scholarly journals Crystal structures of a novel NNN pincer ligand and its dinuclear titanium(IV) alkoxide pincer complex

2017 ◽  
Vol 73 (2) ◽  
pp. 122-126 ◽  
Author(s):  
Jakub Pedziwiatr ◽  
Ion Ghiviriga ◽  
Khalil A. Abboud ◽  
Adam S. Veige
Keyword(s):  
Metal Complex ◽  
Crystal Structures ◽  
Rotation Axis ◽  
Organic Ligand ◽  
Ligand Complex ◽  
Tetrahedral Geometry ◽  
Acta Cryst ◽  
X Ray ◽  
Site Occupation ◽  
X Ray Crystallography

This report describes a synthetic protocols and the crystal structures involving a novel pincer-type H3[NNN] ligand, namely di-μ-bromido-μ-{2-(2,2-dimethylpropanimidoyl)-N-[2-(2,2-dimethylpropanimidoyl)-4-methylphenyl]-4-methylaniline}-bis[(diethyl ether)lithium], [Li2Br2(C24H33N3)(C4H10O)2] (1) and a dinuclear metal complex, namely di-μ-bromido-2:3κ4Br:Br-bis{2-(2,2-dimethylpropanimidoyl)-N-[2-(2,2-dimethylpropanimidoyl)-4-methylphenyl]-4-methylaniline}-1κ3N,N′,N′′;4κ3N,N′,N′′-tetra-μ-isopropanolato-1:2κ4O:O;3:4κ4O:O-diisopropanolato-1κO,4κO-2,3-dilithium-1,4-dititanium, [Li2Ti2Br2(C24H32N3)2(C3H7O)6] or {[NHNNH]Ti(OiPr)3(LiBr)2}2(2). Complex1, which sits on a twofold rotation axis, is a rare example of a pincer-type ligand which bears ketimine side arms. A unique feature of complex1is that the ketimine N atoms have an LiBr(Et2O) fragment bonded to them, with the Li atom adopting a distorted tetrahedral geometry. This particular fragment creates an LiBr bridge between the two ketimine sidearms, which leads to a cage-type appearance of the ligand. Complex2consists of the previously described ligand and a TiIVmetal atom in an octahedral environment, and is located on an inversion center. Complex2crystallizes as a dinuclear species with the metal atoms being bridged by an LiBr entity [the Br atoms are disordered and refined in two positions with their site occupation factors refining to 0.674 (12)/0.372 (12)], and the Li cation being bonded to the isopropoxide O atoms (Li having a tetrahedral coordination as in1). The organic ligand of compound2exhibits disorder in its periphery groups; isopropyl andtert-butyl groups (occupation factors fixed at 0.6/0.4). The novel [NNN]H3pincer-type ligand was characterized by multinuclear and multidimensional NMR, HRMS and X-ray crystallography. The dinuclear metal complex2was characterized by X-ray crystallography. Although each structure exhibits donor N—H groups, no hydrogen bonding is found in either one, perhaps due to the bulky groups around them. One of the ethyl groups of the ether ligand of1is disordered and refined in two parts with site-occupation factors of 0.812 (8) and 0.188 (8). One and a half toluene solvent molecules are also present in the asymmetric unit of2. The toluene molecules were significantly disordered and could not be modeled properly, thusSQUEEZE[Spek (2015).Acta Cryst.C71, 9–18] was used to remove their contributions to the overall intensity data.

Two new zinc(II) and mercury(II) complexes based on N,N′-(cyclohexane-1,2-diylidene)bis(4-fluorobenzohydrazide): synthesis, crystal structures and antibacterial activities

2020 ◽  
Vol 76 (5) ◽  
pp. 476-482
Author(s):  
Al-Ameen Bariz OmarAli ◽  
Ahmed Jasim M. Al-Karawi ◽  
Adil A. Awad ◽  
Necmi Dege ◽  
Sevgi Kansız ◽  
...  
Keyword(s):  
Organic Ligand ◽  
Antibacterial Activities ◽  
Structural Features ◽  
Bacterial Strains ◽  
Tetrahedral Geometry ◽  
X Ray ◽  
X Ray Crystallography ◽  
Growth Inhibitory ◽  
The Difference

Reaction of N,N′-(cyclohexane-1,2-diylidene)bis(4-fluorobenzohydrazide), C20H18F2N4O2, (LF ), with zinc chloride and mercury(II) chloride produced different types and shapes of neutral coordination complexes, namely, dichlorido[N,N′-(cyclohexane-1,2-diylidene)bis(4-fluorobenzohydrazide)-κ2 N,O]zinc(II), [ZnCl2(C20H18F2N4O2)], (1), and dichlorido[N,N′-(cyclohexane-1,2-diylidene)bis(4-fluorobenzohydrazide)-κ4 O,N,N′,O′]mercury(II), [HgCl2(C20H18F2N4O2)], (2). The organic ligand and its metal complexes are characterized using various techniques: IR, UV–Vis and nuclear magnetic resonance (NMR) spectroscopies, in addition to powder X-ray diffraction (PXRD), single-crystal X-ray crystallography and microelemental analysis. Depending upon the data from these analyses and measurements, a typical tetrahedral geometry was confirmed for zinc complex (1), in which the ZnII atom is located outside the bis(benzhydrazone) core. The HgII atom in (2) is found within the core and has a common octahedral structure. The in vitro antibacterial activities of the prepared compounds were evaluated against two different bacterial strains, i.e. gram positive Bacillus subtilis and gram negative Pseudomonas aeruginosa bacteria. The prepared compounds exhibited differentiated growth-inhibitory activities against these two bacterial strains based on the difference in their lipophilic nature and structural features.

Structural Studies of a Series of Organic Non-Linear Optical Materials

1997 ◽  
Vol 53 (5) ◽  
pp. 812-821 ◽  
Author(s):  
J. C. Cole ◽  
J. M. Cole ◽  
G. H. Cross ◽  
M. Farsari ◽  
J. A. K. Howard ◽  
...  
Keyword(s):  
Crystal Structures ◽  
Ground State ◽  
Optical Materials ◽  
Dipole Moments ◽  
Solvent Polarity ◽  
Structural Studies ◽  
Acta Cryst ◽  
X Ray ◽  
Solution State ◽  
X Ray Crystallography

The crystal structures of {4-[bis(diethylamino)methylium]phenyl}dicyanomethanide (I), {4-[cyano(4-methylpiperidyl)methylium]phenyl } dicyanomethanide (II), {4-[cyano(1-pyrrolidinyl)methylium]phenyl}dicyanomethanide (IV) and (Z)-{4-[1,3-dicyano-3-(diethylamino)-2-propenylium]phenyl} dicyanomethanide have been determined by X-ray crystallography. Together with (Z)-{4-[1-cyano-3-(diethylamino)-2-propenylium]phenyl}dicyanomethanide [(III): Cole, J. C., Howard, J. A. K., Cross, G. H. & Szablewski, M. (1995). Acta Cryst. C51, 715–718], these compounds exhibit varying degrees of quinoidal characteristics and yet have predominantly zwitterionic ground state character. The presence of high dipole moments in the crystal can thus be inferred and are substantiated by measurements of high solution-state dipole moments. Negative solvatochromism (hypsochromism on increasing solvent polarity) confirms the zwitterionic character in at least two of the series.

Holographic methods in X-ray crystallography. III. First numerical results

1993 ◽  
Vol 49 (6) ◽  
pp. 866-871 ◽  
Author(s):  
G. J. Maalouf ◽  
J. C. Hoch ◽  
A. S. Stern ◽  
H. Szöke ◽  
A. Szöke
Keyword(s):  
Experimental Data ◽  
Crystal Structures ◽  
Numerical Experiments ◽  
Numerical Results ◽  
Crystallographic Data ◽  
Viable Alternative ◽  
Holographic Method ◽  
Acta Cryst ◽  
X Ray ◽  
X Ray Crystallography

The holographic method for the completion of crystal structures, described in paper II [Szöke (1993). Acta Cryst. A49, 853–866], is implemented numerically. The purpose of these modest calculations is to show that the holographic method can handle real crystallographic data in easy problems and to test various algorithms for its implementation. Both synthetic and experimental data are used and sources of error are systematically introduced. The numerical experiments support the theory presented in paper II and show that the holographic method may be a potentially viable alternative to conventional methods for the completion of crystal structures.

The synthesis and X-ray structures of η1-, η3-, and η5-dienolate complexes of manganese carbonyl

1990 ◽  
Vol 68 (12) ◽  
pp. 2221-2227 ◽  
Author(s):  
Andrew P. Masters ◽  
John F. Richardson ◽  
Ted S. Sorensen
Keyword(s):  
Crystal Structures ◽  
Organic Ligand ◽  
Phenyl Ester ◽  
Ligand Complex ◽  
X Ray ◽  
Manganese Carbonyl

The η1-, η3-, and η5-ester dienolate complexes of Mn(CO)n have been prepared and the crystal structures of the phenyl ester member have been obtained for all three bonding modes. The allyl (anti- η3) member shows some bonding distortions compared to a simple allyl ligand. The structure of the η5-1-oxapentadienyl ligand complex is substantially different from a rhenium analog in that the organic ligand is non-planar with significantly different bond distances. The η5-complex reacts rapidly with triphenylphosphine to generate the syn-η3-complex. Keywords:

scholarly journals A mixed chirality α-helix in a stapled bicyclic and a linear antimicrobial peptide revealed by X-ray crystallography

2021 ◽  
Author(s):  
Stéphane Baeriswyl ◽  
Hippolyte Personne ◽  
Ivan Di Bonaventura ◽  
Thilo Köhler ◽  
Christian van Delden ◽  
...  
Keyword(s):  
Antimicrobial Peptides ◽  
Antimicrobial Peptide ◽  
Crystal Structures ◽  
X Ray ◽  
X Ray Crystallography ◽  
Α Helix

We report the first X-ray crystal structures of mixed chirality α-helices comprising only natural residues as the example of bicyclic and linear membrane disruptive amphiphilic antimicrobial peptides containing seven l- and four d-residues.

Bis(1-phenyl-1-propyne) complexes of tungsten(II): crystal structures of [WI2(CO)(NCR)(η2-MeC2Ph)2] (R = Me, Et, or Ph)

2001 ◽  
Vol 79 (3) ◽  
pp. 263-271
Author(s):  
Paul K Baker ◽  
Michael GB Drew ◽  
Deborah S Evans
Keyword(s):  
Carbon Monoxide ◽  
Solid State ◽  
Crystal Structures ◽  
Octahedral Geometry ◽  
X Ray ◽  
X Ray Crystallography ◽  
Alkyne Complexes ◽  
First Time

Reaction of [WI2(CO)3(NCMe)2] with two equivalents of 1-phenyl-1-propyne (MeC2Ph) in CH2Cl2, and in the absence of light, gave the bis(1-phenyl-1-propyne) complex [WI2(CO)(NCMe)(η2-MeC2Ph)2] (1) in 77% yield. Treatment of equimolar quantities of 1 and NCR (R = Et, i-Pr, t-Bu, Ph) in CH2Cl2 afforded the nitrile-exchanged products, [WI2(CO)(NCR)(η2-MeC2Ph)2] (2-5) (R = Et (2), i-Pr (3), t-Bu (4), Ph (5)). Complexes 1, 2, and 5 were structurally characterized by X-ray crystallography. All three structures have the same pseudo-octahedral geometry, with the equatorial sites being occupied by cis and parallel alkyne groups, which are trans to the cis-iodo groups. The trans carbon monoxide and acetonitrile ligands occupy the axial sites. In structures 1 and 2, the methyl and phenyl substituents of the 1-phenyl-1-propyne ligands are cis to each other, whereas for the bulkier NCPh complex (5), the methyl and phenyl groups are trans to one another. This is the first time that this arrangement has been observed in the solid state in bis(alkyne) complexes of this type.Key words: bis(1-phenyl-1-propyne), carbonyl, nitrile, diiodo, tungsten(II), crystal structures.

Synthesis and crystal structures of bis(imidazolidine-2-thione-κS)bis(thiocyanato-κS)mercury(II) and bis(cyanido)bis(μ2-imidazolidine-2-thione-κS)mercury(II).Hg(CN)2

2017 ◽  
Vol 72 (9) ◽  
pp. 671-676 ◽  
Author(s):  
Muhammad Ashraf Shaheen ◽  
Muhammad Nawaz Tahir ◽  
Sarwat Sabir ◽  
Aneela Anwar ◽  
Anvarhusein A. Isab ◽  
...  
Keyword(s):  
Rotation Axis ◽  
Mercury Atom ◽  
Distorted Octahedral Geometry ◽  
Weakly Bound ◽  
X Ray ◽  
X Ray Crystallography ◽  
Hydrogen Bonding Interactions ◽  
Ir And Nmr Spectroscopy ◽  
Distorted Octahedral ◽  
Cyanide Ligands

AbstractTwo mercury(II) complexes containing imidazolidine-2-thione (Imt) and thiocyanate or cyanide ligands, [Hg(Imt)2(SCN)2] (1) and [Hg(Imt)2(CN)2].Hg(CN)2(2), have been prepared and characterized by IR and NMR spectroscopy and X-ray crystallography. In compound1, the mercury atom is located on a two-fold rotation axis and is coordinated to two thione sulfur atoms of imidazolidine-2-thione (Imt) and to two sulfur atoms of thiocyanate in a distorted tetrahedral mode with the S-Hg-S bond angles in the range of 98.96(3)–148.65(6)°. In2, the mercury atom is hexa-coordinated having a distorted octahedral geometry composed of two cyanide C atoms [Hg-C=2.055(5) Å] and four weakly bound thione S atoms of imidazolidine-2-thione (Imt) [Hg-S=3.1301(13) and 3.1280(13) Å]. One free Hg(CN)2molecule is also present in the crystal. In both complexes, the molecular structure is stabilized by N-H…N and N-H…S hydrogen bonding interactions.

scholarly journals Human insulin polymorphism upon ligand binding and pH variation: the case of 4-ethylresorcinol

IUCrJ ◽  
2015 ◽  
Vol 2 (5) ◽  
pp. 534-544 ◽  
Author(s):  
S. Fili ◽  
A. Valmas ◽  
M. Norrman ◽  
G. Schluckebier ◽  
D. Beckers ◽  
...  
Keyword(s):  
Human Insulin ◽  
Organic Ligand ◽  
European Synchrotron Radiation Facility ◽  
X Ray Diffraction ◽  
Ph Variation ◽  
X Ray ◽  
X Ray Crystallography ◽  
Swiss Light Source ◽  
Crystallization Experiments ◽  
Ph Range

This study focuses on the effects of the organic ligand 4-ethylresorcinol on the crystal structure of human insulin using powder X-ray crystallography. For this purpose, systematic crystallization experiments have been conducted in the presence of the organic ligand and zinc ions within the pH range 4.50–8.20, while observing crystallization behaviour around the isoelectric point of insulin. High-throughput crystal screening was performed using a laboratory X-ray diffraction system. The most representative samples were selected for synchrotron X-ray diffraction measurements, which took place at the European Synchrotron Radiation Facility (ESRF) and the Swiss Light Source (SLS). Four different crystalline polymorphs have been identified. Among these, two new phases with monoclinic symmetry have been found, which are targets for the future development of microcrystalline insulin drugs.

scholarly journals The Synthesis and Characterization of a Novel One-Dimensional Bismuth (III) Coordination Polymer as a Precursor for the Production of Bismuth (III) Oxide Nanorods

Crystals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 113
Author(s):  
Younes Hanifehpour ◽  
Babak Mirtamizdoust ◽  
Jaber Dadashi ◽  
Ruiyao Wang ◽  
Mahboube Rezaei ◽  
...  
Keyword(s):  
Single Crystal ◽  
Coordination Compound ◽  
Organic Ligand ◽  
One Dimensional ◽  
X Ray ◽  
X Ray Crystallography ◽  
Oxide Nanorods ◽  
Pure Phase ◽  
3D Framework

A novel Bi (III) coordination compound, [Bi(HQ)(Cl)4]n ((Q = pyridine-4-carbaldehyde thiosemicarbazone), was prepared in this research using a sonochemical technique. SEM, infrared spectroscopy (IR), XRD, and single-crystal X-ray analysis were utilized to analyze the Bi(III) coordination compound. The structure determined using single-crystal X-ray crystallography indicates that the coordination compound is a 1D polymer in solid state and that the coordination number of bismuth (III) ions is six, (BiSCl5), with one S donor from the organic ligand and five Cl donors from anions. It is equipped with a hemidirectional coordination sphere. It is interesting that the ligand has been protonated in the course of the reaction with a Cl- ion balancing the charge. This compound’s supramolecular properties are directed and regulated by weak directional intermolecular interactions. Through π–π stacking interactions, the chains interact with one another, forming a 3D framework. Thermolysis of the compound at 170 °C with oleic acid resulted in the formation of pure phase nanosized Bi (III) oxide. SEM technique was used to examine the morphology and size of the bismuth (III) oxide product produced.

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