Synthesis, characterization and reactivity of the bis[2,3,7,8,12,13,17,18-octakis(ethylthio)-5,10,15,20-tetraazaporphyrinato] zirconium(IV) complex

Abstract

Treatment of H2oetpz [oetpz2- = 2,3,7,8,12,13,17,18-octakis(ethylthio)-5,10, 15,20-tetraazaporphyrinato dianion] with Zr(NEt)2 afforded the double-decker complex [Zr(oetpz)2] which has been characterized by FAB-MS, 1H and 13C NMR, electronic spectra and cyclic voltammetry. The most relevant features of UV-vis spectra and the electrochemical behaviour of [Zr(oetpz)2] are related both to the dimensions of the ionic radius of ZrIV and to the hybrid structure of the porphyrazinato ring. The reaction of the complex with oxidizing and reducing agents has been followed spectrophotometrically. It has been found that [Zr(oetpz)2] is oxidized reversibly by the nitrosonium cation NO+ to form the EPR and near-IR-active [Zr(oetpz)2]+- radical cation; in contrast, [Zr(oetpz)2] is irreversibly reduced by TDAE leading to charge-transfer green-blue compounds, [Zr (oetpz)2](TDAE)x, with 0.7⪯ x ⪯1.5. The donor capability of the peripheral sulfur atoms towards coordinatively unsaturated metallic centres has been studied in benzene. Spectroscopic changes following the treatment of [Zr(oetpz)2] with [Pd(DMSO)2Cl2] suggest that the formation of oligomers of zirconium diporphyrazine units and PdCl2 bridging fragments is a possible process