Nitrocellulose Membrane,Modified by RC(S)NHP(X)(OiPr)2 (X = S,R = PhNH; X = O,R = PhNH,Ph), for Sorption Extraction of Cobalt Cations

The complexation and extraction properties of RC(S)NHP(X)(OiPr)₂ [X = S, R = PhNH (HL^I); X = O, R = PhNH (HL^II), Ph (HL^III)] towards cobalt cations were studied. The nitrocellulose membrane was used as a carrier for HL^I?III. The maximal degree of extraction of cobalt cations from an aqueous solution is observed at pH = 7.8–8.4. It was established that complexes formed are kept in a water solution on a surface of the carrier and washed away in 96% aqueous ethanol. The membrane modified by HL^I allows extraction and concentration of Co(II) selectively, while the modification by HL^III leads to the selective extraction of Co(III).     

H2X(X=O,S)分子简正模激发态下分子内能量转移的研究

采用准经典轨迹法,考察了H₂O及H₂S分子简正模激发态下分子内各态能量随时间变化的分布关系,讨论了激发能在各态间的转移规律.研究表明:简正模激发态能量转移倾向于频率彼此相近或对称性相同的态间.     

Structure of Coordination Polymer, 〔Zn(bipy)(H_2O)_3SO_4〕·2H_2O (bipy=4,4'-bipyridine)

1　INTRODUCTION4,4' bipyridine( bipy) is a good candidate for building open framework struc ture because of their rodlike rigidity and length.Framework structures formed bytransition metalsbridged by bipy vary with metaland anion.The structures of Zn bipy system include interpenetrating square grid sheets〔 Zn( bipy) 2 ( H2 O) 2 〕Si F6〔1〕,two dimensionallayer〔 Zn( bipy) ( H2 O) 4 〕( NO3) 2 · bipy〔2〕,〔 Zn( bipy) ( H2 O) 4 〕 ( NO3) 2 · 2 bipy· 3 H2 O〔2〕 and〔 Zn( bipy)…     

Ab initio studies of H2PXYH molecules (X,Y = O,S)

Ab initio molecular orbital theory is applied to the study of P? O and P? S bonding in the hypervalent phosphinic (H₂POOH), phosphinothioic (H₂POSH), and phosphinodithioic (H₂PSSH) acid molecules. Intramolecular proton exchange reactions are followed using the intrinsic reaction coordinate and Self-Consistent-Field energy localized orbitals. The P? O and PS bonds are characterized via force constants, phosphorus d orbital populations, and localized orbitals and are best described as either normal single bonds or dative bonds augmented by π back donation from the oxygen or sulfur lone pairs. The anions of these acids are also investigated, and they are found to contain only dative bonds to sulfur and oxygen.     

Donor effect on supramolecular structures of silver(I) perchlorate complexes of macrocycles with O2S2X (X=S, O and NH) donor sets

By virtue of simple one donor variations of O(2)S(2)X-donor macrocycles (L(1): X=S, L(2): X=O and L(3): X=NH) towards silver(I) perchlorates, four supramolecular complexes (1-3) with different topologies have been isolated; L(1) afforded solvent- and anion-free sandwich complex (1), otherwise L(2) and L(3) gave the dimeric (2a), 1-D polymeric (2b), and tetrameric bowl-type (3) complexes with solvent or anion coordination.     

C36X(X=O,NH,S)各种可能异构体的芳香性研究

采用拓扑共振能方法对富勒烯C36X(X=O,NH,S)开环结构中的所有可能的异构体及阳离子和阴离子芳香性进行了理论研究. 计算结果表明,C36X的芳香性高于C36. C36X的阳离子因其共振能为负值而具有反芳香性. 反之,C36X的阴离子因共振能为正值而具有芳香性和较高的稳定性. C36的D6h和D2d异构体中杂原子X插入在5-5键时得到的化合物最稳定. 从理论上预测了C36X的负离子能形成稳定的金属富勒烯. 对C36X的阳离子和阴离子的芳香性进行了解释.     

AuX (X=O,S)低电子态的理论研究

通常要用多参考态方法才能合理处理需考虑旋轨耦合（SOC）效应的开壳层分子如AuO和AuS的低电子态. 事实上,通过选取合适的参考态,采用运动方程耦合簇方法（EOM-CC）也能计算这些分子的一些低电子态,而且EOM-CC方法是单参考态方法,使用起来比多参考态方法更加简单. 本文采用最近发展的含旋轨耦合的EOM-CC 计算电离能的方法（EOMIP-CC）,选取对应的负离子为参考态,在CCSD 级别上计算了AuO 和AuS低电子态的性质. 在不考虑旋轨耦合时,通过比较EOMIP-CCSD和EOMIP-CCSDT的结果考察EOMIPCCSD的精度. 此外,与EOMIP-CCSDT结果相比,如果自旋污染较为显著而且T₁的模较大时,UCCSD（T）方法对能量最低的某一特定对称性的电子态的所对应的电离能误差约为0.1-0.15 eV. 在考虑了旋轨耦合效应后,我们的方法得到的键长和振动频率与实验值吻合较好. 另一方面,虽然EOMIP-SOC-CCSD高估了能量较高的²Δ_3/2态、²Σ_1/2⁺态和²Π_1/2态的能量,但是对于其它能量更低的电子态,它们的能量与已有实验值误差在0.2 eV 左右. 这显示我们所用的含SOC的EOMIP-CCSD方法对原本需要用多参考态方法才能处理的AuO和AuS低电子态能给出可靠的结果.     

AuX(X=O,S)低电子态的理论研究

通常要用多参考态方法才能合理处理需考虑旋轨耦合(SOC)效应的开壳层分子如AuO和AuS的低电子态.事实上,通过选取合适的参考态,采用运动方程耦合簇方法(EOM-CC)也能计算这些分子的一些低电子态,而且EOM-CC方法是单参考态方法,使用起来比多参考态方法更加简单.本文采用最近发展的含旋轨耦合的EOM-CC计算电离能的方法(EOMIP-CC),选取对应的负离子为参考态,在CCSD级别上计算了AuO和AuS低电子态的性质.在不考虑旋轨耦合时,通过比较EOMIP-CCSD和EOMIP-CCSDT的结果考察EOMIPCCSD的精度.此外,与EOMIP-CCSDT结果相比,如果自旋污染较为显著而且T1的模较大时,UCCSD(T)方法对能量最低的某一特定对称性的电子态的所对应的电离能误差约为0.1-0.15 eV.在考虑了旋轨耦合效应后,我们的方法得到的键长和振动频率与实验值吻合较好.另一方面,虽然EOMIP-SOC-CCSD高估了能量较高的2Δ3/2态、2Σ+1/2态和2Π1/2态的能量,但是对于其它能量更低的电子态,它们的能量与已有实验值误差在0.2 eV左右.这显示我们所用的含SOC的EOMIP-CCSD方法对原本需要用多参考态方法才能处理的AuO和AuS低电子态能给出可靠的结果.     

Stereoselective radical cyclizations of N-(2-halobenzoyl)-cyclic ketene-N,X(X=O, S)-acetals

2-Alkyloxazolines and 2-alkylthiazolines react with 2-halobenzoyl chlorides to form N-(2-halobenzoyl)-cyclic ketene-N,O-acetals and N-(2-halobenzoyl)-cyclic ketene-N,S-acetals in excellent yields, respectively. These ketene acetals readily undergo stereocontrolled aryl radical cyclizations to afford the central six-membered rings of substituted-2,3,10,10α-tetrahydrooxazolo[3,2-b]isoquinolin-5-ones and their 2,3,10,10α-tetrahydrothiazolo[3,2-b]isoquinolin-5-one analogs. The tertiary N,O- and N,S-radicals formed upon aryl radical reaction at the ketene-N,X(X=O, S)-acetal double bond appear to have reasonable stability. The stereoselectivity in hydrogen abstractions by these intermediate radicals from both Bu₃SnH and (Me₃Si)₃SiH was investigated. The N,S-heterocyclic fused ring products may have potential medical value.     

Polarity and structure of P(X)-modified (X = O,S) arylcarbamoylmethylphosphine oxides and sulfides

As shown by the dipole moment method and quantum chemical calculations, (arylcarbamoylmethyl) diphenylphosphine oxides and sulfides exist as equilibrium mixtures of several rotational isomers stabilized by H · · · X intramolecular hydrogen bonds (X = O, S). The most energetically favorable rotamer and its fraction have been determined for each compound.     

Computational study on the characteristics of the interaction in naphthalene...(H2X)n=1,2 (X = O,S) clusters

The characteristics of the interaction between the pi cloud of naphthalene and up to two H2O or H2S molecules were studied. Calculations show that clusters formed by naphthalene and one H2O or H2S molecule have similar geometric features, and also present similar interaction energies. Our best estimates for the interaction energy amount to -2.95 and -2.92 kcal/mol for H2O and H2S, respectively, as obtained with the CCSD(T) method. Calculations at the MP2 level employing large basis sets should be avoided because they produce highly overestimated interaction energies, especially for hydrogen sulfide complexes. The MPWB1K functional, however, provides values pretty similar to those obtained with the CCSD(T) method. Although the magnitude of the interaction is similar with both H2X molecules, its nature is somewhat different: the H2O complex presents electrostatic and dispersion contributions of similar magnitude, whereas for H2S the interaction is dominated by dispersion. In clusters containing two H2X molecules several minima were characterized. In water clusters, the total interaction energy is dominated by the presence of a O-H...O hydrogen bond and, as a consequence, structures where this contact is present are the most stable. However, clusters containing H2S show structures with no interaction between H2S moieties which are as stable as the hydrogen bonded ones, because they allow an optimal H2S...naphthalene interaction, which is stronger than the S-H...S contact. Therefore it is possible that in larger polycycles hydrogen sulfide molecules will be spread onto the surface maximizing S-H...pi interactions rather than aggregated, forming H2S clusters.     

The relationship between transannular secondary bonding strength and conformation in diphenyldithiophosphinate stibocanes X(CH2CH2S)2SbS2PPh2 (X = O,S)

The two stibocanes 1-oxa-4,6-dithia-5-stibocane diphenyldithiophosphinate O(CH₂CH₂S)₂SbS₂PPh₂ 1 and 1,3,6-trithia-2-stibocane diphenyldithiophosphinate S(CH₂CH₂S)₂ · SbS₂PPh₂ 2 were prepared from the corresponding chloro oxa- and thia-stibocanes 3 and 6 , and the ammonium salt of diphenyldithiophosphinic acid in CH₂Cl₂. 1 and 2 were characterized by IR, EI-MS and multinuclear NMR (¹H, ¹³C, ³¹P{¹H}). The crystalline state of 1 features two Sb1 ? S1 intermolecular interactions [3.987(2) Å] that results in a dimer. Alongside 1 displays both an endocyclic, transannular Sb1 ? O1 interaction [2.555(6) Å] and an exocyclic Sb1 ? S4 secondary interaction [3.327(2) Å]. The coordination geometry at the antimony could be described as AX₄YE ψ-trigonal bipyramid geometry with A = Sb, X = S1, S2, S3,O1; Y = S4; S1, S2 and the lone pair lays on the equatorial plane with O1 and S4 in axial positions. The Sb1 ? S4 secondary bonding is face capping one of the planes form by the lone pair, S2 and S3 of the trigonal bipyramid. 2 also displays both an endocyclic, transannular Sb1 ? S2 interaction [2.949(3) Å] and an exocyclic Sb1 ? S5 secondary interaction [3.216(3) Å]. The antimony becomes five-coordinate, giving the AX₄YE ψ-trigonal bipyramid geometry with S1, S3 and the lone pair laying on the equatorial plane with S2 and S4 in axial positions. The Sb1 ? S5 also here is face capping the plane form by the lone pair, S3 and S4 of the trigonal bipyramid. The conformation of the eight membered ring in 2 is boat-chair. In 1 the main conformation is chair-planar. Die Konformation des Achtringes in 2 ist Wanne-Sessel. In 1 ist die Konformation des Achtringes Sessel-planar.     

Ruthenium complexes with tridentate PNX (X = O, S) donor ligands

The ligands, PhPNXMe (1), PhPNXPh (2), and PhPNSMe (3), (PhPNX = 2-Ph2P-C6H4CH[double bond, length as m-dash]NC6H4X-2; X = O, S) have been prepared. A range of new ruthenium complexes were synthesised using these and related ligands, namely: [{RuCl(PhPNO)}2Cl] (4), [Ru(PhPNO)2] (5), [RuCl(PhPNXR)(PPh3)]BPh4 [X = O, R = Me (6); X = O, R = Ph (7); X = S, R = Me (8)], [{RuCl(PhPNX'R)}2Cl]X [X' = O, R = Me, X = Cl(-) (9); X' = S, R = Me, X = BPh4(-) or PF6(-) (10)], and [RuCl(PhPNO-eta 6C6H5)]BPh4 (11). The catalytic activity of these complexes with respect to the hydrosilyation of acetophenone and the hydrogenation of styrene has been investigated, giving an insight into the requirements for an active complex in these reactions.     

Crystal chemistry of AB2X4 (X = S,Se, Te) compounds

An attempt is made to correlate the crystal structures of ternary chalcogenides of composition AB₂X₄ with the cationic radius ratio and a pseudo force-constant involving their electronegativities. The resultant diagram adequately resolves structures based on the types K₂SO₄, monoclinic, olivine, MnY₂S₄, Th₃P₄, and CaFe₂O₄ but structure types based on spinel, Cr₃Se₄, and Ag₂HgI₄ are not resolved. Crystal chemical arguments are used to explain these observations and to advance reasons for the successes and failures of this method for predicting structure types.     

XAFS spectroscopic study of Tc2(O2CCH3)4X2 (X = Cl,Br)

Technetium dimers Tc₂(O₂CCH₃)₄X₂ (X =?Cl, Br) were synthesized and studied by X-ray Absorption Fine Structure spectroscopy (XAFS). EXAFS analysis gave for Tc₂(O₂CCH₃)₄Cl₂: d Tc-Tc =?2.18(1) Å, d Tc–Cl =?2.43(1) Å and for Tc₂(O₂CCH₃)₄Br₂: d Tc–Tc =?2.19(1) Å, d Tc-Br =?2.63(1) Å. The Tc Tc separations are in agreement with Raman studies while the Tc–X distances are somewhat larger. Comparison with other Tc(III) quadruply bonded dimers indicates that the carboxylate compounds exhibit larger Tc–Tc separations. The effect of the terminal ligand (nature and position) on the Tc–Tc separation is discussed.     

Mechanism of abstraction reactions of dimetallenes (R2X=XR2; X = C, Si, Ge, Sn, Pb) with halocarbons: a theoretical study

Potential energy surfaces for the abstraction reactions of dimetallenes with halocarbons have been studied using density functional theory (B3LYP). Five dimetallene species, (SiH(3))(2)X=X(SiH(3))(2), where X = C, Si, Ge, Sn, and Pb, have been chosen in this work as model reactants. The present theoretical investigations suggest that the relative dimetallenic reactivity increases in the order C=C < Si=Si < Ge=Ge < Sn=Sn < Pb=Pb. That is to say, for halocarbon abstractions there is a very clear trend toward lower activation barriers and more exothermic reactions on going from C to Pb. Moreover, for a given dimetallene, the overall barrier heights are determined to be in the order CF(4) > CCl(4) > CBr(4) > CI(4). That is, the heavier the halogen atom (Y), the more facile its abstraction from CY(4). Halogen abstraction is always predicted to be much faster than the abstraction of a CY(3) group irrespective of the dimetallene or halocarbon involved. Our model conclusions are consistent with some available experimental findings. Furthermore, both a configuration mixing model based on the work of Pross and Shaik and bonding dissociation energies can be used to rationalize the computational results. These results allow a number of predictions to be made.