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-t hiazole (amtz) yields the compound [(amtz)(dien)Cu](NO3)(2) (dien=1,4,7-tri azaheptane). The compound has been characterised by elemental analyses, mol ar conductance and magnetic measurements, as well as by its electronic and IR spectra and X-ray diffraction. There are two crystallographically discer nible 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) Angs trom in the two Cu-ions, respectively. Amtz is coordinated through its endo cyclic N with Cu-N=2.063(7) and 1.945(6) Angstrom in the two ions, respecti vely. 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 Angs trom) contacts. Ab initio calculations on the constituent fragments [(dien) Cu](2+), [(amtz)Cu](2+) and [(dien)(amtz)Cu](2+) reproduced the average mol ecular structure parameters of the two Cu-ions in the unit cell and also he lped interpret the details of the molecular structure as well as the assign ment of the vibrational and electronic spectra. (C) 1999 Elsevier Science L td. All rights reserved.