The Relationship Between Octahedral and Trigonal-Prismatic Coordination in Bis Tridentate Complexes of TiIV and VIV

1988 ◽  
Vol 41 (4) ◽  
pp. 453 ◽  
Author(s):  
AA Diamantis ◽  
M Manikas ◽  
MA Salam ◽  
MR Snow ◽  
ERT Tiekink
Keyword(s):  
Tridentate Ligand ◽  
Vanadium Complexes ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Titanium Complexes ◽  
Tridentate Ligands ◽  
Space Group ◽  
Trigonal Prismatic Coordination ◽  
Trigonal Prismatic

The crystal structures of two vanadium complexes V( aabh )2 (1) and V( aasalh )2 (2) and of two titanium complexes Ti( aabh )2 (3) and Ti( babh )2 (4), where aabh is the dinegative, tridentate ligand pentane-2,4-dione benzoylhydrazonato (2-), aasalh is pentane-2,4-dione salicyloylhydrazonato (2-) and babh is 4-phenylbutane-2,4-dione benzoylhydrazonato (2-), were determined by X-ray diffraction methods. Crystals of (1) are monoclinic, space group P21/c, a 8.906(3), b 11.840(2), c 22.450(6)Ǻ, β 97.72(3)°, V 2345.8 and Z 4; those of (2) are triclinic, space group Pī , a 9.802(4), b 10.205(3), c 13.688(6)Ǻ, α 100.56(3),β 94.07(4),γ 112.89(3)°, V 1224.6 Ǻ3 and Z 2; those of (3) are monoclinic, space group C2/c, a 18.543(4), b 10.269(4), c 12.589(4)Ǻ, β 106.80(2)°, V 2294.9 Ǻ3 and Z 4; and those of (4) are monoclinic, space group P21/n, a 10.923(4), b 19.139(3), c 14.610(5)Ǻ, β 94.54(3)°, V 3044.7 Ǻ3 and Z 4. The structures were refined by a full-matrix least-squares procedure in each case to final values of R 0.102, 0.044, 0.049 and 0.058 for the structures (1), (2), (3) and (4), respectively, and values of Rw 0.099, 0.049, 0.053 and 0.065 for 1735, 3405, 1185 and 2911 statistically significant reflections, respectively. In the vanadium complexes the coordination geometry is approximately trigonal prismatic, whereas in each of the titanium complexes the two tridentate ligands are in a meridional arrangement with an approximately octahedral coordination. The stabilization of vanadium(IV) in the absence of the oxo function and the role of the metals in producing different coordination geometries are discussed.

Structures of 2 Vanadium(V) Complexes With Tridentate Ligands

1986 ◽  
Vol 39 (7) ◽  
pp. 1081 ◽  
Author(s):  
AA Diamantis ◽  
JM Frederiksen ◽  
MA Salam ◽  
MR Snow ◽  
ERT Tiekink
Keyword(s):  
Tridentate Ligand ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Tridentate Ligands ◽  
Tetragonal Pyramid ◽  
Coordination Environment ◽  
X Ray ◽  
Cell Dimensions ◽  
Unit Cell Dimensions ◽  
Oxo Ligand

The crystal structures of two vanadium(v) complexes, VOL(OCH2CH3)(1) and (VOL)2O (2), where L is the dinegative , tridentate ligand 4- phenylbutane-2,4-dione benzoylhydrazonato (2-), were determined by X-ray diffraction methods. Crystals of (1) are monoclinic, space group P21/n, a 11.064(4), b 7.565(1), c 21.786(5) Ǻ and β 95.93(2)° and Z 4; those of (2) are also monoclinic, C2/ c, with unit cell dimensions a 18.287(3), b 14.991(2), c 11.643(2)Ǻ, β 92.85(2)° for Z 4. The structures were refined by full-matrix least-squares methods to final R 0.036 for 1801 reflections with I ≥ 2.5σ(I) for (1), and R 0.061 for 1272 reflections with I ≥ 2.5σ(I) for (2). The coordination environment of the vanadium atom in both structures is a tetragonal pyramid with the oxo ligand occupying the apical positon.

The Structures of Imidazenil and Iodoimidazenil

2002 ◽  
Vol 55 (11) ◽  
pp. 737 ◽  
Author(s):  
Trevor W. Hambley ◽  
Andrew Katsifis ◽  
Robert B. Knott ◽  
Filomena Mattner ◽  
Branko Dikic
Keyword(s):  
Conformational Changes ◽  
Single Photon ◽  
Benzodiazepine Receptors ◽  
Photon Emission ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Triclinic Space Group ◽  
Space Group ◽  
Iodine 123

The iodinated analogue of imidazobenzodiazepine, imidazenil (1), has been prepared with the aim of radiolabelling it with iodine-123 and including it in a study to determine the role of benzodiazepine receptors in neurodegenerative diseases using single photon emission computer tomography (SPECT) imaging. A comparison of the bromo- and iodo-derivatives, as well as the conformational changes resulting from bromine–iodine substitution are described, and it is concluded that the substitution has no clear effect on the geometry. Crystal structures of (1) and iodoimidazenil (2) have been determined by X-ray diffraction methods and refined to R values of 0.059 (3817 F) and 0.048 (1318 F), respectively. The crystals of imidazenil are triclinic, space group P1–,a 12.537(4), b 18.211(6), c 7.852(2) Å, α 91.07(2), β 106.26(2), γ 77.86(2)�, Z 4, and those of iodoimidazenil are monoclinic, space group P21/a, a 12.185(2), b 7.558(2), c 18.287(2) Å, β 95.23(1)�, Z 4.

New mixed-valent alkali chain sulfido ferrates A1+x[FeS2] (A = K, Rb, Cs; x = 0.333–0.787)

2020 ◽  
Vol 235 (8-9) ◽  
pp. 275-290
Author(s):  
Michael Schwarz ◽  
Pirmin Stüble ◽  
Katharina Köhler ◽  
Caroline Röhr
Keyword(s):  
Alkali Metal ◽  
General Structure ◽  
Variable Number ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Modulated Structure ◽  
Space Group ◽  
X Ray ◽  
Local Coordination ◽  
Natural Pyrite

AbstractFour new mixed-valent chain alkali metal (A) sulfido ferrates of the general structure family ${A}_{1+x}\left[{\text{Fe}}_{x}^{\text{II}}{\text{Fe}}_{1-x}^{\text{III}}{\text{S}}_{2}\right]$ were synthesized in the form of tiny green-metallic needles from nearly stoichiometric melts reacting elemental potassium with natural pyrite (A = K) or previously prepared Rb2S/Cs2S2 with elemental iron and sulfur (A = Rb/Cs). The crystal structures of the compounds were determined by means of single crystal X-ray diffraction: In the (3+1)D modulated structure of K7.15[FeS2]4 (space group Ccce(00σ3)0s0, a = 1363.87(5), b = 2487.23(13), c = 583.47(3) pm, q = 0,0,0.444, R1 = 0.055/0.148, x = 0.787), a position modulation of the two crystallographically different undulated ${}_{\infty }{}^{1}\left[{\text{FeS}}_{4/2}\right]$ tetrahedra chains and the surrounding K cations is associated with an occupation modulation of one of the three potassium sites. In the case of the new monoclinic rubidium ferrate Rb4[FeS2]3 (x = $\frac{1}{3}$; space group P21/c, a = 1640.49(12), b = 1191.94(9), c = 743.33(6) pm, β = 94.759(4)°, Z = 4, R1 = 0.1184) the undulation of the tetrahedra chain is commensurate, the repetition unit consists of six tetrahedra. In the second new Rb ferrate, Rb7[FeS2]5 (x = 0.4; monoclinic, space group C2/c, K7[FeS2]5-type; a = 2833.9(2), b = 1197.36(9), c = 744.63(6) pm, β = 103.233(4)°, Z = 4, R1 = 0.1474) and its isotypic mixed Rb/Cs-analog Rb3.6Cs3.4[FeS2]5 (a = 2843.57(5), b = 1226.47(2), c = 759.890(10) pm, β = 103.7170(9)°, R1 = 0.0376) the chain buckling leads to a further increased repetition unit of 10 tetrahedra. For all mixed-valent ferrates, the Fe–S bond lengths continuously increase with the amount (x) of Fe(II). The buckling of the chains is controlled through the local coordination of the S atoms by the variable number of A cations of different sizes.

Strukturuntersuchungen an Diaryldichalkogeniden: Die Molekülstrukturen von [2,4,6-(CF3)3C6H2S]2,[2,4,6-Me3C6H2Te]2 und [2-Me2N-4,6-(CF3)2C6H2Te]2 / Structural Investigations of Diaryl Dichalcogenides: The Molecular Structures of [2,4,6-(CF3)3C6H2S]2, [2,4,6-Me3C6H2Te]2 and [2-Me2N-4,6-(CF3)2C6H2Te]2

1992 ◽  
Vol 47 (3) ◽  
pp. 305-309 ◽  
Author(s):  
Anja Edelmann ◽  
Sally Brooker ◽  
Norbert Bertel ◽  
Mathias Noltemeyer ◽  
Herbert W. Roesky ◽  
...  
Keyword(s):  
Molecular Structures ◽  
Monoclinic Space Group ◽  
Crystal Data ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
Structural Investigations ◽  
Space Group ◽  
X Ray

Abstract The Molecular Structures of [2,4,6-(CF3)3C6H2S]2 (1) [2,4,6-Me3C6H2Te]2 and [2-Me2N-4,6-(CF3)2C6H2Te]2 (3) have been determined by X-ray diffraction. Crystal data: 1: orthorhombic, space group P212121, Z = 4, a = 822.3(2), b = 1029.2(2), c = 2526.6(5) pm (2343 observed independent reflexions, R = 0.042); 2: orthorhombic, space group Iba 2, Z = 8, a = 1546.5(2), b = 1578.4(2), c = 1483.9(1) pm (2051 observed independent reflexions, R = 0.030); 3: monoclinic, space group P 21/c, Z = 4, a = 1118.7(1), b = 1536.5(2), c = 1492.6(2) pm, β = 98.97(1)° (3033 observed independent reflexions, R = 0.025).

The Crystal and Molecular Structures of Two Modifications of cis-Dichloro-mer-tris-(dimethylphenylphosphine)hydridoiridium(III)

1988 ◽  
Vol 41 (3) ◽  
pp. 283 ◽  
Author(s):  
GB Robertson ◽  
PA Tucker
Keyword(s):  
Heavy Atom ◽  
Molecular Structures ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
X Ray ◽  
Bond Lengths ◽  
Metal Ligand ◽  
Ligand Bond

The structures of two crystalline modifications of mer -(Pme2Ph)3H-cis-Cl2IrIII, (1), have been determined from single-crystal X-ray diffraction data. Modification (A) is monoclinic, space group P21/c with a 12.635(1), b 30.605(3), c 14.992(2)Ǻ, β 110.01(2)° and Z = 8. Modification (B) is orthorhombic, space group Pbca with a 27.646(3), b 11.366(1), c 17.252(2)Ǻ and Z = 8. The structures were solved by conventional heavy atom techniques and refined by full-matrix least- squares analyses to conventional R values of 0.037 [(A), 8845 independent reflections] and 0.028 [(B), 5291 independent reflections]. Important bond lengths [Ǻ] are Ir -P(trans to Cl ) 2.249(1) av. (A) and 2.234(1) (B), Ir -P(trans to PMe2Ph) 2.339(2) av. (A) and 2.344(1), 2.352(1) (B), Ir-Cl (trans to H) 2.492(2), 2.518(2) (A) and 2.503(1) (B) and Ir-Cl (trans to PMe2Ph)2.452(2) av. (A) and 2.449(1)(B). Differences in chemically equivalent metal- ligand bond lengths emphasize the importance of non-bonded contacts in determining those lengths.

Silver(I)-Saccharinato Complexes with 2-(Aminomethyl)pyridine and 2-(2-Aminoethyl)pyridine Ligands: [Ag(sac)(ampy)] and [Ag2(sac)2(μ-aepy)2]

2005 ◽  
Vol 60 (9) ◽  
pp. 978-983 ◽  
Author(s):  
Sevim Hamamci ◽  
Veysel T. Yilmaz ◽  
William T. A. Harrison
Keyword(s):  
Thermal Analysis ◽  
Hydrogen Bonds ◽  
Monoclinic Space Group ◽  
Stacking Interactions ◽  
Coordination Geometry ◽  
X Ray Diffraction ◽  
Triclinic Space Group ◽  
Space Group ◽  
X Ray ◽  
Pyridine Ligands

Two new saccharinato-silver(I) (sac) complexes, [Ag(sac)(ampy)] (1), and [Ag2(sac)2(μ-aepy)2] (2), [ampy = 2-(aminomethyl)pyridine, aepy = 2-(2-aminoethyl)pyridine], have been prepared and characterized by elemental analysis, IR spectroscopy, thermal analysis and single crystal X-ray diffraction. Complexes 1 and 2 crystallize in the monoclinic space group P21/c and triclinic space group P1̄, respectively. The silver(I) ions in both complexes 1 and 2 exhibit a distorted T-shaped AgN3 coordination geometry. 1 consists of individual molecules connected into chains by N-H···O hydrogen bonds. There are two crystallographically distinct dimers in the unit cell of 2 and in each dimer, the aepy ligands act as a bridge between two silver(I) centers, resulting in short argentophilic contacts [Ag1···Ag1 = 3.0199(4) Å and Ag2···Ag2 = 2.9894(4) Å ]. Symmetry equivalent dimers of 2 are connected by N-H···O hydrogen bonds into chains, which are further linked by aromatic π(py)···π(py) stacking interactions into sheets.

The Dichloroplatinum(II) and Dichloropalladium(II) Complexes of 1,4-Diazacycloheptane: Preparative, Structural and Conformational Studies

1996 ◽  
Vol 49 (12) ◽  
pp. 1301 ◽  
Author(s):  
GW Allen ◽  
ECH Ling ◽  
LV Krippner ◽  
TW Hambley
Keyword(s):  
Crystal Structures ◽  
Chelate Ring ◽  
Chair Conformation ◽  
Monoclinic Space Group ◽  
Boat Conformation ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
Membered Chelate Ring ◽  
Alternative Conformation

The preparation and purification of [Pt( hpip )Cl2] and [Pd( hpip )Cl2] ( hpip = homopiperazine = 1,4-diazacycloheptane) are described. Crystal structures of [Pt( hpip )Cl2] and [Pd( hpip )Cl2] have been determined by X-ray diffraction methods and refined to R values of 0.023 (932 F) and 0.023 (948 F). The crystals of [Pt( hpip )Cl2] are orthorhombic, space group Pbcm , a 7.7019(8), b 9.8080(12), c 12.1944(14) Ǻ, and those of [Pd( hpip )Cl2] are monoclinic, space group P21/m, a 6.1001(9), b 11.527(2), c 6.458(I) Ǻ, β 106.30(2)°. The seven- membered rings of the ligands in both complexes adopt boat-like conformations in which the five- membered chelate ring has an eclipsed N-C-C-N group and the six- membered chelate ring adopts a chair conformation. Molecular mechanics methods were used to investigate whether this conformation was a crystallographic artefact but it was found to be real. An alternative conformation in which the six-membered chelate ring adopts a skew-boat conformation was also investigated. It was found to be less stable than the conformation observed in the crystal structures, but to a degree that depends on whether non-bonded interactions involving the metal atom were included or not.

Darstellung von Mononitropentahydrohexaborat(2-) und Kristallstruktur von M2[B6H5(NO2)], M = K, Cs / Preparation of Mononitropentahydrohexaborate(2—) and Crystal Structure of M2[B6H5(NO2)], M = K, Cs

1993 ◽  
Vol 48 (12) ◽  
pp. 1727-1731 ◽  
Author(s):  
A. Franken ◽  
W. Preetz ◽  
M. Rath ◽  
K.-F. Hesse
Keyword(s):  
Crystal Structure ◽  
Ion Exchange ◽  
Ion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Dichloromethane Solution ◽  
Space Group ◽  
X Ray ◽  
Diethylaminoethyl Cellulose

By electrochemical oxidation of [B6H6]2- in the presence of nitrite ions and the base DBU in dichloromethane solution mononitropentahydrohexaborate [B6H5(NO2)]2- ions are formed and can be isolated by ion exchange chromatography on diethylaminoethyl cellulose. The crystal structures of the K and Cs salt were determined from single crystal X-ray diffraction analyses. K2[B6H5(NO2)] is monoclinic, space group P21/m with a = 5.953(1), b = 8.059(4), c = 8.906(1) Å, β = 109.553(9)°; Cs2[B6H5(NO2)] is monoclinic, space group P21/a with a = 9.438(6), b = 9.644(7), c = 11.138(9) Å, β = 101.44(9)°. The B6 octahedron is compressed in the direction of the B—NO2 bond by about 5%, with bond lengths between 1.67 and 1.77 A.

scholarly journals 4-METHYL HYPPURIC ACID: A CASE OF POLYMORPHISM AND SOLVATOMORPHISM

2019 ◽  
Vol 16 (32) ◽  
pp. 812-819
Author(s):  
G. DELGADO ◽  
M. GUILLEN ◽  
A. J. MORA
Keyword(s):  
Pharmaceutical Industry ◽  
Physical Properties ◽  
Crystal Packing ◽  
Solid Material ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Space Group ◽  
Pharmaceutical Ingredients ◽  
Orthorhombic Cell

Polymorphism is known as the ability of a solid material to exist in more than one form or crystal structure, with important applications in the preparation of active pharmaceutical ingredients. Characterization of different polymorphs of the specific metabolite of 4-xylene can contribute to the chemical and pharmaceutical industry. Polymorphism is of particular importance in industrial processes, where different physical properties of polymorphic forms can substantially alter the viability and quality of a manufactured product. This is particularly so for the design and production of drugs in the pharmaceutical industry, as varying physical properties between different polymorphs can affect shelf life and durability, solubility, as well as bioavailability and manufacturing of the drug. The crystallization, spectroscopic and X-ray diffraction characterization of two polymorph and one solvatomorph of 4-methylhippuric acid are presented. These compounds crystallizes in different crystalline systems. Polymorph I (4mH-I) crystalize in an orthorhombic cell with space group P212121. Polymorph II (4mHII) crystallizes in a monoclinic space group P21/c. Solvatomorph (4mH-S) crystallizes in a triclinic P-1 cell. All polymorphs crystallize in neutral form. The crystal packing of the three compounds are governed by hydrogen bonds intermolecular interactions of the type N--H···O and O--H···O forming tridimensional networks.

Crystal Structure and Vibrational Behaviour of Aqua Di(saccharinato)di(nicotinamide)copper(II)

2002 ◽  
Vol 57 (1) ◽  
pp. 43-46 ◽  
Author(s):  
Beatriz S. Parajón-Costaa ◽  
Enrique J. Baran ◽  
Oscar E. Piro ◽  
Eduardo E Castellano
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Ir Spectrum ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray

The crystal structure of [Cu(sac)2(nic)2(H2O)] (sac = saccharinate anion; nic = nicotinamide) has been determined by single-crystal X-ray diffraction. It crystallizes in the monoclinic space group C2/c with Z = 4 and the Cu(II) ion presents a CuN4O square pyramidal coordination. Some comparisons with related structures are made and the most important features of its IR spectrum were also discussed.

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