Reactions of the multiply-bonded dirhenium(II) complexes Re2X4(?-dppm)2(CNR) (X = Cl or Br; R = t-Bu or xylyl) with alkynes. Structural characterization of [Re2Cl3(?-dppm)2(CN-t-Bu)(? 2-HCCH)]O3SCF3 and a comparison with the related carbonyl species(1)

Abstract

The reactions of the triply-bonded monoisocyanide complexes Re2X4(μ-dppm)2(CNR) (X = Cl or Br; dppm = Ph2PCH2PPh2; R = t-Bu or xylyl) with the alkyne ligands HCCH and n-PrCCH in the presence of TlO3SCF3 afford the complexes [Re2X3(μ-dppm)2-(CNR)(η2-HCCR)]O3SCF3 (R = H or n-C3H3). The structure of this set of complexes has been established by an X-ray structure determination on a single crystal of composition [Re2Cl3(μ-dppm)2(CN-t-Bu)(η2-HCCH)]-O3SCF3·CH3C(O)OC2H5(2a). The structure of the dirhenium(II) cation, [(t-BuNC)Cl2Re(μ-dppm)2ReCl-(μ2-HCCH)]+, involves different coordination numbers for the two Re centres and an anti arrangement of the t-BuNC and μ2-HCCH ligands. The 625-01 bond length of 2.3171(5) A accords with the retention of a 625-02 bond.