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1.
The title two‐dimensional coordination polymer, [Na(C2H8NO6P2)]n, was characterized using powder X‐ray diffraction data and its structure refined using the Rietveld method. The asymmetric unit contains one Na+ cation and one (1‐azaniumylethane‐1,1‐diyl)bis(hydrogen phosphonate) anion. The central Na+ cation exhibits distorted octahedral coordination geometry involving two deprotonated O atoms, two hydroxy O atoms and two double‐bonded O atoms of the bisphosphonate anion. Pairs of sodium‐centred octahedra share edges and the pairs are in turn connected to each other by the biphosphonate anion to form a two‐dimensional network parallel to the (001) plane. The polymeric layers are connected by strong O—H...O hydrogen bonding between the hydroxy group and one of the free O atoms of the bisphosphonate anion to generate a three‐dimensional network. Further stabilization of the crystal structure is achived by N—H...O and O—H...O hydrogen bonding.<!?tpb=18.7pt>  相似文献   

2.
A high‐yield synthesis toward 5,5′‐bis(silyl)‐functionalized 3,3′‐dibromo‐2,2′‐dithiophenes with very efficient work‐up procedure is presented. The molecular structures of two silyl functionalized dibromo‐dithiophenes in the solid state have been determined to investigate the structural influences of different functional groups on the degree of π‐conjugation within the dithiophene moieties, as well as their packing properties. The planar alignment of the tert‐butyldimethylsilyl‐functionalized dibromo‐dithiophene shows a significantly higher degree of conjugation of the π‐system with a more favorable molecular packing than the skewed arrangement of the triisopropylsilyl‐substituted species. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

3.
The title coordination polymer, poly[bis[μ3‐4‐(3,2′:6′,3′′‐terpyridin‐4′‐yl)benzoato]cadmium(II)], [Cd(C22H14N3O2)2]n or [Cd(3‐cptpy)2]n, (I), has been synthesized solvothermally and characterized by IR spectroscopy, thermogravimetric analysis, and single‐crystal and powder X‐ray diffraction. The structure is composed of 3‐cptpy? ligands bridging Cd atoms, with each Cd atom coordinated by six ligands and each ligand coordinating to three Cd atoms. Each Cd atom is in a slightly distorted trans‐N2O4 octahedral environment, forming a two‐dimensional layer structure with a (3,6)‐connected topology. Layers are linked to each other by π–π stacking, resulting in a three‐dimensional supramolecular framework. The strong luminescence and good thermal stability of (I) indicate that it can potentially be used as a luminescence sensor. The compound also shows a highly selective and sensitive response to 2,4,6‐trinitrophenol through the luminescence quenching effect.  相似文献   

4.
Single crystals of the vanadate garnet Ca2NaCd2V3O12 (dicalcium sodium dicadmium trivanadate) were synthesized using the floating‐zone method and the crystal structure was investigated using single‐crystal X‐ray diffraction. We considered the effectiveness of substitution of the Y‐site cation with reference to previous structural studies of vanadate garnets. The structures of vanadate garnets are subject to geometric constraints similar to those of silicate garnets. These constraints force the tetrahedral–dodecahedral shared edge length in vanadate garnets to become shorter than the unshared dodecahedral edge length, as in ugrandite (uvarovite, grossular and andradite) garnets. However, the vanadate garnet Ca2NaCd2V3O12 exhibits the normal structural feature, similar to pyralspite (pyrope, almandine and spessartine) garnets, namely that the dodecahedral–dodecahedral shared edge length is shorter than the unshared dodecahedral edge length. With increasing ionic radius of the Y‐site cation, the atomic coordinates x, y and z of oxygen adopt values which satisfy Pauling's third rule.  相似文献   

5.
The structure of γ‐alumina (Al21+1/32+2/3O32) crystals obtained as a product of a corrosion reaction between β‐sialon and steel was refined in the space group Fdm. The oxygen sublattice is fully occupied. The refined occupancy parameters are 0.83 (3), 0.818 (13), 0.066 (14) and 0.044 (18) for Al ions in 8a, 16d, 16c and 48f positions, respectively. The Al ions are distributed over octa­hedral and tetra­hedral sites in a 63:37 ratio, with 6% of all Al ions occupying non‐spinel positions.  相似文献   

6.
In the crystal structure of O,O′‐diethyl N‐(2,4,6‐trimethylphenyl)thiophosphate, C13H22NO2PS, two symmetrically independent thiophosphoramide molecules are linked through N—H…S and N—H…π hydrogen bonds to form a noncentrosymmetric dimer, with Z′ = 2. The strengths of the hydrogen bonds were evaluated using density functional theory (DFT) at the M06‐2X level within the 6‐311++G(d,p) basis set, and by considering the quantum theory of atoms in molecules (QTAIM). It was found that the N—H…S hydrogen bond is slightly stronger than the N—H…π hydrogen bond. This is reflected in differences between the calculated N—H stretching frequencies of the isolated molecules and the frequencies of the same N—H units involved in the different hydrogen bonds of the hydrogen‐bonded dimer. For these hydrogen bonds, the corresponding charge transfers, i.e. lp (or π)→σ*, were studied, according to the second‐order perturbation theory in natural bond orbital (NBO) methodology. Hirshfeld surface analysis was applied for a detailed investigation of all the contacts participating in the crystal packing.  相似文献   

7.
Sodium bis[2‐(3′,6′,9′‐trioxadecyl)‐1,2‐dicarba‐closo‐dodecaborane‐1‐carboxylato]triphenylstannate, [(CH3OCH2CH2OCH2CH2OCH2CH2)‐1,2‐C2B10H10‐9‐COO)2SnPh3]? Na+, compound 1, was synthesized by the 1:1 condensation of triphenyltin(IV) hydroxide with 2‐(3′,6′,9′‐trioxadecyl)‐1,2‐dicarba‐closo‐dodecaborane‐1‐carboxylic acid and crystallized in the presence of sodium bicarbonate. Its structure was determined by spectroscopy, elemental analysis and X‐ray diffraction. The structure of 1 consists of trigonal bipyramidal [Sn(Ph)3(L)2]? anions and Na+ cations coordinated by oxygen atoms of polyoxaalkyl chains of different stannate anions, forming cation–anion chains elongated along the c axis. Compound 1 is significantly more active in vitro against seven tumour cell lines of human origin than 5‐fluorouracil, cis‐platin, carboplatin, and previously reported organotin carboranecarboxylates, but is less active than organotin polyoxaalkylcarboxylates. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

8.
4′‐Substituted derivatives of 2,2′:6′,2′′‐terpyridine with N‐containing heteroaromatic substituents, such as pyridyl groups, might be able to coordinate metal centres through the extra N‐donor atom, in addition to the chelating terpyridine N atoms. The incorporation of these peripheral N‐donor sites would also allow for the diversification of the types of noncovalent interactions present, such as hydrogen bonding and π–π stacking. The title compound, C24H16N4, consists of a 2,2′:6′,2′′‐terpyridine nucleus (tpy), with a pendant isoquinoline group (isq) bound at the central pyridine (py) ring. The tpy nucleus deviates slightly from planarity, with interplanar angles between the lateral and central py rings in the range 2.24 (7)–7.90 (7)°, while the isq group is rotated significantly [by 46.57 (6)°] out of this planar scheme, associated with a short Htpy…Hisq contact of 2.32 Å. There are no strong noncovalent interactions in the structure, the main ones being of the π–π and C—H…π types, giving rise to columnar arrays along [001], further linked by C—H…N hydrogen bonds into a three‐dimensional supramolecular structure. An Atoms In Molecules (AIM) analysis of the noncovalent interactions provided illuminating results, and while confirming the bonding character for all those interactions unquestionable from a geometrical point of view, it also provided answers for some cases where geometric parameters are not informative, in particular, the short Htpy…Hisq contact of 2.32 Å to which AIM ascribed an attractive character.  相似文献   

9.
The title mononuclear CoII complex, [Co(C5H7N6)2(C14H8O5)2(H2O)2]·2H2O, has been synthesized and its crystal structure determined by X‐ray diffraction. The complex crystallizes in the triclinic space group P, with one formula unit per cell (Z = 1 and Z′ = ). It consists of a mononuclear unit with the CoII ion on an inversion centre coordinated by two 2,6‐diamino‐7H‐purin‐1‐ium cations, two 4,4′‐oxydibenzoate anions (in a nonbridging κO‐monodentate coordination mode, which is less common for the anion in its CoII complexes) and two water molecules, defining an octahedral environment around the metal atom. There is a rich assortment of nonbonding interactions, among which a strong N+—H…O bridge, with a short N…O distance of 2.5272 (18) Å, stands out, with the H atom ostensibly displaced away from its expected position at the donor side, towards the acceptor. The complex molecules assemble into a three‐dimensional hydrogen‐bonded network. A variable‐temperature magnetic study between 2 and 300 K reveals an orbital contribution to the magnetic moment and a weak antiferromagnetic interaction between CoII centres as the temperature decreases. The model leads to the following values: A (crystal field strength) = 1.81, λ (spin‐orbit coupling) = −59.9 cm−1, g (Landé factor) = 2.58 and zJ (exchange coupling) = −0.5 cm−1.  相似文献   

10.
A detailed structural analysis has been performed for N,N′‐bis(4‐chlorophenyl)‐7,8,11,12‐tetraoxaspiro[5.6]dodecane‐9,10‐diamine, C20H22Cl2N2O4, (I), N,N′‐bis(2‐fluorophenyl)‐7,8,11,12‐tetraoxaspiro[5.6]dodecane‐9,10‐diamine, C20H22F2N2O4, (II), and N,N′‐bis(4‐fluorophenyl)‐7,8,11,12‐tetraoxaspiro[5.6]dodecane‐9,10‐diamine, C20H22F2N2O4, (III). The seven‐membered ring with two peroxide groups adopts a twist‐chair conformation in all three compounds. The lengths of the C—N and O—O bonds are slightly shorter than the average statistical values found in the literature for azepanes and 1,2,4,5‐tetraoxepanes. The geometry analysis of compounds (I)–(III), the topological analysis of the electron density at the (3, ?1) bond critical points within Bader's quantum theory of `Atoms in molecules' (QTAIM) and NBO (natural bond orbital) analysis at the B3LYP/6‐31G(d,2p) level of theory showed that there are nO→σ*(C—O), nN→σ*(C—O) and nO→σ*(C—N) stereoelectronic effects. The molecules of compounds (I) and (III) are packed in the crystals as zigzag chains due to strong N—H…O and C—H…O hydrogen‐bond interactions, whereas the molecules of compound (II) form chains in the crystals bound by N—H…O, C—H…π and C—H…O contacts. All these data show that halogen atoms and their positions have a minimal effect on the geometric parameters, stereoelectronic effects and crystal packing of compounds (I)–(III), so that the twist‐chair conformation of the tetraoxepane ring remains unchanged.  相似文献   

11.
An efficient approach for the regioselective synthesis of (5‐amino‐3‐methylsulfanyl‐1H‐1,2,4‐triazol‐1‐yl)(2‐fluorophenyl)methanone, C10H9FN4OS, (3), from the N‐acylation of 3‐amino‐5‐methylsulfanyl‐1H‐1,2,4‐triazole, (1), with 2‐fluorobenzoyl chloride has been developed. Heterocyclic amide (3) was used successfully as a strategic intermediate for the preparation of 2‐fluoro‐N‐(3‐methylsulfanyl‐1H‐1,2,4‐triazol‐5‐yl)benzamide, C10H9FN4OS, (4), through a microwave‐assisted Fries rearrangement under catalyst‐ and solvent‐free conditions. Theoretical studies of the prototropy process of (1) and the Fries rearrangement of (3) to provide (4), involving the formation of an intimate ion pair as the key step, were carried out by density functional theory (DFT) calculations. The crystallographic analysis of the intermolecular interactions and the energy frameworks based on the effects of the different molecular conformations of (3) and (4) are described.  相似文献   

12.
We report a new polymorph of (1E,4E)‐1,5‐bis(4‐fluorophenyl)penta‐1,4‐dien‐3‐one, C17H12F2O. Contrary to the precedent literature polymorph with Z′ = 3, our polymorph has one half molecule in the asymmetric unit disordered over two 50% occupancy sites. Each site corresponds to one conformation around the single bond vicinal to the carbonyl group (so‐called anti or syn). The other half of the bischalcone is generated by twofold rotation symmetry, giving rise to two half‐occupied and overlapping molecules presenting both anti and syn conformations in their open chain. Such a disorder allows for distinct patterns of intermolecular C—H…O contacts involving the carbonyl and anti‐oriented β‐C—H groups, which is reflected in three 13C NMR chemical shifts for the carbonyl C atom. Here, we have also assessed the cytotoxicity of three symmetric bischalcones through their in vitro antitumour potential against three cancer cell lines. Cytotoxicity assays revealed that this biological property increases as halogen electronegativity increases.  相似文献   

13.
The photoluminescence characteristics of the [Cd(bipy)3][PF6]2 complex are reported. A moderately large quantum yield (φ) of 1.07 × 10?2 is exhibited in acetonitrile solution at 298 K. Crystallography shows the dication to have a distorted octahedral geometry and the crystal structure to be stabilized by C? H···π and C? H···F interactions. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

14.
The crystal structure of the lanthanum titanium bismuthide La3TiBi5 (Pearson code hP18, Wyckoff sequence b d g2) has been established from single‐crystal X‐ray diffraction data and analyzed in detail using first‐principles calculations. There are no anomalies pertaining to the atomic displacement parameter of the Ti site, previously reported based on a powder X‐ray diffraction analysis of this compound. The anionic substructure contains columns of face‐sharing TiBi6 octahedra and linear Bi chains. Due to a significant La(5d) and Bi(6p) orbital mixing, a perfectly one‐dimensional character of the Bi chains is not realised, while a three‐dimensional electronic structure is established instead. The latter fact explains the stability of the polyanionic pnictide units against Peierls distortions. The hypervalent bonding in the Bi chains is reflected in a rather long Bi—Bi distance of 3.2264 (4) Å and a typical pattern of bonding and antibonding interactions, as revealed by electronic structure calculations.  相似文献   

15.
The application of transition metal chelates as chemotherapeutic agents has the advantage that they can be used as a scaffold around which ligands with DNA recognition elements can be anchored. The facile substitution of these components allows for the DNA recognition and binding properties of the metal chelates to be tuned. Copper is a particularly interesting choice for the development of novel metallodrugs as it is an endogenous metal and is therefore less toxic than other transition metals. The title compound, [Cu(C16H11N2O)2], was synthesized by reacting N‐(quinolin‐8‐yl)benzamide and the metal in a 2:1 ratio. Ligand coordination required deprotonation of the amide N—H group and the isolated complex is therefore neutral. The metal ion adopts a flattened tetrahedral coordination geometry with the ligands in a pseudo‐trans configuration. The free rotation afforded by the formal single bond between the amide group and phenyl ring allows the phenyl rings to rotate out‐of‐plane, thus alleviating nonbonded repulsion between the phenyl rings and the quinolyl groups within the complex. Weak C—H…O interactions stabilize a dimer in the solid state. Density functional theory (DFT) simulations at the PBE/6‐311G(dp) level of theory show that the solid‐state structure (C1 symmetry) is 79.33 kJ mol−1 higher in energy than the lowest energy gas‐phase structure (C2 symmetry). Natural bond orbital (NBO) analysis offers an explanation for the formation of the C—H…O interactions in electrostatic terms, but the stabilizing effect is insufficient to support the dimer in the gas phase.  相似文献   

16.
The crystal structure of the gadolinium iron bismuthide Gd6FeBi2 has been characterized by single‐crystal X‐ray diffraction data and analyzed in detail using first‐principles calculations. The structure is isotypic with the Zr6CoAl2 structure, which is a variant of the ZrNiAl structure and its binary prototype Fe2P (Pearson code hP9, Wyckoff sequence g f d a). As such, the structure is best viewed as an array of tricapped trigonal prisms of Gd atoms centered alternately by Fe and Bi. The magnetic‐ordering temperature of this compound (ca 350 K) is much higher than that of other rare‐earth metal‐rich phases with the same or related structures. It is also higher than the ordering temperature of many other Gd‐rich ternary phases, where the magnetic exchange is typically governed by Ruderman–Kittel–Kasuya–Yosida (RKKY) interactions. First‐principles calculations reveal a larger than expected Gd magnetic moment, with the additional contribution arising from the Gd 5d electrons. The electronic structure analysis suggests strong Gd 5d–Fe 3d hybridization to be the cause of this effect, rather than weak interactions between Gd and Bi. These details are of importance for understanding the magnetic response and explaining the high ordering temperature in this material.  相似文献   

17.
The design of new organic–inorganic hybrid ionic materials is of interest for various applications, particularly in the areas of crystal engineering, supramolecular chemistry and materials science. The monohalogenated intermediates 1‐(2‐chloroethyl)pyridinium chloride, C5H5NCH2CH2Cl+·Cl, (I′), and 1‐(2‐bromoethyl)pyridinium bromide, C5H5NCH2CH2Br+·Br, (II′), and the ionic disubstituted products 1,1′‐(ethylene‐1,2‐diyl)dipyridinium dichloride dihydrate, C12H14N22+·2Cl·2H2O, (I), and 1,1′‐(ethylene‐1,2‐diyl)dipyridinium dibromide, C12H14N22+·2Br, (II), have been isolated as powders from the reactions of pyridine with the appropriate 1,2‐dihaloethanes. The monohalogenated intermediates (I′) and (II′) were characterized by multinuclear NMR spectroscopy, while (I) and (II) were structurally characterized using powder X‐ray diffraction. Both (I) and (II) crystallize with half the empirical formula in the asymmetric unit in the triclinic space group P. The organic 1,1′‐(ethylene‐1,2‐diyl)dipyridinium dications, which display approximate C2h symmetry in both structures, are situated on inversion centres. The components in (I) are linked via intermolecular O—H…Cl, C—H…Cl and C—H…O hydrogen bonds into a three‐dimensional framework, while for (II), they are connected via weak intermolecular C—H…Br hydrogen bonds into one‐dimensional chains in the [110] direction. The nucleophilic substitution reactions of 1,2‐dichloroethane and 1,2‐dibromoethane with pyridine have been investigated by ab initio quantum chemical calculations using the 6–31G** basis. In both cases, the reactions occur in two exothermic stages involving consecutive SN2 nucleophilic substitutions. The isolation of the monosubstituted intermediate in each case is strong evidence that the second step is not fast relative to the first.  相似文献   

18.
Reaction of Ti(OCH2CH2OR)4 (R?CH3 and C2H5) with 8‐hydroxyquinoline in benzene at room temperature resulted in the formation of Ti(C9H6NO)2(OCH2CH2OR)2, characterized by IR, 1H‐NMR, UV and mass spectroscopies. The molecular structure of Ti(C9H6NO)2(OCH2CH2OCH3)2 has been determined by single‐crystal X‐ray structure analysis. The geometry at titanium is a distorted octahedron, with the nitrogen atoms of quinolinate occupying the trans position with respect to oxygens of the 2‐methoxyethoxy groups. The prepared quinolinate derivatives of titanium alkoxides are very stable towards hydrolysis and harsh conditions are required for hydrolytic cleavage. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

19.
In the structure of 2‐(4‐chloroanilino)‐1,3,2λ4‐diazaphosphol‐2‐one, C12H11ClN3OP, each molecule is connected with four neighbouring molecules through (N—H)2…O hydrogen bonds. These hydrogen bonds form a tubular arrangement along the [001] direction built from R 33(12) and R 43(14) hydrogen‐bond ring motifs, combined with a C (4) chain motif. The hole constructed in the tubular architecture includes a 12‐atom arrangement (three P, three N, three O and three H atoms) belonging to three adjacent molecules hydrogen bonded to each other. One of the N—H groups of the diazaphosphole ring, not co‐operating in classical hydrogen bonding, takes part in an N—H…π interaction. This interaction occurs within the tubular array and does not change the dimension of the hydrogen‐bond pattern. The energies of the N—H…O and N—H…π hydrogen bonds were studied by NBO (natural bond orbital) analysis, using the experimental hydrogen‐bonded cluster of molecules as the input file for the chemical calculations. In the 1H NMR experiment, the nitrogen‐bound proton of the diazaphosphole ring has a high value of 17.2 Hz for the 2J H–P coupling constant.  相似文献   

20.
Electrostatic interactions between localized integral charges make the stability and structure of highly charged small and rigid organics intriguing. Can σ/π‐electron delocalization compensate reduced conformational freedom by lowering the repulsion between identical charges? The crystal structure of the title salt, C14H16N42+·2CF3SO3, (2), is described and compared with that of the 2,2′′‐bis(diphenylphosphanyl) derivative, (4). The conformations of the dications and their interactions with neighbouring trifluoromethanesulfonate anions are first analyzed from the standpoint of formal electrostatic effects. Neither cation exhibits any geometrical strain induced by the intrinsic repulsion between the positive charges. In contrast, the relative orientation of the imidazolium rings [i.e. anti for (2) and syn for (4)] is controlled by different configurations of the interactions with the closest trifluoromethanesulfonate anions. The long‐range arrangement is also found to be specific: beyond the formal electrostatic packing, C—H…O and C—H…F contacts have no definite `hydrogen‐bond' character but allow the delineation of layers, which are either pleated or flat in the packing of (2) or (4), respectively.  相似文献   

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