Two series of germanium compounds, (pTol) 3 Ge-MMe 3 (M = Si (1), Ge (2), Sn (3)) and (Me 3 Si) 3 Ge-MPh 3 (M = Ge (4), Sn (5)), were prepared using lithium or potassium intermediates. The changing of the reaction conditions results in trigermane Ph 3 Ge-Ge(SiMe 3 ) 2 -GePh 3 (6). The molecular structures of 1, 2, and 6 were investigated by X-ray analysis. By UV/visible spectroscopy it is established that introduction of a tin atom results in a significant bathochromic absorption shift. Furthermore, according to cyclic voltammetry, oxidation potentials decrease in the order 1 > 2 > 3. The electronic structures of 1−4 and related (Me 3 Si) 3 GeSiPh 3 were investigated by DFT calculations. Fluorescence properties of 1−3 were studied in the solid state and in solution; for compound 3 phosphorescence (lifetime is 4.58 ms) is observed in the solid state.

The secondary coordination sphere contributes to the stability of complexes, the extraction behaviour of the reagents and europium phosphorescence lifetimes.

Hybrid donor extractants are a promising class of compounds for the separation of trivalent actinides and lanthanides. Here, we investigated a series of sterically loaded diphosphonate ligands based on bipyridine (BiPy-PO-iPr and BiPy-PO-cHex) and phenanthroline (Phen-PO-iPr and Phen-PO-cHex). We studied their complex formation with nitrates of trivalent f-elements in solvent extraction systems (Am and Eu) and homogeneous acetonitrile solutions (Nd, Eu, and Lu). Phenanthroline extractants demonstrated the highest efficiency and selectivity [SF(Am/Eu) up to 14] toward Am­(III) extraction from nitric acid solutions among all of the studied diphosphonates of N-heterocycles. The binding constants established by UV–vis titration also indicated stronger binding of sterically impaired diphosphonates compared to the primary substituted diphosphonates. NMR titration and slope analysis during solvent extraction showed the formation of 2:1 complexes at high concentrations (>10–3 mol/L) for phenanthroline-based ligands. According to UV–vis titrations at low concentrations (10–5–10–6 mol/L), the phenanthroline-based ligands formed 1:1 complexes. Bipyridine-based ligands formed 1:1 complexes regardless of the ligand concentration. Luminescence titrations revealed that the quantum yields of the complexes with Eu­(III) were 81 ± 8% (BiPy-PO-iPr) and 93 ± 9% (Phen-PO-iPr). Single crystals of the structures [Lu­(μ2,κ4-(iPrO)2P­(O)­Phen­(O)2(OiPr))­(NO3)2]2 and Eu­(Phen-PO-iPr)­(NO3)3 were obtained by chemical synthesis with the Phen-PO-iPr ligand. X-ray diffraction studies revealed a closer contact of the f-element with the aromatic N atoms in the case of sterically loaded PO ligands compared with sterically deficient ligands. Density functional theory calculations allowed us to rationalize the observed selectivity trends in terms of the bond length, Mayer bond order, and preorganization energy.

New phosphinoyl-containing tetradentate heterocycles preorganised for metal ion binding were designed and prepared in high yields. The X-ray structures of two allied phosphinoyl-bearing 2,2'-bipyridyl and phenanthroline ligands, as well as closely related structures of 2,6-bis(diphenylphosphinoyl)pyridine and 9-(diphenylphosphinoyl)-1,10-phenanthroline-2-one, are reported. Complexes of nitrates of several lanthanides and trifluoroacetate of Eu(iii) with two phosphinoyl-bearing 2,2'-bipyridyl and phenanthroline ligands were isolated and characterised. The first structures of lanthanide complexes with phosphinoyl-bearing 2,2'-bipyridyl and phenanthroline ligands are reported. The nature of the counter-ion is crucial for the coordination environment of the metal ion. The photophysical properties of the complexes differring in both the nature of the ligand and counter-ion were investigated. The photophysical properties of the complexes are strongly ligand- and counter-ion-dependent. Absorbance and luminescence excitation spectra of complexes showed main peaks in the UV range which correspond to the absorption of light by the ligand and these are ligand-dependent. Luminescence spectra of complexes show typical europium emission in the red region with a high quantum yield, which corresponds to the transitions D → F (J = 0-6). The value of deviation of the components of D → F and D → F transitions from the inversion centre shows a larger dependence on the counter-ion than on the nature of the ligand. The value of the luminescence quantum yield is larger for europium complexes with 2,2'-bipyridyl-based ligands and NO counter-ions than for complexes with phenanthroline-based ligands and NO counter-ions. A low dependence of the luminescence lifetime of Eu complexes on the nature of the ligand has been demonstrated: values in the solid state were in the range 1.1-2.0 ms.

A series of germanes Ar 3 GeX, containing electron-withdrawing substituents [Ar = p-FC 6 H 4 , 1a−d, 1a (X = Cl), 1b (X = Br), 1c (X = H), 1d (X = NMe 2 ); p-F 3 CC 6 H 4 , 2a−d, 2a (X = Cl), 2b (X = Br), 2c (X = H), 2d (X = NMe 2 )], was synthesized and used to prepare symmetrical digermanes Ar 3 Ge−GeAr 3 , (p-FC 6 H 4 ) 3 GeGe(C 6 H 4 F-p) 3 (3), and (p-F 3 CC 6 H 4 ) 3 GeGe(C 6 H 4 CF 3 -p) 3 (4) and trigermane [(p-F 3 CC 6 H 4 ) 3 Ge] 2 Ge(C 6 F 5 ) 2 ( 5) by hydrogermolysis reaction. The properties of all compounds were investigated by multinuclear NMR and for oligogermanes by UV/vis and fluorescence spectroscopy, as well as by electrochemical methods. In addition, the molecular structures of 1a, 1b, 2b, 2c, and 3−5 were studied by X-ray diffraction analysis. Compound 5 showed a significantly shifted UV/visible absorption to the red field in comparison with previously described derivatives.