Some molecular rods: gold(i) complexes of 1,3-diynes. Crystal structures of Au(CCCCH)(PPh3) and {Cu3(μ-dppm)3}(μ3-I)(μ3-CCCCAuCCCCH)

Abstract

Reaction of buta-1,3-diyne with AuCl(PPh₃) and (AuCl)₂(μ-dppm) in the presence of base gave the diynyl complexes Au(CCCCH)(PPh₃) 1 and {Au(CCCCH)}₂(μ-dppm) 2, respectively. Similar reaction of W(CCCCH)(CO)₃Cp with the two gold(I) complexes gave the heteronuclear diyndiyls W{CCCC[Au(PPh₃]}(CO)₃Cp (known) and {Au(CCCC[W(CO)₃Cp])}₂(μ-dppm) 3. Reaction of [ppn][Au(acac)₂] with the appropriate diynes afforded [ppn][Au(CCCCH)₂] 4, [ppn][Au{CCCC[W(CO)₃Cp]}₂] 5, [ppn][Au{CCCC[Au(PPh₃)]}₂] 6 and [ppn][Au(CCC₆H₄CCPh)₂] 7; the latter anion was also obtained as the very unstable NMe₄ salt. The reaction between 2 and {Au(OTf)}₂(μ-dppm) likely afforded cyclo-{Au₂(μ-CCCC)(μ-dppm)}₂8, although this compound was not structurally characterised. On one occasion, the molecular rod {Cu₃(μ-dppm)₃}(μ₃-I)(μ₃-η¹-CCCCAuCCCCH) 9 was isolated and crystallographically characterised; a rational approach to 8 from [ppn][Au(CCCCH)₂] and [{Cu₃(μ-dppm)₃}(μ₃-I)₂]I gave instead the molecular dumbbell [{Cu₃(μ₃-I)(μ-dppm)₃}₂(μ₃:μ₃-CCCCAuCCCC)]I 10.