Search

The synthesis, characterization, and reductive elimination reactivity of a bis(NHC)borate-supported thorium bis(phosphido) complex (2Mes) is described. Treating 2Mes with 2,2'-bipyridine leads to the reductive elimination of dimesityldiphosphine (4) and the formation of the previously reported NHC-thorium-bpy complex (3). The kinetics of the bpy-induced reductive elimination were studied by 31P NMR and suggest the presence of an intermediate. Treatment with alternative oxidants also leads to diphosphine elimination, but the corresponding thorium species have not been isolated cleanly. Additional primary (2Ph) and secondary (2PPh2) Th-bis(phosphido) complexes were synthesized but do not demonstrate the same facile reductive elimination as 2Mes. [ABSTRACT FROM AUTHOR]

Four new coordination polymers [Zn(3-Nbdc)(bpa)] ( 1), [Cd(3-Nbdc)(bpa)(HO)] ( 2), [Zn(3-Nbdc)(bpp)] ( 3) and {[Zn(3-Nbdc)(bpe)]·1.5HO} ( 4) (3-Nbdc = 3-nitrobenzene-1,2-dicarboxylate, bpa = 1,2-bi(4-pyridyl)ethane, bpp = 1,3-bis(4-pyridyl)propane and bpe = 1,2-bi(4-pyridyl)ethene), were synthesized hydrothermally and characterized structurally by single crystal X-ray diffractions, elemental analysis and infrared spectroscopy. Complexes 1 and 3 exhibit three-dimensional (3D) metal-organic frameworks with the (6) dia topology and (6·8) cds topology, respectively, and both of them contain metal-carboxylate helix chains. Compounds 2 and 4 show 2D → 3D interpenetrated networks with (4,4) grid layers and 2D layer, respectively, and both of them contain metal-carboxylate binuclear units. The thermal stabilities and fluorescence properties for complexes 1- 4 are investigated. The blue-shift of the luminescent wavelength in 2 may be due to the absence of interligand π··· π effects compared with that of other three compounds, but there exist the strong face-to-face π··· π interactions in 1 and edge-to-face π··· π interactions in 3 and 4, showing a certain degree of interchromophore coupling interaction. [ABSTRACT FROM AUTHOR]

A series of lanthanide(III) complexes (Ln = La to Lu) with 2,2′-bipyridyl-6,6′-dicarboxamide ligands were obtained. The X-ray structure of the di( N-ethylanilide) of 2,2′-bipyridyl-6,6′-dicarboxylic acid is reported. The structures of the amides in the gas phase were modeled by DFT calculations. The global minima of the structures on the potential energy surface (PES) strongly depend on the nature of the substituents on the amidic nitrogen atom. The UV/Vis titration results of three diamides of 2,2′-bipyridyl-6,6′-dicarboxylic acid with lanthanide(III) metal nitrates show the composition of the complexes formed and allow us to determine the binding constants. Compounds with a 1:1 metal-to-ligand ratio are formed with the three diamide ligands under study. The binding constants are high, log β1 being higher than 5.5. The values of the constants decrease from LaIII to LuIII. The first structures, obtained by single-crystal X-ray diffraction, for GdIII and TbIII complexes of 2,2′-bipyridyl-6,6′-dicarboxamide ligands are described. Decacoordinated metal ions are bonded by the tetradentate ligand and three bidentate nitrate groups. 2D ROESY experiments with LaIII, LuIII, and EuIII complexes allow us to conclude that the structures of the complexes in solution are the same as those in the solid state. The photophysical properties of these Ln complexes were determined in the solid state at 77 and 300 K. Intense red and green luminescence was observed for both Eu and Tb complexes, and an intrinsic quantum yield of 90 % was determined for the europium complex. [ABSTRACT FROM AUTHOR]