Unusual reaction of a tungsten alkylidyne complex with water.Formation,characterization,and crystal structures of oxo trimers

The reaction of the alkyl alkylidyne W(CH2CMe3)3(CSiMe3)(1) with H2O in THF and with D2O in benzene-d6 gave two new trimeric oxo complexes:W3O3(μ=O)3(CH2CMe3)6(THF)3(2) and [W3O3(μ=O)3(CH2CMe3)6(D2O)3]·2benzene-d6(3·2benzene-d6),respectively,each containing two alkyl ligands per W atom.This is in contrast to the dimer W2O2(μ-O)(CH2CMe3)6,containing three alkyl ligands per W atom,from the previously reported reaction of the alkyl alkylidyne analog W(CH2CMe3)3-(≡CCMe3) with H2O.In the reaction of 1 with D2O in THF,an unstable intermediate W2O2(μ-O)(CD2SiMe3)2(CH2CMe3)4(4-d4) was identified.Kinetic studies of the reactions of 1 with excess H2O and D2O in THF-d8,yielding 4 and 4-d4,respectively,give a kinetic isotope effect(KIE) of 3.46(3) at 298(1) K,suggesting that the disappearance of 1 is a rate-determining step.

The reaction of the alkyl alkylidyne W（CH2CMe3）3（=CSiMe3） （1） with H20 in THF and with D20 in benzene-d6 gave two new trimeric oxo complexes： W3O3（μ=O）3（CH2CMe3）6（THF）3 （2） and [W303（μ=O）3（Ch2CMe3）6（D2O）3] 2benzene-d6 （3.2benzened6）, respectively, each containing two alkyl ligands per W atom. This is in contrast to the dimer W2o（β-O）（CH2CMe3）6, containing three alkyl ligands per W atom, from the previously reported reaction of the alkyl alkylidyne analog W（CH2CMe3）3- （=-CCMe3） with H2O. In the reaction of 1 with D20 in THF, an unstable intermediate W2O2（μ-O）（CD2SiMe3）2（CH2CMe3）4 （4-d4） was identified. Kinetic studies of the reactions of 1 with excess H2O and D2O in THF-ds, yielding 4 and 4-d4, respectively, give a kinetic isotope effect （KIE） of 3.46（3） at 298（1） K, suggesting that the disappearance of 1 is a rate-determining step.