The crystal and molecular structures of (diethylenetriamino)copper(II) nitrate

Abstract

The blue needle-like (H 2NCH 2CH 2NHCH 2CH 2NH 2)Cu(NO 3) 2 or Cu(dien)(NO 3) 2 for short was studied by X-ray diffraction, magnetic measurements, infrared and electronic spectra, and electric conductivity. It crystallizes in the space group Pmnb with Z=4 and a=9.050(4), b=9.066(4), c=12.944(4) Å, V=1062.0 Å 3 and D x= 1.818 g cm −3. The symmetry plane contains the Cu atom, one NO 3 − group (asymmetric bidentate and bridging, CuO1=2.13 Å, CuO2=2.56 Å), the dien NH group (CuN=1.99 Å) and an intermolecular contact with the neighbouring bridging NO 3 − group (CuO2″=2.29 Å). The two terminal NH 2 groups provide almost linear (∢NCuN′=169°) out-of-plane CuN bonds (1.994 Å long). Viewed down the intermolecular contact, parallel to the symmetry plane, Cu is five-coordinate in a distorted square pyramidal (with O2″ in the apical position) arrangement or a distorted trigonal pyramid with N, N′ apical contacts. The second (uncoordinated) NO 3 − group is hydrogen bonded to dien. Magnetic and solid state spectral data are in agreement with this molecular structure. Solution spectra, however, and electric conductivity data indicate a monomeric Cu(dien)(NO 3) + unit with a four-coordinate Cu atom.