Two seven‐membered heterocycles with 1,2‐diaza ring N atoms: 3,5,7‐triphenyl‐1,2‐diazacyclohepta‐1(7),2‐diene and 3,7‐bis(2‐hydroxyphenyl)‐5‐phenyl‐1,2‐diazacyclohepta‐1(7),2‐diene

The title compounds, 3,5,7‐triphenyl‐1,2‐diazacyclohepta‐1(7),2‐diene, C₂₃H₂₀N₂, (I), and 3,7‐bis(2‐hydroxyphenyl)‐5‐phenyl‐1,2‐diazacyclohepta‐1(7),2‐diene, C₂₃H₂₀N₂O₂, (II), constitute the first structurally characterized examples of seven‐membered heterocycles with 1,2‐diaza ring N atoms. Compound (I) crystallizes in the space group P, with two independent molecules in the asymmetric unit that differ in the conformation of one of the phenyl rings, while (II) crystallizes in the space group C2/c. The C₅N₂ ring in each of (I) and (II) adopts a twist‐boat conformation. Compound (I) exhibits neither C—H...π interactions nor π–π stacking interactions, whereas (II) shows both intramolecular O—H...N hydrogen bonds and a C—H...π interaction that joins the molecules into an infinite chain in the [010] direction.     

(8RS)‐4‐Amino‐6‐(4‐chlorophenyl)‐8‐(2,4‐dichlorothiazol‐5‐yl)‐8,9‐dihydro‐7H‐pyrimido[4,5‐b][1,4]diazepine N,N‐dimethylformamide monosolvate: sheets built from N—H...N and C—H...O hydrogen bonds

In the title compound, C₁₆H₁₁Cl₃N₆S·C₃H₇NO, the seven‐membered ring adopts a conformation which is close to the twist‐boat form. The molecular components are linked into sheets by a combination of two N—H...N hydrogen bonds and two C—H...O hydrogen bonds. Comparisons are made with other aminopyrimidine derivatives.     

A square‐planar tellurium(II) complex with Te,Te′‐chelating ligands

While exploring the chemistry of tellurium‐containing dichalcogenidoimidodiphosphinate ligands, the first all‐tellurium member of a series of related square‐planar E^II(E′)₄ complexes (E and E′ are group 16 elements), namely bis(P,P,P′,P′‐tetraphenylditelluridoimidodiphosphinato‐κ²Te,Te′)tellurium(II) (systematic name: 2,2,4,4,8,8,10,10‐octaphenyl‐1λ³,5,6λ⁴,7λ³,11‐pentatellura‐3,9‐diaza‐2λ⁵,4λ⁵,8λ⁵,10λ⁵‐tetraphosphaspiro[5.5]undeca‐1,3,7,9‐tetraene), C₄₈H₄₀N₂P₄Te₅, was obtained unexpectedly. The formally Te^II centre is situated on a crystallographic inversion centre and is Te,Te′‐chelated to two anionic [(TePPh₂)₂N]⁻ ligands in an anti conformation. The central Te^II(Te)₄ unit is approximately square planar [Te—Te—Te = 93.51 (3) and 86.49 (3)°], with Te—Te bond lengths of 2.9806 (6) and 2.9978 (9) Å.     

(5RS)‐5‐(4‐Methoxyphenyl)‐2‐(methylsulfanyl)benzo[g]pyrimido[4,5‐b]quinoline‐4,6,11(3H,5H,12H)‐trione,with Z′ = 3, forms a three‐dimensional hydrogen‐bonded framework containing five types of hydrogen bond

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.     

Cocrystals of 1,4‐diethynylbenzene with 1,3‐diacetylbenzene and benzene‐1,4‐dicarbaldehyde exhibiting strong nonconventional alkyne–carbonyl C—H…O hydrogen bonds between the components

Weak interactions between organic molecules are important in solid‐state structures where the sum of the weaker interactions support the overall three‐dimensional crystal structure. The sp‐C—H…N hydrogen‐bonding interaction is strong enough to promote the deliberate cocrystallization of a series of diynes with a series of dipyridines. It is also possible that a similar series of cocrystals could be formed between molecules containing a terminal alkyne and molecules which contain carbonyl O atoms as the potential hydrogen‐bond acceptor. I now report the crystal structure of two cocrystals that support this hypothesis. The 1:1 cocrystal of 1,4‐diethynylbenzene with 1,3‐diacetylbenzene, C₁₀H₆·C₁₀H₁₀O₂, (1), and the 1:1 cocrystal of 1,4‐diethynylbenzene with benzene‐1,4‐dicarbaldehyde, C₁₀H₆·C₈H₆O₂, (2), are presented. In both cocrystals, a strong nonconventional ethynyl–carbonyl sp‐C—H…O hydrogen bond is observed between the components. In cocrystal (1), the C—H…O hydrogen‐bond angle is 171.8 (16)° and the H…O and C…O hydrogen‐bond distances are 2.200 (19) and 3.139 (2) Å, respectively. In cocrystal (2), the C—H…O hydrogen‐bond angle is 172.5 (16)° and the H…O and C…O hydrogen‐bond distances are 2.25 (2) and 3.203 (2) Å, respectively.     

Dimers linked by type‐I C—F...F—C contacts in (Z)‐3‐methyl‐4‐[2‐(4‐methylphenyl)hydrazinylidene]‐1‐(pentafluorophenyl)‐1H‐pyrazol‐5(4H)‐one

The title compound, C₁₇H₁₁F₅N₄O, is described and compared with two closely related analogues in the literature. There are two independent molecules in the asymmetric unit, linked by N—H...O hydrogen bonds and π–π interactions into dimeric entities, presenting a noticeable noncrystallographic C₂ symmetry. These dimers are in turn linked by a medium‐strength type‐I C—F...F—C interaction into elongated tetramers. Much weaker C—H...F contacts link the tetramers into broad two‐dimensional substructures parallel to (101).     

π‐stacking and C—X...D (X = H,NO2; D = O, π) interactions in the crystal network of both C—H...N and π‐stacked dimers of 1,2‐bis(4‐bromophenyl)‐1H‐benzimidazole and 2‐(4‐bromophenyl)‐1‐(4‐nitrophenyl)‐1H‐benzimidazole

Molecules of 1,2‐bis(4‐bromophenyl)‐1H‐benzimidazole, C₁₉H₁₂Br₂N₂, (I), and 2‐(4‐bromophenyl)‐1‐(4‐nitrophenyl)‐1H‐benzimidazole, C₁₉H₁₂BrN₃O₂, (II), are arranged in dimeric units through C—H...N and parallel‐displaced π‐stacking interactions favoured by the appropriate disposition of N‐ and C‐bonded phenyl rings with respect to the mean benzimidazole plane. The molecular packing of the dimers of (I) and (II) arises by the concurrence of a diverse set of weak intermolecular C—X...D (X = H, NO₂; D = O, π) interactions.     

A new two‐dimensional managnese(II) coordination polymer constructed by 2,2′‐(1,2‐phenylene)bis(1H‐imidazole‐4,5‐dicarboxylate)

In recent years, N‐heterocyclic carboxylate ligands have attracted much interest in the preparation of new coordination polymers since they contain N‐atom donors, as well as O‐atom donors, and have a rich variety of coordination modes which can lead to polymers with intriguing structures and interesting properties. A new two‐dimensional coordination polymer, namely poly[[μ₃‐2,2′‐(1,2‐phenylene)bis(4‐carboxy‐1H‐imidazole‐5‐carboxylato)‐κ⁶O⁴,N³,N^3′,O^4′:O⁵:O^5′]manganese(II)], [Mn(C₁₆H₈N₄O₈)]_n or [Mn(H₄Phbidc)]_n, has been synthesized by the reaction of Mn(OAc)₂·4H₂O (OAc is acetate) with 2,2′‐(1,2‐phenylene)bis(1H‐imidazole‐4,5‐dicarboxylic acid) (H₆Phbidc) under solvothermal conditions. In the polymer, each Mn^II ion is six‐coordinated by two N atoms from one H₄Phbidc²⁻ ligand and by four O atoms from three H₄Phbidc²⁻ ligands, forming a significantly distorted octahedral MnN₂O₄ coordination geometry. The Mn^II ions are linked by hexadentate H₄Phbidc²⁻ ligands, leading to a two‐dimensional structure parallel to the ac plane. In the crystal, adjacent layers are further connected by N—H…O hydrogen bonds, forming a three‐dimensional structure in the solid state.     

Different molecular conformations co‐exist in each of three 2‐aryl‐N‐(1,5‐dimethyl‐3‐oxo‐2‐phenyl‐2,3‐dihydro‐1H‐pyrazol‐4‐yl)acetamides: hydrogen bonding in zero,one and two dimensions

4‐Antipyrine [4‐amino‐1,5‐dimethyl‐2‐phenyl‐1H‐pyrazol‐3(2H)‐one] and its derivatives exhibit a range of biological activities, including analgesic, antibacterial and anti‐inflammatory, and new examples are always of potential interest and value. 2‐(4‐Chlorophenyl)‐N‐(1,5‐dimethyl‐3‐oxo‐2‐phenyl‐2,3‐dihydro‐1H‐pyrazol‐4‐yl)acetamide, C₁₉H₁₈ClN₃O₂, (I), crystallizes with Z′ = 2 in the space group P, whereas its positional isomer 2‐(2‐chlorophenyl)‐N‐(1,5‐dimethyl‐3‐oxo‐2‐phenyl‐2,3‐dihydro‐1H‐pyrazol‐4‐yl)acetamide, (II), crystallizes with Z′ = 1 in the space group C2/c; the molecules of (II) are disordered over two sets of atomic sites having occupancies of 0.6020 (18) and 0.3980 (18). The two independent molecules of (I) adopt different molecular conformations, as do the two disorder components in (II), where the 2‐chlorophenyl substituents adopt different orientations. The molecules of (I) are linked by a combination of N—H…O and C—H…O hydrogen bonds to form centrosymmetric four‐molecule aggregates, while those of (II) are linked by the same types of hydrogen bonds forming sheets. The related compound N‐(1,5‐dimethyl‐3‐oxo‐2‐phenyl‐2,3‐dihydro‐1H‐pyrazol‐4‐yl)‐2‐(3‐methoxyphenyl)acetamide, C₂₀H₂₁N₃O₃, (III), is isomorphous with (I) but not strictly isostructural; again the two independent molecules adopt different molecular conformations, and the molecules are linked by N—H…O and C—H…O hydrogen bonds to form ribbons. Comparisons are made with some related structures, indicating that a hydrogen‐bonded R₂²(10) ring is the common structural motif.     

Intra‐ and intermolecular Se...X (X = Se,O) interactions in selenium‐containing heterocycles: 3‐benzoylimino‐5‐(morpholin‐4‐yl)‐1,2,4‐diselenazole

In the selenium‐containing heterocyclic title compound {systematic name: N‐[5‐(morpholin‐4‐yl)‐3H‐1,2,4‐diselenazol‐3‐ylidene]benzamide}, C₁₃H₁₃N₃O₂Se₂, the five‐membered 1,2,4‐diselenazole ring and the amide group form a planar unit, but the phenyl ring plane is twisted by 22.12 (19)° relative to this plane. The five consecutive N—C bond lengths are all of similar lengths [1.316 (6)–1.358 (6) Å], indicating substantial delocalization along these bonds. The Se...O distance of 2.302 (3) Å, combined with a longer than usual amide C=O bond of 2.252 (5) Å, suggest a significant interaction between the amide O atom and its adjacent Se atom. An analysis of related structures containing an Se—Se...X unit (X = Se, S, O) shows a strong correlation between the Se—Se bond length and the strength of the Se...X interaction. When X = O, the strength of the Se...O interaction also correlates with the carbonyl C=O bond length. Weak intermolecular Se...Se, Se...O, C—H...O, C—H...π and π–π interactions each serve to link the molecules into ribbons or chains, with the C—H...O motif being a double helix, while the combination of all interactions generates the overall three‐dimensional supramolecular framework.     

Octyl 1‐(5‐tert‐butyl‐1H‐pyrazol‐3‐yl)‐2‐(4‐chlorophenyl)‐1H‐benzimidazole‐5‐carboxylate: complex sheets built from N—H...N,C—H...N and C—H...O hydrogen bonds

In the title compound, C₂₉H₃₅ClN₄O₂, the bond lengths provide evidence for aromatic delocalization in the pyrazole ring but bond fixation in the fused imidazole ring, and the octyl chain is folded, rather than adopting an all‐trans chain‐extended conformation. A combination of N—H...N, C—H...N and C—H...O hydrogen bonds links the molecules into sheets, in which the hydrogen bonds occupy the central layer with the tert‐butyl and octyl groups arranged on either side, such that the closest contacts between adjacent sheets involve only the octyl groups. Comparisons are made with the supramolecular assembly in some simpler analogues.     

Synthesis and crystal structure of a two‐dimensional sodium coordination polymer of 4,4′‐(diazenediyl)bis(1H‐1,2,4‐triazol‐5‐one)

The crystal engineering of coordination polymers has aroused interest due to their structural versatility, unique properties and applications in different areas of science. The selection of appropriate ligands as building blocks is critical in order to afford a range of topologies. Alkali metal cations are known for their mainly ionic chemistry in aqueous media. Their coordination number varies depending on the size of the binding partners, and on the electrostatic interaction between the ligands and the metal ions. The two‐dimensional coordination polymer poly[tetra‐μ‐aqua‐[μ₄‐4,4′‐(diazenediyl)bis(5‐oxo‐1H‐1,2,4‐triazolido)]disodium(I)], [Na₂(C₄H₂N₈O₂)(H₂O)₄]_n, (I), was synthesized from 4‐amino‐1H‐1,2,4‐triazol‐5(4H)‐one (ATO) and its single‐crystal structure determined. The mid‐point of the imino N=N bond of the 4,4′‐(diazenediyl)bis(5‐oxo‐1H‐1,2,4‐triazolide) (ZTO²⁻) ligand is located on an inversion centre. The asymmetric unit consists of one Na⁺ cation, half a bridging ZTO²⁻ ligand and two bridging water ligands. Each Na⁺ cation is coordinated in a trigonal antiprismatic fashion by six O atoms, i.e. two from two ZTO²⁻ ligands and the remaining four from bridging water ligands. The Na⁺ cation is located near a glide plane, thus the two bridging O atoms from the two coordinating ZTO²⁻ ligands are on adjacent apices of the trigonal antiprism, rather than being in an anti configuration. All water and ZTO²⁻ ligands act as bridging ligands between metal centres. Each Na⁺ metal centre is bridged to a neigbouring Na⁺ cation by two water molecules to give a one‐dimensional [Na(H₂O)₂]_n chain. The organic ZTO²⁻ ligand, an O atom of which also bridges the same pair of Na⁺ cations, then crosslinks these [Na(H₂O)₂]_n chains to form two‐dimensional sheets. The two‐dimensional sheets are further connected by intermolecular hydrogen bonds, giving rise to a stabile hydrogen‐bonded network.     

N—H...O,O—H...O hydrogen‐bonded supramolecular sheet formation in the bis(2‐aminoanilinium) fumarate, 3‐methylanilinium hydrogen fumarate and 4‐chloroanilinium hydrogen fumarate salts

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.     

New rac‐XP(O)(OC6H5)(NHC6H4‐p‐CH3) [X = N(CH3)(cyclo‐C6H11) and NH(C3H5)] and rac‐(C6H5CH2NH)P(O)(OC6H5)(NH‐cyclo‐C6H11) mixed‐amide phosphinates

The mixed‐amide phosphinates, rac‐phenyl (N‐methylcyclohexylamido)(p‐tolylamido)phosphinate, C₂₀H₂₇N₂O₂P, (I), and rac‐phenyl (allylamido)(p‐tolylamido)phosphinate, C₁₆H₁₉N₂O₂P, (II), were synthesized from the racemic phosphorus–chlorine compound (R,S)‐(Cl)P(O)(OC₆H₅)(NHC₆H₄‐p‐CH₃). Furthermore, the phosphorus–chlorine compound ClP(O)(OC₆H₅)(NH‐cyclo‐C₆H₁₁) was synthesized for the first time and used for the synthesis of rac‐phenyl (benzylamido)(cyclohexylamido)phosphinate, C₁₉H₂₅N₂O₂P, (III). The strategies for the synthesis of racemic mixed‐amide phosphinates are discussed. The P atom in each compound is in a distorted tetrahedral (N¹)P(=O)(O)(N²) environment. In (I) and (II), the p‐tolylamido substituent makes a longer P—N bond than those involving the N‐methylcyclohexylamido and allylamido substituents. In (III), the differences between the P—N bond lengths involving the cyclohexylamido and benzylamido substituents are not significant. In all three structures, the phosphoryl O atom takes part with the N—H unit in hydrogen‐bonding interactions, viz. an N—H...O=P hydrogen bond for (I) and (N—H)(N—H)...O=P hydrogen bonds for (II) and (III), building linear arrangements along [001] for (I) and along [010] for (III), and a ladder arrangement along [100] for (II).     

Two Fe3(μ3‐S)2(CO)8 clusters with terminal N‐heterocyclic carbenes

The title compounds with terminal N‐heterocyclic carbenes, namely octacarbonyl(imidazolidinylidene‐κC²)di‐μ₃‐sulfido‐triiron(II)(2 Fe—Fe), [Fe₃(C₃H₆N₂)(μ₃‐S)₂(CO)₈], (I), and octacarbonyl(1‐methylimidazo[1,5‐a]pyridin‐3‐ylidene‐κC³)di‐μ₃‐sulfido‐triiron(II)(2 Fe—Fe), [Fe₃(C₈H₈N₂)(μ₃‐S)₂(CO)₈], (II), have been synthesized. Each compound contains two Fe—Fe bonds and two S atoms above and below a triiron triangle. One of the eight carbonyl ligands deviates significantly from linearity. In (I), dimers generated by an N—H...S hydrogen bond are linked into [001] double chains by a second N—H...S hydrogen bond. These chains are packed by a C—H...O hydrogen bond to yield [101] sheets. In (II), dimers generated by an N—H...S hydrogen bond are linked by C—H...O hydrogen bonds to form [111] double chains.     

(5RS)‐6H‐Spiro[pyrazolo[1,5‐c]quinazoline‐5,4′‐thiochroman]: efficient synthesis under mild conditions,molecular structure and supramolecular assembly

Pyrazolo[1,5‐c]quinazolines are fused‐quinazoline derivatives which have been reported as potential agents against neurological disorders. The normal synthesis routes to these compounds require harsh reaction conditions, long reaction times or multistep sequences. The title compound, C₁₈H₁₅N₃S, has been prepared under very mild conditions by condensation of thiochroman‐4‐one with 5‐(2‐aminophenyl)‐1H‐pyrazole, which had itself been prepared by the reaction of hydrazine hydrate with 4‐hydroxyquinoline mediated by a brief period of microwave heating. Within the molecule in the crystal structure, the reduced pyrimidine ring adopts an envelope conformation, whereas the thiane ring adopts a half‐chair conformation. Molecules are linked into sheets by a combination of one N—H...S hydrogen bond and two independent C—H...π(arene) hydrogen bonds, which utilize the same aryl ring as the acceptor, with one C—H bond donating to each face of the ring. Comparisons are made with some related compounds.     

Heterocyclic tautomerism: reassignment of two crystal structures of 2‐amino‐1,3‐thiazolidin‐4‐one derivatives

The structures of 5‐(2‐hydroxyethyl)‐2‐[(pyridin‐2‐yl)amino]‐1,3‐thiazolidin‐4‐one, C₁₀H₁₁N₃O₂S, (I), and ethyl 4‐[(4‐oxo‐1,3‐thiazolidin‐2‐yl)amino]benzoate, C₁₂H₁₂N₂O₃S, (II), which are identical to the entries with refcodes GACXOZ [Váňa et al. (2009). J. Heterocycl. Chem. 46 , 635–639] and HEGLUC [Behbehani & Ibrahim (2012). Molecules, 17 , 6362–6385], respectively, in the Cambridge Structural Database [Allen (2002). Acta Cryst. B 58 , 380–388], have been redetermined at 130 K. This structural study shows that both investigated compounds exist in their crystal structures as the tautomer with the carbonyl–imine group in the five‐membered heterocyclic ring and an exocyclic amine N atom, rather than the previously reported tautomer with a secondary amide group and an exocyclic imine N atom. The physicochemical and spectroscopic data of the two investigated compounds are the same as those of GACXOZ and HEGLUC, respectively. In the thiazolidin‐4‐one system of (I), the S and chiral C atoms, along with the hydroxyethyl group, are disordered. The thiazolidin‐4‐one fragment takes up two alternative locations in the crystal structure, which allows the molecule to adopt R and S configurations. The occupancy factors of the disordered atoms are 0.883 (2) (for the R configuration) and 0.117 (2) (for the S configuration). In (I), the main factor that determines the crystal packing is a system of hydrogen bonds, involving both strong N—H...N and O—H...O and weak C—H...O hydrogen bonds, linking the molecules into a three‐dimensional hydrogen‐bond network. On the other hand, in (II), the molecules are linked via N—H...O hydrogen bonds into chains.     

Adsorption behaviour of a CdII–triazole MOF for butan‐2‐one in a single‐crystal‐to‐single‐crystal (SCSC) fashion: the role of hydrogen bonding and C—H…π interactions

The adsorption behaviour of the Cd^II–MOF {[Cd(L)₂(ClO₄)₂]·H₂O ( 1 ), where L is 4‐amino‐3,5‐bis[3‐(pyridin‐4‐yl)phenyl]‐1,2,4‐triazole, for butan‐2‐one was investigated in a single‐crystal‐to‐single‐crystal (SCSC) fashion. A new host–guest system that encapsulated butan‐2‐one molecules, namely poly[[bis{μ₃‐4‐amino‐3,5‐bis[3‐(pyridin‐4‐yl)phenyl]‐1,2,4‐triazole}cadmium(II)] bis(perchlorate) butanone sesquisolvate], {[Cd(C₂₄H₁₈N₆)₂](ClO₄)₂·1.5C₄H₈O}_n, denoted C₄H₈O@Cd‐MOF ( 2 ), was obtained via an SCSC transformation. MOF 2 crystallizes in the tetragonal space group P4₃2₁2. The specific binding sites for butan‐2‐one in the host were determined by single‐crystal X‐ray diffraction studies. N—H…O and C—H…O hydrogen‐bonding interactions and C—H…π interactions between the framework, ClO₄^? anions and guest molecules co‐operatively bind 1.5 butan‐2‐one molecules within the channels. The adsorption behaviour was further evidenced by ¹H NMR, IR, TGA and powder X‐ray diffraction experiments, which are consistent with the single‐crystal X‐ray analysis. A ¹H NMR experiment demonstrates that the supramolecular interactions between the framework, ClO₄^? anions and guest molecules in MOF 2 lead to a high butan‐2‐one uptake in the channel.