Thermal, spectroscopic, and structural properties of aqua(malonato-O,O′)(1,10-phenanthroline)copper(II) hydrate (1/1.5)

Abstract

Aqua(malonato-O,O′)(1,10-phenanthroline)copper(II) crystallizes in the triclinic space group P with a= 11.560(4), b= 11.734(5), c= 12.491(2)Å, α= 92.12(2), β= 105.50(2), γ= 109.28(3)°, and Z= 2. The structure consists of two independent monomeric [Cu(phen)(mal)(H₂O)] molecules with three water molecules in the lattice. The CuN₂O₂O′ chromophore is distorted square pyramidal with a symmetrically co-ordinated phen molecule (mean Cu–N 2.018 Å) and a symmetrically co-ordinated malonate ion (mean Cu–O 1.914 Å) in the plane of the square pyramid and a water molecule at 2.266 Å. The relatively short Cu–O distance has been attributed to phen being a stronger π-acid. The compound and its several related complexes show complete loss of water molecules at ca. 100 °C followed by stepwise degradation of the organic ligands. Thermogravimetric analysis and visible reflectance spectral results are discussed in relation to the known structure of the title compound.