Some Reactions Involving [W(N-2,6-Me2C6H3)(OCMe2CF3)2]2, a Symmetric d/d Dimer that Contains No Bridging Ligands

(Me2CF3CO)2(Ar′N)WdW(NAr′)(OCMe2CF3)2 (Ar′ ) 2,6-Me2C6H3) reacts immediately at room temperature with 1 equiv of CCl4 to give the sparingly soluble [W(OCMe2CF3)2Cl]2(μ-NAr′)2. [W(NAr′)(OCMe2CF3)2]2 forms 1:1 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)2]2 yields [W(NAr′)(OCMe2CF3)2]2(μ-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)2]2(μ-C2H4) produces (OCMe2CF3)2(Et)W(μ-NAr′)(μ-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)2]2 with 2-butyne yields [W(NAr′)(OCMe2CF3)2]2(μ-MeCCMe). Addition of 4 equiv of CH3CN to [W(NAr′)(OCMe2CF3)2]2 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 [μ-NC(Me)dC(Me)N] ligand in an unsymmetric dimer in which one nitrogen of the [μ-NC(Me)dC(Me)N] ligand is bridging while the other is bound in a terminal fashion to one metal. Compound A is proposed to be a Cs-symmetric structural isomer of B in which the [N(Me)CdC(Me)N] ligand is symmetrically bridging the two metal centers. X-ray studies are reported for [W(OCMe2CF3)2Cl]2(μNAr′)2, [W(NAr′)(OCMe2CF3)2]2(μ-MeCCMe), and B.