scholarly journals Targeted Synthesis of Regioisomerically Pure Dodecasubstituted Type I Porphyrins Through the Exploitation of Peri-Interactions

2020 ◽  
Author(s):  
Marc Kielmann ◽  
Keith Flanagan ◽  
Mathias Senge
Keyword(s):  
Single Crystal ◽  
Structural Features ◽  
Type I ◽  
Steric Strain ◽  
X Ray ◽  
Sterically Demanding ◽  
Separation Of Isomers

A targeted synthesis of dodecasubstituted type I porphyrins that utilizes the reaction of unsymmetrical 3,4-difunctionalized pyrroles and sterically demanding aldehydes was developed. This way, type I porphyrins could be obtained as the only type isomers, likely due to a minimization of the steric strain arising from peri-interactions. Uniquely, this method does not depend on lengthy precursor syntheses, the separation of isomers, or impractical limitations of the reaction scale. In addition, single crystal X-ray analysis elucidated the structural features of the macrocycles.

scholarly journals Targeted Synthesis of Regioisomerically Pure Dodecasubstituted Type I Porphyrins Through the Exploitation of Peri-Interactions

2020 ◽  
Author(s):  
Marc Kielmann ◽  
Keith Flanagan ◽  
Mathias Senge
Keyword(s):  
Single Crystal ◽  
Structural Features ◽  
Type I ◽  
Steric Strain ◽  
X Ray ◽  
Sterically Demanding ◽  
Separation Of Isomers

A targeted synthesis of dodecasubstituted type I porphyrins that utilizes the reaction of unsymmetrical 3,4-difunctionalized pyrroles and sterically demanding aldehydes was developed. This way, type I porphyrins could be obtained as the only type isomers, likely due to a minimization of the steric strain arising from peri-interactions. Uniquely, this method does not depend on lengthy precursor syntheses, the separation of isomers, or impractical limitations of the reaction scale. In addition, single crystal X-ray analysis elucidated the structural features of the macrocycles.

The Transition Metal-rich Orthophosphate Arrojadite with Special Structural Features

2010 ◽  
Vol 65 (12) ◽  
pp. 1427-1433 ◽  
Author(s):  
Christoph Kallfaß ◽  
Constantin Hoch ◽  
Hermann Schier ◽  
Arndt Simon ◽  
Helmut Schuber
Keyword(s):  
Crystal Structure ◽  
Transition Metal ◽  
Single Crystal ◽  
Structural Features ◽  
Nickel Plate ◽  
Single Crystal Diffraction ◽  
X Ray ◽  
Different Types ◽  
New Feature

The crystal structure of the transition metal-rich orthophosphate mineral arrojadite was reexamined, and the disorder phenomena were analyzed applying modern X-ray single-crystal diffraction and refinement methods on samples from Nickel Plate (USA) and Hagendorf (Germany). As a new feature of the arrojadite structure, two different types of channels oriented along [010] are described. The occupancy of the atomic positions inside these channels have been elucidated.

New Intermetallic Compounds RE4Co2Mg3 (RE = Pr, Gd, Tb, Dy) – Syntheses, Structure, and Chemical Bonding

2007 ◽  
Vol 62 (2) ◽  
pp. 162-168 ◽  
Author(s):  
Selcan Tuncel ◽  
Ute Ch. Rodewald ◽  
Samir F. Matar ◽  
Bernard Chevalier ◽  
Rainer Pöttgena
Keyword(s):  
Single Crystal ◽  
Intermetallic Compounds ◽  
Chemical Bonding ◽  
Structural Features ◽  
Induction Melting ◽  
Geometrical Constraint ◽  
X Ray Diffraction ◽  
X Ray ◽  
Bonding Analysis ◽  
Magnesium Compounds

The magnesium compounds RE4Co2Mg3 (RE = Pr, Gd, Tb, Dy) were prepared by induction melting of the elements in sealed tantalum tubes. The samples were studied by powder X-ray diffraction. The structures of the gadolinium and of the terbium compound were refined from single crystal diffractometer data: Nd4Co2Mg3-type, P2/m, Z = 1, a = 754.0(4), b = 374.1(1), c = 822.5(3) pm, β = 109.65(4)°, wR2 = 0.0649, 730 F2 values for Gd4Co2Mg3 and a = 750.4(2), b = 372.86(6), c = 819.5(2) pm, β = 109.48(3)°, wR2 = 0.0398, 888 F2 values for Tb4Co2Mg3 with 30 variables each. The RE4Co2Mg3 structures are 3 : 1 intergrowth variants of distorted CsCl and AlB2 related slabs of compositions REMg and RECo2. Characteristic structural features (exemplary for Tb4Co2Mg3) are relatively short Tb-Co (271 pm), Co-Co (232 pm) and Mg-Mg (314 pm) distances. The latter are a geometrical constraint of the distortion of the REMg and RECo2 slabs. Chemical bonding analysis (ELF and ECOV data) for Gd4Co2Mg3 reveals strong Gd-Co bonding followed by Mg-Co, while the Mg-Mg interactions can be considered as weak. The Co-Co contacts are only weakly bonding. The bonding and antibonding states are almost filled.

scholarly journals Lead-antimony sulfosalts from Tuscany (Italy). XVIII. New data on the crystal-chemistry of boscardinite

2017 ◽  
Vol 81 (1) ◽  
pp. 47-60 ◽  
Author(s):  
Cristian Biagioni ◽  
Yves Moëlo
Keyword(s):  
Single Crystal ◽  
Diffraction Study ◽  
Type Specimen ◽  
Structural Features ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Parameters ◽  
Mineral Associations ◽  
Crystal Chemical Data ◽  
New Findings

AbstractBoscardinite, ideally TlPb4(Sb7As2)∑9S18, has been described recently as a new homeotypic derivative of baumhauerite, found at Monte Arsiccio mine, Apuan Alps, Tuscany, Italy. New findings of boscardinite in different mineral associations of this deposit have allowed the collection of new crystal-chemical data. Electron-microprobe analysis of the crystal used for the single-crystal X-ray diffraction study gave (in wt.%): Ag 1.81(5), Tl 12.60(21), Pb 17.99(12), Hg 0.14(5), As 9.36(12), Sb 33.60(27), S 23.41(30),Cl 0.06(1), total 98.97(100). On the basis of ∑Me= 14 apfu, it corresponds to Ag0.42Tl1.52Pb2.14Hg0.02(Sb6.82As3.08)∑9.90S18.04Cl0.04. With respect to the type specimen, these new findings are characterized by a strong Pb depletion, coupled with higher Tl contents, and a significant As enrichment. The single-crystal X-ray diffraction study of this (Tl,As)-enriched boscardinite confirms the structural features described for the type sample. The unit-cell parameters area= 8.1017(4),b= 8.6597(4),c= 22.5574(10) Å, α = 90.666(2), β = 97.242(2), γ = 90.850(2)°,V= 1569.63(12) Å3, space groupP̄1. The crystal structure was refined down toR1= 0.0285 on the basis of 6582 reflections withFo> 4σ(Fo). Arsenic is dominant in threeMeS3sites, compared to one in type boscardinite. The main As-enrichment is observed in the sartorite-type sub-layer. Owing to this chemical peculiarity, (Tl, As)-rich boscardinite shows alternation, alongb, of Sb-rich sites and As-rich sites; this feature represents the main factor controlling the 8 Å superstructure. The chemical variability of boscardinite is discussed; the Ag increase observed here gets closer to stoichiometric AgTl3Pb4(Sb14As6)∑20S36(Z= 1), against possible extension up to AgTl2Pb6(Sb15As4)∑19S36for type boscardinite.

The perchlorotriphenylmethyl (PTM) radical

2013 ◽  
Vol 69 (3) ◽  
pp. 255-257 ◽  
Author(s):  
Judith Guasch ◽  
Xavier Fontrodona ◽  
Imma Ratera ◽  
Concepció Rovira ◽  
Jaume Veciana
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Diffraction Data ◽  
The Other ◽  
X Ray Diffraction ◽  
Monoclinic Symmetry ◽  
Steric Strain ◽  
High Chemical ◽  
X Ray ◽  
Cl Atoms

In spite of the considerable understanding and development of perchlorotriphenylmethyl (PTM) radical derivatives, the preparation of crystals of the pure unsubstituted PTM radical, C19Cl15, suitable for single-crystal X-ray diffraction has remained a challenge since its discovery, and only two studies dealing with the crystal structure of the unsubstituted PTM radical have been published. In one study, the radical forms clathrates with aromatic solvents [Veciana, Carilla, Miravitlles & Molins (1987).J. Chem. Soc. Chem. Commun.pp. 812–814], and in the other the structure was determinedab initiofrom powder X-ray diffraction data [Rius, Miravitlles, Molins, Crespo & Veciana (1990).Mol. Cryst. Liq. Cryst.187, 155–163]. We report here the preparation of PTM crystals for single-crystal X-ray diffraction and their resolution. The structure, which shows monoclinic symmetry (C2/c), revealed a nonsymmetric molecular propeller conformation (D3symmetry) caused by the steric strain between theortho-Cl atoms, which protect the central C atom (sp2-hybridization and major spin density) and give high chemical and thermal persistence to the PTM. The supramolecular structure of PTM shows short Cl...Cl intermolecular interactions and can be described in terms of layers formed by rows of molecules positioned in a head-to-tail manner along thecaxis.

Syntheses and molecular structures of some di(amidino)monosilanes

2021 ◽  
Vol 44 (1) ◽  
pp. 228-238
Author(s):  
Markus Bös ◽  
Marcus Herbig ◽  
Uwe Böhme ◽  
Edwin Kroke
Keyword(s):  
Raman Spectroscopy ◽  
Single Crystal ◽  
High Field ◽  
Structural Features ◽  
Molecular Structures ◽  
X Ray Diffraction ◽  
One Pot ◽  
X Ray ◽  
Field Shift ◽  
Nmr Signals

Abstract The syntheses of three different amidinosilanes of the type Me2Si[N=C(Ph)R]2 with R = pyrrolidino, morpholino, and diethylamino and one derivative with the composition R2Si[N=C(Ph)R]2 with R = morpholino are reported. These compounds were prepared in one-pot syntheses including three consecutive steps. All products are analysed by single crystal X-ray diffraction, NMR, and Raman spectroscopy. The Si–N=C–N units of these compounds show characteristic structural features and cause a significant high field shift of the 29Si NMR signals.

The synthesis, structure and reactivity of an imine-stabilized carboranylphosphorus(i) compound

2016 ◽  
Vol 52 (45) ◽  
pp. 7280-7283 ◽  
Author(s):  
Tek Long Chan ◽  
Zuowei Xie
Keyword(s):  
Dft Calculations ◽  
Single Crystal ◽  
X Ray ◽  
Sterically Demanding

An imine-stabilized carboranylphosphorus(i) compound has been synthesized, where the imine moiety serves as a σ donor and sterically demanding carboranyl ligand prevents the dimerization, which has been supported by single-crystal X-ray analyses, DFT calculations and reactivity studies.

scholarly journals N-Acetyl Indole Linked to a Fused Triazolo/Thiadiazole Scaffold: Synthesis, Single Crystal X-Ray Structure, and Molecular Insight

Crystals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 600
Author(s):  
Ahmed T. A. Boraei ◽  
Saied M. Soliman ◽  
Sammer Yousuf ◽  
Memoona Bibi ◽  
Assem Barakat
Keyword(s):  
Single Crystal ◽  
High Resolution Mass Spectrometry ◽  
Atomic Charge ◽  
Dft Method ◽  
Chemical Yield ◽  
Structural Features ◽  
Strong Interactions ◽  
X Ray ◽  
Reactivity Descriptors ◽  
Hirshfeld Analysis

The designed target compound of N-acetyl indole linked to a fused triazolo/thiadiazole scaffold was synthesized via the reaction of 4-amino-5-(1H-indol-2-yl)-1,2,4-triazol-3(2H)-thione as the starting material with acetic anhydride under reflux conditions for 6 h, resulting in an excellent and pure chemical yield. The structural features of the designed compound were confirmed using spectroscopic tools including single crystal X-ray diffraction analysis along with 1H-NMR, 13C-NMR, 2D-NMR, and high resolution mass spectrometry. Using Hirshfeld analysis, we determined the molecular packing depends on strong interactions (O···H and N···H) along with weak interactions (S···H, C···H and H···H). The shortest contacts corresponding to the N3···H12 (2.490 Å), N2···H5 (2.503 Å), and O1···H2 (2.490 Å) interactions were confirmed based on the Hirshfeld analysis. The calculated dipole moment was 6.6557 Debye. The atomic charge distribution, molecular electrostatic potential map, and reactivity descriptors are also discussed. The computed NMR spectra of the requisite compound correlated well with the results obtained experimentally. The UV-Vis electronic spectra of the requisite compound were simulated using the TD-DFT method and compared with the experimental data. The different σ→σ*, π→π*, n→σ*, and n→π* donor–acceptor interactions and their interaction energies stabilized the studied system to 9.84, 20.65, 29.33, and 45.82 kcal/mol, respectively.

scholarly journals Complex Disorder in Type-I Clathrates: Synthesis and Structural Characterization of A8GaxSn46−x (A = Rb, Cs; 6.9 < x < 7.5)

Crystals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 298
Author(s):  
Sviatoslav A. Baranets ◽  
Amanda B. Childs ◽  
Hua He ◽  
Svilen Bobev
Keyword(s):  
Single Crystal ◽  
Exact Nature ◽  
Type I ◽  
X Ray Diffraction ◽  
Structural Variations ◽  
Zintl Phases ◽  
Experimental Conditions ◽  
Group 13 ◽  
X Ray ◽  
The Matrix

Exploratory studies in the systems Rb–Ga–Sn and Cs–Ga–Sn yielded the cubic type-I clathrates with refined compositions Rb8GaxSn46−x and Cs8GaxSn46−x (6.9 < x < 7.5). Nearly single-phase materials with good crystallinity were obtained from stoichiometric reactions of the elements. The structures were characterized by means of single-crystal X-ray diffraction methods. Both Rb8GaxSn46−x and Cs8GaxSn46−x represents cases, where a Group 13 element randomly substitutes a Group 14 element in the structure. The extent of Ga/Sn mixing is apparently governed by the drive of the system to achieve an optimal valence electron count, and hence, Rb8GaxSn46−x and Cs8GaxSn46−x (x ≈ 8) can be regarded as Zintl phases. This notion is supported by structure refinements on a multitude of single-crystal X-ray diffraction data, which also confirm that both types of cages in the cubic type-I structure are fully occupied by Rb and Cs atoms. The open-framework, comprised of 46 nodes per formula unit, adapts to the incorporation of nearly eight Ga atoms within the matrix of Sn, whereby small, short-range distortions result. The exact nature of these effects is still unclear, as so far, the structural variations could only be modeled as both positional and occupational disorder at one of three framework sites. Since vacancies in the structures of the binary type-I clathrates A8Sn46−x☐x (A = Rb, Cs; ☐ = missing Sn atom) are also known to cause local distortions, the latter were also synthesized with the same protocols used for the synthesis of A8GaxSn46−x and structurally re-analyzed. The results from the latter studies confirm that homogeneity issues abound, and that the final structures/compositions are an intricate function of the experimental conditions.

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