Spectroscopic and thermal studies of cyano bridged hetero-metallic polymeric complexes derived from ligands containing N and S donor atoms

Abstract

The new cyano bridged hetero-metallic polymeric complexes [Cu(dmtu)2Pd(CN)4]∙H2O and [Cu(H2O)2(detu)2Pd(CN)4]∙2H2O (dmtu = N,N'-dimethylthiourea, detu = N,N'-diethylthiourea; abbreviated henceforth as Cu–Pd–dmtu and Cu–Pd–detu) have been synthesized for the first time in powder form and their structures have been determined by vibrational (FT-IR and Raman) spectroscopy, thermal and elemental analysis techniques. Using vibration spectra of the complexes, it has been discussed whether the ligands are bound to metal atoms or not. According to the results obtained from the spectra of the complexes, the palladium atom is four coordinated with four cyano groups in a square planar geometry whereas the copper(II) atom of Cu–Pd–detu is six coordinated with two bridging cyano groups, two aqua and two detu ligands (four bridging cyano groups and two dmtu ligands for Cu–Pd–dmtu) in a distorted octahedral geometry. In addition, complex Cu–Pd–dmtu is similar to structure of the Hofmann type complexes and its structure consists of polymeric layers of |Cu–Pd(CN)4|∞ with the dmtu ligand bounded to the copper(II) atom. Thermal stabilities and decomposition products of the complexes were also investigated in the range of 30–1000 ºC in the static air atmosphere using TG, DTG and DTA techniques.                     KEY WORDS: Tetracyanopalladate(II), N,N'-dimethylthiourea, N,N'-diethylthiourea, Cyano-bridged complex, Vibration spectra   Bull. Chem. Soc. Ethiop. 2020, 34(2), 365-376 DOI: https://dx.doi.org/10.4314/bcse.v34i2.13