Platinum(II) and Mixed Platinum(II)/Gold(I) σ-Alkynyl Complexes. The First Anionic σ-Alkynyl Metal Polymers

Abstract

The alkynes C6Me4(C⋮CH)2-1,4, C6Me4(C⋮CH)2-1,2, and C6Me3(C⋮CH)3-1,3,5 react with cis-[PtCl2(PAr3)2] and NHEt2 and a catalytic amount of CuI to give complexes trans-[Pt(C⋮CC6Me4C⋮CH-4)2(PAr3)2] [Ar = Ph (1a), C6H4Me-4 (To) (1b)], trans-[Pt(C⋮CC6Me4C⋮CH-2)2(PAr3)2] [Ar = Ph (2a), To (2b)], and trans-[Pt{C⋮CC6Me3(C⋮CH)2-3,5}2(PAr3)2] [Ar = Ph (3a), To (3b)], respectively. The reactions of [Au(acac)PAr3] (acac = acetylacetonato) with complex 1a or 1b (2:1) or with 3b (4:1) give the neutral mixed PtIIAuI2 or PtIIAuI4 σ-alkynyl complexes trans-[Pt(C⋮CC6Me4C⋮CAuPAr3-4)2(PAr3)2] [Ar = Ph (4a), To (4b)] or trans-[Pt{C⋮CC6Me3(C⋮CAuPTo3)2-3,5}2(PTo3)2] (5b), respectively. Additionally, the replacement of the triarylphosphine ligands present in 1a, 2a, 4b, or 5b with various trialkylphosphines produces the homologous derivatives with PMe3 (1c, 2c, 4c, 5c), PEt3 (1d), or P(nBu)3 (1e), respectively. PPN[Au(acac)2] reacts with complex 1a, 1c, or 1e (1:1) to give (PPN)n[trans-Pt{(C⋮CC6Me4C⋮C-4)2Au}(PR3)2]n [R = Ph (6a), Me (6c), nBu (6e)], while its reaction with 3b (2:1) produces (PPN)2n[trans-Pt{C⋮CC6Me3(C⋮C)2-3,5Au2(PTo3)2]n (7). Complexes 6a, 6c, 6e, and 7 are the first anionic σ-alkynyl metal polymers described so far. The crystal structures of 1a·CHCl3, 2b·2CHCl3, and 4b·5CH2Cl2 have been determined. Each complex displays crystallographic inversion symmetry.