The d3/d2alkyne complexes [MX2(η-RC
CR)Tp′]z (X = halide, z = 0 and 1+): final links in a d6–d2 redox family tree†
Abstract
The d4 halide complexes [MX(CO)(η-RCCR)Tp′] {R = Me, M = W, X = F; R = Ph, M = Mo or W, X = F or Cl; Tp′ = hydrotris(3,5-dimethylpyrazolyl)borate} undergo two-electron
CPh)Tp′]+ (R = Me, M = W, X1 = X2 = F; R = Ph, M = Mo, X1 = X2 = F or Cl; M = W, X1 = X2 = F or Cl; X1 = F, X2 = Cl). Each monocation (R = Ph) shows two reversible one-electron reductions (the second process was not detected for R = Me) corresponding to the stepwise formation of the neutral d3 and monoanionic d4 analogues, [MX1X2(η-PhC
CPh)Tp′] and [MX1X2(η-PhC
CPh)Tp′]− respectively; the potentials for the two processes can be ‘tuned’ over a range of ca. 1.0 V by varying M and X. Chemical one-electron
CPh)Tp′]+ gave [MX2(η-PhC
CPh)Tp′] (M = Mo or W, X = F or Cl). X-Ray structural studies on the redox pairs [WX2(η-PhC
CPh)Tp′]z (X = F and Cl, z = 0 and 1+) show the
CPh)Tp′] showed equivalent fluorine atoms, i.e the
CPh)Tp′]+ and [MX2(η-PhC
CPh)Tp′] completes a series in which d6 to d2alkyne complexes are linked in a redox family tree by sequential one-