Two-, three- and four-co-ordinate gold(I) complexes of 1,2-bis(diphenylphosphino)-1,2-dicarba-closo-dodecaborane

Abstract

Treatment of (PPh₂)₂C₂B₁₀H₁₀ with gold(I)complexes [AuX(tht)](tht = tetrahydrothiophene, X = Cl or C₆F₅) gives two-co-ordinate [(AuX)₂{(PPh₂)₂C₂B₁₀H₁₀}] or three-co-ordinate [AuX{(PPh₂)₂C₂B₁₀H₁₀}] species. Other three-co-ordinate compounds have been prepared starting from [Au(tht)L]ClO₄(L = tht, PR₃, or ylide) by reaction with the diphosphine. Substitution of tht in [Au(tht){(PPh₂)₂C₂B₁₀H₁₀}]ClO₄ affords [AuL{(PPh₂)₂C₂B₁₀H₁₀}]ClO₄ where, depending on the ligand, three-co-ordinate (L = SPPh₃, AsPh₃, or C₅H₄NSH) or four-co-ordinate complexes [L = 1,10-phenanthroline or (PPh₂)₂C₂B₁₀H₁₀] can be synthesised. The bis-chelated gold(I) phosphine complex [Au{(PPh₂)₂C₂B₁₀H₁₀}₂]ClO₄ has been isolated. The crystal structure of [Au(PPh₃){(PPh₂)₂C₂B₁₀H₁₀}]ClO₄·CH₂Cl₂ has been established by X-ray crystallography: monoclinic space group P2₁/n, a= 11.760(3), b= 20.290(5), c= 21.375(6)Å, β= 105.10(2)°, Z= 4, R= 0.032. The gold atom exhibits trigonal-planar co-ordination, by three phosphorus atoms with Au–P 2.318(1), 2.405(1) and 2.417(1)Å(the longer bonds are to the diphosphine).