Copper(I), silver(I), and gold(I) complexes with nido-pentaborane anions

Abstract

The 16-electron copper(I) complexes [Cu(µ-1-BrB₅H₇)(PPh₃)₂] and [Cu(µ-B₅H₈)(dppe)](dppe = Ph₂PCH_2- CH₂PPh₂) have been prepared and shown to be similar to [Cu(µ-B₅H₈)(PPh₃)₂] whose structure has recently been established by single-crystal X-ray analysis. The corresponding silver(I) complex [Ag(µ-B₅H₈)(PPh₃)₂] has been prepared as a colourless photosensitive solid which decomposes fairly rapidly in solution even in the absence of light; however, ¹¹B n.m.r. spectroscopy shows that the complex is non-fluxional in dichloromethane. A gold complex, possibly [Au(B₅H₈)(PPh₃)], is formed at –78 °C but is too unstable to isolate.