Addition of halogens to [{Au(CH2)2PPh2}2RX] complexes. The structures of cis,trans-[{Au(CH2)2PPh2}2(CH2CF3)Br3] and trans,trans-[{Au(CH2)2PPh2}2(CHCl2)Br2Cl]

Abstract

The syntheses and X-ray structures of the dinuclear gold(III) phosphorus ylide complexes cis,trans-[{Au(CH₂)₂PPh₂}₂(CH₂CF₃)Br₃] and trans,trans-[{Au(CH₂)₂PPh₂}₂(CHCl₂)Br₂Cl] are reported. In CDCl₃, cis,trans-[{Au(CH₂)₂PPh₂}₂(CH₂CF₃)Br₃] is stable towards isomerisation after 4 d at 25°C. The cis,trans and trans,trans complexes are obtained from the oxidative addition of Br₂ to the gold(II) alkyl halide complex [{Au(CH₂)₂PPh₂}₂(CH₂CF₃)I] and the reaction of [{Au(CH₂)₂PPh₂}₂] with an excess of CHCl₂Br, respectively. Crystallographic data: cis,trans-[{Au(CH₂)₂PPh₂}₂(CH₂CF₃)Br₃]·(C₂H₅)₂O, triclinic, space group P(no. 2), a= 10.995(3), b= 13.056(3), c= 15.028(3)Åα= 93.35(2), β= 105.45(2), γ= 109.43(2)°, Z= 2, R= 0.058, R′= 0.058 for 2 782 unique reflections with |F₀|² > 3σ(|F₀|²); trans,trans-[{Au-(CH₂)₂PPh₂}₂(CHCl₂)Br₂Cl] triclinic, space group P(no. 2), a= 11.716(4), b= 14.634(4), c= 9.619(3)Å, α= 94.44(3), β= 96.26(3), γ= 83.41(3)°, Z= 2, R= 0.081, R′= 0.086 for 2 254 reflections with |F₀|² > 3σ(|F₀|²). Both complexes contain four-co-ordinate gold atoms in the +3 oxidation state with an approximate square-planar arrangement of the bridging lignds. The metal atoms are separated by non-binding distances of 3.103(1) and 3.070(9)Å respectively.