PLATINUM THIOETHER MACROCYCLIC CHEMISTRY - SYNTHESIS AND ELECTROCHEMISTRY OF [PTL][PF6]2(L = [12]-ANES(4), [14]-ANES(4) OR [16]-ANES(4)) AND [PT2([28]ANES8)][PF6]4 - CRYSTAL-STRUCTURE OF [PT([12]ANES4)][PF6]2-CENTER-DOT-MECN

A series of mono- and bi-nuclear platinum(II) complexes [PtL][PF6]2 (L = [12]-, [14]- or [161-aneS4) and [Pt2([28]aneS8)] [PF6]4 have been synthesised by reaction of the crown thioethers with platinum(II) salts. Spectroscopic and structural data confirm square-planar homoleptic thioether co-ordination at Pt(II) in each case. The complex [Pt([12]aneS4)] [PF6]2.MeCN crystallises in the orthorhombic space group Pnma with a = 16.7983(9), b = 9.3213(7), c = 14.1954(8) angstrom and Z = 4. The structure shows the cation disordered over a mirror plane, with the Pt(II) ion bound to all four thioether donors in a distorted square-planar stereochemistry, Pt-S(1) 2.266(4), Pt-S(4) 2.297(4) angstrom, and the metal ion lying 0.282 angstrom above the S4 co-ordination plane. The methylene carbons of the macrocycle are all directed to the opposite side of the S4 plane from the Pt(II) ion leaving the top face of the metal centre exposed. Electrochemical studies on [PtL]2+ show an irreversible one-electron reduction at E(pc) = -1.41, -1.45 and -1.50 V vs. ferrocene-ferrocenium for L = [12]-, [14]- and [16]-aneS4 respectively at a scan rate of 180 mV s-1. The complex [Pt2([28]aneS8)]4+ exhibits an irreversible two-electron reduction at E(pc) = -1.48 V vs. ferrocene-ferrocenium.