REACTIONS OF TRIETHYLAMMONIUM SALTS OF THE [(MU-CO)(MU-RS)FE2(CO)6]- ANION WITH ALKYLMERCURIC, ARYLMERCURIC, AND VINYLMERCURIC HALIDES - FORMAL C-ALKYLATION OF THE BRIDGING CO LIGAND

The reaction of alkyl- and arylmercuric halides with [Et3NH][(mu-CO)(mu-RS)Fe2(CO)6] gives bridging acyl complexes, (mu-R'C = O)(mu-RS)Fe2(CO)6. In the case of vinylmercuric halides the bridging acyl complexes are less stable and, in some cases (CH2 = CHHgBr, PhCH = CHHgCl, ClCH = CHHgCl), they undergo decarbonylation to give the mu-sigma, pi-vinyl complexes, (mu-CH = CH2)(mu-RS)Fe2(CO)6 in the case of CH2 = CHHgBr. Methyl substituents on the vinyl carbon atoms stabilize the mu-acyl complex. The reaction of CH3OCH2CH2HgCl with [Et3NH][mu-CO)(mu-RS)Fe2(CO)6] gave the bridging carboxylato complex (mu-CH3CO2)(mu-RS)Fe2(CO)6. Such compounds are more readily prepared by the reaction of Hg(O2CR')2 with [Et3NH][(mu-CO)(mu-RS)Fe2(CO)6]. The reaction of Hg(SCH3)2 with [Et3NH][(mu-CO)(mu-PhS)Fe2(CO)6] resulted in formation of (mu-CH3S)(mu-PhS)Fe2(CO)6. Possible mechanisms of these reactions are discussed. The structure of (mu-CH3CO2)(mu-t-BuS)Fe2(CO)6 has been determined by X-ray techniques. This compound crystallizes in the triclinic space group P1BAR with a = 13.608 (2) angstrom, b = 16.945 (1) angstrom, c = 8.599 (1) angstrom, alpha = 98.52 (1)-degrees, beta = 99.00 (1)-degrees, gamma = 113.03 (1)-degrees, V = 1753.8 angstrom 3, and Z = 4. Refinement has converged at R = 0.055 and R(w) = 0.093 on the basis of 325 parameters varied and 3310 unique observations. Both independent molecules have essentially identical geometries in which the Fe2(CO)6 moiety is bridged by a 1,1-dimethylethanethiolate and an acetate ligand.