三环己基羧酸锡的分子结构和晶体结构

用单晶X射线衍射技术测定了三个三环己基羧酸锡化合物—三环己基丁酸锡(1), 三环己基-间氯代苯甲酸锡(2), 三环己基-间溴代苯甲酸锡(3)的分子和晶体结构. 三种化合物均属正交晶系, 空间群分别为P212121(1), Pnaa(2), Pnaa(3). 1的晶胞参数为:a=9.963(2), b=11.004(3), c=20.144(6)埃, Z=4. 2的晶胞参数为: a=8.135(2),b=16.716(3), c=36.426(6)埃, Z=8. 3的昌胞参数为: a=8.165(1), b=16.714(3),c=36.710(4)埃, Z=8. 在1的晶体中, 锡原子呈五配位的三角双锥构型. 桥联的羧基使其结构成为含有两种不同Sn-O键(2.198(4)和2.427(3)埃)的线型聚合物. 2和3的晶体则是由孤立的分子所组成. 在每个分子中, 四配位的锡原子呈畸变的四面体构型, 羧基不能象在化合物1中那样在锡原子之间成桥, 可能主要是由于环己基与卤代苯甲酸根之间的空间位阻效应所致.     

The crystal and molecular structures of 1,2,3,6-tetramethyl-o-carborane

Conclusions We have carried out a complete x-ray structural analysis of (CCH₃)₂B₁₀H₈(CH₃)₂, one of the products resulting from the methylation of aminated dianions of 1,2-dimethyl-o-carborane, and have shown that the compound with all methyl groups joined to the four neighboring vertices of the carborane ring is 1,2,3,6-tetramethyl-o-carborane.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 859–864, April, 1978.     

The crystal and molecular structures of some germatrane derivatives

The crystal and molecular structures of seven germatrane derivatives have been determined from three-dimensional X-ray data in order to investigate the main geometrical regularities of the germatrane molecules.     

The crystal and molecular structures of three germatrane derivatives

The molecular and crystal structure of three germatrane compounds: 1-(1-bromobicyclo[4.1.0]hept-7-yl)germatrane, l-(1-trimethylsilanyl-cyclopropyl)-germatrane and 1-(1-Methyl-1,2-dicarba-closo-dodecaboranyl)germatrane has been determined by X-ray diffraction method in order to investigate main geometrical regularities of the germatrane molecules. There were established all values of the main structural parameters above-mentioned molecules.     

Calculation of molecular chemisorption on a crystal surface

Theoretical and Experimental Chemistry -     

The molecular and crystal structures of two diastereomeric 3,4-dihydropyrromethenones

The molecular and crystal structures of the two racemic diastereomeric 3,4-dihydropyrromethenone derivatives1 and2 of configurations (Z) and (E) were determined at 93 K (1, 2) and at room temperature (1). From an analysis of the crystallographically observed temperature coefficients a pseudorotation flexibility of the pyrrolidinone ring in the crystal is deduced. In both compounds a nearly orthogonal arrangement between the two heterocyclic ring systems is observed, which is ascribed to the steric bulk of the substituents in positions 1 and 3 of the pyrrolidinone ring.Herrn Prof.Josef Schurz zum 60. Geburtstag gewidmet.     

Regulating the stability of 2D crystal structures using an oxidation state-dependent molecular conformation

The oxidation state of the phenol-substituted porphyrin TDtBHPP is coupled with its structure so that its 2-electron oxidation leads to a coplanarization of the molecule and a substantial stabilization of its surface self-assembled structures adsorbed at metal substrates.     

Donor—acceptor interactions of substituted benzenes with molecular chlorine and carbon disulfide

CNDO molecular orbital calculations have been performed to analyze donor—acceptor interactions between molecular chlorine and benzene, toluene, mesitylene and hexamethylbenzene and the, as yet, unreported chlorine—hexafluorobenzene and carbon disulfide—benzene pairs. The stabilization energy and the dipole moment and its derivative (?p/?R_CICI) calculated for the benzene—chlorine complex are in good agreement with the estimated experimental values. The trends in the experimental stabilization energies and the Cl-Cl vibrational frequencies with increasing methyl substitution appear to be well reproduced by the calculations. The charge transferred from the benzene donor is polarized toward the outer chlorine atom or sulfur atom. For hexafluorobenzene-chlorine the direction of electronic charge polarization is reversed from that of the benzene and methylbenzene complexes. The calculated results are discussed within the framework of Muliiken's simplified resonance theory for complexes.     

Complexes of mono- and bis(2-carboxyethyl)-2-picolylamine: Synthesis and crystal and molecular structures

N-(2-Pyridylmethyl)iminodipropionic (I) and N-(2-pyridylmethyl)-3-aminopropionic acids (II) were obtained. A reaction of acid I with a Cu(II) salt gave a 2: 2 complex (III); a reaction of acid II with a Ni(II) salt yielded a 1 : 2 complex (IV). The crystal structures of these complexes were determined by X-ray diffraction. The abilities of compounds I and II to form complexes were compared with the literature data for other ligands containing the N-(2-pyridylmethyl)amino fragment. The structural features of the chelate complexes with 2-aminomethylpyridine derivatives were revealed, depending on the other substituents and the metal center.     

Synthesis and crystal structures of hydrogen and carbon stabilized lutetium monochloride,LuClHx and Lu2Cl2C

Single crystals of the, basically, four-layer slab structure …?ClLuLuCl…? of the apparently as such nonexisting lutetium monochloride, LuCl, stabilized by interstitial hydrogen or carbon have been obtained from reactions of LuCl₃ and cesium (LuClH_x, due to ubiquitous hydrogen) and C_sCl, lutetium and carbon (Lu₂Cl₂C), respectively, in sealed tantalum containers at elevated temperatures (above 700°C). Both exhibit so-called 3R structures (space group R3 m): LuClH_x (a = 363.83(3), c = 2710.2(3) pm, Z = 6) crystalizes with the ZrCl type structure with hydrogen in tetrahedral interstices and Lu₂Cl₂C (a = 360.17(3), c = 2716.0(3) pm, Z = 3) with the tetradymite type (Bi₂Te₂S) with carbon in octahedral interstices between the double metal layers. Power X-ray diffraction shows that for Lu₂Cl₂C a 1T structure is also adopted (a = 359.72(3), c = 909.25(9) pm, p3 m1, Z = 1).     

Applications of molecular mechanics to refine and understand polymer crystal structures

A computational approach to refine and analyze polymer crystal structures is presented, where both intra- and intermolecular interactions are simultaneously optimized by minimizing the total crystal potential energy in cartesian coordinates and utilizing a full-atom force field. The advantages of the present methodology are illustrated through several applications, including very recent results concerning the polymorphism of isotactic polypropylene. Some features of the computer program for molecular mechanics CHAMP, developed in our laboratory, are also described.     

三苄基和三丁基锡5-叔丁基呋喃甲酸酯的分子和晶体结构研究

用单晶X射线衍射技术测定了三苄基锡5-叔丁基呋喃甲酸酯(1)和三丁基锡5-叔丁基呋喃甲酸酯(2)的分子和晶体结构。1为三斜晶系P1, 晶胞参数a=1.1253(2),b=1.3138(3), c=1.8920(2)nm, α=89.39(1), β=89.22(1), γ=71.50(2)°, Z=4; 2为单斜晶系P21/n, 晶胞参数a=1.4732(2), b=1.0266(3), c=1.6385(3)nm, β=101.45(1)°, Z=4。两个化合物中Sn原子均分别与5-叔丁基呋喃甲酸的羰基氧配位形成五配位三角双锥构型的线型聚合物。2的Sn-O键长为0.2440(2), 0.2171(6)nm; 与之不同的是1有四种不同的Sn-O键, 其键长分别为0.2462(6), 0.2186(5), 0.2389(5)和0.2204(5)nm, Sn(1)和Sn(2)周围的苄基和呋喃酰基的平面夹角相差很大, 是一类由两个中心锡原子组成一个结构单元的五配位线型聚合的有机锡化合物。     

八乙基卟啉及其锌配合物的分子和晶体结构

测定了中位(meso)取代八乙基卟啉和无轴向配位卟啉锌(II)配合物的结构, 讨论了锌离子配位前后卟啉环的平面性, 并比较了有锌和无锌配位卟啉阴离子的几何构型。研究结果表明卟啉骨架的构型不仅决定于卟啉骨架中央孔穴的大小, 配位离子的尺寸和电子结构, 而且还决定于骨架上的取代基团。本文还分析了在卟啉骨架上取代硝基的几何构型以及它们在卟啉共轭效应中的作用。     

Reaction of 1-boryl-2-phosphinoethenes with carbon disulfide

1-Butyl-1-dibutylboryl-2-diethylphosphino-2-phenylethene reacts with chloral and oxygen in a manner similar to 1-butyl-1-dibutylboryl-2-dipheylphosphino-2-phenylethene but, unlike the former, can also react with carbon disulfide to form a cyclic complex through an intramolecular S B coordination bond; charge density transfer from sulfur to boron consisted of about 0.3 e.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2613–2616, November, 1990.     

Potential energy surfaces for the molecular and free radical dissociations of H2CS,F2CS and Cl2CS: An ab initio SCF MO study

Energies along the planar symmetric (C_2v) and planar assymetric (C_s paths to molecular dissociation of the ground state thiocarbonyl halides, F₂CS and Cl₂CS, together with their transition state geometries, have been calculated by ab initio SCF MO methods using the STO-3G and 4-31G basis sets. For comparison, results on H₂CS at similar levels of calculation are also included in this report. In addition, the 4-31G^** basis set has been employed to predict the geometries of the ground state species and the endothermicities of their free radical dissociations. The results of experiments in which the lowest excited singlet states of these molecules have been photoexcited are interpreted in light of these calculations. Thermodynamic data for both molecular and free radical dissociations are evaluated and discussed.