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Inorganic Chemistry 45 (2006) 1305-1315
Chemistry and electrochemistry of the heterodinuclear complex ClPd(dppm)(2)PtCl: A M-M ' bond providing site selectivity
D. Evrard 1, Sébastien Clément 2, Dominique Lucas 1, Bernard Hanquet 1, Michael Knorr 2, Carsten Strohmann 3, Andreas Decken 4, Yves Mugnier 1, Pierre D. Harvey 5

he heterodinuclear d(9)-d(9) title compound 1, whose crystal structure has been solved, reacts with dppm [bis(diphenylphosphino)methane] in the presence of NaBF4 to generate the salt [ClPd(mu-dPPM)(2)Pt(eta(1)-dppm)][BF4] (2a), which contains a Pt-bound dangling dppm ligand. 2a has been characterized by H-1 and P-31 NMR, Fourier transform Raman [v(Pd-Pt) = 138 cm(-1)], and UV-vis spectroscopy [lambda(max)(d sigma-d sigma*) = 366 nm]. In a similar manner, [ClPd(mu-dppm)(2)Pt(eta(1)-dppm=O)][BF4] (2b), ligated with a dangling phosphine oxide, has been prepared by the addition of dppm=O. The molecular structure of 2b has been established by an X-ray diffraction study. 2a reacts with 1 equiv of NaBH4 to form the platinum hydride complex [(eta(1)-dppm)Pd(mu-dppm)(2)Pt(H)][BF4] (3). Both 2a and 3 react with an excess of NaBH4 to provide the mixed-metal d(10)-d(10) compound [Pd(mu-dppm)(3)Pt] (4). The photophysical properties of 4 were studied by UV-vis spectroscopy [lambda(max)(d sigma-d sigma*) = 460 nm] and luminescence spectroscopy (lambda(emi) = 724 nm; tau(e) = 12 +/- 1 mu s, 77 K). The protonation of 1 and 4 leads to [ClPd(mu-dppm)(2)(mu-H)PtCl](+) (5) and 3, respectively. Stoichiometric treatment of 1 with cyclohexyl or xylyl isocyanide yields [CIPd(mu-dppm)(2)Pt(CNC6H11)]Cl (6a) and [ClPd(mu-dppm)(2)Pt(CN-xylyl)]Cl (6b) ligated by terminal-bound CNR ligands. In contrast, treatment of 1 with the phosphonium salt [C&3bond; NCH2PPh3]Cl affords the structurally characterized A-frame compound [ClPd(mu-dppm)(2)(mu-C=NCH2PPh3)PtCl]Cl (6c), spanned by a bridging isocyanide ligand. The electrochemical reduction of 2a at -1.2 V vs SCE, as well as the reduction of 5 in the presence of dppm, leads to a mixture of products 3 and 4. Further reduction of 3 at -1.7 V vs SCE generates 4 quantitatively. The reoxidation at 0 V of 4 in the presence of Cl- ions produces back complex 2a. The whole mechanism of the reduction of 1 has been established.
1 :  Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB)
CNRS : UMR6302 – Université de Bourgogne
2 :  Univers, Transport, Interfaces, Nanostructures, Atmosphère et environnement, Molécules (UTINAM)
CNRS : UMR6213 – INSU – Université de Franche-Comté
3 :  Universität Würzburg
Universität Würzburg
4 :  University of New Brunswick (UNB)
University of New Brunswick
5 :  Université de Sherbrooke
Université de Sherbrooke
Chimie/Chimie de coordination

Chimie/Chimie inorganique