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1.
The results of seven cocrystallization experiments of the antithyroid drug 6‐methyl‐2‐thiouracil (MTU), C5H6N2OS, with 2,4‐diaminopyrimidine, 2,4,6‐triaminopyrimidine and 6‐amino‐3H‐isocytosine (viz. 2,6‐diamino‐3H‐pyrimidin‐4‐one) are reported. MTU features an ADA (A = acceptor and D = donor) hydrogen‐bonding site, while the three coformers show complementary DAD hydrogen‐bonding sites and therefore should be capable of forming an ADA/DAD N—H...O/N—H...N/N—H...S synthon with MTU. The experiments yielded one cocrystal and six cocrystal solvates, namely 6‐methyl‐2‐thiouracil–2,4‐diaminopyrimidine–1‐methylpyrrolidin‐2‐one (1/1/2), C5H6N2OS·C4H6N4·2C5H9NO, (I), 6‐methyl‐2‐thiouracil–2,4‐diaminopyrimidine (1/1), C5H6N2OS·C4H6N4, (II), 6‐methyl‐2‐thiouracil–2,4‐diaminopyrimidine–N,N‐dimethylacetamide (2/1/2), 2C5H6N2OS·C4H6N4·2C4H9NO, (III), 6‐methyl‐2‐thiouracil–2,4‐diaminopyrimidine–N,N‐dimethylformamide (2/1/2), C5H6N2OS·0.5C4H6N4·C3H7NO, (IV), 2,4,6‐triaminopyrimidinium 6‐methyl‐2‐thiouracilate–6‐methyl‐2‐thiouracil–N,N‐dimethylformamide (1/1/2), C4H8N5+·C5H5N2OS·C5H6N2OS·2C3H7NO, (V), 6‐methyl‐2‐thiouracil–6‐amino‐3H‐isocytosine–N,N‐dimethylformamide (1/1/1), C5H6N2OS·C4H6N4O·C3H7NO, (VI), and 6‐methyl‐2‐thiouracil–6‐amino‐3H‐isocytosine–dimethyl sulfoxide (1/1/1), C5H6N2OS·C4H6N4O·C2H6OS, (VII). Whereas in cocrystal (I) an R22(8) interaction similar to the Watson–Crick adenine/uracil base pair is formed and a two‐dimensional hydrogen‐bonding network is observed, the cocrystals (II)–(VII) contain the triply hydrogen‐bonded ADA/DAD N—H...O/N—H...N/N—H...S synthon and show a one‐dimensional hydrogen‐bonding network. Although 2,4‐diaminopyrimidine possesses only one DAD hydrogen‐bonding site, it is, due to orientational disorder, triply connected to two MTU molecules in (III) and (IV).  相似文献   

2.
A fixed hydrogen‐bonding motif with a high probability of occurring when appropriate functional groups are involved is described as a `supramolecular hydrogen‐bonding synthon'. The identification of these synthons may enable the prediction of accurate crystal structures. The rare chiral hydrogen‐bonding motif R53(10) was observed previously in a cocrystal of 2,4,6‐trichlorophenol, 2,4‐dichlorophenol and dicyclohexylamine. In the title solvated salt, 2C4H12N+·C6H3Cl2O·(C6H3Cl2O·C6H4Cl2O)·2C4H8O, five components, namely two tert‐butylammonium cations, one 2,4‐dichlorophenol molecule, one 2,4‐dichlorophenolate anion and one 2,6‐dichlorophenolate anion, are bound by N—H…O and O—H…O hydrogen bonds to form a hydrogen‐bonded ring, with the graph‐set motif R53(10), which is further associated with two pendant tetrahydrofuran molecules by N—H…O hydrogen bonds. The hydrogen‐bonded ring has internal symmetry, with a twofold axis running through the centre of the 2,6‐dichlorophenolate anion, and is isostructural with a previous and related structure formed from 2,4‐dichlorophenol, dicyclohexylamine and 2,4,6‐trichlorophenol. In the title crystal, helical columns are built by the alignment and twisting of the chiral hydrogen‐bonded rings, along and across the c axis, and successive pairs of rings are associated with each other through C—H…π interactions. Neighbouring helical columns are inversely related and, therefore, no chirality is sustained, in contrast to the previous case.  相似文献   

3.
In bis(2‐aminoanilinum) fumarate, 2C6H9N2+·C4H2O42−, (I), the asymmetric unit consists of two aminoanilinium cations and one fumarate dianion, whereas in 3‐methylanilinium hydrogen fumarate, C7H10N+·C4H3O4, (II), and 4‐chloroanilinium hydrogen fumarate, C6H7ClN+·C4H3O4, (III), the asymmetric unit contains two symmetry‐independent hydrogen fumate anions and anilinium cations with a slight difference in their geometric parameters; the two salts are isostructural. In (II) and (III), the carboxylic acid H atoms of the anions are disordered across both ends of the anion, with equal site occupancies of 0.50. Both the 4‐chloroanilinium cations of (III) are disordered over two orientations with major occupancies fixed at 0.60 in each case. The hydrogen fumarate anions of (II) and (III) form one‐dimensional anionic chains linked through O—H...O hydrogen bonds. Salts (II) and (III) form two‐dimensional supramolecular sheets built from R44(16), R44(18), R55(25) and C22(14) motifs extending parallel to the (010) plane, whereas in (I), an (010) sheet is formed built from two R43(13) motifs, two R22(9) motifs and an R44(18) motif.  相似文献   

4.
A path to new synthons for application in crystal engineering is the replacement of a strong hydrogen‐bond acceptor, like a C=O group, with a weaker acceptor, like a C=S group, in doubly or triply hydrogen‐bonded synthons. For instance, if the C=O group at the 2‐position of barbituric acid is changed into a C=S group, 2‐thiobarbituric acid is obtained. Each of the compounds comprises two ADA hydrogen‐bonding sites (D = donor and A = acceptor). We report the results of cocrystallization experiments of barbituric acid and 2‐thiobarbituric acid, respectively, with 2,4‐diaminopyrimidine, which contains a complementary DAD hydrogen‐bonding site and is therefore capable of forming an ADA/DAD synthon with barbituric acid and 2‐thiobarbituric acid. In addition, pure 2,4‐diaminopyrimidine was crystallized in order to study its preferred hydrogen‐bonding motifs. The experiments yielded one ansolvate of 2,4‐diaminopyrimidine (pyrimidine‐2,4‐diamine, DAPY), C4H6N4, (I), three solvates of DAPY, namely 2,4‐diaminopyrimidine–1,4‐dioxane (2/1), 2C4H6N4·C4H8O2, (II), 2,4‐diaminopyrimidine–N,N‐dimethylacetamide (1/1), C4H6N4·C4H9NO, (III), and 2,4‐diaminopyrimidine–1‐methylpyrrolidin‐2‐one (1/1), C4H6N4·C5H9NO, (IV), one salt of barbituric acid, viz. 2,4‐diaminopyrimidinium barbiturate (barbiturate is 2,4,6‐trioxopyrimidin‐5‐ide), C4H7N4+·C4H3N2O3, (V), and two solvated salts of 2‐thiobarbituric acid, viz. 2,4‐diaminopyrimidinium 2‐thiobarbiturate–N,N‐dimethylformamide (1/2) (2‐thiobarbiturate is 4,6‐dioxo‐2‐sulfanylidenepyrimidin‐5‐ide), C4H7N4+·C4H3N2O2S·2C3H7NO, (VI), and 2,4‐diaminopyrimidinium 2‐thiobarbiturate–N,N‐dimethylacetamide (1/2), C4H7N4+·C4H3N2O2S·2C4H9NO, (VII). The ADA/DAD synthon was succesfully formed in the salt of barbituric acid, i.e. (V), as well as in the salts of 2‐thiobarbituric acid, i.e. (VI) and (VII). In the crystal structures of 2,4‐diaminopyrimidine, i.e. (I)–(IV), R22(8) N—H…N hydrogen‐bond motifs are preferred and, in two structures, additional R32(8) patterns were observed.  相似文献   

5.
Doubly and triply hydrogen‐bonded supramolecular synthons are of particular interest for the rational design of crystal and cocrystal structures in crystal engineering since they show a high robustness due to their high stability and good reliability. The compound 5‐methyl‐2‐thiouracil (2‐thiothymine) contains an ADA hydrogen‐bonding site (A = acceptor and D = donor) if the S atom is considered as an acceptor. We report herein the results of cocrystallization experiments with the coformers 2,4‐diaminopyrimidine, 2,4‐diamino‐6‐phenyl‐1,3,5‐triazine, 6‐amino‐3H‐isocytosine and melamine, which contain complementary DAD hydrogen‐bonding sites and, therefore, should be capable of forming a mixed ADADAD N—H…S/N—H…N/N—H…O synthon (denoted synthon 3sN·S;N·N;N·O), consisting of three different hydrogen bonds with 5‐methyl‐2‐thiouracil. The experiments yielded one cocrystal and five solvated cocrystals, namely 5‐methyl‐2‐thiouracil–2,4‐diaminopyrimidine (1/2), C5H6N2OS·2C4H6N4, (I), 5‐methyl‐2‐thiouracil–2,4‐diaminopyrimidine–N,N‐dimethylformamide (2/2/1), 2C5H6N2OS·2C4H6N4·C3H7NO, (II), 5‐methyl‐2‐thiouracil–2,4‐diamino‐6‐phenyl‐1,3,5‐triazine–N,N‐dimethylformamide (2/2/1), 2C5H6N2OS·2C9H9N5·C3H7NO, (III), 5‐methyl‐2‐thiouracil–6‐amino‐3H‐isocytosine–N,N‐dimethylformamide (2/2/1), (IV), 2C5H6N2OS·2C4H6N4O·C3H7NO, (IV), 5‐methyl‐2‐thiouracil–6‐amino‐3H‐isocytosine–N,N‐dimethylacetamide (2/2/1), 2C5H6N2OS·2C4H6N4O·C4H9NO, (V), and 5‐methyl‐2‐thiouracil–melamine (3/2), 3C5H6N2OS·2C3H6N6, (VI). Synthon 3sN·S;N·N;N·O was formed in three structures in which two‐dimensional hydrogen‐bonded networks are observed, while doubly hydrogen‐bonded interactions were formed instead in the remaining three cocrystals whereby three‐dimensional networks are preferred. As desired, the S atoms are involved in hydrogen‐bonding interactions in all six structures, thus illustrating the ability of sulfur to act as a hydrogen‐bond acceptor and, therefore, its value for application in crystal engineering.  相似文献   

6.
In order to examine the preferred hydrogen‐bonding pattern of various uracil derivatives, namely 5‐(hydroxymethyl)uracil, 5‐carboxyuracil and 5‐carboxy‐2‐thiouracil, and for a conformational study, crystallization experiments yielded eight different structures: 5‐(hydroxymethyl)uracil, C5H6N2O3, (I), 5‐carboxyuracil–N,N‐dimethylformamide (1/1), C5H4N2O4·C3H7NO, (II), 5‐carboxyuracil–dimethyl sulfoxide (1/1), C5H4N2O4·C2H6OS, (III), 5‐carboxyuracil–N,N‐dimethylacetamide (1/1), C5H4N2O4·C4H9NO, (IV), 5‐carboxy‐2‐thiouracil–N,N‐dimethylformamide (1/1), C5H4N2O3S·C3H7NO, (V), 5‐carboxy‐2‐thiouracil–dimethyl sulfoxide (1/1), C5H4N2O3S·C2H6OS, (VI), 5‐carboxy‐2‐thiouracil–1,4‐dioxane (2/3), 2C5H4N2O3S·3C6H12O3, (VII), and 5‐carboxy‐2‐thiouracil, C10H8N4O6S2, (VIII). While the six solvated structures, i.e. (II)–(VII), contain intramolecular S(6) O—H…O hydrogen‐bond motifs between the carboxy and carbonyl groups, the usually favoured R22(8) pattern between two carboxy groups is formed in the solvent‐free structure, i.e. (VIII). Further R22(8) hydrogen‐bond motifs involving either two N—H…O or two N—H…S hydrogen bonds were observed in three crystal structures, namely (I), (IV) and (VIII). In all eight structures, the residue at the ring 5‐position shows a coplanar arrangement with respect to the pyrimidine ring which is in agreement with a search of the Cambridge Structural Database for six‐membered cyclic compounds containing a carboxy group. The search confirmed that coplanarity between the carboxy group and the cyclic residue is strongly favoured.  相似文献   

7.
In the structure of (6R*,11R*)‐5‐acetyl‐11‐ethyl‐6,11‐dihydro‐5H‐dibenzo[b,e]azepine‐6‐carboxylic acid, C19H19NO3, (I), the molecules are linked into sheets by a combination of O—H...O and C—H...O hydrogen bonds; in the structure of the monomethyl analogue (6RS,11SR)‐5‐acetyl‐11‐ethyl‐2‐methyl‐6,11‐dihydro‐5H‐dibenzo[b,e]azepine‐6‐carboxylic acid, C20H21NO3, (II), the molecules are linked into simple C(7) chains by O—H...O hydrogen bonds; and in the structure of the dimethyl analogue (6RS,11SR)‐5‐acetyl‐11‐ethyl‐1,3‐dimethyl‐6,11‐dihydro‐5H‐dibenzo[b,e]azepine‐6‐carboxylic acid, C21H23NO3, (III), a combination of O—H...O, C—H...O and C—H...π(arene) hydrogen bonds links the molecules into a three‐dimensional framework structure. None of these structures exhibits the R22(8) dimer motif characteristic of simple carboxylic acids.  相似文献   

8.
Cyclohexylamine reacts with 5‐chloro‐3‐methyl‐1‐(pyridin‐2‐yl)‐1H‐pyrazole‐4‐carbaldehyde to give 5‐cyclohexylamino‐3‐methyl‐1‐(pyridin‐2‐yl)‐1H‐pyrazole‐4‐carbaldehyde, C16H20N4O, (I), formed by nucleophilic substitution, but with 5‐chloro‐3‐methyl‐1‐phenyl‐1H‐pyrazole‐4‐carbaldehyde the product is (Z)‐4‐[(cyclohexylamino)methylidene]‐3‐methyl‐1‐phenyl‐1H‐pyrazol‐5(4H)‐one, C17H21N3O, (II), formed by condensation followed by hydrolysis. Compound (II) crystallizes with Z′ = 2, and in one of the two independent molecular types the cyclohexylamine unit is disordered over two sets of atomic sites having occupancies of 0.65 (3) and 0.35 (3). The vinylogous amide portion in each compound shows evidence of electronic polarization, such that in each the O atom carries a partial negative charge and the N atom of the cyclohexylamine portion carries a partial positive charge. The molecules of (I) contain an intramolecular N—H...N hydrogen bond, and they are linked by C—H...O hydrogen bonds to form sheets. Each of the two independent molecules of (II) contains an intramolecular N—H...O hydrogen bond and each molecular type forms a centrosymmetric dimer containing one R22(4) ring and two inversion‐related S(6) rings.  相似文献   

9.
The title compound, C23H17N3O4S, crystallizes with Z′ = 3 in the space group P. Two of the three independent molecules are broadly similar in terms of both their molecular conformations and their participation in hydrogen bonds, but the third molecule differs from the other two in both of these respects. The molecules are linked by a combination of N—H...O, N—H...N, C—H...O, C—H...N and C—H...π(arene) hydrogen bonds to form a continuous three‐dimensional framework structure within which a centrosymmetric six‐molecule aggregate can be identified as a key structural element.  相似文献   

10.
The structures of the 1:1 hydrated proton‐transfer compounds of isonipecotamide (piperidine‐4‐carboxamide) with oxalic acid, 4‐carbamoylpiperidinium hydrogen oxalate dihydrate, C6H13N2O+·C2HO4·2H2O, (I), and with adipic acid, bis(4‐carbamoylpiperidinium) adipate dihydrate, 2C6H13N2O+·C6H8O42−·2H2O, (II), are three‐dimensional hydrogen‐bonded constructs involving several different types of enlarged water‐bridged cyclic associations. In the structure of (I), the oxalate monoanions give head‐to‐tail carboxylic acid O—H...Ocarboxyl hydrogen‐bonding interactions, forming C(5) chain substructures which extend along a. The isonipecotamide cations also give parallel chain substructures through amide N—H...O hydrogen bonds, the chains being linked across b and down c by alternating water bridges involving both carboxyl and amide O‐atom acceptors and amide and piperidinium N—H...Ocarboxyl hydrogen bonds, generating cyclic R43(10) and R32(11) motifs. In the structure of (II), the asymmetric unit comprises a piperidinium cation, half an adipate dianion, which lies across a crystallographic inversion centre, and a solvent water molecule. In the crystal structure, the two inversion‐related cations are interlinked through the two water molecules, which act as acceptors in dual amide N—H...Owater hydrogen bonds, to give a cyclic R42(8) association which is conjoined with an R44(12) motif. Further N—H...Owater, water O—H...Oamide and piperidinium N—H...Ocarboxyl hydrogen bonds give the overall three‐dimensional structure. The structures reported here further demonstrate the utility of the isonipecotamide cation as a synthon for the generation of stable hydrogen‐bonded structures. The presence of solvent water molecules in these structures is largely responsible for the non‐occurrence of the common hydrogen‐bonded amide–amide dimer, promoting instead various expanded cyclic hydrogen‐bonding motifs.  相似文献   

11.
The title compound, C18H18N4OS2, was prepared by reaction of S,S‐diethyl 2‐thenoylimidodithiocarbonate with 5‐amino‐3‐(4‐methylphenyl)‐1H‐pyrazole using microwave irradiation under solvent‐free conditions. In the molecule, the thiophene unit is disordered over two sets of atomic sites, with occupancies of 0.814 (4) and 0.186 (4), and the bonded distances provide evidence for polarization in the acylthiourea fragment and for aromatic type delocalization in the pyrazole ring. An intramolecular N—H...O hydrogen bond is present, forming an S(6) motif, and molecules are linked by N—H...O and N—H...N hydrogen bonds to form a ribbon in which centrosymmetric R22(4) rings, built from N—H...O hydrogen bonds and flanked by inversion‐related pairs of S(6) rings, alternate with centrosymmetric R22(6) rings built from N—H...N hydrogen bonds.  相似文献   

12.
The crystallization and characterization of a new polymorph of 2‐thiouracil by single‐crystal X‐ray diffraction, Hirshfeld surface analysis and periodic density functional theory (DFT) calculations are described. The previously published polymorph (A ) crystallizes in the triclinic space group P , while that described herein (B ) crystallizes in the monoclinic space group P 21/c . Periodic DFT calculations showed that the energies of polymorphs A and B , compared to the gas‐phase geometry, were −108.8 and −29.4 kJ mol−1, respectively. The two polymorphs have different intermolecular contacts that were analyzed and are discussed in detail. Significant differences in the molecular structure were found only in the bond lengths and angles involving heteroatoms that are involved in hydrogen bonds. Decomposition of the Hirshfeld fingerprint plots revealed that O…H and S…H contacts cover over 50% of the noncovalent contacts in both of the polymorphs; however, they are quite different in strength. Hydrogen bonds of the N—H…O and N—H…S types were found in polymorph A , whereas in polymorph B , only those of the N—H…O type are present, resulting in a different packing in the unit cell. QTAIM (quantum theory of atoms in molecules) computational analysis showed that the interaction energies for these weak‐to‐medium strength hydrogen bonds with a noncovalent or mixed interaction character were estimated to fall within the ranges 5.4–10.2 and 4.9–9.2 kJ mol−1 for polymorphs A and B , respectively. Also, the NCI (noncovalent interaction) plots revealed weak stacking interactions. The interaction energies for these interactions were in the ranges 3.5–4.1 and 3.1–5.5 kJ mol−1 for polymorphs A and B , respectively, as shown by QTAIM analysis.  相似文献   

13.
Methyl 4‐(4‐fluorophenyl)‐6‐methyl‐2‐oxo‐1,2,3,4‐tetrahydropyrimidine‐5‐carboxylate, ( I ), was found to exhibit solvatomorphism. The compound was prepared using a classic Biginelli reaction under mild conditions, without using catalysts and in a solvent‐free environment. Single crystals of two solvatomorphs and one anhydrous form of ( I ) were obtained through various crystallization methods. The anhydrous form, C13H13FN2O3, was found to crystallize in the monoclinic space group C2/c. It showed one molecule in the asymmetric unit. The solvatomorph with included carbon tetrachloride, C13H13FN2O3·0.25CCl4, was found to crystallize in the monoclinic space group P2/n. The asymmetric unit revealed two molecules of ( I ) and one disordered carbon tetrachloride solvent molecule that lies on a twofold axis. A solvatomorph including ethyl acetate, C13H13FN2O3·0.5C4H8O2, was found to crystallize in the triclinic space group P with one molecule of ( I ) and one solvent molecule on an inversion centre in the asymmetric unit. The solvent molecules in the solvatomorphs were found to be disordered, with a unique case of crystallographically induced disorder in ( I ) crystallized with ethyl acetate. Hydrogen‐bonding interactions, for example, N—H…O=C, C—H…O=C, C—H…F and C—H…π, contribute to the crystal packing with the formation of a characteristic dimer through N—H…O=C interactions in all three forms. The solvatomorphs display additional interactions, such as C—F…N and C—Cl…π, which are responsible for their molecular arrangement. The thermal properties of the forms were analysed through differential scanning calorimetry (DSC), hot stage microscopy (HSM) and thermogravimetric analysis (TGA) experiments.  相似文献   

14.
The title compound {systematic name: 4‐amino‐5‐cyclopropyl‐7‐(2‐deoxy‐β‐D‐erythro‐pentofuranosyl)‐7H‐pyrrolo[2,3‐d]pyrimidine}, C14H18N4O3, exhibits an anti glycosylic bond conformation, with the torsion angle χ = −108.7 (2)°. The furanose group shows a twisted C1′‐exo sugar pucker (S‐type), with P = 120.0 (2)° and τm = 40.4 (1)°. The orientation of the exocyclic C4′—C5′ bond is ‐ap (trans), with the torsion angle γ = −167.1 (2)°. The cyclopropyl substituent points away from the nucleobase (anti orientation). Within the three‐dimensional extended crystal structure, the individual molecules are stacked and arranged into layers, which are highly ordered and stabilized by hydrogen bonding. The O atom of the exocyclic 5′‐hydroxy group of the sugar residue acts as an acceptor, forming a bifurcated hydrogen bond to the amino groups of two different neighbouring molecules. By this means, four neighbouring molecules form a rhomboidal arrangement of two bifurcated hydrogen bonds involving two amino groups and two O5′ atoms of the sugar residues.  相似文献   

15.
The structures of two hydrated salts of 4‐aminophenylarsonic acid (p‐arsanilic acid), namely ammonium 4‐aminophenylarsonate monohydrate, NH4+·C6H7AsNO3·H2O, (I), and the one‐dimensional coordination polymer catena‐poly[[(4‐aminophenylarsonato‐κO)diaquasodium]‐μ‐aqua], [Na(C6H7AsNO3)(H2O)3]n, (II), have been determined. In the structure of the ammonium salt, (I), the ammonium cations, arsonate anions and water molecules interact through inter‐species N—H...O and arsonate and water O—H...O hydrogen bonds, giving the common two‐dimensional layers lying parallel to (010). These layers are extended into three dimensions through bridging hydrogen‐bonding interactions involving the para‐amine group acting both as a donor and an acceptor. In the structure of the sodium salt, (II), the Na+ cation is coordinated by five O‐atom donors, one from a single monodentate arsonate ligand, two from monodentate water molecules and two from bridging water molecules, giving a very distorted square‐pyramidal coordination environment. The water bridges generate one‐dimensional chains extending along c and extensive interchain O—H...O and N—H...O hydrogen‐bonding interactions link these chains, giving an overall three‐dimensional structure. The two structures reported here are the first reported examples of salts of p‐arsanilic acid.  相似文献   

16.
The reaction of 2‐cyanopyridine with N‐phenylthiosemicarbazide afforded 2‐[amino(pyridin‐2‐yl)methylidene]‐N‐phenylhydrazine‐1‐carbothioamide (Ham4ph) and crystals of 4‐phenyl‐5‐(pyridin‐2‐yl)‐2,4‐dihydro‐3H‐1,2,4‐triazole‐3‐thione (pyph3NS, 1 , C13H10N4S). Crystals of methyl 2‐{[4‐phenyl‐5‐(pyridin‐2‐yl)‐4H‐1,2,4‐triazol‐3‐yl]sulfanyl}acetate (phpy2NS, 2 , C16H14N4O2S), derived from 1 , were obtained by the reaction of Ham4ph with chloroacetic acid, followed by the acid‐catalyzed esterification of the carboxylic acid with methyl alcohol. Crystals of bis(methanol‐κO)bis(methyl 2‐{[4‐phenyl‐5‐(pyridin‐2‐yl)‐4H‐1,2,4‐triazol‐3‐yl‐κ2N1,N5]sulfanyl}acetato)zinc(II)/cadmium(II) hexabromidocadmate(II), [Zn0.76Cd0.24(C16H14N4O2S)2(CH3OH)2][Cd2Br6] or [Zn0.76Cd0.24(phpy2NS)2(MeOH)2][Cd2Br6], 3 , and dichlorido(methyl 2‐{[4‐phenyl‐5‐(pyridin‐2‐yl)‐4H‐1,2,4‐triazol‐3‐yl‐κ2N1,N5]sulfanyl}acetato)mercury(II), [HgCl2(C16H14N4O2S)] or [Hg(phpy2NS)Cl2], 4 , were synthesized using ligand 2 and CdBr2 or HgCl2, respectively. The molecular and supramolecular structures of the compounds were studied by X‐ray diffractometry. The asymmetric unit of 3 is formed from CdBr3 and M(phpy2NS)(MeOH) units, where the metal centre M has a 76% occupancy of ZnII and 24% of CdII. The M2+ centre of the cation, located on a crystallographic inversion centre, is hexacoordinated and appears as a slightly distorted octahedral [MN4O2]2+ cation. The Cd centre of the anion is coordinated by two terminal bromide ligands and two bridging bromide ligands that generate [Cd2Br6]2? cadmium–bromide clusters. These clusters display crystallographic inversion symmetry forming two edge‐shared tetrahedra and serve as agents that direct the structure in the formation of supramolecular assemblies. In mononuclear complex 4 , the coordination geometry around the Hg2+ ion is distorted tetrahedral and comprises two chloride ligands and two N‐atom donors from the phpy2NS ligand, viz. one pyridine N atom and the other from triazole. In the crystal packing, all four compounds exhibit weak intermolecular interactions, which facilitate the formation of three‐dimensional architectures. Along with the noncovalent interactions, the structural diversity in the complexes can be attributed to the metal centre and to the coordination geometry, as well as to its ionic or neutral character.  相似文献   

17.
The synthesis, 1H and 13C NMR spectra, and X‐ray structures are described for three dialkoxy ethynylnitrobenzenes that differ only in the length of the alkoxy chain, namely 1‐ethynyl‐2‐nitro‐4,5‐dipropoxybenzene, C14H17NO4, 1,2‐dibutoxy‐4‐ethynyl‐5‐nitrobenzene, C16H21NO4, and 1‐ethynyl‐2‐nitro‐4,5‐dipentoxybenzene, C18H25NO4. Despite the subtle changes in molecular structure, the crystal structures of the three compounds display great diversity. Thus, 1‐ethynyl‐2‐nitro‐4,5‐dipropoxybenzene crystallizes in the trigonal crystal system in the space group , with Z = 18, 1,2‐dibutoxy‐4‐ethynyl‐5‐nitrobenzene crystallizes in the monoclinic crystal system in the space group P 21/c , with Z = 4, and 1‐ethynyl‐2‐nitro‐4,5‐dipentoxybenzene crystallizes in the triclinic crystal system in the space group , with Z = 2. The crystal structure of 1‐ethynyl‐2‐nitro‐4,5‐dipropoxybenzene is dominated by planar hexamers formed by a bifurcated alkoxy sp‐C—H…O,O′ interaction, while the structure of the dibutoxy analogue is dominated by planar ribbons of molecules linked by a similar bifurcated alkoxy sp‐C—H…O,O′ interaction. In contrast, the dipentoxy analogue forms ribbons of molecules alternately connected by a self‐complementary sp‐C—H…O2N interaction and a self‐complementary sp2‐C—H…O2N interaction. Disordered solvent was included in the crystals of 1‐ethynyl‐2‐nitro‐4,5‐dipropoxybenzene and its contribution was removed during refinement.  相似文献   

18.
The preparation and X‐ray and spectroscopic studies of the title copper(II) complex, [Cu(C12H8N3O2)(CN)(H2O)], are reported. The CuII cation is five‐coordinated, forming a distorted square‐planar pyramid with an Addison τ parameter of 0.14. The UV–vis spectrum shows a dd transition of the CuII centre at 638 nm, and the electron paramagnetic resonance (EPR) spectrum confirms that the CuII cation has an axial symmetry coordination and that the unpaired electrons occupy the dx2y2 orbital. Cyclic voltammetric studies show two irreversible oxidation and reduction peaks.  相似文献   

19.
In the title compound, [Fe(C10H8N2)3](C9H5N4O)2·2H2O, the chiral cations lie across twofold rotation axes in the space group C2/c. The anions and the water molecules are linked by two independent O—H...N hydrogen bonds to form C22(8) chains, and these chains are linked by the cations via C—H...N and C—H...O hydrogen bonds to form two interpenetrating three‐dimensional frameworks, each of which contains only one enantiomeric form of the chiral cation.  相似文献   

20.
A systematic quantum chemical study reveals the effects of chirality on the intermolecular interactions between two chiral molecules bound by hydrogen bonds. The methods used are second‐order Møller–Plesset perturbation theory (MP2) with the 6‐311++g(d,p) basis set. Complexes via the O? H···O hydrogen bond formed between the chiral 2‐methylol oxirane (S) and chiral HOOH (P and M) molecules have been investigated, which lead to four diastereomeric complexes. The nomenclature of the complexes used in this article is enantiomeric configuration sign corresponding to English letters. Such as: sm, sp. The relative positions of the methylol group and the hydrogen peroxide are designated as syn (same side) and anti (opposite side). The largest chirodiastaltic energy was ΔEchir = ?1.329 kcal mol?1 [9% of the counterpoise correct average binding energy De(corr)] between the sm‐syn and sp‐anti in favor of sm‐syn. The largest diastereofacial energy was ?1.428 kcal mol?1 between sm‐syn and sm‐anti in favor of sm‐syn. To take into account solvents effect, the polarizable continuum model (PCM) method has been used to evaluate the chirodiastaltic energies, and diastereofacial energies of the 2‐methylol oxirane···HOOH complexes. The chiral 2,3‐dimethylol oxirane (S, S) is C2 symmetry which offers two identical faces. Hence, the chirodiastaltic energy is identical to the diastereomeric energy, and is ΔEchir = 0.563 kcal mol?1 or 5.3% of the De(corr) in favor of s,s‐p. The optimized structures, interaction energies, and chirodiastaltic energies for various isomers were estimated. The harmonic frequencies, IR intensities, rotational constants, and dipole moments were also reported. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009  相似文献   

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