Complexes with the ligand 1,3-bis-(2-hydroxyphenyl)-1,3-propanedione (bhppH3) of formula M(bhppH2)2 · 2 solvent (M = Co, Ni, Zn) can be desolvated by controlled heating. These compounds contain the metal ion tetracoordinated in a square-planar fashion by the β-ketonic oxygen atoms of the ligand, and they behave as Lewis acids toward Lewis bases, like pyridine or pyridine derivatives. Two pyridine molecules complete the octahedral coordination of the metal. The pyridine coordination is weak, as evidenced by the CdN bond length (2.342 Å), compared to that of the CdO bond (mean value, 2.248 Å). In addition, the easy substitution reactions support this assumption. The new compounds are more soluble in common solvents than their parent compounds. The molecular structure of Cd(bhppH2)2 · 2 pyridine is reported, being monoclinic, space group P21/c with a = 8.868(6), b = 11. 128(3), c = 17.508(4) Å, β = 100.84(5)°, V = 1697 Å3, Z = 2, Dc, = 1.53 g cm-3 and μ = 8.79 cm-1. © 1989.
Casabó, J., Colomer, J., Llobet, A., Teixidor, F., Molins, E., & Miravitlles, C. (1989). Reactivity of metal complexes of 1,3-bis-(2-hydroxyphenyl)-1,3-propanedione toward pyridine derivatives, lewis bases. Crystal structure of bis(1,3-bis-(2- hydroxyphenyl)- 1,3-propanedione)bispyridinecadmium(II). Polyhedron, 8(23), 2743-2747. https://doi.org/10.1016/S0277-5387(00)80530-6