scholarly journals Bismuth Polycations Revisited: Alternative Synthesis and Electronic Structure of Bi6Br7, and Bonding in Main-Group Polyatomic Ions from a Direct Space Perspective

Crystals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 940
Author(s):  
Ekaterina A. Stroganova ◽  
Sergey I. Troyanov ◽  
Igor V. Morozov ◽  
Alexey N. Kuznetsov
Keyword(s):  
Main Group ◽  
Basis Sets ◽  
Narrow Gap ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ionic Salt ◽  
Main Group Metal ◽  
Gradient Furnace ◽  
Structure Description ◽  
Density Analysis

A bismuth subbromide, Bi6Br7, was synthesized in the form of single crystals using the reaction between Bi and Hg2Br2 in a gradient furnace. Its crystal structure was reinvestigated by low-temperature single-crystal X-ray diffraction (Pnnm, a = 15.4996(6) Å, b = 23.6435(7) Å, c = 9.0231(2) Å, Z = 8, R1 = 0.041, wRall = 0.087). Based on the diffraction data, the structure description was revised as containing Bi95+ cluster polycations and 1∞[Bi3Br145−] ladder-like anions. DFT calculations of band structure showed the compound to be a narrow-gap semiconductor with a band gap of ca. 1.3 eV, with the nature of the compound as ionic salt confirmed by charge density analysis. Direct-space bonding analysis based on the ELF topology and QTAIM partitioning, performed for all known homoatomic bismuth polycations, as well as isoelectronic main-group metal ions, shows patterns of localized pairwise and three-center bonding forming the frameworks of the clusters. In addition to obtaining new data, the use of highly augmented basis sets allowed us to revise and amend several previously made conclusions regarding bonding in such species.

Über Verbindungen subvalenter Hauptgruppenmetallkationen mit Dithiolaten, 3. Mitteilung [1]. Die Kristallstruktur von [As(C6H5)4]2[Pb(S2C=C(CN)2)2]/Compounds of Subvalent Main Group Metal Cations with Dithiolates, Part 3 [1] Crystal Structure of [As(C6H5)4]2[Pb(S2C=C(CN)2)2]

1989 ◽  
Vol 44 (3) ◽  
pp. 293-295 ◽  
Author(s):  
Hans-Ulrich Hummel ◽  
Hermann Meske
Keyword(s):  
Crystal Structure ◽  
Complex Anion ◽  
Lone Pair ◽  
Metal Cations ◽  
Main Group ◽  
X Ray Diffraction ◽  
X Ray ◽  
Group Metal ◽  
Main Group Metal

The crystal structure of [AsPh4]2[Pb(S2C=C(CN)2)2] has been determined by X-ray diffraction. In the pyramidal complex anion [Pb(S2C=C(CN)2)2]2- Pb is coordinated to the sulfur atoms of the dithiolates. The geometry is indicative for a stereochemically active lone-pair at the apex of the square pyramid.

Crystal structures of highly stabilized ylides: methyl(3-methoxy,2-methoxycarbonylbenzoyl) triphenyl- phosphoranylideneacetate and methyl(2-methoxycarb-6-nitrobenzoyl)triphenyl phos phoranyl ideneacetate and the salt methyl(triphenylphosphoranylidene)acetate tetrafluoroborate

1998 ◽  
Vol 76 (12) ◽  
pp. 1844-1852
Author(s):  
Fernande D Rochon ◽  
Robert Melanson ◽  
Margaret M Kayser
Keyword(s):  
Key Words ◽  
Crystal Structures ◽  
Nitro Derivative ◽  
Transient Species ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ionic Salt ◽  
Higher Temperature ◽  
Cyclic Anhydrides ◽  
Wittig Reactions

At lower temperatures stabilized ylides react with unsymmetrically substituted phthalic anhydrides to give two acyclic adducts. When the reactions are allowed to proceed at higher temperature enol lactones are formed. Identification of the acyclic intermediates was necessary to understand the mechanism of these Wittig reactions. The transient species trapped in the reaction with trimethyloxonium tetrafluoroborate were unambiguously identified by crystallographic methods. The crystal structures of the tetrafluoroborate salt of methyl(triphenylphosphoranyl idene)- acetate (8), methyl(3-methoxy,2-methoxycarbonylbenzoyl)triphenylphosphoranylideneacetate (6β), and methyl(2-methoxycarbonyl,6-nitrobenzoyl)triphenylphosphoranylideneacetate (7α) were studied by X-ray diffraction. The ionic salt (8) is monoclinic, P21c,a= 12.640(5), b = 13.945(9), c = 14.825(6) Å, β = 125.32(3)°, Z = 4, and R = 0.065 (F >5.4 σ(F)). Crystal 6 β is monoclinic, P21c,a = 16.391(16), b = 9.029(6), c = 19.835(19) Å, β = 116.60(6)°, Z = 4, and R = 0.070 (F > 4.6 σ(F)), while crystal 7α is also monoclinic, P21c,a = 9.513(5), b = 9.361(3), c = 30.908(13) Å, β = 98.42(3)°, Z = 4, and R = 0.057 (F >5 σ(F)). In the BF 4- salt (12), the four P-C distances are equal (1.791(5)-1.801(7) Å) with identical tetrahedral angles. For the two triphenylphosphoranylideneacetate compounds, the fourth P-C(1) bond is shorter (1.762(6)-1.734(5) Å) than the three P-C(Ph) bonds (avg. 1.809(5) Å). The angles C(1)-P-C(Ph) are also larger (avg. 112.9(2)° for 6β and 111.9(2)° for 7α) than the C(Ph)-P-C(Ph) angles (avg. 105.8(2)° for 6 β and 106.9(2)° for 7α). These values suggest a multiple nature for the P-C(1) bond. In the nitro derivative, the nitro and the ester groups are disordered equally in positions 2 and 6. Key words: Wittig reactions, cyclic anhydrides, stabilized ylide, phosphoranylidenes, crystal structures.

scholarly journals Accurate H-atom parameters for the two polymorphs of L-histidine at 5, 105 and 295 K

2021 ◽  
Vol 77 (5) ◽  
pp. 785-800
Author(s):  
Giulia Novelli ◽  
Charles J. McMonagle ◽  
Florian Kleemiss ◽  
Michael Probert ◽  
Horst Puschmann ◽  
...  
Keyword(s):  
Neutron Diffraction ◽  
Single Crystal ◽  
Diffraction Data ◽  
Crystal Packing ◽  
Basis Sets ◽  
X Ray Diffraction ◽  
X Ray ◽  
Refinement Method ◽  
Primary Amino ◽  
Precision And Accuracy

The crystal structure of the monoclinic polymorph of the primary amino acid L-histidine has been determined for the first time by single-crystal neutron diffraction, while that of the orthorhombic polymorph has been reinvestigated with an untwinned crystal, improving the experimental precision and accuracy. For each polymorph, neutron diffraction data were collected at 5, 105 and 295 K. Single-crystal X-ray diffraction experiments were also performed at the same temperatures. The two polymorphs, whose crystal packing is interpreted by intermolecular interaction energies calculated using the Pixel method, show differences in the energy and geometry of the hydrogen bond formed along the c direction. Taking advantage of the X-ray diffraction data collected at 5 K, the precision and accuracy of the new Hirshfeld atom refinement method implemented in NoSpherA2 were probed choosing various settings of the functionals and basis sets, together with the use of explicit clusters of molecules and enhanced rigid-body restraints for H atoms. Equivalent atomic coordinates and anisotropic displacement parameters were compared and found to agree well with those obtained from the corresponding neutron structural models.

scholarly journals Synthesis, X-Ray Crystallography, Thermal Analysis, and DFT Studies of Ni(II) Complex with 1-Vinylimidazole Ligand

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Fatih Şen ◽  
Ramazan Şahin ◽  
Muharrem Dinçer ◽  
Ömer Andaç ◽  
Murat Taş
Keyword(s):  
Density Functional ◽  
Computational Study ◽  
Basis Sets ◽  
Mulliken Charge ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Dft Methods ◽  
X Ray ◽  
X Ray Crystallography ◽  
The Density Functional Theory

The paper presents a combined experimental and computational study of hexa(1-vinylimidazole)Ni(II) perchlorate complex. The complex was prepared in the laboratory and crystallized in the monoclinic space group P21/n with a=8.442(5), b=13.686(8), c=16.041(9) Å, α=γ=90, β=96.638(5), and Z=1. The complex has been characterized structurally (by single-crystal X-Ray diffraction) and its molecular structure in the ground state has been calculated using the density functional theory (DFT) methods with 6-31G(d) and LanL2DZ basis sets. Thermal behaviour and stability of the complex were studied by TGA/DTA analyses. Besides, the nonlinear optical effects (NLO), molecular electrostatic potential (MEP), frontier molecular orbitals (FMO), and the Mulliken charge distribution were investigated theoretically.

Charge-density analysis in polymorphs of urea–barbituric acid co-crystals

2011 ◽  
Vol 67 (2) ◽  
pp. 144-154 ◽  
Author(s):  
Marlena Gryl ◽  
Anna Krawczuk-Pantula ◽  
Katarzyna Stadnicka
Keyword(s):  
Hydrogen Bond ◽  
High Resolution ◽  
Hydrogen Bonds ◽  
Charge Density ◽  
Barbituric Acid ◽  
Van Der Waals Interactions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Density Analysis ◽  
Resolution Single

High-resolution single-crystal X-ray diffraction measurements at 100 K were performed for the two polymorphs of urea–barbituric acid co-crystals: (I) P21/c and (II) Cc. Experimental and theoretical charge density and its properties were analysed for (I) and (II) in order to confirm the previous observation that in the polymorphs studied the barbituric acid molecules adopt different mesomeric forms, leading to different hydrogen-bond systems. Koch and Popelier criteria were applied to distinguish between hydrogen bonds and van der Waals interactions in the structures presented.

Mehrfachbindungen zwischen Hauptgruppenelementen und Übergangsmetallen, LXXXIX / Multiple Bonds between Main Group Elements and Transition Metals, LXXXIX

1991 ◽  
Vol 46 (6) ◽  
pp. 747-752 ◽  
Author(s):  
Wolfgang A. Herrmann ◽  
Dieter W. Marz ◽  
Eberhardt Herdtweck
Keyword(s):  
Molecular Structure ◽  
Transition Metals ◽  
Single Crystal ◽  
Main Group ◽  
X Ray Diffraction ◽  
Multiple Bonds ◽  
Main Group Elements ◽  
X Ray ◽  
Clean Synthesis

Reaction of (N-trimethylsilyl)-α-aminopicolin with the rhenium(V) oxohalogenide (η5-C5Me5)ReOCl2 (Me = CH3) exemplifies a simple, clean synthesis of imido-metallosiloxanes, compounds of the structure R3SiO—M=N—R′. The compound (η5-C5Me5)ReCl[OSi(CH3)3](NCH2-2-C5H4N) thus formed under HCl elimination has a square-pyramidal molecular structure (single crystal X-ray diffraction).

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