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Acta Crystallographica. Section C, Structural Chemistry

Chun Li Liu, Xu Wei, Qiu Ying Huang, Xiang Ru Meng
Due to their strong coordination ability and the diversities of their coordination modes, N-heterocyclic organic compounds are used extensively as ligands for the construction of complexes with fascinating structures and potential applications in many fields. Two new complexes, namely bis{1-[(benzotriazol-1-yl)methyl]-1H-imidazole-κN(3)}dibromidozinc(II), [ZnBr2(C10H9N5)2], (I), and bis{1-[(benzotriazol-1-yl)methyl]-1H-imidazole-κN(3)}diiodidozinc(II), [ZnI2(C10H9N5)2], (II), have been synthesized by reaction of the unsymmetrical N-heterocyclic ligand 1-[(benzotriazol-1-yl)methyl]-1H-imidazole (bmi) with Zn(acetate)2 in the presence of KBr or KI...
November 1, 2016: Acta Crystallographica. Section C, Structural Chemistry
Eleonora Freire, Griselda Polla, Ricardo Baggio
Lamotrigine is a drug used in the treatment of epilepsy and related convulsive diseases. The drug in its free form is rather inadequate for pharmacological use due to poor absorption by the patient, which limits its bioavailability. On the other hand, the lamotrigine molecule is an excellent hydrogen-bonding agent and this has been exploited intensively in the search for better formulations. The formulation presently commercialized (under the brand name Lamictal) is rather complex and includes a number of anions in addition to the active pharmaceutical ingredient (API)...
November 1, 2016: Acta Crystallographica. Section C, Structural Chemistry
Liubov M Lifshits, Varun Singh, Matthias Zeller, Jeremy K Klosterman
The photophysical properties of organic fluorophores are sensitive to the local sterics of the surrounding environment. Restriction of torsional motion in aggregates and crystals can give rise to enhanced emissive behavior. N-Aryl-substituted carbazoles serve an essential role as ubiquitous host matrices for organic light-emitting diodes, due to their large band gaps and high triplet energies, and so studies connecting photophysical behaviors with detailed crystallographic structural information are important...
November 1, 2016: Acta Crystallographica. Section C, Structural Chemistry
Xin Hua Lu, Kai Long Zhong
The self-assembly of coordination polymers and the crystal engineering of metal-organic coordination frameworks have attracted great interest, but it is still a challenge to predict and control the compositions and structures of the complexes. Employing multidentate organic ligands and suitable metal ions to construct inorganic-organic hybrid materials through metal-ligand coordination and hydrogen-bonding interactions has become a major strategy. Recently, imidazole-containing multidentate ligands that contain an aromatic core have received much attention...
November 1, 2016: Acta Crystallographica. Section C, Structural Chemistry
Ping Liu, Qiuxia Liu, Ning Zhao, Caixia An, Zhaoxun Lian
The design of nonlinear optical (NLO) materials with large NLO responses has been a challenge for materials scientists and chemists. Recently, organic polymers have received attention regarding their NLO properties and fast nonlinear response, and clusters involving delocalized dπ-pπ systems and conjugated dπ-pπ systems are expected to be a new class of NLO materials. Metal-organic coordination polymers combine the advantages of the organic and inorganic species. Thus far, tuning the third-order NLO properties of these materials has been a significant challenge...
November 1, 2016: Acta Crystallographica. Section C, Structural Chemistry
Tamara J Bednarchuk, Vasyl Kinzhybalo, Adam Pietraszko
Hybrid materials, fabricated by the combination of inorganic and organic components, have potential applications in chemistry and are endowed with the advantages of both building elements. There are several types of intermolecular interactions present in these hybrid compounds, including electrostatic forces, π-π stacking and hydrogen-bonding interactions, the latter playing an important role in the construction of three-dimensional architectures and stabilizing supramolecular crystal structures. Analysis of the intermolecular interactions and their influence on packing modes therefore requires focused scientific attention...
November 1, 2016: Acta Crystallographica. Section C, Structural Chemistry
Majid I Tamboli, Shobhana Krishanaswamy, Rajesh G Gonnade, Mysore S Shashidhar
Minor variations in the molecular structure of constituent molecules of reactive crystals often yield crystals with significantly different properties due to altered modes of molecular association in the solid state. Hence, these studies could provide a better understanding of the complex chemical processes occurring in the crystalline state. However, reactions that proceed efficiently in molecular crystals are only a small fraction of the reactions that are known to proceed (with comparable efficiency) in the solution state...
November 1, 2016: Acta Crystallographica. Section C, Structural Chemistry
David K Geiger, Matthew R DeStefano
The structural characterization of several polymorphic forms of a compound allow the interplay between molecular conformation and intermolecular interactions to be studied, which can contribute to the development of strategies for the rational preparation of materials with desirable properties and the tailoring of intermolecular interactions to produce solids with predictable characteristics of interest in crystal engineering. The crystal structures of two new polymorphs of 5,6-dimethyl-2-(pyridin-2-yl)-1-[(pyridin-2-yl)methyl]-1H-benzimidazole, C20H18N4, are reported...
November 1, 2016: Acta Crystallographica. Section C, Structural Chemistry
Rüdiger W Seidel, Richard Goddard, Thomas Mayer-Gall, Iris M Oppel
Porphyrin assemblies display interesting photophysical properties and a relatively high thermal stability. Moreover, meso-functionalized porphyrins with virtually fourfold symmetry can be relatively readily synthesized from pyrrole and the appropriate aldehyde. A number of metallo derivatives of 5,10,15,20-tetrakis(4-cyanophenyl)porphyrin, where the N atom of the linear cyano group can act both as a donor for coordination bonds or as an acceptor for hydrogen bonds, have been structurally characterized by single-crystal X-ray analysis...
November 1, 2016: Acta Crystallographica. Section C, Structural Chemistry
Matthias Tacke, Oyinlola Dada, Cillian O'Beirne, Xiangming Zhu, Helge Müller-Bunz
Gold monochloride and monobromide can be transformed into monomeric complexes by ligands such as CO, PPh3 or Me2S, and such ligand-stabilized gold monochloride compounds have been investigated as catalysts, luminescent materials and anticancer drugs, especially when coordinated to a lipophilic benzyl-substituted N-heterocyclic carbene (NHC) ligand. The triclinic structures of NHC-Au-Cl {chlorido(1,3-dibenzyl-4,5-diphenylimidazol-2-ylidene)gold, [AuCl(C29H24N2)]} and NHC-Au-Br {bromido(1,3-dibenzyl-4,5-diphenylimidazol-2-ylidene)gold, [AuBr(C29H24N2)]}, determined by X-ray crystallography at 100 K, have one and four molecules, respectively, in their asymmetric units...
November 1, 2016: Acta Crystallographica. Section C, Structural Chemistry
H V Rasika Dias, Naveen Kulkarni
Tris(pyrazolyl)borates are used extensively in metal coordination chemistry and belong to a class of ligands generally referred to as scorpionates. The steric and electronic properties of these ligands can be modified quite easily by varying the substituents on the 3-, 4-, and 5-positions of the pyrazolyl moieties on the B atom. Fluorinated tris(pyrazolyl)borates are useful in the stabilization of rare silver(I) complexes. The silver(I) adduct (acetonitrile-κN){tris[5-methyl-3-(trifluoromethyl)pyrazol-1-yl-κN(2)]hydroborato}silver(I), [Ag(C15H13BF9N6)(CH3CN)] or [HB{3-(CF3),5-(CH3)Pz}3]AgNCCH3, was obtained by treating [HB{3-(CF3),5-(CH3)Pz}3]Na with CF3SO3Ag in the presence of acetonitrile, and was isolated in 85% yield...
November 1, 2016: Acta Crystallographica. Section C, Structural Chemistry
Yunzhe Jiao, William W Brennessel, William D Jones
Tris(pyrazolyl)borate complexes of rhodium are well known to activate C-H bonds. The reactive [Tp'Rh(PMe3)] fragment [Tp' is tris(3,5-dimethylpyrazol-1-yl)hydroborate] is found to react with valeronitrile to give the κ(1)N-bound complex (pentanenitrile-κN)(trimethylphosphane-κP)[tris(3,5-dimethylimidazol-1-yl)hydroborato-κ(2)N(2),N(2')]rhodium(I), [Rh(C15H22BN6)(C5H9N)(C3H9P)]. In contrast to the widespread evidence for the reaction of this fragment with C-H bonds via oxidative addition, no evidence for such a complex is observed...
November 1, 2016: Acta Crystallographica. Section C, Structural Chemistry
Emmanuel Nicolas, Thibault Cheisson, G Bas de Jong, Cornelis G J Tazelaar, J Chris Slootweg
The anionic tris(pyrazolyl)borates, or scorpionates, have proven to be extremely useful ligands. Neutral tris(pyrazolyl)methane ligands, however, are difficult to prepare and require numerous purification steps for a number of substitution patterns. We have previously outlined two different routes for accessing neutral tris(pyrazolyl) ligands. We describe here an adaptation of the previously published procedures for the synthesis of the electron-poor ligand tris(3,4,5-tribromopyrazol-1-yl)phosphine oxide, C9Br9N6OP...
November 1, 2016: Acta Crystallographica. Section C, Structural Chemistry
Tomoaki Takayama, Jun Nakazawa, Shiro Hikichi
Poly(pyrazol-1-yl)borates have been utilized extensively in coordination compounds due to their high affinity toward cationic metal ions on the basis of electrostatic interactions derived from the mononegatively charged boron centre. The original poly(pyrazol-1-yl)borates, christened `scorpionates', were pioneered by the late Professor Swiatoslaw Trofimenko and have expanded to include various borate ligands with N-, P-, O-, S-, Se- and C-donors. Scorpionate ligands with boron-carbon bonds, rather than the normal boron-nitrogen bonds, have been developed and in these new types of scorpionate ligands, amines and azoles, such as pyridines, imidazoles and oxazolines, have been employed as N-donors instead of pyrazoles...
November 1, 2016: Acta Crystallographica. Section C, Structural Chemistry
Yasuhiro Arikawa, Kei Ichiro Inada, Masayoshi Onishi
The discovery of polypyrazolylborate ligands allowed the development of various chemical fields and these ligands are an alternative to cyclopentadienyl, because both ligands have the same charge and donate the same number of electrons, as well as adopting the same facial geometry. Easy control of the bulkiness of polypyrazolylborate ligands is possible by modification of the substituents in the 3- and 5-positions of the pyrazolyl rings. The title complex, bis[tetrakis(3-methyl-1H-pyrazol-1-yl)borato]samarium(II), [Sm(C16H20BN8)2], was synthesized from the reaction of SmI2 with potassium tetrakis(3-methyl-1H-pyrazol-1-yl)borate, denoted K[B(3-Mepz)4], in tetrahydrofuran...
November 1, 2016: Acta Crystallographica. Section C, Structural Chemistry
Radu F Semeniuc, Daniel L Reger, Mark D Smith
The reaction of a third generation tetratopic tris(pyrazolyl)methane ligand, namely 1,2,4,5-{[2,2,2-tris(1H-pyrazol-1-yl)ethoxy]methyl}benzene {1,2,4,5-C6H2[CH2OCH2C(pz)3]4, L4}, and [Cd2(thf)5](BF4)4 (thf is tetrahydrofuran) produces the coordination polymer catena-poly[[[bis[acetonitrilecadmium(II)]-μ4-1,2,4,5-{[2,2,2-tris(1H-pyrazol-1-yl)ethoxy]methyl}benzene] tetrakis(tetrafluoroborate)]-diethyl ether-acetonitrile (1/2/2)], {[Cd2(CH3CN)2(C54H54N24O4)](BF4)4·2C4H10O·2CH3CN}n. The Cd(II) center is coordinated in a κ(3)-fashion by one tris(pyrazolyl)methane group and in a κ(2)-κ(0) fashion by another, while the sixth coordination site on the Cd(II) cation is occupied by an acetonitrile molecule...
November 1, 2016: Acta Crystallographica. Section C, Structural Chemistry
Radu F Semeniuc, Daniel L Reger, Mark D Smith
Heterotopic ligands offer the possibility of preparing polynuclear bimetallic complexes. Recent studies of heteroditopic ligands and their metal complexes have focused on novel supramolecular systems, biological activity, and the development of MRI contrast agents. The heteroditopic ligand Bipy-CH2-O-CH2-C(pz)3 (Bipy-L; Bipy is 2,2'-bipyridine and pz is pyrazolyl) reacts with AgBF4 to produce the coordination polymer catena-poly[[silver(I)-(μ-5-{[tris(pyrazol-1-yl)methoxy]methyl-κ(2)N,N'}-2,2'-bipyridine-κ(2)N,N')] diethyl ether hemisolvate], {[Ag(C22H20N8O)]BF4·0...
November 1, 2016: Acta Crystallographica. Section C, Structural Chemistry
Lourdes Infantes, Rosa M Claramunt, Dionisia Sanz, Ibon Alkorta, José Elguero
The introduction of poly(1H-pyrazolyl)borate anions, better known as scorpionates, as negatively charged ligands for a great diversity of metal cations has had a tremendous influence in coordination chemistry. The structures of two salts of tetrakispyrazolylborate, namely [tetrakis(3-phenyl-1H-pyrazol-1-yl)borato]thallium(I), [Tl(C36H28BN8)], and catena-poly[potassium-[μ2-tetrakis(3-cyclopropyl-1H-pyrazol-1-yl)borato]], [K(C24H28BN8)]n, have been determined at 296 K in the monoclinic P21/c and C2/c space groups, respectively...
November 1, 2016: Acta Crystallographica. Section C, Structural Chemistry
Eric R Sirianni, Daniel C Cummins, Glenn P A Yap, Klaus H Theopold
Scorpionate (or trispyrazolylborate) ligands have seen much structural variation due to the relative ease of modifying their electronic and steric effects. Second-generation scorpionates were created by increasing the bulk in the 3-position of the pyrazole (pz) ring. A new class of third-generation scorpionates was obtained by modifying the remaining boron substituent. A series of thallium(I) and cobalt(II) complexes of the ferrocenyltris(3-R-pyrazolyl)borate ligand [FcTp(R); R = isopropyl ((i)Pr) or tert-butyl ((t)Bu)] have been synthesized in order to expand the range of redox-active third-generation scorpionates...
November 1, 2016: Acta Crystallographica. Section C, Structural Chemistry
Yi Rong, David Sambade, Gerard Parkin
Cyclopentadienyl and tris(pyrazolyl)hydroborate have found much use as supporting ligands in the chemistry of titanium, zirconium and hafnium, especially with respect to applications involving olefin polymerization catalysis. In contrast, closely related tris(1-alkyl-2-mercaptoimidazolyl)hydroborate, [Tm(R)], ligands have so far found little application to the chemistry of these elements, despite the fact that such ligands are currently used extensively in coordination chemistry. In view of the fact that a substituent in the 2-position exerts a direct influence on the steric environment of the metal center, we report here the application of the sterically demanding tris(1-tert-butyl-2-mercaptoimidazolyl)hydroborate [Tm(t-Bu)] ligand to these metals...
November 1, 2016: Acta Crystallographica. Section C, Structural Chemistry
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