Reversible co-ordination of alkali metals to sulfur-based organometallic ligands [M(SC6F5)4(cp)]–(M = Mo or W, cp =η5-C5H5)
Abstract
The photochemical reaction of Tl[Mo(SC6F5)2(CO)2(cp)](cp =η5-C5H5) with C6F5SSC6F5 in tetrahydrofuran (thf) solution affords the tetrathiolate Tl[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 [MI3(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 solvated 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 133Cs and 19F NMR spectra 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)≈ 58 Hz, at low temperatures providing evidence for reversible co-ordination between Cs+ and the organometallic anion.