Br Hydrogen Bonds Research Articles

Effects of strong hydrogen bonds and weak intermolecular interactions on supramolecular assemblies of 4-fluorobenzylamine

A series of supramolecular salts have been obtained by the self-assembly of 4-fluorobenzylamine and halide ions or metal chloride with 18-crown-6 as the host in the hydrochloric acid medium, i.e. (C7H9FN)+⋅X− (X=Cl−, 1; Br−, 2), [(C7H9FN)2⋅(18-crown-6)2]2+⋅(MCl4)2− (M=Mn, 3; Co, 5; Zn, 7; Cd, 8), [(C7H9FN)⋅(18-crown-6)]+⋅(FeCl4)− (4) and [(C7H9FN)⋅(18-crown-6)]+⋅1/2(CuCl4)2− (6). Structural analyses indicate that 1–2 crystallize in the triclinic space group P−1, 4 in orthorhombic space group Pnma and 3, 5, 6–8 in the monoclinic space group P21/c or C2/c. In these compounds, extensive intermolecular interactions have been utilized for the self-assembly of diverse supramolecular architectures, ranging from strong N–H⋯X (X=O, Cl, Br) hydrogen bonds to weak C–H⋯Y (Y=F, Cl, π) interactions. N–H⋯Cl/Br hydrogen bonds offer the major driving force in the crystal packing of salts 1–2 while N–H⋯O hydrogen bonds are found in salts 3–8.

Synthesis and Structural Studies of a New Complex of Di[hexabromobismuthate (III)] 2,5-Propylaminepyrazinium [C10H28N4]Bi2Br10

A new organic-inorganic hybrid material, [C10H28N4]Bi2Br10, has been synthesized and characterized. The compound crystallizes in monoclinic P21/c space group with a = 11.410(4) Å, b = 11.284(4) Å, c = 12.599(3) Å, β = 115.93(2)°, and V = 1458.8(8) Å3. The structure consists of discrete dinuclear [Bi2Br10]4− anions and [C10H28N4]4+ cations. It consists of a 0-D anion built up of edge-sharing bioctahedron. The crystal net contains N–H⋯Br hydrogen bonds. The differential scanning calorimetry (DSC) reveals an irreversible phase transition at −17°C. The frontier molecular orbital and the energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) calculation allow the classification of the material as an insulator.

Caesium bis(5-bromosalicylaldehyde thiosemicarbazonato-κ3O,N,S)ferrate(III): supramolecular arrangement of low-spin FeIII complex anions mediated by Cs+ cations.

The synthesis and crystal structure determination (at 293 K) of the title complex, Cs[Fe(C(8)H(6)BrN(3)OS)(2)], are reported. The compound is composed of two dianionic O,N,S-tridentate 5-bromosalicylaldehyde thiosemicarbazonate(2-) ligands coordinated to an Fe(III) cation, displaying a distorted octahedral geometry. The ligands are orientated in two perpendicular planes, with the O- and S-donor atoms in cis positions and the N-donor atoms in trans positions. The complex displays intermolecular N-H...O and N-H...Br hydrogen bonds, creating R4(4)(18) rings, which link the Fe(III) units in the a and b directions. The Fe(III) cation is in the low-spin state at 293 K.

Crystal structure of catena-poly[[cadmium(II)-di-μ2-bromido-μ2-l-proline-κ(2) O:O'] monohydrate

In the title coordination polymer, {[CdBr2(C5H9NO2)]·H2O} n , the Cd(II) ion is coordinated by four bromido ligands and two carboxyl-ate oxygen atoms of two symmetry-related proline ligands, which exist in a zwitterionic form, in a distorted octa-hedral geometry. There is an intra-molecular N-H⋯O hydrogen bond between the amino group and the carboxyl-ate fragment. Each coordinating ligand bridges two Cd(II) atoms, thus forming polymeric chains running along the c-axis direction. The water mol-ecules of crystallization serve as donors for the weak inter-molecular O-H⋯O and O-H⋯Br hydrogen bonds that link adjacent polymeric chains, thus forming a three-dimensional structure. N-H⋯O and N-H⋯Br hydrogen bonds also occur.

Crystal structure of 1,3-bis-(4-methyl-benz-yl)-1H-1,3-benzimidazol-3-ium bromide monohydrate.

In the title hydrated symetrically substituted 1,3-bis­(4-methyl­benz­yl)benzimidazolium salt, C23H23N2 +·Br−·H2O, the dihedral angles between the benzimidazole ring system (r.m.s. deviation = 0.003 Å) and the pendant benzene rings are 73.18 (16) and 77.52 (16)°. Both benzene rings lie to the same side of the benzimidazole ring system, giving the cation an overall U-shape. In the crystal, the cation is linked to the water mol­ecule by a short C—H⋯O hydrogen bond and the water mol­ecule forms O—H⋯Br hydrogen bonds. Together, these inter­actions lead to [010] chains. The packing is consolidated by C—H⋯Br hydrogen bonds and aromatic π–π stacking inter­actions [centroid–centroid distances = 3.5401 (17) and 3.8815 (18) Å], generating a three-dimensional network.

Crystal structure of 2-aza-niumyl-3-bromo-6-oxo-5,6-di-hydro-pyrido[1,2-a]quinoxalin-11-ium dibromide.

The title salt, C12H10BrN3O2+·2Br−, was synthesized from the reaction of N 1,N 4-bis­(pyridin-2-yl­methyl­idene)benzene-1,4-di­amine and bromine in a methanol solution. All non-H atoms of the 2-aza­niumyl-3-bromo-6-oxo-5,6-di­hydro­pyrido[1,2-a]quinoxalin-11-ium cation are nearly coplanar, the maximum deviation being 0.114 (4) Å. In the crystal, the cations and anions are linked through N—H⋯Br hydrogen bonds and weak C—H⋯Br inter­actions, forming a three-dimensional supra­molecular architecture. A short Br⋯Br contact [3.3088 (9) Å] is observed in the crystal.

Crystal structures of 2-benzyl-amino-4-(4-bromo-phen-yl)-6,7,8,9-tetra-hydro-5H-cyclo-hepta-[b]pyridine-3-carbo-nitrile and 2-benzyl-amino-4-(4-chloro-phen-yl)-6,7,8,9-tetra-hydro-5H-cyclo-hepta[b]pyridine-3-carbo-nitrile.

In the title compounds, C24H22BrN3, (I), and C24H22ClN3, (II), the 2-amino-pyridine ring is fused with a cyclo-heptane ring, which adopts a half-chair conformation. The planes of the phenyl and benzene rings are inclined to that of the central pyridine ring [r.m.s. deviations = 0.0083 (1) and 0.0093 (1) Å for (I) and (II), respectively] by 62.47 (17) and 72.51 (14)°, respectively, in (I), and by 71.44 (9) and 54.90 (8)°, respectively, in (II). The planes of the aromatic rings are inclined to one another by 53.82 (17)° in (I) and by 58.04 (9)° in (II). In the crystals of both (I) and (II), pairs of N-H⋯Nnitrile hydrogen bonds link the mol-ecules, forming inversion dimers with R 2 (2)(12) ring motifs. In (I), the resulting dimers are connected through C-H⋯Br hydrogen bonds, forming sheets parallel to (10-1), and π-π inter-actions [inter-centroid distance = 3.7821 (16) Å] involving inversion-related pyridine rings, forming a three-dimensional network. In (II), the resulting dimers are connected through π-π inter-actions [inter-centroid distance = 3.771 (2) Å] involving inversion-related pyridine rings, forming a two-dimensional network lying parallel to (001).

Crystal structure of 4,4'-(ethane-1,2-di-yl)bis-(2,6-di-bromo-aniline).

In the title compound, C14H12Br4N2, the mol-ecule lies across an inversion center and hence the benzene rings are strictly coplanar. In the crystal, mol-ecules are linked by N-H⋯N and weak N-H⋯Br hydrogen bonds, forming a two-dimensional network parallel to (101). In addition, type II Br⋯Br inter-actions [3.625 (4) Å] complete a three-dimensional supra-molecular network.

A new class of cuprous bromide cluster-based hybrid materials: direct observation of the stepwise replacement of hydrogen bonds by coordination bonds.

Although a variety of functional metal-organic frameworks (MOFs) have been synthesized, post-modified, and applied in various areas, there is little knowledge about how molecular cluster building units are stepwise evolved into MOFs via intermediates. Coordination bonds are generally stronger than hydrogen bonds, and thus equivalent replacement of X-H···Y hydrogen bonds by X-M-Y coordination bonds can transform hydrogen bond networks into MOFs. In this work, solvothermal in situ reduction reactions of CuBr2 and 1,4-diazoniabicyclo[2,2,2]octane (DABCO) generated a myriad of tunable photoluminescent cuprous body-centered cubic bromide cluster-based networks with the general formula [Cu4+xH4-xBr6(DABCO)4](HCO2)2·S (x = 0, 0.56, 0.81, 1.27, 1.39, 2.56, 2.78, and 4 for compounds 1-8, respectively). All of these compounds crystallize in the cubic space group with the largest volume difference being only 5.2%, but they belong to three remarkably different kinds of crystals. Complex 1 is a molecular crystal and consists of tetrahedral [Cu4Br6(HDABCO)4](2+) clusters with monodentate HDABCO groups that are supported via N-H···Br synthons in the hydrogen bond network. Compound 8 is a [Cu8Br6](2+) cube cluster-based MOF with bridged DABCO ligands. Complexes 2-7 are seemingly impossible Cu/H-substituted solid solutions of 1 and 8. The CuBr framework components in 1-8 are Cu4Br6, Cu4.56Br6, Cu4.81Br6, Cu5.27Br6, Cu5.39Br6, Cu6.56Br6, Cu6.78Br6, and Cu8Br6, respectively. Crystallization kinetics studies revealed that the [Cu4Br6(HDABCO)4](2+) cluster-based hydrogen bond network (1) was initially formed such that N-H···Br hydrogen bonds could be stepwise replaced by N-Cu-Br coordination bonds to form the [Cu8Br6](2+) cube cluster-based MOF (8) via solid solutions. These observations directly reveal the equivalence and transformation between the N-H···Br hydrogen bond and the N-Cu-Br coordination bond and the evolutionary mechanism of a molecular crystal to a MOF via solid solutions, which is of fundamental importance in materials but has never before been revealed. DFT calculations suggest that equivalent replacement of a N-H···Br hydrogen bond by a N-Cu-Br coordination bond is exothermic and exergonic, which also supports the transformation from molecule 1 to MOF 8.

The Structures of Uncommon Cationic N‐alkenyl Purine and Pyrimidine Bases

The structures of 1,3 bis‐(allyl)cytosinium bromide (1), 7,9 bis‐(allyl)adeninium bromide hydrate (2) and 3‐(butenyl)adeninium bromide (3) have been determined. 1 is dimeric via N―H…Br hydrogen bonds, which further associate into ribbons via weaker C―H…Br interactions. 2 is also dimeric, now from N―H…N hydrogen bonds, which build up further through a complex array of hydrogen bonds involving both the anion and water of crystallization (O―H…N, O―H…Br, C―H…Br). 3 does not dimerise but forms polymeric sheets via a series of N―H…N, C―H…N and C―H…Br hydrogen bonds.

Crystal structure of bromido-fac-tricarbon-yl[5-phenyl-3-(pyridin-2-yl)-1H-1,2,4-triazole-κ(2) N,N']rhenium(I).

In the title compound, [ReBr(C13H10N4)(CO)3], the Re(I) atom has a distorted octa-hedral coordination environment. Two N atoms of the 5-phenyl-3-(pyridin-2-yl)-1H-1,2,4-triazole ligand and two of the three carbonyl groups occupy the equatorial plane of the complex, with the third carbonyl ligand and the bromide ligand in the axial positions. The three carbonyl ligands are arranged in a fac configuration around the Re(I) atom. Mutual N-H⋯Br hydrogen bonds arrange mol-ecules into centrosymmetric dimers. Additional stabilization within the crystal structure is provided by C-H⋯O and C-H⋯Br hydrogen bonds, as well as by slipped π-π stacking inter-actions [centroid-to-centroid distance = 3.785 (5) Å], defining a three-dimensional network.

Crystal structure of 3-amino-1-propyl-pyridinium bromide.

The title mol-ecular salt, C8H13N2 (+)·Br(-), crystallizes with two independent 3-amino-pyridinium cations and two bromide anions in the asymmetric unit (Z' = 2). In the pyridine ring, the N atom is alkyl-ated by a propyl group. The dihedral angle between the mean planes of the pyridinium ring and the propyl group is 84.84 (2)° in cation A, whereas the corresponding angle is 89.23 (2)° in cation B. In the crystal, the anions and cations are linked via N-H⋯Br and C-H⋯Br hydrogen bonds, forming chains propagating along [100].

Crystal structure of 4-amino-1-(4-methyl-benz-yl)pyridinium bromide.

The title mol­ecular salt, C13H15N2 +·Br−, crystallized with two independent ion pairs (A and B) in the asymmetric unit. In the cations, the planes of the pyridine and benzene rings are inclined to one another by 79.32 (8) and 82.30 (10)° in ion pairs A and B, respectively. In the crystal, the anions and cations are connected by N—H⋯Br hydrogen bonds, forming a centrosymmetric tetra­mer-like unit enclosing an R 8 4(16) ring motif. These units are linked via C—H⋯Br hydrogen bonds, forming a three-dimensional network.

Crystal structure of methyl 2-(2H-1,3-benzodioxol-5-yl)-7,9-di-bromo-8-oxo-1-oxa-spiro-[4.5]deca-2,6,9-triene-3-car-boxyl-ate.

The title compound, C18H12Br2O6, was synthesized from Morita–Baylis–Hillman adducts. It incorporates the bromin­ated spiro-hexa­dienone moiety typically exhibited by compounds of this class that exhibit biological activity. Both the brominated cyclo­hexa­dienone and the central five-membered rings are nearly planar (r.m.s. deviations of 0.044 and 0.016 Å, respectively), being almost perpendicularly oriented [inter­planar angle = 89.47 (5)°]. With respect to the central five-membered ring, the brominated cyclo­hexa­dienone ring, the benzodioxol ring and the carboxyl­ate fragment make C—O—C—C, O—C—C—C and C—C—C—O dihedral angles of −122.11 (8), −27.20 (11) and −8.40 (12)°, respectively. An intra­molecular C—H⋯O hydrogen bond occurs. In the crystal, mol­ecules are linked by non-classical C—H⋯O and C—H⋯Br hydrogen bonds resulting in a molecular packing in which the brominated rings are in a head-to-head orientation, forming well marked planes parallel to the b axis.

Crystal structure of 1,3-bis-(2,6-diiso-propyl-phen-yl)-4,5-dimethyl-1H-imid-azol-3-ium bromide di-chloro-methane disolvate.

The title solvated salt, C29H41N2 +·Br−·2CH2Cl2 was obtained from the reaction of the Arduengo-type carbene 1,3-bis­(2,6-diiso­propyl­phen­yl)-1,3-dihydro-4,5-dimethyl-2H-imidazol-2-ylidene with Si2Br6 in di­chloro­methane. The complete cation is generated by a crystallographic mirror plane and the dihedral angle between the five-membered ring and the benzene ring is 89.8 (6)°; the dihedral angle between the benzene rings is 40.7 (2)°. The anion also lies on the mirror plane and both di­chloro­methane mol­ecules are disordered across the mirror plane over two equally occupied orientations. In the crystal, the cations are linked to the anions via C—H⋯Br hydrogen bonds.

Crystal structure of bis-[2-(1H-benzimid-azol-2-yl)-4-bromo-phenolato-κ(2) N (3),O]cobalt(II).

The asymmetric unit of the title CoII complex, [Co(C13H8BrN2O)2], contains two independent mol­ecules (A and B). In both mol­ecules, the CoII cation is N,O-chelated by two 2-(1H-benzimidazol-2-yl)-4-bromo­phenolate anions in a distorted tetra­hedral geometry. In mol­ecule A, both chelating rings display an envelope conformation, with the flap Co atom lying 0.614 (6) and 0.483 (6) Å from the mean planes of the remaining atoms. In mol­ecule B, both chelating rings are approximately planar, the maximum deviations being 0.039 (4) and 0.076 (3) Å. In the crystal, mol­ecules are linked by classical N—H⋯O hydrogen bonds and weak C—H⋯O and C—H⋯Br hydrogen bonds into a three-dimensional supra­molecular network. Extensive π–π stacking is observed between nearly parallel aromatic rings of adjacent mol­ecules with centroid–centroid distances in the range 3.407 (3)–3.850 (4) Å.

Crystal structure of bromido-bis-(naph-thal-en-1-yl)anti-mony(III).

In the title compound, [SbBr(C10H7)2], the SbIII atom has a distorted trigonal–pyramidal coordination geometry and the planes of the two naphthalene ring systems make a dihedral angle of 80.26 (18)°. An intra­molecular C—H⋯Br hydrogen bond forms an S(5) ring motif. In the crystal, weak C—H⋯Br inter­actions link the mol­ecules into helical chains along the b-axis direction.

Primary- and secondary-octahedral distortion factors in bis(1,4-H2-1,2,4-triazolium) pentabromidoantimonate(III)–1,4-H2-1,2,4-triazolium bromide

The analysis of octahedral distortion in the structure of inorganic–organic (C2H4N3)2[SbBr5]·(C2H4N3)Br (BTPTB) bromidoantimonate(III) determined at 295 and 85K, supported by the Hirshfeld surface analysis and the data retrieved from the Cambridge Structural Database, is presented. The anionic substructure of BTPTB is built from distorted [SbBr6]3− octahedra that are connected by the cis corners forming polymeric one-dimensional [{SbBr5}n]2n− zig-zag chains running parallel to the a axis and isolated Br− ions. The organic substructure consists of the fully ordered 1,4-H2-1,2,4-triazolium cations. The oppositely charged substructures are linked by the system of N(C)–H⋯Br hydrogen bonds causing further distortion of [SbBr6]3− octahedra. The comparison of octahedral geometry and distortions found in the structure of BTPTB determined at room and low temperature, to access the attractive nature of hydrogen bonds, clearly shows that hydrogen bond interactions are responsible for secondary distortion of octahedra and the observed deviations are comparable to primary distortion that is caused by the intrinsic interactions within inorganic substructure. Furthermore, a comparison of packing features and interactions in BTPTB with those in the structure of organic 1,4-H2-1,2,4-triazolium bromide, (C2H4N3)Br (TB), also determined at 295 and 85K, confirms the importance and hierarchy of factors that are responsible for polyhedral distortion.

Crystal structure of (3,5-dibromo-2-hy-droxyphenyl){1-[(naphthalen-1-yl)carbonyl]-1H-pyrazol-4-yl}methanone.

In the title compound, C21H12Br2N2O3, a 1,4-diaroyl pyrazole derivative, the dihedral angles between the naphthalene ring system and the pyrazole ring, the pyrazole and benzene rings, and the naphthalene ring system and benzene ring are 50.0 (2), 51.1 (2) and 1.34 (16)°, respectively. The phenolic proton forms an intra­molecular O—H⋯O hydrogen bond with the adjacent carbonyl O atom. In the crystal, mol­ecules are linked by C—H⋯O hydrogen bonds, forming inversion dimers. The dimers are linked by C—H⋯Br hydrogen bonds, forming double stranded chains along [01-1]. The chains are linked by π–π inter­actions between the pyrazole rings and between the naphthalene and benzene rings [centroid–centroid distances = 3.592 (4) and 3.632 (4) Å, respectively].

Reversible De-/Rehydration Process in Paroxetine Hydrobromide

Paroxetine (PRX) is an antidepressant widely used in depression treatment for decades. The anhydrous and hemidrate chloride forms have been used in pharmaceutical formulations. During their developing a discussion associated with its physical forms and the complex hydration/dehydration behavior involving these phases were established. To improve our understanding of this issue we investigate the crystal structure of paroxetine bromide hemidrate, (PRX+.Br-).H2O, as a model for understanding the stability anhydrous/hemihydrate paroxetine arrangements and the nature of the intermolecular interaction of water within the crystal lattice by single crystal X-ray diffraction experiments. A combination of complementary characterization techniques were also used including Differential Scanning Calorimetry (DSC), thermogravimetric analysis (TGA), Hot Stage microscopy and solubility measurements. As expected the paroxetine bromide hemidrate, (PRX+.Br-).H2O, is isostructural with the paroxetine chloride hemidrate, (PRX+.Cl-).H2O. As in that case, the crystal packing of (PRX+.Br-).H2O is stabilized by strong NH2+...O and NH2+...Br hydrogen bonds which forms infinite channels along the b axis. The water and bromide anions are located along these channels. The DSC/TGA analysis for (PRX+.Br-).H2O show an endothermic desolvation process with an onset temperature of 77.09 °C, that is not present in the paroxetine chloride hemidrate DSC curve. This process leaves to a paroxetine anhydrous bromide crystal structure that is isomorphic to the anhydrous chloride one. However, this structure is spontaneously rehydrated at ambient atmosphere. This rehydration phenomenon probe the stability of paroxetine hemihydrate arrangement, since (PRX+.Br-) is slightly more soluble that its hydrate form. As opposed to chloride hemidrate, the rehydration of paroxetine bromide only involves a rearrangement of the water molecule within the cavities.