Search

The crystal structures of three S-(pyridin-2-yl) benzo­thio­esters with varying para-phenyl substituents are presented, namely, S-(pyridin-2-yl) 4-nitro­benzo­thio­ate (1, C12H8N2O3S), S-(pyridin-2-yl) 4-methyl­benzo­thio­ate (2, C13H11NO2S) and S-(pyridin-2-yl) 4-meth­oxy­benzo­thio­ate (3, C13H11NO2S). This class of compounds are used in the mono-acyl­ation of pyrrolic species to yield multifunctional tetra­pyrroles. The structures presented herein are the first of their compound class. The dominant inter­actions present in this series are π-π stacking and C--H⋯O inter­actions, and as the para-phenyl motif changes from electron withdrawing (NO2, 1) to electron donating (OCH3, 3), changes are observed in the inter­actions present in the crystal packing, from predominant π-π stacking in 1 to exclusively C--H⋯O/N inter­actions (Car­yl--H⋯Ocarbonyl, C--H⋯Ometh­oxy and Caryl--H⋯Npyridine) in 3. [ABSTRACT FROM AUTHOR]

Recently prochiral solvating agents (pro-CSA) came under the spotlight for the detection of enantiopurity by NMR. Chemical shift non-equivalency in achiral hosts introduced by the presence of chiral guests yields observable resonance signal splitting (Δδ) correlating to the enantiomeric excess (e.e.). In this work, symmetry is our lens to explain porphyrin-based supramolecular receptor activity in a chiral environment. Based on extensive NMR analyses of the atropisomeric receptors, the host symmetry is shown to be affected by porphyrin nonplanarity and further desymmetrized in the presence of a chiral guest. As such, the exposed porphyrin inner core (N–H), with its strong hydrogen bond abilities, for the first time, has been exploited in enantiomeric composition analysis. Our approach in e.e. detection by N–H signals appearing in a previously underutilized region of the spectrum (below 0 ppm) shows chemical shift splitting (Δδ) three times more sensitive to enantiomeric compositions than previously reported systems. [ABSTRACT FROM AUTHOR]

The solid state structure of the pentaborate anion templated by a doubly protonated TMEDA cation is reported. The structure is typical of this family of ligands, featuring extensive hydrogen bonding. Spectroscopic characterisation is also reported. The structure of [TMEDAH2][B5O6(OH)4]2 is reported and hydrogen bonding gives a 'brickwall' type structure. This is a blue emitter in solution. [ABSTRACT FROM AUTHOR]

The solid state structure of the pentaborate anion templated by a doubly protonated TMEDA cation is reported. The structure is typical of this family of ligands, featuring extensive hydrogen bonding. Spectroscopic characterisation is also reported. The structure of [TMEDAH2][B5O6(OH)4]2 is reported and hydrogen bonding gives a 'brickwall' type structure. This is a blue emitter in solution. [ABSTRACT FROM AUTHOR]

The crystal structures of the title compounds, two solvates (CHCl3 and THF) of a symmetric and highly substituted porphyrin, C44H2Br8F20N4 or OBrTPFPP, are described. These structures each feature a non-planar porphyrin ring, exhibiting a similar conformation of the strained ring independent of solvent identity. These distorted porphyrins are able to form hydrogen bonds and subvan der Waals halogen interactions with enclathrated solvent; supramolecular interactions of proximal macrocycles are additionally affected by solvent choice. The crystal studied for compound 1·CHCl3 was refined as an inversion twin. One pentafluorophenyl group was modelled as disordered over two sites [occupancy ratio = 0.462 (7):0.538 (7)]. The chloroform solvate was also modelled as disordered over two orientations [occupancy ratio = 0.882 (7): 0.118 (7). [ABSTRACT FROM AUTHOR]

The solid state structure of an N-heterocyclic borane 1,1,3,3-tetramethyl-1,3λ4,2-diazaborolidin-1-ium chloride is reported. This molecule features numerous Cl⋯H hydrogen bonds.Graphical Abstract: The crystal structure of 1,1,3,3-tetramethyl-1,3λ4,2-diazaborolidin-1-ium chloride shows multiple C-H⋯Cl interactions in the solid state. [ABSTRACT FROM AUTHOR]

The solid state structure of 1,1,1,2,2,3,3-heptachloropropane is reported. This molecule features numerous type I and type II Cl⋯Cl interactions in the solid state as well as Cl⋯H hydrogen bonds. A Hirshfeld surface analysis is also presented. Graphical Abstract: The crystal structure of 1,1,1,2,2,3,3-heptachloropropane shows type I and type II Cl⋯Cl interactions in the solid state. [ABSTRACT FROM AUTHOR]

An analysis is made of the supramolecular interactions in the two polymorphic structures of 3,5-dibromo-2,6-diaminopyridinium bromide, with particular emphasis on the roles of hydrogen and halogen bonding. Because of the extensive hydrogen bonding capabilities, hydrogen bonding interactions dominate in both phases. This causes a competition between C-Br···Br-C and C-Br···Br halogen bonding interactions, with the former dominating in the orthorhombic Pbca phase and the latter in the monoclinic P2/c phase. For Pbca phase a = 5.5197(11) Å, b = 15.040(3) Å, c = 23.2555(5) Å, and for P2/c phase a = 8.1143(19) Å, b = 14.226(3) Å, c = 8.9005(18) Å, β = 113.18(2)°. Graphical Abstract: The two polymorphic structures of 3,5-dibromo-2,6-diaminopyridinium bromide differ mainly in halogen-halogen bonding. In the more compact and more stable P2/c phase the halogen-halogen interaction, C-Br···Br-C, is 0.36 Å longer than in the less compact Pbca phase. On the other hand the charge assisted halogen-halide interactions, C-Br···Br, is dominant in the P2/c phase while there are no such in-plane type contacts in the Pbca phase.[Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The crystal structure of [Ph4P][NCS]·HNCS is reported. This is the first structural determination of isothiocyanic acid and hydrogen bonding between the NCS anion and HNCS fragment explored using computational chemistry. [ABSTRACT FROM AUTHOR]

The title compound, [Cu2Br4(C5H4N2O3)2], is a centrosymmetric dimer that contains a central planar Cu2O2 rhombus with the O atom of the N-oxide group bridging two Cu atoms [Cu—O—Cu = 109.08 (19)° and O—Cu—O = 70.92 (19)°]. The two-dimensional sheet structure is built up via semi-coordinate intermolecular Cu·Br bonds [3.226 (1) and 3.810 (1) Å] and weak hydrogen bonding [C·Br = 3.733 (7), 3.781 (7) and 3.830 (7) Å]. [ABSTRACT FROM AUTHOR]

The title compound, C24H28N2O7, is the product of a novel synthetic procedure in which a highly functionalized heterocycle is formed. The crystal packing involves dimers, utilizing non-classical weak C—H⋯O interactions ( ca 3.36–3.46 Å) and an antiparallel π–π interaction between two of the pseudo-aromatic isoxazole moieties. These dimers are associated into a three-dimensional network via further non-classical hydrogen bonding. [ABSTRACT FROM AUTHOR]

AbstractFive new copper(II) complexes of substituted quinoxaline ligands have been prepared and characterized via single crystal X-ray diffraction, including [Cu(5-Mequinox)2(NO3)2] (2), [Cu(5-Mequinox)(NO3)(H2O)(μ-1,3-NO3)]n (3), the chloride salt (5-MequinoxH)2[Cu3Cl8] (4), the complex [Cu(6-Mequinox)2(NO3)2] (5) and [(2-carboxylato-3-methylquinox)(2-hydroxymethyl-3-methylquinox)nitratocopper(II)]. CH3CN (6) [quinox = quinoxaline; 5-Mequinox = 5-methylquinoxaline; 6-Mequinox = 6-methylquinoxaline]. None of the complexes produced diazine bridged chain structures (as seen in [(quinox)Cu(NO3)2]n (1)), although 3 forms chains via a bridging nitrate ion. Crystal packing is controlled primarily through hydrogen bonding and π-stacking of nitrate ions. The temperature dependent magnetic susceptibility data of the parent compound [(quinox)Cu(NO3)2]n are also reported and discussed. [ABSTRACT FROM AUTHOR]

The title compound, C28H20ClNO4, is a very stable enol produced by a Dess–Martin oxidation, not the expected ketone. The enol form is stabilized by intra­molecular hydrogen bonding and the mol­ecules associate into dimers via weak C—H⋯N hydrogen bonding. [ABSTRACT FROM AUTHOR]

The title compound crystallizes in the monoclinic P21/c space group with a = 11.2470(3) Å, b = 5.9034(2) Å, c = 12.0886(3) Å, β = 115.143(1)°, and V = 726.58(4) Å3 and consists of discrete monomeric NiCl2(o-phenylendiamine)2 molecules. Each o-phen ligand coordinates in a bidentate mode with the chloride ions occupying trans positions in the resulting tetragonally distorted octahedral coordination sphere. Two discrete sets of N-H⋯Cl hydrogen bonds link the octahedral molecules into a two-dimensional network, with type 1 interactions linking adjacent monomers along the c axis and type 2 interactions linking monomers along the diagonals in the bc plane. Analysis of the magnetic data reveals the existence of weak antiferromagnetic coupling within the layers via these hydrogen bonds, in addition to the presence of zero field splitting, with the best fit obtained for a 1d antiferromagnetic model with g = 2.0917(7), J/k = -2.11(4) K [J = -1.47(3) cm-1], and D = 1.05(3) cm-1 [β = D/∣J∣ = 0.72(6)] for the model with D > 0 and g = 2.0911(6), J/k = -2.26(1) K [J = -1.57(1) cm-1], and D = -0.86(1) cm-1 [β = D/∣J∣ = 0.55(6)] for the model with D < 0. Theoretical calculations of the exchange coupling confirm the experimental results, yielding values of J1 = -1.39 cm-1 for the type 1 hydrogen bonds and J2/k = -0.56 cm-1 for the type 2 hydrogen bonds. [ABSTRACT FROM AUTHOR]

Abstract: The role that the linear arylbromine–halide ion synthons, in conjunction with traditional hydrogen bonding synthons, play in the development in the crystal structures of the 2,5-dibromopyridinium halide salts, (25DBP)X, and the 3,5-dibromopyridinium halide salts, (35DBP)X (X=Cl, Br, I), are analyzed. In the Cl− and Br− salts of the 25DBP+ cation, the extremely short, nearly linear C–Br···X− and N–H···X− interactions link the cations and anions together into ladder structures; the C–Br···X− synthons form the rails while the N–H···X− synthons form the rungs. In (25DBP)I, chains formed from the C–Br···X− synthons are cross-linked into a two-dimensional network by the N–H···X− synthons. The competition between N–H···X− and C–Br···X− synthons indicates that the C–Br···X− synthons are of a comparable importance with strong N–H···X− hydrogen bonds. In the 35DBP+ salts, C–Br···Br–C synthons compete with the C–Br···X− synthons, so the Br···X− distances increase, but still significantly shorter than, the sum of the van der Waals radii. In the chloride and monoclinic form of the bromide salt, chains are again formed. However, in contrast, C–Br···X− and N–H···X− synthons alternate on the rails and C–Br···X− synthons form the rungs in the 35DBP+ salts. The analysis of the experimental values of C–Br···X− (avg.=169.7°) and N–H···X− (avg.=161.7°) angles indicates that the C–Br···X− angles are closer to a linear arrangement in comparison to the corresponding N–H···X− angles. This conclusion is authenticated through theoretical calculations of the optimized structures of the model n-bromopyridinum halids salts: (nBP)X (X=Cl, Br; n =2 and 3). [Copyright &y& Elsevier]

The crystal structures are reported for two compounds containing novel perforated layer structures, [DBA]2Cd9Cl20·2H2O and [Cu(TIM)]2Cu13Cl30(H2O)2·xH2O, where [DBA]+ = din-butylammonium and TIM = 2,3,9,10-tetramethyl-1,3,8,10-tetraenecyclo- 1,4,8,11-tetraazatetradecane. In the former compound, single Cd2+ ions are excised from the parent CdCl2 layers, with water molecules hydrogen bonded to chloride ions on both sides of the excision. Lattice stability is provided by the DBA+ cations, which have an all-trans conformation. These lie between the layers, hydrogen bonding to the adjacent [Cd9Cl20(H2O)2]n2n- sheets. In the copper compound, the modification of the parent CuCl2 structure is much more complex. In this compound, [Cu2Cl2]2+ moieties are excised in a regular fashion. In addition, at 50% of the Cu1 sites, CuCl2 species are replaced by pairs of water molecules in a random fashion. The Cu(TIM)2+ cations bridge the layers via the formation of two semicoordinate bonds to chloride ions at the edge of the [Cu2Cl2]2+ excision sites of adjacent layers. [ABSTRACT FROM AUTHOR]

The complex [Ni(PCy2NBz2)2)(BF4)2, 1, reacts rapidly and reversibly with carbon monoxide (1 atm) at 25 °Cto form [Ni(CO)(PCy2NBz2)2](BF4)2, 2, which has been characterized by spectroscopic data and by an X-ray diffraction study. In contrast, analogous Ni(II) carbonyl adducts were not observed in studies of several other related nickel(II) diphosphine complexes. The unusual reactivity of 1 is attributed to a complex interplay of electronic and structural factors, with an important contribution being the ability of two positioned amines in the second coordination sphere to act in concert to stabilize the CO adduct. The proposed interaction is supported by X-ray diffraction data for 2 which shows that all of the chelate rings of the cyclic ligands are in boat conformations, placing two pendant amines close (3.30 and 3.38 A) to the carbonyl carbon. Similar close C-N interactions are observed in the crystal structure of the more sterically demanding isocyanide adduct, [Ni(CNCy)(PCy2NBz2)2]2(BF4)2, 4. The data suggest a weak electrostatic interaction between the lone pairs of the nitrogen atoms and the positively charged carbon atom of the carbonyl or isocyanide ligand, and illustrate a novel (non-hydrogen bonding) second coordination sphere effect in controlling reactivity. [ABSTRACT FROM AUTHOR]

Three Cu2+-containing coordination polymers were synthesized and characterized by experimental (X-ray diffraction, magnetic susceptibility, pulsed-field magnetization, heat capacity, and muon-spin relaxation) and electronic structure studies (quantum Monte Carlo simulations and density functional theory calculations). [Cu(HF2)(pyz)2]SbF6 (pyz = pyrazine) (1a), [Cu2F(HF)(HF2)(pyz)4](SbF6)2 (1b), and [CuAg(H3F4)(pyz)5](SbF6)2 (2) crystallize in either tetragonal or orthorhombic space groups; their stwctures consist of 2D square layers of [M(pyz)2]n+ that are linked in the third dimension by either HF2- (1a and 1b) or H3F4- (2). The resulting 3D frameworks contain charge-balancing SbF6- anions in every void. Compound lb is a defective polymorph of 1a, with the difference being that 50% of the HF2- links are broken in the former, which leads to a cooperative Jahn-Teller distortion and dx²-y² orbital ordering. Magnetic data for 1a and 1b reveal broad maxima in χ at 12.5 and 2.6 K and long-range magnetic order below 4.3 and 1.7 K, respectively, while 2 displays negligible spin interactions owing to long and disrupted superexchange pathways. The isothermal magnetization, M(B), for 1a and 1b measured at 0.5 K reveals contrasting behaviors: la exhibits a concave shape as B increases to a saturation field, Bc, of 37.6 T, whereas 1b presents an unusual two-step saturation in which M(B) is convex until it reaches a step near 10.8 T and then becomes concave until saturation is reached at 15.8 T. The step occurs at two-thirds of Msat, suggesting the presence of a ferrimagnetic structure. Compound 2 shows unusual hysteresis in M(B) at low temperature, although χ vs T does not reveal the presence of a magnetic phase transition. Quantum Monte Carlo simulations based on an anisotropic cubic lattice were applied to the magnetic data of la to afford g= 2.14, J= -13.4 K(Cu-pyz-Cu), and J⊥ = -0.20 K(Cu-F⋯:H⋯:F-Cu), while χ vs T for 1b could be well reproduced by a spin-1/2 Heisenberg uniform chain model for g = 2.127(1), J1 = -3.81(1), and zJ2 = -0.48(1) K, where J1 and J2 are the intra- and interchain exchange couplings, respectively, which considers the number of magnetic nearest-neighbors (z). The M(B) data for 1b could not be satisfactorily explained by the chain model, suggesting a more complex magnetic structure in the ordered state and the need for additional terms in the spin Hamiltonian. The observed variation in magnetic behaviors is driven by differences in the H⋯F hydrogen-bonding motifs. [ABSTRACT FROM AUTHOR]

Abstract: The structural and magnetic properties of the series of (4,4′-bipyridinium)Cu2Cl6− x Br x salts are investigated. All of the compounds are isomorphous, triclinic, space group . Structurally, the compounds contain pseudo-planar dimeric species that form stacks due to weak coordination of adjacent dimer anions via semi-coordinate Cu⋯X bonds. Hydrogen bonding from the 4,4′-bipyridinium dications tie the stacks together into a two-dimensional structural framework. Secondary C–H⋯X hydrogen bonds force short X⋯X contacts between the dimers on adjacent layers, with X⋯X distances of 3.645–3.690Å. In this manner, magnetic chains are expected to exist with alternating exchange pathways: the intradimer exchange coupling and the X⋯X pathway. An additional pathway exists within stacks of dimers via the semi-coordinate Cu⋯X bonds, although this pathway is expected to be relatively weak and is ignored for simplicity. Magnetic studies indicate that these systems behave as alternating AFM chains with very strong coupling, demonstrating that the halide⋯halide contacts are effective exchange pathways. The AFM coupling is observed to increase monotonically as the bromide content increases. The values for the salt are J 1/k =−57.2(6)K and J 2/k =−27(4)K while those of the salt are −162(2) and −93(5)K, respectively. Analysis of the pathways suggests that J 2 value corresponds to the intradimer coupling while the J 1 value is assigned to the two-halide pathway. [Copyright &y& Elsevier]