Maleic and phthalic acids are found to react with Be(OH)(2), generated in situ from BeSO4(aq) and Ba(OH)(2)(aq), in aqueous solution at pH 3.0 or 4.4, respectively (25 degrees C), to give solutions containing the complexes (H2O)(2)Be[(OOCCH)(2)] (1) and (H2O)(2)Be[(OOC)(2)C6H4] (3). The products can be isolated in high yield and identified by microanalytical data. With 2 equiv of the dicarboxylic acids and the pH adjusted to 5.5 and 5.9, respectively, by addition of ammonia, the bis-chelate complexes [(NH4)(+)](2){[Be[(OOCCH)(2)](2)}(2-) (2) and [(NH4)(+)](2){Be[(OOC)(2)C6H4](2)}(2-) (4) are obtained, which can also be isolated. The compounds show distinct Be-9, H-1, and C-13 resonances in their NMR spectra in aqueous solutions. Layering of an aqueous solution of compound 4 with acetone at ambient temperature reads to the precipitation of single crystals suitable for an X-ray structure determination. This salt (5) was found to contain the bis-chelated dianion {Be[(OOC)(2)C6H4](2)}(2-) with the beryllium atom in the spiro center of two seven-membered rings and an overall geometry approaching closely Ct symmetry. These anions are associated with two crystallographically independent but structurally similar counterions [MeC(O)CH2CMe2NH3](+), which are the product of a condensation reaction of the ammonium cation with the acetone solvent. In the crystal the ammonium hydrogen atoms of the cations form N-H ... O hydrogen bonds with the oxo functions of the dianion.