Mononuclear Ni(II) and dinuclear Cd(II) complexes of 4-phenyl-2H-1,2,4-triazole-3-thione and Mn(II) catalyzed disulphide bond formation in 3,3′-dithiobis (4-phenyl-1,2,4-triazole): Syntheses, structural characterization, thermal analysis and DFT calculati

• Ni(II) and Cd(II) complexes with 4-phenyl-2H-1,2,4-triazole-3-thione are reported.
• In Cd(II) complex, metal is bonded through thiolato sulfur via thiolato bridging.
• Ni(II) complex is octahedral where as cadmium complex is square pyramidal.
• The complexes are stabilized by various types of hydrogen bonding.
• Cd(II) complex possesses an intense fluorescence property.

New complexes [Ni(phtt)2(en)2] (2) and [Cd2(μ-phtt)2(phtt)2(bpy)2] (3) have been synthesized by the reactions of M(NO3)2·xH2O and 4-phenyl-2H-1,2,4-triazole-3-thione (Hphtt) in the presence of ethylenediamine/bipyridy. Mn(NO3)2·4H2O yielded a new compound 3,3′-dithiobis (4-phenyl-1,2,4-triazole) (1, dbpht) by aerial oxidation of Mn(II) which oxidized the ligand. The compounds have been characterized by various physicochemical methods. In complex 2, the nickel centre is bonded through the triazole ring nitrogen whereas in complex 3, cadmium is bonded through the thiolato sulfur forming a dimeric structure via thiolato bridging. Complexes are stabilized by various types of inter and intramolecular hydrogen bonding. The DFT results of optimized molecular geometry of all compounds are presented and compared with the experimental X-ray diffraction data. Thermogravimetric analyses of the complexes have been investigated which indicate for NiO and CdS as the final residue. Photoluminescence properties indicate that complex 2 is nonfluorescent and complex 3 has characteristic fluorescence emissions which make it a desirable target for photophysical studies and electronics applications.

Complexes [Ni(phtt)2(en)2] (2) and [Cd2(μ-phtt)2(phtt)2(bpy)2] (3) derived from 4-phenyl-2H-1,2,4-triazole-3-thione (Hphtt) have been described. Under similar condition, the ligand does not form Mn(II) complex when treated with (MnNO3)2 4H2O, but yields a new compound 3,3′-dithiobis (4-phenyl-1,2,4-triazole (1, dbpht). In complex 2, the nickel centre is covalently bonded through the deprotonated triazole ring nitrogen whereas in complex 3, cadmium is bonded through the thiolato sulfur forming a dimeric structure via thiolato bridging. Complex 2 is nonfluorescent but complex 3 shows characteristic fluorescence emissions which make it as a desirable target for photophysical studies and electronics applications.Figure optionsDownload as PowerPoint slide