共查询到20条相似文献,搜索用时 10 毫秒
1.
P. A. Slepukhin E. S. Salmina V. A. Potemkin M. A. Grishina 《Journal of Structural Chemistry》2013,54(6):1091-1100
X-ray crystallography is used to investigate heteromolecular crystals of 3,6-bis(3,5-dimethylpyrazole-1-yl)-1,2,4,5-tetrazine with NH-donating azole derivatives. The effect is studied of the structure of azole on molecular packing in the crystal and the characteristics of covalent bonds in the molecule of 3,6-disubstituted tetrazine. The distribution of electron density critical points inside crystal cells is analyzed to identify and quantitatively describe the intermolecular interactions underlying the formation of lateral and stacking motifs. 相似文献
2.
The synthesis and properties of rhodium(I) complexes of formulae [“RhCl(diolefin)”2(L)] (or [Rh(Cl(diolefin)(L)]), and [Rh(diolefin)(L)]n(ClO4)n are reported. These complexes react with carbon monoxide to yield the related carbonyl derivatives. Ligands used were pyridazine, 4,6-dimethyl-pyrimidine, 4,6-bis(3,5-dimethylpyrazol-1-yl)pyrimidine, 3,6-bis(3,5-dimethylpyrazol-1-yl)pyridazine and 3-(3,5-dimethyl-pyrazol-1-yl)-6-chloropyridazine. Related iridium(I) and gold(I) compounds are also reported. 相似文献
3.
4.
Pérez-Juste I Graña AM Carballeira L Mosquera RA 《The Journal of chemical physics》2004,121(21):10447-10455
Linear sulfur-carbon chains C(n)S (n=1-6) of astronomical interest were examined by means of several theoretical methods. The three smallest compounds of the series were chosen to evaluate the performance of several computational models, including Hartree-Fock theory, density functional theory with the Becke's three parameter exchange functional and the correlation functional of Lee, Yang, and Parr (B3LYP), and electron-correlated methods (second-order Moller-Plesset perturbation method (MP2), configuration interaction method including single and double excitations (CISD), and quadratic configuration interaction method including single and double excitations (QCISD) in combination with a large variety of basis sets. The systematic comparison between the experiment and theory indicates that the B3LYP/6-311G** method can be considered suitable for the study of the electronic structures of the C(n)S compounds. The electronic ground states of the C(n)S molecules alternate between 1Sigma and 3Sigma for odd and even values of n, respectively. The B3LYP/6-311G** wave functions for these electronic ground states were analyzed by means of the atoms in molecules (AIM) and natural bond orbital (NBO) methods. Both approaches suggest that the electronic structures for the singlet and triplet compounds must be considered separately. According to the NBO method, singlet compounds can be properly represented by acetylenic structures with alternating single and triple bonds (S[triple bond]C-C[triple bond]C...). However, triplet compounds are better described by means of double bond-double bond cumulenic structures (S=C=C=C=C...) as a consequence of the average between different alpha and beta electronic densities. AIM delocalization indexes and NBO interactions between localized orbitals also indicate that these structures are strongly pi delocalized. Finally, the different singlet and triplet structures proposed provide a consistent explanation for the geometries, dipole moments, and spin-density values of the C(n)S compounds studied. 相似文献
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6.
The least-energy dissociation path of the ground state of CH2N2 was determined fromab initio calculations using in a complementary way basis sets of minimal size (STO-3G) and double-zeta (DZ) quality. The results indicate that the least-energy point of attack of the N2 molecule on CH2 (1
A
1) is roughly perpendicular to the molecular plane (93 °), the C and N atoms being almost co-linear (angle C-N-N203 ° with outermost N atom pointing away from CH2). The potential barrier of 1.2 eV found previously on theC
2v
dissociation path, disappears completely along the least-energy dissociation path (point groupC
s
(out-of-plane)). These findings corroborate the Woodward-Hoffman rules for this process since the outermost orbitals of the two intersecting states found in point groupC
2v
(...2b
1 and ...8a
1) both correlate to the same irreducible representation (10á) in point groupC
s
(out-of-plane).Larger basis set calculations (DZ + polarization functions on all centers, 3d
c and 3d
N developed here), were also carried out on CH2N2 (1
A
1,3
A
2 and1
A
2) at the1
A
1 equilibrium geometry and on CH2 (3
B
1) and N2 (1
g
+
) at their respective equilibrium geometries. These calculations, together with consideration of correlation energy differences, yieldD
0
0
(CH2N2,1
A
1) = 19 kcal/mole and vertical excitation energies of 67 and 73 kcal/mole for the3
A
2 and1
A
2 states respectively. The latter value is in good agreement with the measured experimental value: 72.4 kcal/mole corresponding to the maximum of intensity in the1
A
21
A
1 absorption band. 相似文献
7.
8.
A. V. Virovets E. V. Lider V. N. Elokhina M. B. Bushuev L. G. Lavrenova 《Journal of Structural Chemistry》2005,46(2):358-362
1,2,4-Triazole derivative substituted in the 4th position — 4-(3,4-dichlorphenyl)-1,2,4-tirazole — has been synthesized. Crystal and molecular structure of the compound were determined by single crystal X-ray diffraction. Molecular geometry optimization and effective charge calculations were performed by DFT methods. 相似文献
9.
Abraham F. Jalbout Ali Jameel Hameed Bartosz Trzaskowski 《Journal of organometallic chemistry》2007,692(5):1039-1047
A series of 1-(4, 5 and 6-selenenyl derivatives-3-formyl-phenyl) pyrrolidinofullerenes molecules C60-C2H4N-[3-(CHO)C6H3SeX] were investigated theoretically by performing Density Functional Theory calculations at the B3LYP/3-21G∗ level of the theory. The substituents include: X = CN, CH2CH(NH2)CO2H and CH2CH2CH(NH2)CO2H. We have selected these substituents to be in ortho, meta and para positions with relation to formyl group in order to show the effect of such structural change on the electronic properties of the molecules. The theoretical IR spectra, physical, chemical and thermodynamics properties of the molecules studied are obtained and discussed. 相似文献
10.
以卤代吡啶为起始原料与水合肼反应合成肼基吡啶衍生物中间体,该中间体进一步与2,4-戊二酮关环合成了一类新型1-吡啶基-3,5-二甲基吡唑衍生物。对合成目标化合物进行了质谱、核磁表征。并且采用X射线单晶衍射分析方法进一步测定了目标化合物1-(3,5,6-三氯吡啶-2-基)-3,5-二甲基-1氢吡唑(3f)的晶体结构。 相似文献
11.
M. G. Voronkov é. A. Zel’bst V. S. Fundamenskii V. A. Bruskov A. A. Kashaev A. S. Soldatenko Yu. I. Bolgova O. M. Trofimova 《Journal of Structural Chemistry》2011,52(4):828-830
The crystal and molecular structure of a 1-(1-silatranylmethyl)-3,5-dimethylpyrazole complex with zinc dichloride (I) is determined by XRD. The coordination polyhedron of the zinc atom is a tetrahedron formed by two covalent Zn-Cl bonds and
coordination Zn ← N and Zn ← O bonds. Compound I is the first example of how an endocyclic oxygen atom of the silatranyl fragment participates in the coordination of the
metal atom with the formation of a six-membered heterocycle. 相似文献
12.
Nina G. Furmanova Natalya I. Sorokina Valery I. Andrianov Ursula Bologa Alexandru T. Balaban 《Structural chemistry》1991,2(7):651-654
The structure of 1-(3,5-dimethyl-2-furyl)-3-(p-tolyl)-prop-2-en-1-one, C16H16O2 is determined by single-crystal x-ray diffractometry. Crystals are triclinic,
, a=7.381(7), b=8.871(5), c=10.745(13) Å, =93.53(7), =102.25(8),=95.43(7)°, V=682(1) Å3, Z=2, dcalc=1.170 g cm–3, (Cu K)=1.54178 Å,=5.697 cm–1, M=270.30, F(000)=256, R=0.077 for 1601 unique observed reflections. The trans-geometry of the C=C double bond, thes-cis-geometry of the C=C-C=O moiety, and thes-trans arrangement of the carbonyl and furane oxygen atoms are proved. 相似文献
13.
The reactions of azido‐cyclization in 3,6‐di(azido)‐1,2,4,5‐tetrazine were studied by B3LYP hybrid density functional method. The geometries of the reactants, transition states and products were optimized, and the conformation of the initial reactant was determined by IR spectra. In addition, the nucleus‐independent chemical shift (NICS) indices were used to discuss the aromaticity of the products. Moreover, solvent effects were investigated. Results show that the polar solvent DMSO can hardly influence the activation barriers of all the reaction paths; however, it can stabilize the products. Since the activation barriers of azido‐rotation are far less than that of the rate‐determining step (the cyclization of second azido), the products are most probably the mixtures of two isomers (DAT2c and DAT2c'). 相似文献
14.
《Journal of Coordination Chemistry》2012,65(3):550-558
A copper(II) complex with 6-(3,5-dimethyl-1H-pyrazol-1-yl)-2-(pyridin-2-yl)pyrimidin-4-amine (L), [CuLCl2], has been synthesized. This compound is formed irrespective of the Cu?:?L molar ratio (Cu?:?L?=?1?:?1, 2?:?1, and 20?:?1) in the MeOH/H2O/DMF mixture as a single product. ESI-MS data demonstrate that the additional amount of CuCl2 above the Cu?:?L?=?1?:?1 molar ratio, is effectively solvated, and high-nuclearity species are formed in trace amounts in the solution. The complex adopts a distorted square-pyramidal geometry with two chlorides and three nitrogen atoms from L. The electronic spectrum of the complex contains a broad band with a maximum at 12,820?cm?1 within the region characteristic for square-pyramidal chromophores CuA5 (A?=?Cl, N). Due to Cu?···?Cl contacts, the molecules of [CuLCl2] form the dinuclear [CuLCl2]2 unit. Surprisingly, the NH2-group participates in the formation of NH?···?Cl hydrogen bonds instead of the formation of (NH?···?N3(pyrimidine))2 synthon, which is common for N-heteroaromatic compounds containing the NH2-group in the α-position to aza-atom. These hydrogen bonds together with Cu?···?Cl contacts result in the formation of a 3-D-structure. 相似文献
15.
I. B. Dzvinchuk A. N. Chernega M. O. Lozinskii A. A. Tolmachev 《Chemistry of Heterocyclic Compounds》2008,44(6):682-689
2-(3,6-Diaryl-2,5-dihydropyridazin-4-yl)-1H-benzimidazoles undergo a previously unknown type of recyclization of the pyridazine
ring to a pyrazole to give 2-[(3,5-diarylpyrazol-4-yl)methyl]-1H-benzimidazoles. It is suggested that the mechanism of this
conversion, which includes formation of a secondary enhydrazine group in the diazine ring and its subsequent contraction,
occurs after the intramolecular formation and opening of a cyclopropane ring.
__________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 853–861, June, 2008. 相似文献
16.
We report a theoretical study based on density functional theory (DFT) on the geometric and electronic structure, linear optical and second-order nonlinear optical properties of a series of new inorganic-organic hybrid hexamolybdate-organoimido-(car)boranes. By the incorporation of borane/carborane at the end of the phenyl ring of the organoimido segment, the studied systems show excellent nonlinear optical (NLO) response than the organoimido-substituted hexamolybdate. The computed static first hyperpolarizability β(vec) value of [Mo(6)O(18)(NC(8)H(8))(B(12)H(11))](4-) (II) is largest, -167.2 × 10(-30) esu, and a higher β(vec) value of [Mo(6)O(18)(NC(8)H(8))(C(2)B(10)H(11))](2-) (III-2p) is 58.6 × 10(-30) esu. Moreover, the time-dependent (TD)DFT calculation illustrates that the maximum absorption, which is helpful for the large NLO responses, is mainly assigned to the charge transfer (CT) from (car)borane and organoimido segment to the hexamolybdate cluster. The density of density (DOS) calculations further illustrate the excitation from valence orbitals of boron atoms to that of Mo and O atoms in hexamolybdate can be responsible for larger NLO responses. The linear and nonlinear optical properties of species III both vary with the position of the vertex on the carborane. Furthermore, the order of the β(vec) values is consistent with the bathochromic shift of the maximum absorption for our studied systems, and the studied systems show a wider transparency range extending into the entire visible and infrared (IR) region. 相似文献
17.
The title compounds, C16H16O5 (I) and C16H16O5·H2O (II), were structurally characterized by single-crystal X-ray diffraction. Compound I crystallizes in monoclinic space group P21/c with a = 10.5574(10), b = 8.3576(9), c = 16.5528(16) , β = 91.762(3)°, Z = 4, R = 0.0524 and wR = 0.1084. The molecules are jointed into a chain by intermolecular O-H···O and C-H···O hydrogen bonds, which form layers parallel to (001). The chains run along the [110] and [110] directions alternatively layer by layer, and are assembled into a network by intermolecular O-H···O (carboxyl) hydrogen bonds. On the other hand, the hydrate complex (II) crystallizes in the triclinic space group P1 with a = 5.1451(2), b = 10.4583(4), c = 14.8267(5) , α = 70.900(2), β = 82.478(2), γ = 81.359(2)°, Z = 2, R = 0.0393 and wR = 0.0983. The molecules are linked into infinite two-dimensional ribbons by O-H···O (carbonyl) and solvent-bridged O-H···O hydrogen bonds. 相似文献
18.
The electronic structure and the stability of both neutral and singly charged (TiO2)n clusters with n = 1-9 have been investigated using the density functional B3LYP/LANL2DZ method. The lowest-lying singlet clusters tend to form some compact structures with one or two terminal Ti-O bonds, which are about 1.4-2.5 eV more stable than the corresponding triplet structures. For the lowest-lying structures, strong infrared absorption lines at 988-1020 cm(-1) due to terminal Ti-O bonds and below 930 cm(-1) due to Ti-O-Ti bridging bonds may be observed, with some characteristic lines at 530-760 cm(-1) due to 3-fold coordinated O-atoms that are comparable with the spectra of rutile and anatase bulk. The holes and excited electrons within triplet structures tend to be localized on the least coordinated O- and Ti-atoms, respectively, with some exceptions possibly due to the electron-hole interaction. The extra electrons within (TiO2)n- clusters and the holes within (TiO2)n+ clusters show a clearer preference of location on the least coordinated Ti- and O-atoms, respectively. For the lowest-lying (TiO2)n clusters, the cluster formation energy per TiO2 unit and the electron affinity tend to increase whereas the ionization potential tends to decrease with the cluster size n. On the other hand, the singlet-triplet and HOMO-LUMO gaps represent the lower and upper limits of the TiO2 bulk band gaps, respectively. The theoretical results agree well with the available experimental data and may be helpful for understanding the chemistry of small (TiO2)n clusters. 相似文献
19.
S. T. Malinovskii V. P. Tashchi M. Z. Krimer A. B. Kamenskii Yu. G. Putsykin 《Russian Chemical Bulletin》1995,44(4):695-698
The synthesis and X-ray structural study of 1-(4-chlorophenyl)-3-(5-methyl-1,3-dioxan-5-yl)-(1,2), (3,4)-diepoxybutane are described.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 715–718, April, 1995. 相似文献
20.
The (TCNE)(2)(2)(-) dimer dianion formed by connecting two TCNE(-) anions via a four-center, two-electron pi-orbital bond is studied using ab initio theoretical methods and a model designed to simulate the stabilization due to surrounding counterions. (TCNE)(2)(2)(-) is examined as an isolated species and in a solvation environment representative of tetrahydrofuran (THF) solvent. The intrinsic strength of this novel bond and the influences of internal Coulomb repulsions, of solvent stabilization and screening, and of counterion stabilization are all considered. The geometry, electronic and thermodynamic stabilities, electronic absorption spectra, and electron detachment energies of this novel dianion are examined to help understand recent experimental findings. Our findings lead us to conclude that the (TCNE)(2)(2)(-) dianion's observation in solid materials is likely a result of its stabilization by surrounding countercations. Moreover, our results suggest the dianion is geometrically metastable in THF solution, with a barrier to dissociation into two TCNE(-) anions that can be quickly surmounted at room temperature but not at 77 K. This finding is consistent with what is observed in laboratory studies of low- and room-temperature solutions of salts containing this dianion. Finally, we assign two peaks observed (at 77 K in methyl-THF glass) in the UV-vis region to (1) electronic transitions involving the four-center orbitals and (2) detachment of an electron from the four-center pi-bonding orbital to generate (TCNE)(2)(-) + e(-). 相似文献