Phosphine-gold(I) derivatives of 1,1′-bis(alkynyl)metallocenes: Molecular structures of Fc’(Ctriple bond; length of mdashCX)2 [X = Au(PPh3), SiMe3] and Au4{(Ctriple bond; length of mdashC)2Fc’}2(PPh3)2 [Fc’ = Fe(η-C5H4-)2]

Desilylation of Fc’(Ctriple bond; length of mdashCSiMe3)2 [1; Fc’ = Fe(η-C5H4−)2] with LiMe or KOH/MeOH, followed by addition of AuCl(PR3), afforded Fc’{Ctriple bond; length of mdashCAu(PR3)}2 [R = Ph 2a, tol 2b]; the Ru analogue of 2a was also prepared. The XRD structures of 1 and 2a are reported. In the presence of CuI, a similar reaction over 2 h afforded the Au4 cluster Au4{(Ctriple bond; length of mdashC)2Fc’}2(PPh3)23. The X-ray determined structure of 3 showed a planar centrosymmetric Au4 rhomb, two opposed Au atoms being σ-bonded to the Ctriple bond; length of mdashC group, while the other two Au atoms are each η2-bonded to the Ctriple bond; length of mdashC group and a PPh3 ligand.