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The benzodiphosphaalkene ligand and its Pd-II and Pt-II complexes : their synthesis, structure and an ESR study of their reduction products

Published inJournal of the American Chemical Society, vol. 117, no. 8, p. 2251-2258
Publication date1995
Abstract

The new diphosphaalkene 1,3-bis[2-(2,4,6-tri-tert-butylphenyl)phosphanediylmethyl]benzenLe,, h as been synthesized. Due to the presence of two P=C bonds three isomers (EE, EZ, ZZ) were observed by 31P NMR, and the crystal structures of two of them could be determined (EE, ZZ). The electrochemical behavior of L has been studied by cyclic voltametry: a quasi-reversible reduction occurs at -1.89 V/SCE and corresponds to the formation of a radical anion which has been studied by ESR at variable temperature. The experimental 31P and 'H hyperfine constants are consistent with free rotation about the P=C and Cphosphaalkene-Cbenzene bonds at room temperature and agree with ab initio predictions. One of the isomers of L forms complexes with palladium(I1) and platinum(I1) ions. The crystal structures show that L is orthometalated and acts as a terdentate ligand by coordinating the metal with each phosphorus atom. These complexes are electrochemically reduced between -0.92 and - 1.29 V, and the resulting paramagnetic species are studied by ESR in liquid and frozen solutions. This reduction process was shown to be a ligand-centered process, an appreciable part of the unpaired electron is localized on each of the phosphaalkene carbons (20%) and phosphorus atoms (5%).

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Citation (ISO format)
JOUAITI, Abdelaziz et al. The benzodiphosphaalkene ligand and its Pd-II and Pt-II complexes : their synthesis, structure and an ESR study of their reduction products. In: Journal of the American Chemical Society, 1995, vol. 117, n° 8, p. 2251–2258. doi: 10.1021/ja00113a014
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ISSN of the journal0002-7863
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