| Bis-{mu-chloro-[2-(phenylazo-kN2)-phenyl]palladium},[Pd(mu-Cl)(C6H4N=NPh)]2, is the prototype cyclo-metallated compound, and constitutes a good example to illustrate the ease of formation of some M-C alpha bonds along with their resistance to atmospheric agents. The compound was first obtained by A. C. Cope and R. W. Siekman 30 years ago, and since then many derivatives have been prepared, especially by cleaving the chlorine bridges with bases and by replacing them with a variety of ligands. In recent years, a number of closely related compounds have attracted considerable attention in the development of new organometallic liquid crystals.
A procedure for the synthesis of [Pd(mu-Cl)(C6H4N=NPh)]2 using palladium(II) chloride and azobenzene, via Li2[PdCl4], has been described recently. However, this procedure, which is followed widely to prepare a variety of cyclo-palladated compounds, requires six to eight hours when starting with PdCl2, and two to three hours if a solution of Li2[PdCl4] in methanol is available.
The procedure proposed in this article consists of reacting PdCl2 with azobenzene in dimethyl sulfoxide (DMSO) and is appropriate especially for the microscale laboratory because it offers some advantages with respect to previously reported procedures.
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