Trivalent Actinide Ions Showing Tenfold Coordination in Solution.

Trivalent actinides generally exhibit ninefold coordination in solution. 2,6-Bis(5,6-dipropyl-1,2,4-triazin-3-yl)pyridine (nPr-BTP), a tridentate nitrogen donor ligand, is known to form ninefold coordinated 1:3 complexes, [An(nPr-BTP)] (An = U, Pu, Am, Cm) in solution. We report a Cm(III) complex with tenfold coordination in solution, [Cm(nPr-BTP)(NO)].

Evidence for covalence in a N-donor complex of americium(III).

The molecular origin of the selectivity of N-donor ligands, such as alkylated bis-triazinyl pyridines (BTPs), for actinide complexation in the presence of lanthanides is still largely unclear. NMR investigations of an Am(nPrBTP)3(3+) complex with a (15)N labelled ligand showed that it exhibits large differences in (15)N chemical shift for coordinating N-atoms in comparison to both lanthanide(III) complexes and the free ligand. The temperature dependence of NMR chemical shifts observed for this complex indicates a weak paramagnetism.

Complexation of europium(III) by bis(dialkyltriazinyl)bipyridines in 1-octanol.

The present work focuses on highly selective ligands for An(III)/Ln(III) separation: bis(triazinyl)bipyridines (BTBPs). By combining time-resolved laser-induced fluorescence spectroscopy, nanoelectrospray ionization mass spectrometry, vibronic sideband spectroscopy, and X-ray diffraction, we obtain a detailed picture of the structure and stoichiometry of the first coordination sphere of Eu(III)-BTBP complexes in an octanolic solution. The main focus is on the 1:2 complexes because extraction studies revealed that those are the species extracted into the organic phase.

A TRLFS study on the complexation of Cm(III) and Eu(III) with 4-t-butyl-6,6'-bis-(5,6-diethyl-1,2,4-triazin-3-yl)-2,2'-bipyridine in a water/2-propanol mixture.

The complexation of Cm(III) and Eu(III) with 4-t-butyl-6,6'-bis-(5,6-diethyl-1,2,4-triazin-3-yl)-2,2'-bipyridine (t-Bu-C2-BTBP) in water/2-propanol solution is studied. With increasing ligand concentration, 1 : 2 complexes [M(t-Bu-C2-BTBP)(2)(H(2)O)](3+) form from the solvated metal ions. The stability constants are log K(Cm(III)) = 11.