Some Reactions Involving [W(N-2,6-Me2C6H3)(OCMe2CF3)2]2, a Symmetric d2/d2 Dimer that Contains No Bridging Ligands
摘要:
(me2CF3CO)2(Ar'N)W=W(NAr')(OCMe2CF3)2 (Ar' = 2,6-Me2C6H3) reacts immediately at room temperature with I equiv Of CC14 to give the sparingly soluble [W(OCMe2CF3)2C1]2(u-NAr')2, [W(NAr')(OCMe2CF3)212 forms IA adducts with simple donor ligands such as PMe3, PPhMe2, and pyridine, in which the base is likely to be coordinated to a single W center. Addition of ethylene to [W(NAr')(OCMe2CF3)212 yields I_W(NAr')(OCMe2CF3)212(U-C2H4), in which ethylene is bound essentially to one W, although it also could be argued that a 1,2-dimetallacyclobutane ring is present. Heating a toluene solution of [W(NAr')(OCMe2CF3)212(U-C2H4) produces (OCMe2CF3)2(Et)W(u-NAr')(,a-N-2-CH26-MeC6H3)W(OCMe2CF3)2, in which the proton required to form the ethyl ligand arises through CH activation in one of the methyl groups of the NAr' ligand. Treatment of [W(NAr')(OCMe2CF3)212 with 2-butyne yields [W(NAr')(OCMe2CF3)212(Y-MeCCMe). Addition of 4 equiv of CH3CN to [W(NAr')(OCMe,CF3)212 in benzene gives a mixture of two products, A and B, which have the empirical formula W(NAr')(OCMe2CF3)2(CH3CN), according to elemental analyses. Compound B was found to contain the [y-NC(Me)=C(Me)N]4- ligand in an unsymmetric dimer in which one nitrogen of the Lu-NC(Me)=C(Me)N]4- ligand is bridging while the other is bound in a terminal fashion to one metal. Compound A is proposed to be a C,-symmetric structural isomer of B in which the [N(Me)C=C(Me)N]4ligand is symmetrically bridging the two metal centers. X-ray studies are reported for [W(OCMe,,CF3)2CI12(UNAr')2, [W(NAr')(0cme2CF3)212(y-MeCCMe), and B.