REVERSIBLE COORDINATION OF ALKALI-METALS TO SULFUR-BASED ORGANOMETALLIC LIGANDS [M(SC6F5)4(CP)]- (M=MO OR W, CP=ETA(5)-C5H5)

The photochemical reaction of Tl[Mo(SC6F5)2(CO)2(cp)] (cp = eta5-C5H5) with C6F5SSC6F5 in tetrahydrofuran (thf) solution affords the tetrath iolate TI[Mo(SC6F5)4(cp)]. Similarly the photochemical reaction of [W( SC6F5)(CO)3(cp)] with 4 equivalents of Tl(SC6F5) gave Tl[W(SC6F5)4(cp) ] in low yield. Reactions of [Ml3(CO)2(cp)] (M = Mo or W) and [W(SC6F5 )3(CO)(cp)] with M'(SC6F5) in thf solution gave the ionic derivatives Cs[Mo(SC6F5)4(cp)], M'[W(SC6F5)4(cp)] (M' = Cs, Rb or K) and the solva ted derivatives [M'(thf)n][W(SC6F5)4(cp)] (M' = Li, n = 4; M' = Na, n = 1). Fluorine-19 NMR studies reveal fluxional behaviour involving the C6F5 groups in all the derivatives. Dynamic Cs-133 and F-19 NMR spect ra of Cs[M(SC6F5)4(cp)] in addition show coupling between caesium and four of the ortho-fluorines of the SC6F5 groups, J(Cs-F) almost-equal- to 58 Hz, at low temperatures providing evidence for reversible co-ord ination between Cs+ and the organometallic anion.