Syntheses, crystal structures and photoluminescent properties of new homoleptic and heteroleptic zinc(II) dithiocarbamato complexes

Novel homoleptic dinuclear zinc(II) complex {[Zn2(μ-ppdtc)2(ppdtc)2] [Zn2(μ2-ppdtc)2(ppdtc)2]} (1) and three new heteroleptic complexes [Zn(ppdtc)2(bipy)] (2), [Zn(2-mppdtc)2(py)] (3) and [Zn(mpdtc)2(py)] (4) (ppdtc = phenyl piperazine dithiocarbamate, mppdtc = 2-methoxy phenyl piperazine dithiocarbamate and mpdtc = methyl piperazine dithiocarbamate) have been synthesized and characterized by various physicochemical techniques. Homoleptic complex {[Zn2(μ-ppdtc)2(ppdtc)2][Zn2(μ2-ppdtc)2(ppdtc)2]} (1) contains two different asymmetric units of [Zn2(μ-ppdtc)2(ppdtc)2] (B) and [Zn2(μ2-ppdtc)2(ppdtc)2] (A) in which each Zn(II) ion in one asymmetric dinuclear unit (B) possess tetrahedral geometry, whereas in other asymmetric dinuclear unit (A) both metal ions have five coordinate square pyramidal geometry. Complex [Zn(ppdtc)2(bipy)] (2) has an octahedral geometry, coordinated through two nitrogen atoms of the bipyridyl and four sulfur atoms of the two units of the dithiocarbamato ligands. Complexes 1 and 2 are highly fluorescent in solution and emit light at 410 and 420 nm upon excitation at 330 and 360 nm wavelengths.