Synthesis, characterization and luminescent properties of polymeric cadmium(II) bridged-thiocyanato and mononuclear thiocyanato-zinc(II) complexes of pyridine-N-oxide deratives

The synthesis and structural characterization of six new d10 Cd(II) and Zn(II) thiocyanato complexes with pyridine-N-oxide compounds: the polymeric catena-[Cd(μ2-2-picoline-N-oxide)(μN,S-NCS)2] (1), catena-[Cd(μ2-3-picoline-N-oxide)(μN,S-NCS)2] (2), catena-[Cd(4-nitropyridine-N-oxide)2(μN,S-NCS)2] (3), the dinuclear [Cd(4-cyanopyridine-N-oxide)2(μN,S-NCS)(NCS)(H2O)]2 (4) and the mononuclear complexes [Zn(2-picoline-N-oxide)2(NCS)2(H2O)] (5) and [Zn(4-cyanopyridine-N-oxide)2(NCS)2(H2O)] (6) are reported. Single crystal X-ray crystallography revealed the 2D polymeric nature in complexes 1 and 2, the 1D chain in 3 and the dimeric structure in complex 4 with the doubly-bridged Cd(μN,S-NCS)2Cd moiety. Five-coordinate monomeric Zn(II) complexes were obtained in 5 and 6, where the thiocyanto ligands are acting as monodentate N-bonded. The emission spectral properties of the six complexes were investigated. Very strong enhancing fluorescence intensity was observed in complex 3.