Alkynethiolato and Alkyneselenolato Ruthenium Half-Sandwich Complexes:  Synthesis, Structures, and Reactions with (η⁵-C₅H₅)₂Zr

Alkynethiolato and alkyneselenolato complexes of ruthenium, CpRu(PPh₃)₂(EC⋮CR) (Cp = η⁵-C₅H₅; E = S, R = Ph (1a), SiMe₃ (1b), ^tBu (1c); E = Se, R = Ph (2a), SiMe₃ (2b)), were synthesized by the reactions of CpRuCl(PPh₃)₂ with corresponding lithium alkynechalcogenolates in THF. An analogous reaction of Cp*RuCl(PEt₃)₂ (Cp* = η⁵-C₅Me₅) with LiSC⋮CPh produced Cp*Ru(PEt₃)₂(SC⋮CPh) (3). Complexes 1a and 2a were allowed to react in THF with “Cp₂Zr”, generated in situ from Cp₂ZrCl₂ and 2 equiv of n-BuLi, from which the S-bridged Ru−Zr dinuclear complexes CpRu(PPh₃)(C⋮CPh)(μ-S)ZrCp₂ (4a) and CpRu(PPh₃)(C⋮CPh)(μ-Se)ZrCp₂ (4b) were isolated, respectively. In these complexes, C−S(Se) bond cleavage of the alkynechalcogenolate ligands was promoted by “Cp₂Zr”, and the Zr atom was oxidized from II to IV. Treatment of 4a and 4b in THF under 1 atm CO gave rise to CpRu(CO)(C⋮CPh)(μ-E)ZrCp₂ (E = S (5a), Se (5b)), while addition of tert-butyl isocyanide to a THF solution of 4b afforded CpRu(CN^tBu)(C⋮CPh)(μ-Se)ZrCp₂ (6). The crystal structures of 1a, 1c, 2a, 2b, 3, 4a, 4b, and 5b were determined by X-ray diffraction analysis.