Synthesis, structural and spectroscopic characterisation of three di-μ-fluoro-bis[dioxouranyl] complexes

Three novel uranyl complexes with organic phosphine oxide ligands and bridging fluorides have been synthesised and structurally characterised. In [ UO₂(μ-F)(TPPO)_{3 2}][BF₄]₂ · ⁿC₆H₁₄, 1, and [ UO₂(-μF)(TBPO)_{3 2}][BF₄]₂ 2, (where TPPO and TBPO are triphenylphosphine oxide and tri-n-butylphosphine oxide, respectively) two UO₂ ²⁺ moieties are bridged by two fluorides with three additional terminal PO donor ligands coordinated to each uranium centre. The dicationic complexes are both charge balanced by two uncoordinated tetrafluoroborate anions. In the related structure, [UO₂(μ-F)(F)(DPPMO₂)]₂ · 2MeOH (3), terminal fluoride is also coordinated to both uranyl centres (where DPPMO₂ = bis(diphenylphosphine oxide)methane). All three complexes were prepared during attempted syntheses of complexes with tetrafluoroborate directly coordinated to uranium. It is clear from these results that the fluorophilicity of UO₂ ²⁺ causes the abstraction of fluoride from [BF₄]⁻, with the weakly coordinating anion only present as a counter cation in 1 and 2, and absent completely in 3.     

分子动力学方法模拟不同温度下铀酰在叶腊石上的吸附和扩散行为

采用分子动力学方法研究了铀酰在叶腊石表面的吸附和扩散。在碳酸根离子存在的情况下,探究了温度对铀酰吸附和扩散的影响。碳酸根离子与铀酰存在较强的作用力,不同数目的碳酸根离子与铀酰结合会形成多种铀酰种态。在不同温度的模拟中,得到了UO_2~(2+)、UO_2CO_3、UO_2(CO_3)_2~(2-)、UO_2(CO_3)_3~(4-)四种铀酰种态和铀酰聚合物。通过原子密度图,观察了粒子在溶液中的分布情况。发现UO_2~(2+)+和UO_2CO_3容易吸附在叶腊石上,而UO_2(CO_3)_2~(2-)和UO_2(CO_3)_3~(4-)主要存在于扩散层中。随着时间的推移,越来越多的碳酸根离子与铀酰配位,使得铀酰在叶腊石上的吸附逐渐减少。本文计算了不同温度下,各铀酰种态的扩散系数。在扩散层中,各种态的扩散系数随温度的变化较为一致,而在吸附层中,UO_2~(2+)和UO_2CO_3的扩散速率随温度的变化较UO_2(CO_3)_2~(2-)和UO_2(CO_3)_3~(4-)慢。但是在同一温度下,同一个吸附层或扩散层中,铀酰种态的扩散系数大小顺序始终保持不变:UO_2~(2+)UO_2CO_3UO_2(CO_3)_2~(2-)UO_2(CO_3)_3~(4-)。说明在碳酸根存在的情况下,UO_2~(2+)可能是主要的扩散形式。     

The formation and stability of hydrated and anhydrous uranyl phosphates

The stabilities of the hydrated uranyl phosphates (UO₂)₃(PO₄)₂ · 4 H₂O, UO₂HPO₄ · 4 H₂O, and UO₂(H₂PO₄) · 3 H₂O have been reinvestigated. The compounds identified by thermal analysis have been prepared isothermally and characterized by their strongest X-ray reflections. During dehydration, oxygen was not evolved and the crystalline compounds (UO₂)₃(PO₄)₂, (UO₂)₂P₂O₇, UO₂(PO₃)₂, and probably (UO₂)₃P₄O)₁₃ were found.

At still higher temperatures, the uranyl phosphates are reduced. The decomposition products lose phosphorus oxide above 1300–1400°C. The present results are summarized in a tentative pseudo-binary phase diagram UO_x(x = 3 to 2)—UO₂(PO₃)₂.     

1:2型硝酸铀酰二苯并-18-冠-6氢键夹心式配合物的晶体结构

化合物[UO₂(NO₃)₂(H₂O)₂]·(DB18C6)₂晶体属单斜晶系,空间群为P21/k。晶体学参数:a=11.782(2)Å,b=8.584(2)Å,c=22.631(2),β=98.29(2)Å°,Z=2.用3024个I≥3σ(I)的三维X射线独立衍射数据进行结构解析,最终的R=0.066。结构分析表明,两个双齿配体硝酸根及两个水分子配位于线型铀酰离子的赤道平面上,铀的配位数是8,配位几何构型为稍有扭曲的六方双锥。配位水分子的4个氢原子分别与上下两层冠醚环上的氧原子生成氢键。形成夹心式分子缔合物。     

The formation and stability of hydrated and anhydrous uranyl arsenates

Three hydrated uranyl arsenates, (UO₂)₃(AsO₄)₂ · 11 H₂O, UO₂HAsO₄ · 4 H₂O, and UO₂(H₂AsO₄)₂ · 1 H₂O, have been prepared. The dehydration of these compounds has been studied by thermal analysis. Three crystalline anhydrous uranyl arsenates, (UO₂)₃(AsO₄)₂, (UO₂(AsO₃)₂, have been found. These show melting phenomena and lose arsenic oxide vapour at high temperatures to result, finally, in U₃O₈ at 1500°C in air. The anhydrous compounds have been prepared under isothermal conditions and the strongest X-ray reflections are given. A tentative phase diagram in the composition range UO₃ to As₂O₅ has been constructed.     

锕系元素冠醚配合物研究(Ⅲ)——二水合硝酸铀酰苯并-15-冠-5配合物的晶体结构

锕系元素冠醚配合物中,研究得最多的是铀酰与冠醚形成的配合物,以往的工作主要集中在配合物的合成及性质研究方面,而对其结构很少研究。迄今为止,只测定过硝酸铀酰与18-冠-6配合物的晶体结构,铀酰与其它种类冠醚形成的配合物的结构文献中还未见报道。我们在乙腈溶液中培养出硝酸铀酰与苯并-15-冠-5的配合物[UO_2(NO_3)_2(H_2O)_2]·(B15C5)单晶,并研究该配合物的晶体及分子结构。     

Synthesis, characterization and reactivity of some novel dinuclear mixed-ligand peroxouranium(VI) complexes

Novel anionic dinuclear mixed-ligand peroxo complexes of the type [(UO₂)₂(O₂)₃L(H₂O)₂]³⁻ (L = Histidinate, aspartate, salicylate, Imidazolate and glutamate) have been synthesized from the interaction of uranyl ion (UO₂²⁺) with peroxide (O₂²⁻) in the presence of the respective coligand (L) at pH 9–10. The sparingly soluble complexes were characterized by elemental analyses, FT-IR, laser Raman (LR) and UV-vis spectroscopy and solution electrical conductance measurements. Based on these studies, a double bridged dinuclear structure involving one peroxo and the mixed ligand L (via-COO⁻) has been tentatively proposed. Infra-red coupled with LR spectra evidenced structurally different metal bound peroxides (ν² and σ:σ). An aqueous solution of the salicylate and aspartate complexes have been shown to convert triphenylphosphine (PPh₃), cyclohexene, styrene and SO₂ to the corresponding OPPh₃, 1,2 cyclohexanediol, phenylethyleneglycol and SO₄²⁻, respectively.     

Preparation and characterization of cellulose acetate complexes

Summary Metal chelates of secondary cellulose acetate (SCA) with chromium(III), copper(II), cobalt(II), nickel(II) and UO ₂ ²⁺ were prepared and characterized by elemental analyses, magnetic moments and spectral studies. SCA acts as a uninegatively charged bidentate ligand and reacts with the metal ion via the oxygen atom of the secondary unacetylated hydroxyl group in the glucose subunit of the polymer, plus the oxygen atom of the vicinal ester group, to form a five-membered chelate ring.     

Some actinide complexes of pyridin-, pyrrol-, furan- and thiophen-aldazine Schiff bases

Actinide chloride complexes with pyridinaldazine (PAA), pyrrolaldazine (PyAA-H₂), furanaldazine (FAA), and thiophenaldazine (TAA): An(L)Cl_n·m-H₂O, where An = Th, UO₂; L = PAA, PyAA-H₂, FAA, TAA; n = 2, 4; m = 0, 2, 3, 5 (also, mononuclear with 2L, dinuclear and trinuclear complexes) have been prepared by the reaction of ThCl₄, UO₂Cl₂ or UO₂(Ac)₂·2H₂O with PAA, PyAA-H₂, FAA or TAA and characterized by spectral data, electrical conductance, thermal and elemental analysis.     

The effects of transition metal complexes on the permeation of small gas molecules through cellulose acetate membranes

Cellulose acetate (CA) membranes containing RuCl₃·3H₂O and RhCl [P(C₆H₅)₃]₃ were prepared reproducibly. Such membranes, on treatment with CO, formed metal-carbonyl species at relatively low temperature. The Ru-carbonyls formed in CA were quite stable at 40°C in comparison with the Rh-carbonyl species and, interestingly, there was no permeation of CO gas through the ruthenium-containing CA membrane at 40°C. However, the permeation of other gas molecules, such as H₂, N₂ and O₂, through the same membrane was reduced only slightly, probably due to the cross-linking effect of the transition metal complexes in CA. It was found that essentially pure H₂ gas could be recovered from a 1: 1 mixture of H₂ and CO gases using ruthenium-containing cellulose acetate membranes.     

M(CO)4 (M = Mo or W) complexes of 2,6-bis(methylthiomethyl)pyridine (L) and 2,6-bis(p-tolylthiomethyl)pyridine (L): a dynamic NMR study

The hybrid S/N/S donor ligands 2,6-bis(methylthiomethyl)pyridine (L¹) and 2,6-bis(p-tolylthiomethyl)pyridine (L²) react with the [M(CO)₅(THF)] (M = Mo or W) compounds to form complexes of general formula [M(CO)₄L] (M = Mo, L = L²; M = W, L = L¹ or L²), where both L¹ and L² act in a S/N bidentate chelate fashion. In solution, these complexes undergo three fluxional processes, viz. inversion at the coordinated S atom, S¹–S² switching, and combined inversion and S¹–S² switching, leading to an interconversion of the four possible permutational isomers. Energy barriers for all three processes have been evaluated by standard one-dimensional band-shape analysis techniques. The mechanism of the S¹–S² switch is discussed.     

Potential characteristics of a pseudoliquid membrane electrode including coordinatively solvated UO(2)(NO(3))(2).2TBP complexes

Mechanisms of formation of electrode potential with a pseudoliquid membrane phase including uranyl nitrate complexes coordinatively solvated by tri-n-butyl phosphate were investigated. It was stated that the electrode function of these membranes could be of cationic or anionic character depending on concentration UO₂ (NO₃)₂ in an aqueous phase. The influence of extraction and salting out on membrane phase composition and the slope of calibration curve was studied. It was shown that in the concentration range c > 0.1M the electrode potential depends on value of salt distribution coefficient between aqueous and organic phases. The dependence describing the electrode function in this concentration range was derived.     

Ion-pair extraction of uranyl ion from aqueous medium using crown ethers

Ion-pair extraction behaviour of uranyl ion from aqueous solutions was studied at pH 3.0 employing crown ethers viz. benzo 15 crown 5 (B15C5), 18 crown 6 (18C6), dibenzo 18 crown 6 (DB18C6), and dibenzo 24 crown 8 (DB24C8) in chloroform as the organic phase and picric acid as the organophilic counter anion. The stoichiometry of the extracted species corresponded to [UO₂(crown ether)_n]²⁺·[pic⁻]₂ where n=1.5 for benzo 15 crown 5 and 1 for 18 crown 6 as well as dibenzo 18 crown 6. Adducts of DB24C8 could not be observed as practically no extraction was possible using this reagent. The separation behaviour of fission products from an irradiated uranium target was also studied. An interesting observation on the separation of trivalent lanthanides from uranyl ion is reported.     

Monomeric dioxouranium(VI), chromium(III), cobalt(II), nickel(II) and copper(II) complexes with primary cellulose acetate (PCA)

Monomeric UO ₂ ²⁺ , Cr^III, CO^II, Ni^II and Cu^II complexes with primary cellulose acetate (PCA) have been prepared and characterized. Infrared,¹H NMR, UV/visible spectroscopy, elemental analysis, therniogravimetry, conductance and magnetic measurements were used to assign the mode of coordination in the isolated species. The investigation revealed that PCA exhibits octahedral coordination with Cr^III, Co^II, Ni^II and a square planar form with Cu^II whereas the UO₂ moiety is virtually linear. PCA acts as a neutral bidentate chelating agent via the two oxygen atoms of the vicinal ester groups in the secondary positions forming a five-membered chelate ring. A comparative study between chelates of PCA and those previously prepared with secondary cellulose acetate (SCA) has been undertaken.     

13C-NMR spectral studies on the distribution of substituents in water-soluble cellulose acetate

The degree of substitution (DS) and distribution of O-acetyl groups of water-soluble cellulose acetate (CA) were investigated by ¹³C-NMR. For this purpose, three different series of CA samples with low DS were prepared by respective homogeneous reaction, i.e., (1) deacetylation of cellulose triacetate (CTA) in acetic acid—water solution (D-series), (2) reaction of CTA with hydrazine (H-series), and (3) acetylation of cellulose with acetic anhydride in a 10% LiCl-dimethylacetamide solution (A-series). It was found that (i) water-soluble CA can be obtained only from D-series products, (ii) the DS value of water-soluble CA ranges from 0.5 to 1.1, (iii) the D-series products exhibit little difference between the relative DS values at C-2, C-3 and C-6 hydroxyl groups, and (iv) the relative DS at C-6 hydroxyl groups is very high compared to those at C-2 and C-3 hydroxyl groups in H- and A-series products. Aqueous solution of water-soluble CA (D-series sample) showed no gel—sol transition, even when the temperature was raised to 95°C. X-ray diffraction observations revealed that the water-soluble D-series samples were essentially noncrystalline, but the water-insoluble A-series samples were crystalline. It was also found that the relative ease of acetylation is C-6 > C-2 > C-3.     

Synthesis and structural characterization of mixed ligand η-2-hydroxyacetophenone complexes of cobalt(III)

A tridentate Schiff base ligand [(CH₃)₂NCH₂CH₂N=C(CH₃)C₆H₄OH)] (LH) has been synthesized from 2-hydroxyacetophenone and 2-dimethylaminoethylamine. This ligand forms the neutral complexes [Co(L)(N₃){o-(CH₃C=O)C₆H₄O}] (1) and [Co(L)(SCN){o-(CH₃C=O)C₆H₄O}]·1/2H₂O (2) in presence of equivalent amount of Co(II) acetate, and sodium azide for 1 and sodium thiocyanate for 2. The complexes have been characterized by spectroscopic and crystallographic methods. The coordination geometry around Co(III) in both the complexes is distorted octahedral with one tridentate ligand L, one bidentate 2-hydroxyacetophenone and one monodentate azide for 1 and thiocyanate for 2. The azide and thiocyanate ligands in the two complexes occupy different positions relative to the coordination sites of L.     

Stereochemically non-rigid transition metal complexes of 2,6-bis[(1-phenylimino) ethyl]pyridine (BIP) part 1. Dynamic NMR studies of [M(C6F5) 2(BIP)] (M = Pd or Pt)

The complexes [M(C₆F₅)₂(BIP)] (M = Pd^II or Pt^II, BIP = 2,6-bis[(1-phenylimino)ethyl]pyridine) have been synthesised and characterised as involving BIP as a bidentate chelate ligand. In solution they undergo 1,4 metallotropic shifts of the M(C₆ F₅)₂ moiety, E,Z isomerisation of the pendant imine bond, and restricted C-C rotation of the pendant portion of the BIP ligand. ¹H and ¹⁹F dynamic NMR studies yielded activation energies for these three types of fluxion. ΔG^≠ (298 K) values for the three processes were 89.6, 86.6 and 47.4kJmol⁻¹ respectively for the Pt^II complex. Values for the Pd^II complex were significantly lower in magnitude, namely 71.6, 70.4 and 41.8 kJ mol⁻¹ respectively.     

Thermotropic mesomorphism in penta- and hepta-coordinated metal complexes

New Ni(II) and UO₂(II) metallomesogens obtained from mesomorphic N,N'-salicyliden(3,3'-diamine-N-methyldipropylamine) ligands containing a pentadentate N₃O₂ chelating cavity and bearing two or four lateral substituents, are isolated and fully characterized. Some of the synthesized nickel and dioxouranium complexes show a SmC mesophase. To the best of our knowledge, these species are the first pentacoordinated Ni(II) and heptacoordinated UO₂(II) metallomesogens to be reported.     

过渡金属配合物与铀酰-有机框架复合:两例新型铀/铜异金属配合物的合成、晶体结构及其性能研究

在水热条件下,将铜金属配合物插入到铀酰有机框架化合物中,合成了两例新型铀/铜异金属杂化配合物[Cu(bipy)(UO₂)(bdc)₂·H₂O]_n(1),{[Cu(phen)(UO₂)(bdc)(bc)(H₂O)]·H₂O}_n(2)(bipy=2,2′-联吡啶,bdc=对苯二甲酸,phen=1,10-邻菲罗琳,bc=苯甲酸),并通过X射线单晶衍射对其结构进行了表征。配合物1属于单斜晶系,P2₁/c空间群,M_r=833.99,a=7.9077(5)A,b=23.1076(13)A,c=14.6172(8)A,β=101.4180(10)°,V=2618.1(3)A³,Z=4,D_c=2.116 g·cm-3,μ=7.056 mm^-1,F(000)=3003,最终偏离因子R=0.0210,wR=0.0560。配合物2属于单斜晶系,P2/c空间群,Mr=829.99,a=7.9327(2)A,b=11.6546(3)A,c=13.8618(4)A,β=96.2230(10)°,V=1274.01(6)A³,Z=2,Dc=2.164 g·cm^-3,μ=7.247 mm^-1,F(000)=786,最终偏离因子R=0.0273,wR=0.0749。在对苯二甲酸配体桥联下这两个配合物都具有三维异金属网络结构(CCDC:860177,1;CCDC:857137,2)。此外,测试了配合物1和2的固态紫外-可见吸收光谱并研究了配合物1的固态荧光性能。     

Chiral Nematic Cellulose Acetate Films; Reflectivity and Effect of Deacetylation

Cellulose acetate samples with a range of degrees of substitution (DS) were prepared by deacetylation of cellulose acetate (DS = 2.5). Chiral nematic solutions of the samples were prepared in formic acid. A handedness reversal from left to right was observed as the DS used to prepare the mesophase increased from 1.8 to 2.4. By selection of a suitably long-pitch mesophase, chiral nematic films cast from a CA (DS = 2.2)/formic acid solution showed a feint reflection of circularly polarized blue light. Deacetylation of this CA film gave a chiral nematic cellulose film with a more intense reflection band at the same wavelength. The improvement in intensity is attributed to the higher intrinsic birefringence of cellulose compared to cellulose acetate.