Crystal and molecular structures of [(2-amino-5-methyl-1,3-thiazole)(1,4,7-triazaheptane)copper(II)] dinitrate

Abstract

The reaction of (1,4,7-triazaheptane)Cu(NO 3) 2 with 2-amino-5-methyl-1,3-thiazole (amtz) yields the compound [(amtz)(dien)Cu](NO 3) 2 (dien=1,4,7-triazaheptane). The compound has been characterised by elemental analyses, molar conductance and magnetic measurements, as well as by its electronic and IR spectra and X-ray diffraction. There are two crystallographically discernible cations [(amtz)(dien)Cu] 2+ and four NO 3 − in the asymmetric unit of the structure. Dien is tridentate with mean Cu–N=1.997(5) and 2.021(5) Å in the two Cu-ions, respectively. Amtz is coordinated through its endocyclic N with Cu–N=2.063(7) and 1.945(6) Å in the two ions, respectively. The CuN 4 unit is approximately square planar and almost perpendicular to the tz plane. Both the cations make two long (trans-Cu…O=2.6–2.7 Å) contacts. Ab initio calculations on the constituent fragments [(dien)Cu] 2+, [(amtz)Cu] 2+ and [(dien)(amtz)Cu] 2+ reproduced the average molecular structure parameters of the two Cu-ions in the unit cell and also helped interpret the details of the molecular structure as well as the assignment of the vibrational and electronic spectra.