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.