Synthesis and structural characterisation of ruthenium and osmium carbonyl clusters containing organomercurials

Abstract

Reaction of the activated cluster [Os₃(CO)₁₀(NCMe)₂] with [PhHgS(C₅H₄N)] afforded two new Os–Hg clusters cis-[Os(CO)₄{Os₃(CO)₁₀(µ-η²-SC₅H₄N)(µ-Hg)}₂] 1 and [{Os₃(CO)₁₀(µ-η²-SC₅H₄N)}₂(µ₄-Hg)] 2 in 25 and 30% yields, respectively. Cluster 1 consists of two {Os₃(CO)₁₀(µ-η²-SC₅H₄N)(µ-Hg)} subunits bonded to a central Os(CO)₄ moiety in a cis configuration. Cluster 2 comprises two skewed Os–Hg metal butterflies sharing a common wingtip Hg atom. Treatment of the same organomercurial with [Ru₃(CO)₁₀(NCMe)₂] produced the cluster compound cis-[Ru(CO)₄{Ru₃(CO)₉(µ-η³-SC₅H₄N)(µ-Hg)}₂] 3 (48%). This has a metal skeleton similar to that of 2 with the {S(C₅H₄N)} ligand moiety bonding to the ruthenium atoms in a µ-η³ fashion. Treatment of [Os₃(CO)₁₀(NCMe)₂] with [PhHg(mbt)] (Hmbt = 2-mercaptobenzothiazole) afforded [{Os₃(CO)₁₀(µ-η²-mbt)}₂(µ₄-Hg)] 4 (35%) and [Os₃(CO)₁₀(µ-η²-mbt)(µ-η²-Hg(mbt)] 5 (20%). Cluster 4 is very similar to 2, but the S(C₅H₄N) ligand is replaced by the mbt ligand, while 5 consists of an Os₃ triangle having one edge spanned by both [µ-η²-mbt] and [µ-η²-Hg(mbt)] moieties. The reaction of [Os₅C(CO)₁₅] and [Ru₃(CO)₁₂] with another class of organomercurial (diphenylthiocarbazono)phenylmercury reagent [PhHgL′] [L′ = SC(NNPh)(NNHPh)] containing a NN functionality under thermal conditions produced [{Os₅C(CO)₁₄(µ-η²-SPh)}₂(µ₄-Hg)] 6 (26%) and [{Os₅C(CO)₁₄(µ-η²-L′)}₂(µ₄-Hg)] 7 (34%) and [Ru₂(CO)₄Ph{µ-η²-C(O)Ph}(µ₂-S)(µ-η²-L′)] 8 (15%), [Ru₂(CO)₄{C(O)Ph}{µ-η²-C(O)Ph}(µ₂-S)(µ-η²-L′)] 9 (15%) and [{Ru(CO)₂Ph}₂(µ-η²-L′)] 10 (45%), respectively. In clusters 6 and 7, two {Os₅C(CO)₁₄} subunits linked by a common wingtip mercury atom, are bonded with both µ-η²-SPh in 6 and µ-η²-L′ in 7. However, in the case of complexes 8, 9 and 10, only binuclear ruthenium carbonyl complexes formed instead of the expected formation of mixed-metal clusters. Complexes 1–10 result from the cleavage of both Hg–C and Hg–S bonds in the parent organomercury species. All these complexes have been fully characterized by both spectroscopic and crystallographic techniques.