The course of oxidative addition reactions of haloalkynes and haloalkenes to dimethyl- and dialkynylaurate(I) anions [RAuR]^-

The reactions of halo-alkynes Cl-C{triple bond, long}CH, C-lC{triple bond, long}C-Cl or PhC{triple bond, long}C-I with solutions of Li⁺[MeAuMe]^- in diethylether containing Ph₃P do not give the expected oxidative addition products Me₂(RC{triple bond, long}C)Au(PPh₃) with R = H, Cl, Ph. A mixture of other complexes is obtained instead which are generated in secondary reactions involving reductive elimination of ethane and/or dialkyne. However, addition of the halo-alkene H(Cl)C{double bond, long}CCl₂ to the same substrate solution affords trans-Me₂[trans-H(Cl)C{double bond, long}C(Cl)]Au(PPh₃) in good yield. Its molecular structure with pseudo-C_s symmetry has been determined by the solution NMR spectra and a single-crystal X-ray diffraction study. The reaction of methyl iodide with solutions of Li⁺[RC{triple bond, long}CAuC{triple bond, long}CR]^- in diethylether containing PPh₃ give the quaternary salts Ph₃PMe⁺ [RC{triple bond, long}CAuC{triple bond, long}CR]^- as the main products and only small amounts of cis-Me₂(RC{triple bond, long}C)Au(PPh₃) complexes probably formed in a series of oxidative addition, reductive elimination, and substitution reactions. The structure of Ph₃PMe⁺ [PhC{triple bond, long}CAuC{triple bond, long}CPh]^- has been determined.