Nickel thioether chemistry: a re-examination of the electrochemistry of [Ni([9]aneS3)2]2+. The single-crystal X-ray structure of a nickel(III) thioether complex, [NiIII([9]aneS3)2][H5O2]3[ClO4]6([9]aneS3= 1,4,7-trithiacyclononane)

Publisher Website
Google Scholar
Abstract
Cyclic voltammetry of [Ni([9]aneS3)2][PF6]2([9]aneS3= 1,4,7-trithiacyclononane) in MeCN (0.1 mol dm–3 NBu4PF6) at 293 K at platinum electrodes shows the previously reported chemically reversible oxidation at E½=+0.98 V, ΔEp= 82 mV and a quasi-reversible reduction at E½=–1.11 V vs. ferrocene–ferrocenium, ΔEp= 90 mV. These redox processes have been investigated spectroelectrochemically using ESR and electronic spectroscopy which indicate [Ni([9]aneS3)2]3+ to be a genuine d7 nickel(III) complex. The [Ni([9]aneS3)2]3+ cation can be generated quantitatively and stabilised for extended periods by dissolution of [Ni([9]aneS3)2]2+ in HClO4 solution. The complex [NiIII([9]aneS3)2][H5O2]3[ClO4]6 crystallises in the rhombohedral space group Rc. The single-crystal X-ray structure confirms octahedral homoleptic thioether co-ordination with Ni–S bond lengths of 2.3129(25)Å. These Ni–S distances are significantly shorter than in the nickel(II) analogue [Ni([9]aneS3)2]2+ and confirm the formulation of a mononuclear nickel(III)–thioether complex cation. Cyclic voltammetry of [Zn([9]aneS3)2][PF6]2 reveals one irreversible oxidation and one irreversible reduction at Epa=+1.30 and Epc=–1.77 V respectively at a scan rate of 400 mV s–1. Significantly, the redox potential for the oxidation of the zinc(II) species is more anodic than for the nickel(II) analogue.

This publication has 47 references indexed in Scilit: