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Electrochemical reduction properties of A-frame compounds and crystal structure of Pd2(dppm)2(Me)2(Br) dimer |
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| Authors: | David Evrard Katherine Groison Yves Mugnier Pierre D Harvey |
| Institution: | a Département de Chimie, Université de Sherbrooke, 2500 Boul. Universite, Sherbrooke, Qué., Canada J1K 2R1 b Laboratoire de Synthèse et d’Electrosynthèse Organométalliques, CNRS UMR 5188, Faculté des Sciences Mirande, Université de Bourgogne, 9 avenue Alain Savary, 21100 Dijon, France c Department of Chemistry, University of New Brunswick, Fredericton, NB, Canada E3B 6E2 |
| Abstract: | Two series of A-frame complexes, Pd2(dppm)2(R)2(μ-X)]+ (R = Me and X = Cl, Br, I, H; R = Mes and X = Br, I), were investigated by cyclic voltammetry (CV). The 2-electron reduction potentials for the first series increase from I (−1.10), Br (−1.17), Cl (−1.25) to H (−1.65 V versus SCE, in CHCl3), as well as in the second series; Br (−1.35) and I (−1.38 V versus SCE, in THF). The nature of the LUMO where the electron reduction takes place is qualitatively addressed by DFT on the corresponding model complexes Pd2(H2PCH2PH2)2(R)2(μ-X)]+. The LUMO and (LUMO + 1) of the halide derivatives exhibit the presence of Pd dx2-y2 atomic orbitals interacting in an anti-bonding fashion with the n-donor orbitals of X−, P, and Me−, explaining in part the observed reactivity upon reduction. The X-ray structure of Pd2(dppm)2(Me)2(μ-Br)]+ compound exhibits the typical A-frame structure with a Pd?Pd non-bonding distance of 3.036(1) Å, and long Pd-Br bonds of 2.5623(5) and 2.5793(5) Å. |
| Keywords: | Palladium A-frame Electrochemistry X-ray crystallography Molecular orbitals |
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