [MoCl(CO)(3)(eta(5 )-C5H5)] with 2 molar equivalents of Tl[SC6F4H-4] in diethyl ether gav e a mixture of [Mo(SC6F4H-4)(CO)(3)(eta(5)-C5H5)] 2 and Tl[Mo(SC6F4H-4 )(2)(CO)(2)(eta(5)-C5H5)] 3. The photochemical reaction of Tl[Mo(SC6F4 H-4)(2)(CO)(2)(eta(5)-C5H5)] and (SC6F4H-4), in tetrahydrofuran (thf) afforded Tl[Mo(SC6F4H-4)(4)(eta(5)-C5H5)] 4a whilst [WBr3(CO)(2)(eta(5 )-C5H5)] and 5 equivalents of Tl[SC6F4H-4] gave Tl[W(SC6F4H-4)(4)(eta( 5)-C5H5)] 4b. These were converted into [N(PPh(3))(2)][M(SC6F4H-4)(4)( eta(5)-C5H5)] (M = Mo or W) on reaction with [N(PPh(3))(2)]Cl. Reactio ns of [W(SC6F4H-4)(3)(CO)(eta(5)-C5H5)] with alkali-metal derivatives M'[SC6F4H-4] in thf afforded M'[W(SC6F4H-4)(4)(eta(5)-C5H5)] (M' = K 4 c, Rb 4d or Cs 4e). With M' = Na the tetrathiolate complex was obtaine d as a thf solvate Na[W(SC6F4H-4)(4)(eta(5)-C5H5)]. thf 5. Fluorine-19 NMR spectroscopy revealed that 1c and 3-5 undergo several dynamic pro cesses, viz. fluxional behaviour involving rotation/inversion of the S C6F4H-4 groups. The spectra of the thallium and caesium derivatives {a nd Cs-133 spectra in the case of Cs[M(SC6F4H)(4)(eta(5)-C5H5)]} in add ition show coupling between the metal M' and four of the o-fluorines o f the SC6F4H-4 groups at low temperatures providing evidence for rever sible co-ordination between the M'(+) cation and the organometallic an ion. This behaviour is solvent,dependent, occurring more readily in mo re polar solvents.