Metallorganische 5d6‐Übergangsmetallkomplexe von zwei 1‐Methyl‐(2‐alkylthiomethyl)‐1H‐benzimidazol‐Liganden: Strukturen und elektrochemische Oxidation

Organometallic 5d⁶ Transition Metal Complexes of 1‐Methyl‐(2‐alkylthiomethyl)‐1H‐benzimidazole Ligands: Structures and Electrochemical Oxidation The complexes [(mmb)Re(CO)₃Cl], [(mtb)Re(CO)₃Cl], [(mmb)OsCl(Cym)](PF₆) and [(Cym)OsCl(mtb)](PF₆) where Cym = p‐cymene, mmb = 1‐methyl‐(2‐methylthiomethyl)‐1H‐benzimidazole and mtb = 1‐methyl‐(2‐tert‐butylthiomethyl)‐1H‐benzimidazole were synthesized and, except for the latter, structurally characterized. In comparison with other late transition metal compounds of these N‐S chelate ligands the rhenium(I) systems exhibit a balanced coordination to both N and S donor atoms. Anodic one‐electron oxidation produces EPR‐silent rhenium(II) states whereas the osmium(III) species [(mmb)OsCl(Cym)]²⁺ could be identified via EPR and UV/VIS spectroelectrochemistry.     

Structures and conformations of 1-aryl-1,4-dihydro-3(2H)-isoquinolinones

The X-ray crystal structures of series of 1-aryl-1,4-dihydro-3(2H)-isoquinolinones (1-7) have been determined. Lactame heterocyclic ring possesses more or less deformed boat conformation in all examined structures. The aryl substituent adopts the equatorial position in the structures 1-3 and the axial one in 5-7. In the structure of 4, due to extremely flattened heterocyclic ring, aryl substituent location can be named as bisectional. In all solved structures the molecules are joined into the dimers via two N-H?O hydrogen bonds. At the same time, ¹H NMR studies in DMSO-d₆ solutions were accomplished and profound analysis of ²J, ³J, and ⁵J coupling constants have shown that in isoquinolinone system the heterocyclic ring adopts the boat conformation in all investigated compounds. The stereochemical orientations of the phenyl ring at C1 do not depend on the nature of the substituent but, exclusively, on the mode of substitution. However, three forms of undulated laktam heterocyclic ring conformation in respect of 1-aryl substituent positions were confirmed by calculation (conformational analysis).     

Toward a Unified Approach to the Crystal Chemistry of Aurivillius-Type Compounds.: I. The Structural Model

A generalized structural model of Aurivillius-type compounds is presented using a 4D superspace group analysis where Aurivillius structures are considered as cation-deficient perovskites with the general formula AB_1−xO₃. Being essentially composition independent, the model is valid for any Aurivillius-type compounds where x is the only composition-dependent parameter. The atomic domains representing the atoms in superspace are described by means of crenel functions. For any composition, the conventional space groups can be easily derived from a unique superspace group. This work is supported by a TEM investigation where the continuously variable character of the diffraction diagram indicates that the various stacking sequences can be interpreted in terms of a structural modulation over a common average structure.     

Neue neutrale und kationische Mono‐Aziridin‐Komplexe des Typs [CpMn(CO)2Az], [CpCr(NO)2Az]+ und [(Ph3P)(CO)4ReAz]+ über CO‐, Hydrid‐ und Chlorid‐Abspaltungsreaktionen

Novel Neutral and Cationic Mono‐Aziridine Complexes of the Type [CpMn(CO)₂Az], [CpCr(NO)₂Az]⁺, and [(Ph₃P)(CO)₄ReAz]⁺ via CO‐, Hydride‐, and Chloride‐Elimination Reactions The monoaziridine complexes 1 — 5 are obtained by three differently induced substitution reactions. The photolytically induced CO substitution reaction of [CpMn(CO)₃] with 2, 2‐dimethylaziridine leads to the neutral N‐coordinate aziridine complex [Cp(CO)₂Mn{$\overline{N(H)CMe₂C}$ H₂}] ( 1 ). The protonation of [(Ph₃P)(CO)₄ReH] with CF₃SO₃H and consecutive treatment with 2, 2‐dimethylaziridine or 2‐ethylaziridine gives the salt‐like aziridine complexes [(Ph₃P)(CO)₄Re{$\overline{N(H)CMe₂C}$ H₂}](CF₃SO₃) ( 2 ) or [(Ph₃P)(CO)₄Re{ H₂}](CF₃SO₃) ( 3 ) by hydride elimination reactions. The like‐wise salt‐like complexes [Cp(NO)₂Cr{$\overline{N(H)CMe₂C}$ H₂}](BF₄) ( 4 ) and [Cp(NO)₂Cr{ H₂}](CF₃SO₃) ( 5 ) are synthesized from [CpCr(NO)₂Cl] by chloride elimination with AgX (X = BF₄, CF₃SO₃) in the presence of 2, 2‐dimethylaziridine or 2‐ethylaziridine, respectively. As a result of X‐ray structure analyses, the metal atoms are trigonal pyramidally ( 1, 4, 5 ) or octahedrally ( 2, 3 , cis‐position) configurated; the intact three‐membered rings coordinate through the distorted tetrahedrally configurated N atoms. All compounds 1‐5 are stable with respect to the directed thermal alkene elimination to give the corresponding nitrene complexes; the IR, ¹H‐ and ¹³C{¹H}‐NMR, and MS spectra are reported and discussed.     

Polysulfonylamine. CLX [1] Kristallstrukturen von Metall‐di(methansulfonyl)amiden. 10 [2] Die dreidimensionalen Koordinationspolymere M[(CH3SO2)2N] mit M = Kalium,Rubidium, Caesium (isotype Strukturen für M = K,Rb)

Polysulfonylamines. CLX. Crystal Structures of Metal Di(methanesulfonyl)amides. 10. The Three‐Dimensional Coordination Polymers M[(CH₃SO₂)₂N], where M is Potassium, Rubidium, Cesium (Isotypic Structures for M = K, Rb) Low‐temperature X‐ray crystal structures are reported for KA (monoclinic, space group P2₁/c, Z′ = 1), RbA (isotypic and isostructural with KA), and CsA (monoclinic, P2₁/n, Z′ = 1), where A^— denotes the anion obtained by deprotonation of the strong nitrogen acid (MeSO₂)₂NH. In KA and RbA, the anion is distorted into a rare C₁ conformation, whereas the standard C₂ conformation is retained in the cesium complex. The structures consist of three‐dimensional coordination networks, in which each cation adopts an irregular (O₆N)‐heptacoordination by forming close contacts to one (O, N)‐chelating, one (O, O)‐chelating and three κ¹O‐bonding ligands; however, the coordination number for Cs⁺ is effectively increased to 8 by a very short Cs···Cs contact distance of 422.5 pm. The crystal packings of the isotypic compounds KA and RbA display lamellar layer substructures that involve six independent ligand‐metal bonds and comprise an internal cation lamella and peripheral regions built up from anion monolayers; the 3D framework is completed by one independent M—O bond cross‐linking the layer substructures. In contrast, CsA features anion monolayers that intercalate planar zigzag chains of cations (Cs···Cs alternatingly 422.5 and 487.5 pm, Cs···Cs···Cs 135.7°), whereby each chain is surrounded and coordinated by four anion stacks and each anion stack connects two cation chains. All structures exhibit close C—H···A interanion contacts consistent with weak hydrogen bonding.     

C40异构体的结构和稳定性的理论研究

利用Gaussian98程序,采用密度泛函(DFT)方法中的B3LYP,选用6-31G基组对富勒烯(Fullerene)C40的6种异构体[D5d,Td,D2h,C3v,D2(Ⅰ),D2(Ⅱ)]进行了几何构型优化,其中,对于Td对称性的C40由于易发生Jahn-Teller畸变,则降低其对称性为D2d,再进行优化.对它们的平衡几何和电子结构进行了比较具体的分析,同时,根据计算得到的总能量推断出这6种异构体的稳定性顺序是D2(Ⅰ)>D5d>Td>C3v>D2h>D2(Ⅱ).     

Experimental Verification of the Theoretical Prediction of High‐Temperature Superconductivity in Phases of Titanium Borides TiB k

Theoretical predictions of hightemperature superconductivity (HTSC) in titanium borides, TiBk, have been experimentally verified. These predictions have been reported previously in the form of theoretical phase diagrams. They predicted the existence of HTSC in TiB _k (1.43 < k < 2.57) phases and in TiB_1.5–1.6. An abrupt decrease at 110 K was found on the temperature curve of conductivity R(T) for titanium samples whose surfaces were coated with diffuse layers of depthvariable boride compositions TiB _k . This indicates that the layers include phases possessing HTSC. This behavior of the R(T) curves is explained assuming that the inclusions of HTSC phases have a strong effect on the resistance of the composite materials at T_c. The composition of the boride layers has been investigated by mass spectrometry. Diffuse boride layers were applied to titanium surface by treating its surface with a B₂H₆ + H₂ gas mixture at 610–700°C followed by annealing in vacuum.