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

Resumen

The homoleptic σ-bonded tetrakis (acetylide) complexes [NBu4]2[Pt(C≡CR)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-C≡CR)2Pt(C≡CR) 2]·H2O (R = But 1 or SiMe3 2). Similar treatment of [NBu4]2[Pt(C≡CR)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-C≡CR)2Pt(μ-C≡CR) 2Pt(C6F5)2] (R = Ph 3, But 4 or SiMe3 5). 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-C≡CPh)2Pt(μ-C≡CPh) 2Pt(C6F5)2] 3. The structure of the anion has shown that one of the σ-alkynyl groups of [Pt(C≡CPh)4]2- has migrated to one of the two 'Pt(C6F5)2' fragments yielding a formally dianionic dinuclear fragment [(C6F5)2Pt(μ-C≡CPh) 2Pt(C≡CPh)2] which in its turn acts as chelate metallo ligand to the other 'Pt(C6F5)2' unit.