Reactions of the dirhenium(III,III) complex cis-Re₂(μ-O₂CMe)2Cl₄(H₂O)₂ that lead to the dirhenium(III,II) complexes Re₂(μ-O₂CMe)Cl₄(PR₃)₂ and tetrarheniumcyclodiyne clusters of the type Re₄(μ-O)₄Cl₄(PR₃)₄

Abstract

The reaction of cis-Re₂(μ-O₂CMe)₂Cl₄(H₂O)₂1 with P(C₆H₄OMe-p)₃ gives the tetranuclear complex Re₄(μ-O)₄Cl₄[P(C₆H₄OMe-p)₃]₄14 along with the salt [(C₆H₄OMe-p)₃PMe]₂Re₂Cl₈15. Compound 14 is the first symmetrical, neutral, tetrarheniumcyclodiyne type cluster that contains phosphine ligands. Complexes of this same type with PPh₃ (16) and PMe₂Ph (17) have been prepared by alternative methods but have poor solubility properties. The paramagnetic complex Re₂(μ-O₂CMe)Cl₄(PPh₃)₂2, which is prepared from 1 by reaction with PPh₃, undergoes phosphine substitution reactions when treated with dichloromethane solutions of other phosphines. Simple non-redox reactions can occur upon reaction of 2 with monodentate and bridging bidentate phosphines to afford complexes of the types Re₂(μ-O₂CMe)Cl₄(PR₃)₂ [PR₃=PBz₃3, P(C₆H₄OMe-p)₃4 or PMePh₂5] and trans-Re₂(μ-O₂CMe)Cl₄(μ-PP)₂ [PP=dppm 9, Ph₂PNHPPh₂10 or (Ph₂P)₂CCH₂11]. However, reactions that lead either to reduction to dirhenium(II) complexes or Re–Re bond cleavage are encountered in the case of the reactions of 2 with PMePh₂, PMe₂Ph, PCy₃ and dppe these have led to the isolation of Re₂Cl₄(PMePh₂)₄6, Re₂Cl₄(PMe₂Ph)₄7, mer-trans-ReOCl₃(PCy₃)₂8, α-Re₂Cl₄(dppe)₂12, and trans-[ReO₂(dppe)₂]Cl 13. The structures of compounds 3, 8, 13, 14 and 15 have been determined by X-ray crystallography.