Critical Points in a Crystal and Procrystal

The critical points in the model electron density distributions of LiF, NaF, NaCl, and MgO crystals, constructed from accurate X-ray diffraction data, are determined. For LiF and MgO they are compared with those obtained from a Hartree–Fock electron density calculation. Both experiment and theory show the same type of critical points on the bond lines. The topological features in areas between structural units, where the electron density is low and near-uniform, turn out to be model dependent and cannot be established well with the data available. Topological analysis of procrystals (hypothetical systems consisting of spherical atoms or ions placed on the same sites as atoms in real crystal) show that (3, –1) critical points, usually connected with bonding interaction, are observed on interatomic lines in these nonbonded systems as well.     

First heteroleptic Mo<Subscript>3</Subscript>S<Subscript>7</Subscript> clusters containing non-innocent phenanthroline ligands

Reaction of the thiobromide [Mo₃S₇Br₆]²⁻ cluster anion with 5,6-dimethyl-1,10-phenanthroline (Me₂Phen) in solution leads to the substitution of two bromide ligands and the subsequent formation of a new mixed-ligand neutral complex [Mo₃S₇Br₄(Me₂Phen)] (I). Reaction of [Mo₃S₇Br₆]²⁻ with 5,6-dimethyl-1,10-phenanthroline in CH₂Cl₂ followed by treatment of I with Na(Dtc) · 3H₂O (Dtc = diethyldithiocarbamate) results in the new mixed-ligand cluster complex [Mo₃S₇(Dtc)₂(Me₂Phen)]²⁺ (IIa). Slow evaporation of the CHCl₃ solution of the complex in the presence of PF₆⁻ gives crystals of {[Mo₃S₇(Dtc)₂(Me₂Phen)]Br}PF₆ · 3CHCl₃ (II) characterized by X-ray structural analysis. Close contacts S...S result in the formation of cationic dimers {[Mo₃S₇(Dtc)₂(Me₂Phen)]₂}⁴⁺ which form infinite chains through additional S_ax...Br contacts. All compounds were characterized by IR, elemental analysis and ESI-MS. Synthesized complexes represent the first examples of heteroleptic Mo₃S₇ clusters containing phenanthroline ligands.     

Triangular telluride complexes containing a cluster fragment [M3(µ3-Te)(µ2-Te2)3]4+ (M = Mo, W): Study of specific non-valence interactions

Various synthetic approaches are used to obtain new triangular complexes with rare cluster nuclei M₃Te₇ ⁴⁺ (M = Mo, W), as well as with partial substitution for chalcogen W₃Te_3.8Se _3.2 ⁴⁺ . The crystalline structure has been identified for K₅{[Mo₃Te₇(CN)₆]₂I}·2.5H₂O (I), K₃{[Mo₃Te₇(CN)₆]SeCN}·3.25H₂O (II), Cs₂K{ [W₃Te₇(CN)₆]Br_0.8Cl_0.2}·2.5H₂O (III), Cs₃{ [W₃Te₇(CN)₆]Br}·2H₂O (IV), Cs_1.59K_1.41{[W₃Te_3.8Se_3.2× ×(CN)₆]Br}·1,5H₂O (V), [W₃Te₇((EtO)₂PS₂)₃]Br (VI). The compounds are characterized by IR methods and electronic spectroscopy, electrospray-mass-spectrometry. The crystalline structure of this class of compounds is analyzed. Specific non-valence interactions in these systems are considered in detail.     

Synthesis, complex-formation, and extracting ability of new derivatives of dithia-13(16)-crown-4(5) ethers

Various methods of synthesizing functional derivatives of dithia-13(16)-crown-4(5) ethers are proposed. Complex-formation of the obtained compounds with Ag⁺ and Pb²⁺ ions has been studied using ¹H NMR. A radiometric method was used to investigate the extracting ability of substituted dithia-13(16)-crown-4(5) ethers in relation to Ag⁺ and Cd²⁺ ions from aqueous solution in the presence of anions of various degree of hardness, with determination of the metal content. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 233–243, February, 2006.     

Synthesis of Oxathiacrown Compounds by the Reactions of Sulfur Dichloride with Unsaturated Compounds and Their Extraction Characteristics. (Review)

Published data of the last 10-15 years on the use of the reactions of sulfur dichloride with various unsaturated compounds for the synthesis of oxathia- and thiacrown compounds and study of their extraction characteristics toward various transition and heavy metals are reviewed. Some previously unpublished results and associated experimental data are also included.     

Supramolecular Systems Based on Ca2+, [Mo3O2S2Cl6(H2O)3]2s-, [Mo3S4Cl6.75Br0.25(H2O)2]3s- and Cucurbit[6]uril

Adducts of cucurbit[6]uril with Ca²⁺ and trinuclear cluster chloroaquacomplexes (H₉O₄)₂(H₇O₃)₂[(Ca(H₂O)₅)2(C₃₆H₃₆N₂₄O₁₂)]Cl₈·0.67H₂O (1) and [(Ca(H₂O)₅)₂(C₃₆H₃₆N₂₄O₁₂)]× [Mo₃O₂S₂Cl₆(H₂O)₃]₂·13H₂O (2) are obtained and structurally characterized. The structures of both compounds contain polymeric [Ca(H₂O) _n ]₂² CB[6]∞ cations that form infinite columns; the space between them is filled with Cl^s- (1) and [Mo₃O₂S₂Cl₆(H₂O)₃]^2s- (2). A new (H₇O₃)₂(H₅O₂)× [Mo₃S₄Cl_6.25Br_0.25(H₂O)₂](C₃₆H₃₆N₂₄O₁₂)·CH₂Cl₂·6H₂O complex (3) is also obtained and structurally characterized.     

A novel polybromide complex of bismuth – (Et4N)3{[Bi2Br9](Br2)}: synthesis and structural features

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The theoretical research of the medium effect on the vibrational spectrum and the energy of intramolecular coordination O → Si in (benzoyloxymethyl)trifluorosilane molecule

The characteristics of (benzoyloxymethyl)trifluorosilane C₆H₅C(O)OCH₂SiF₃ containing a five-membered heterocycle closed by intramolecular coordination O → Si bond (Ia) and its most stable acyclic isomer (Ib) have been calculated by HF, MP2(Full) non-empirical methods, and DFT(B3LYP) using 6-311G(d) and 6-311 + G(2d,p) basis sets. The (C₈H₁₈, C₆H₆, (C₄H₉)₂O, CHCl₃, (CH₂)₄O, CH₂Cl₂, CH₃CN) medium effect on the energy and structural characteristics, dipole moments, and vibrational spectra of Ia and Ib isomers was calculated by the DFT(B3LYP)/6-311 + G(2d,p) method in the Onsager SCRF model approximation. The DFT(B3LYP)/6-311 + G(2d,p) calculation reasonably reproduces the medium effect on coordination energy, geometry, dipole moments, and band frequencies in the vibrational spectrum of Ia.     

Synthesis and structures of Mo3Se7Te2Br10, Mo3Se7TeI6, and Mo6Te21I22 containing TeX3- (X=Br, I) ligands coordinated to a triangular cluster core

New ternary and quaternary molybdenum cluster chalcohalides were obtained by high-temperature reactions between Mo, chalcogens, and halogens in evacuated ampules. The crystal structures of [Mo3Se7(TeBr3)Br2]2[Te2Br10] (1), [Mo3Se7(TeI3)I2]I (2), and [Mo3Te7(TeI3)3]2(I)(TeI3) (3) were determined by single-crystal X-ray diffraction. The structures of 1 and 2 consist of positively charged zigzag chains infinity1 [Mo3Se7(TeX3)X4/2] (X=Br, I), with Te2Br102- and I-, respectively, as counterions. The TeI3- and TeBr3- ions function as bidentate ligands in 1 and 2. In 3, TeI3- is not coordinated to the metal but acts as a counterion to the [Mo3Te7(TeI3)3]+ cluster cation.