Crystal structure and spectroscopic study of bis{1,3-bis[3-(5-amino-1,2,4-triazolyl)]triazenido-N′4,N2,N″4}nickel(II) tetrahydrate

The title compound [Ni(batt)2]·4H2O, in which Hbatt is 1,3-bis[3-(5-amino-1,2,4-triazolyl)]triazene, has been prepared and its crystal structure determined by X-ray diffraction methods. The compound crystallizes in the tetragonal space group I4/m (a = 10.5645(8) Å, c = 9.1336(6) Å, and Z = 2). The Ni(batt)2 molecule has local 4¯ symmetry, but it is located on a crystallographic 4/m site and is disordered over the mirror plane. The ligand batt− is tridentate with nitro-type coordination of the triazenido group and N4 coordination of the two outer triazolyl substituents. The complex has a distorted octahedral geometry with meridional configuration of the two nearly planar batt− ligands. The geometry of the tridentate cavity is examined and a comparison is made with the Ni-terpyridyl system, which shows similar coordination around the nickel center. The FTIR, micro-Raman, and UV-vis spectra are analyzed in relation with the structure.