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 P1 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.