Structural characterization of the derivatives of bis{[2,6-(dimethylamino)methyl]phenyl} selenide with palladium(II) and mercury(II).

The intramolecularly coordinated homoleptic diorgano selenide bis{2,6-bis[(dimethylamino)methyl]phenyl} selenide, CHNSe or RSe, where R is 2,6-(MeNCH)CH, 14, was synthesized and its ligation reactions with Pd and Hg precursors were explored. The reaction of 14 with SOCl and KPdCl resulted in the formation of the meta C-H-activated dipalladated complex {μ-2,2'-bis[(dimethylamino)methyl]-4,4'-bis[(dimethylazaniumyl)methyl]-3,3'-selanediyldiphenyl-κC,N:C,N}bis[dichloridopalladium(II)], [PdCl(CHNSe)] or [{R(H)PdCl}Se], 15. On the other hand, when ligand 14 was reacted with HgCl, the reaction afforded a dimercurated selenolate complex, {μ-bis{2,6-bis[(dimethylamino)methyl]benzeneselanolato-κN,Se:Se,N}-μ-chlorido-bis[chloridomercury(II)], [Hg(CHNSe)Cl] or RSeHgCl, 16, where two Hg ions are bridged by selenolate and chloride ligands. In palladium complex 15, there are two molecules located on crystallographic twofold axes and within each molecule the Pd moieties are related by symmetry, but there are still two independent Pd centers. Mercury complex 16 results from the cleavage of one of the Se-C bonds to form a bifurcated SeHg moiety with the formal charge on the Se atom being -1. In addition, one of the Cl ligands bridges the two Hg atoms and there are two terminal Hg-Cl bonds. Each Hg atom is in a distorted environment which can be best described as a T-shaped base with the bridging Cl atom in an apical position, with several angles close to 90° and with one angle much larger and closer to 180°.