Complexes of beryllium(II) with substituted malonates.: Crystal structure of K2[Be(C4H6(COO)2)2]•2H2O

The complexes formed by beryllium(II) with the dicarboxylate ligands methylmalonate, phenylmalonate, dimethylmalonate and cyclobutane-1,1-dicarboxylate have been investigated in aqueous solution through potentiometric and Be-9 NMR spectroscopic measurements. The species BeL, [BeL2](2-), [Be-3(OH)(3)L-3](3-) and [Be-3(OH)(3)L](+) have been identified and their formation constants have been determined at 25 degrees C in 0.5 mol dm(-3) NaClO4. The stability of the complexes is discussed in relation to the bite size of the chelating ligands; the formation constants of the beryllium(II) phthalate complexes have also been determined for this purpose. A crystalline salt of formula K-2[Be(C4H6(COO)(2))(2)]. 2H(2)O has been isolated and its structure has been determined by an X-ray structure analysis. The metal atom is tetrahedrally coordinated by four oxygen atoms of the dicarboxylate ligands, the coordination polyhedron being only slightly distorted from tetrahedral. (C) 1999 Elsevier Science Ltd, All rights reserved.