Some molecular rods: gold(I) complexes of 1,3-diynes. Crystal structures of Au(C≡CC≡CH)(PPh₃) and {Cu₃(µ-dppm)₃}(µ₃-I)(µ₃-C≡CC≡CAuC≡CC≡CH)

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(C≡CC≡CH)(PPh₃) 1 and {Au(C≡CC≡CH)}₂(µ-dppm) 2, respectively. Similar reaction of W(C≡CC≡CH)(CO)₃Cp with the two gold(I) complexes gave the heteronuclear diyndiyls W{C≡CC≡C[Au(PPh₃]}(CO)₃Cp (known) and {Au(C≡CC≡C[W(CO)₃Cp])}₂(µ-dppm) 3. Reaction of [ppn][Au(acac) ₂] with the appropriate diynes afforded [ppn][Au(C≡CC≡CH)₂] 4, [ppn][Au{C≡CC≡C[W(CO)₃Cp]}₂] 5, [ppn][Au{C≡CC≡C[Au(PPh₃)]}₂] 6 and [ppn][Au(C≡CC₆H₄C≡CPh)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-C≡CC≡C)(µ-dppm)}₂ 8, although this compound was not structurally characterised. On one occasion, the molecular rod {Cu₃(µ-dppm)₃}(µ₃-I)(µ₃-ŋ¹-C≡CC≡CAuC≡CC≡CH) 9 was isolated and crystallographically characterised; a rational approach to 8 from [ppn][Au(C≡CC≡CH)₂] and [{Cu₃(µ-dppm)₃}(µ₃-I)₂]I gave instead the molecular dumbbell [{Cu₃(µ₃-I)(µ-dppm)₃}₂(µ₃:µ₃-C≡CC≡CAuC≡CC≡C)]I 10.