Metal Complexes Containing Homoleptic Diorganoselenium(II) Ligands: Synthesis, Characterization and Investigation of Optical Properties.

[( Z )-2'-{ 2 -C 6 H 5 -(4 H )-oxazol-5-one}CHC 6 H 4 ] 2 Se ( 5 , L 1 ) and [( Z )-4'-{2-C 6 H 5 -(4 H )-oxazol-5-one}CHC 6 H 4 ] 2 Se ( 6 , L 2 ) were prepared, structurally characterized and used as ligands to obtain new metal complexes of types [MX(L n )] [L 1 : M = Ag, X = OTf ( 7 ); M = Au, X = Cl ( 13 ); L 2 : M = Ag, X = OTf ( 8 ); M = Au, X = Cl ( 14 )], [(MX) 2 (L n )] [M = Ag, X = OTf, L 1 ( 9 ); L 2 ( 10 )], [ZnCl 2 (L n )] [L 1 ( 15 ); L 2 ( 16 )] and [Ag(L n )][PF 6 ] [L 1 ( 11 ); L 2 ( 12 )]. The silver complexes 7 and 8 were ionic species (1:1 electrolytes) in a MeCN solution, while in the solid state, the triflate fragments were bonded to the silver cations. Similarly, the 2:1 complexes 9 and 10 were found to behave as 1:2 electrolytes in a MeCN solution, but single-crystal X-ray diffraction demonstrated that compound 9 showed the formation of a dimer in the solid state: a tetranuclear [Ag(OTf)] 4 built through bridging triflate ligands was coordinated by two bridging organoselenium ligands through the nitrogen from the oxazolone ring and the selenium atoms in a 1κN:2κSe fashion. Supramolecular architectures supported by intermolecular C-H∙∙∙π, C-H∙∙∙O, Cl∙∙∙H and F∙∙∙H interactions were observed in compounds 4 , 5 and 9 . The compounds exhibited similar photophysical properties, with a bathochromic shift in the UV-Vis spectra caused by the position of the oxazolone ring on the phenyl ring attached to the selenium atoms.