Synthesis, spectroscopic, and X-ray crystallographic characterisation of thorium(IV) and uranium(IV) malonato and substituted malonato compounds

With doubly protonated piperazine or ethylenediamine as cations, eight Th(I V) malonato or substituted malonato complexes have been prepared and charac terised by elemental analysis, thermal analysis, IR and C-13 CPMAS NMR spec troscopy. One polymeric U(IV) malonato complex has also been prepared and c haracterised by elemental analysis, thermal analysis and IR spectroscopy. ( C4H12N2)(2)[Th(C3H2O4)(4)]. H2O (2), (C2H10N2)(2)[Th(C3H2O4)(4)(H2O)] (3), (C4H12N2)(2)[Th(C4H4O4)(4)]. 2H(2)O (4), (C2H10N2)(2)[Th(C5H6O4)(4)]. 5H(2) O (6) and [U(C3H2O4)(2)(H2O)(3)](n) (9) have been further characterised by single-crystal X-ray diffraction. Two types of monomeric anion structure ar e identified in the Th compounds: four 1,5-bidentate ligands in a distorted square antiprismatic geometry, giving coordination number (CN) 8; and four 1,5-bidentate ligands and a coordinated H2O molecule in a capped square an tiprismatic geometry, giving CN 9. The U compound has a 3D polymeric struct ure, with U in an approximately capped square antiprismatic geometry, achie ving CN 9 from two 1,5-bidentate ligands, each of which also bridges throug h a carbon yl oxygen to an adjacent U centre, and three H2O molecules. In t he crystallographically-characterised Th compounds, the Th-O and C-O distan ces are correlated with the carbonyl resonance positions in the C-13 CPMAS NMR spectra, allowing prediction of structural types in the non-crystalline compounds. (C) 2000 Elsevier Science Ltd. All rights reserved.