Synthesis, molecular structures, fluxional properties and catalytic activity of a series of alkyne complexes of molybdenum(II) and tungsten(II) containing phosphite donor ligands

摘要

Treatment of [MoI_2(CO)(NCMe)(#eta#~2-R'C_2R")_2] with one equivalent of P(OPh)_3 in diethyl ether at room temperature afforded the crystallographically characterised complexes [MoI_2(CO)(NCMe){P(OPh)_3}(#eta#~2-R'C_2R")] (R' = R" = Me or Ph; R' = Me, R" = Ah) which have five different ligand attached in a pseudo-octahedral arrangement. Reaction of [MI_2(CO)(NCMe)(#eta#~2-R'C_2R")_2] with two equivalents of P(OR)_3 in diethyl ether at room temperature gave high yields of the bis(phosphite) complexes [MI_2(CO){P(OR)_3}_2(#eta#~2-R'C_2R")] {R = Ph, R' = Me, R" = Ph (M = Mo only); M = Mo or W, R = Me, R' = R" = Me or Ph (M = Mo only), R' = Me, R" = Ph (M = W only); R' = Me, R" = Ph (M = W only); R = Et, R' = R" = Me or Ph (M = Mo only), R' = Me, R" = Ph (M = W only); R = ~iPr, R' = R" = Me or Ph (M = Mo only), R' = Me, R" + Ph (M = W only); R = ~nBu, R' = R" = Me, Ph (M = Mo only for both complexes)}. The crystal structures for [MI_2(CO){P(OR)_3}_2(#eta#~2-R'C_2R")] {M = Mo, R = Me, ~iPr; R' = R" = Me; M = Mo, R = Ph, R' = Me, R" = Ph; M = W, R = Et or ~iPr; R' = R" = Me; R' = Me, R" = Ph (R = ~iPr only)} have been determined, and all have trans-phosphite ligands except for M = Mo, R = R' = R" = Me which has cis-phosphite groups. The trimerisation of MeC_2Ph by the reaction of [MoI_2(CO)(NCMe)(#eta#~2-MeC_2Ph)_2] with P(O~iPr)_3 to give the crystallographically characterised trimer of MeC_2Ph, 1, 2, 4-trimethyl-3, 5, 6-triphenylbenzene, is also described. The fluxional properties of selected complexes have been investigated.