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

The reaction of (1,4,7-triazaheptane)Cu(NO3)(2) with 2-amino-5-methyl-1,3-thiazole (amtz) yields the compound [(amtz)(dien)Cu](NO3)(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 NO3- in the asymmetric unit of the structure. Dien is tridentate with mean Cu-N=1.997(5) and 2.021(5) Angstrom in the two Cu-ions, respectively. Amtz is coordinated through its endocyclic N with Cu-N=2.063(7) and 1.945(6) Angstrom in the two ions, respectively. The CuN4 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 Angstrom) 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. (C) 1999 Elsevier Science Ltd. All rights reserved.