Thorium Compounds

Detailed theoretical investigations on the electronic and magnetic properties of the ThFe 11 C 2 compound have been performed using both the linear muffin-tin orbital and Korringa-Kohn-Rostocker methods of band structure calculation. The structure of the ThFe 11 C 2 compound has three inequivalent iron sites with different local environment. A strongly enhanced magnetic moment is observed on certain Fe positions, coexisting with much lower magnetic moments on other iron positions of the lattice. Band structure calculations indeed show that the Fe magnetic moments depend strongly on the local environment. The average Fe magnetic moment obtained from these calculations is in good agreement with the experimental average Fe moment obtained from magnetization measurements. The orbital contribution to the magnetic moment is found to be especially large on the Fe 4b position. Comparing calculated hyperfine fields with experimental results, it is found that the calculated and experimental hyperfine fields are correlated. However, similarly to the results reported before for elemental Fe, the magnitude of all calculated Fe hyperfine fields is about 25% smaller. The agreement with the Mössbauer measurements is improved by scaling the core polarization contribution and by estimating the orbital valence d-electrons contribution to the magnetic hyperfine fields using the local spin density approximation þ dynamical mean field theory calculated orbital moments.

RATIONALE: Electrospray ionisation mass spectrometry (ESI-MS) is a useful tool for exploring the speciation of solutionphase metal complexes; however, the quantification of ternary systems is challenging due to the differences in the electrospray response of different species. Here, the Th-Mn-EDTA system was investigated to evaluate the capability of ESI-MS for quantifying the species present. METHODS: Increasingly complex mixtures of Th(IV), Mn(II) and EDTA were analysed using manual flow injection of samples into an HPLC grade water mobile phase delivered to an ion trap mass spectrometer fitted with an ESI interface (ThermoQuest Finnigan Mat LCQ). Mass spectra were obtained in the positive and negative ion modes over a mass-to-charge (m/z) range from 50-2000. RESULTS: The instrumental response to EDTA was affected by the addition of Th(NO 3) 4 but not MnCl 2 , while the response to both Th-EDTA and Mn-EDTA species was affected by addition of the other metal salt. Internal standards were also found to suppress signals to different extents. Therefore, each signal suppression was carefully quantified as the solution became more complex, and signal correction factors were used in conjunction with regular external calibration. Mixed metal signals were quantified adequately. CONCLUSIONS: This study showed the complexity of quantifying a ternary system involving different co-existing species. Nonetheless, the step-wise protocol developed provided quantitative data on the displacement of Mn from its EDTA complex by Th.

With through space and through bond experiments in two-dimensional NMR we analyze the transformation from the thorium phosphate-hydrogen phosphate hydrate (TPHPH) to the b form of the thorium phosphate diphosphate (b-TPD) in relation with the phosphorus networks. These techniques are complementary: the through space coupling gives an insight on the dipolar phosphorus networks while the through bond coupling is particularly efficient in the detection of the P 2 O 7 groups. With these experiments we show that in a first step, by heating the precursor TPHPH above 250 1C, it transforms into an a form of TPD. This transformation is due to the complete condensation of hydrogen phosphate groups HPO 4 into P 2 O 7 entities. By heating a-TPD above 950 1C it transforms into its well-known b form. The a form is characterized by a hygroscopic behavior: some water molecules are present near the P 2 O 7 groups that makes non-equivalent their phosphorus nuclei. PO 4 dipolar networks are always present in the a form. The main effect of these PO 4 and P 2 O 7 units is to give the system a channel structure and the water enters in them.

With through space and through bond experiments in two-dimensional NMR we analyze the transformation from the thorium phosphate-hydrogen phosphate hydrate (TPHPH) to the b form of the thorium phosphate diphosphate (b-TPD) in relation with the phosphorus networks. These techniques are complementary: the through space coupling gives an insight on the dipolar phosphorus networks while the through bond coupling is particularly efficient in the detection of the P 2 O 7 groups. With these experiments we show that in a first step, by heating the precursor TPHPH above 250 1C, it transforms into an a form of TPD. This transformation is due to the complete condensation of hydrogen phosphate groups HPO 4 into P 2 O 7 entities. By heating a-TPD above 950 1C it transforms into its well-known b form. The a form is characterized by a hygroscopic behavior: some water molecules are present near the P 2 O 7 groups that makes non-equivalent their phosphorus nuclei. PO 4 dipolar networks are always present in the a form. The main effect of these PO 4 and P 2 O 7 units is to give the system a channel structure and the water enters in them.