Di- and tri-nuclear platinum complexes with double acetylide bridges. Molecular structure of [NBu4]2[Pt3(C6F5)4(µ-CCPh)4]·4thf (thf = tetrahydrofuran)

Abstract

The homoleptic σ-bonded tetrakis (acetylide) complexes [NBu4]2[Pt(CCR)4]·2H2O (R = But or SiMe3) reacted with cis-[Pt(C6F5)2(thf)2](thf = tetrahydrofuran) in a 1 : 1 molar ratio to give the dinuclear derivatives [NBu4]2[(C6F5)2Pt(µ-CCR)2Pt(CCR)2]·H2O (R = But1 or SiMe32). Similar treatment of [NBu4]2[Pt(CCR)4]·nH2O (R = Ph, n= 0; R = But or SiMe3, n= 2) with cis-[Pt(C6F5)2(thf)2] in a 1 : 2 molar ratio afforded the trinuclear bridging tetraacetylide complexes [NBu4]2[(C6F5)2Pt(µ-CCR)2Pt(µ-CCR)2Pt(C6F5)2](R = Ph 3, But4 or SiMe35). Complexes 4 and 5 are also obtained from the reaction of 1 and 2 with cis-[Pt(C6F5)2(thf)2](1 : 1 molar ratio). An unambiguous structural assignment for the trinuclear bridging tetrakis (acetylide) complexes 3–5 has been established by an X-ray diffraction study on [NBu4]2[(C6F5)2Pt(µ-CCPh)2Pt(µ-CCPh)2Pt(C6F5)2]3. The structure of the anion has shown that one of the σ-alkynyl groups of [Pt(CCPh)4]2– has migrated to one of the two ‘Pt(C6F5)2’ fragments yielding a formally dianionic dinuclear fragment [(C6F5)2Pt(µ-CCPh)2Pt(CCPh)2] which in its turn acts as chelate metallo ligand to the other ‘Pt(C6F5)2’ unit.