scholarly journals Metal-Rich Metallaboranes: Synthesis, Structures and Bonding of Bi- and Trimetallic Open-Faced Cobaltaboranes

Inorganics ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 28
Author(s):  
Kriti Pathak ◽  
Chandan Nandi ◽  
Jean-François Halet ◽  
Sundargopal Ghosh
Keyword(s):  
Electronic Structures ◽  
Density Functional ◽  
Room Temperature ◽  
Electron Pair ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
X Ray ◽  
Cluster 2 ◽  
Cobalt Center

Synthesis, isolation, and structural characterization of unique metal rich diamagnetic cobaltaborane clusters are reported. They were obtained from reactions of monoborane as well as modified borohydride reagents with cobalt sources. For example, the reaction of [Cp*CoCl]2 with [LiBH4·THF] and subsequent photolysis with excess [BH3·THF] (THF = tetrahydrofuran) at room temperature afforded the 11-vertex tricobaltaborane nido-[(Cp*Co)3B8H10] (1, Cp* = η5-C5Me5). The reaction of Li[BH2S3] with the dicobaltaoctaborane(12) [(Cp*Co)2B6H10] yielded the 10-vertex nido-2,4-[(Cp*Co)2B8H12] cluster (2), extending the library of dicobaltadecaborane(14) analogues. Although cluster 1 adopts a classical 11-vertex-nido-geometry with one cobalt center and four boron atoms forming the open pentagonal face, it disobeys the Polyhedral Skeletal Electron Pair Theory (PSEPT). Compound 2 adopts a perfectly symmetrical 10-vertex-nido framework with a plane of symmetry bisecting the basal boron plane resulting in two {CoB3} units bridged at the base by two boron atoms and possesses the expected electron count. Both compounds were characterized in solution by multinuclear NMR and IR spectroscopies and by mass spectrometry. Single-crystal X-ray diffraction analyses confirmed the structures of the compounds. Additionally, density functional theory (DFT) calculations were performed in order to study and interpret the nature of bonding and electronic structures of these complexes.

DFT Study on Two Plausible Mechanistic Routes to Pyrazolo[3,4-d]pyrimidine-4- Amines from Pyrazoloformimidate

2020 ◽  
Vol 24 (2) ◽  
pp. 216-229
Author(s):  
Amal Al-Azmi
Keyword(s):  
Density Functional ◽  
Room Temperature ◽  
Dft Calculation ◽  
Reaction Pathways ◽  
Nucleophilic Attack ◽  
X Ray Diffraction ◽  
Dimroth Rearrangement ◽  
Functional Theory ◽  
X Ray ◽  
Moderate Yield

Pyrazolo[3,4-d]pyrimidine-4-amine was prepared at room temperature in a catalyst- free medium with moderate yield and characterized by spectroscopic and X-ray diffraction techniques. Two possible mechanistic routes were suggested for its formation. Route 1 entails attack by the N of the amine on the imidate carbon followed by Dimroth rearrangement after cyclization. Route 2 is the nucleophilic attack by the amine on the CN function followed by cyclization to pyrazolo[3,4-d]pyrimidine-4-amine. Density functional theory (DFT) calculation studies of the two proposed reaction pathways illustrated that the Route 2 reaction was more likely than that of Route 1.

X-ray characterization of tripyridinium bis[tetrabromidoferrate(III)] bromide asymmetric unit in solution by Debye function analysis

2016 ◽  
Vol 30 (24) ◽  
pp. 1650174
Author(s):  
F. Baniasadi ◽  
N. Sahraei ◽  
M. B. Fathi ◽  
M. M. Tehranchi ◽  
N. Safari ◽  
...  
Keyword(s):  
Density Functional ◽  
Function Analysis ◽  
Dilute Solution ◽  
Asymmetric Unit ◽  
X Ray Diffraction ◽  
Debye Function ◽  
Functional Theory ◽  
X Ray ◽  
Diluted Solution

Abundant asymmetric unit of the [FeBr4]2[py.H]3Br magnetic molecule in the acetonitrile solvent was characterized via Debye function analysis (DFA) of the X-ray powder diffraction pattern from dilute solution. A diluted solution of the material in acetonitrile solvent has been prepared to reduce, as far as possible, the interaction between the molecular units. The X-ray diffraction from the sample was measured and Debye function simulations of three out of ten chemically plausible molecular units were observed to suitably comply with the experimental results. These three configurations were further optimized with first-principles method in the framework of density functional theory (DFT) and the most stable structure according to the calculated total energy is presented.

scholarly journals Synthesis, Characterization, Absorption Properties, and Electronic Structures of Paddlewheel-Type Dirhodium(II) Tetra-μ-(n-naphthoate) Complexes: An Experimental and Theoretical Study

Molecules ◽  
2019 ◽  
Vol 24 (3) ◽  
pp. 447 ◽  
Author(s):  
Yusuke Kataoka ◽  
Raiki Fukumoto ◽  
Natsumi Yano ◽  
Daiki Atarashi ◽  
Hidekazu Tanaka ◽  
...  
Keyword(s):  
Electronic Structures ◽  
Density Functional ◽  
Dft Calculation ◽  
X Ray Diffraction ◽  
Absorption Properties ◽  
Thermal Stabilities ◽  
Functional Theory ◽  
X Ray ◽  
Light Region ◽  
Ligand Charge Transfer

The reactions of [Rh2(O2CCH3)4(OH2)2] with n-naphthalenecarboxylic acids (n = 1: 1-HNC, n = 2: 2-HNC) afford the dirhodium tetra-μ-(n-naphthoate) complexes [Rh2(1-NC)4] (1) and [Rh2(2-NC)4] (2), respectively. Single crystal X-ray diffraction analyses of [1(OCMe2)2] and [2(OCMe2)2], which were obtained by recrystallization from acetone (OCMe2) solutions of 1 and 2, reveal that the dirhodium cores are coordinated by four equatorially bridging naphthoate ligands and two axial OCMe2 ligands. Density functional theory (DFT) calculation confirmed that (i) the single Rh–Rh bond is formed between the two Rh ions and (ii) the electronic structures between two Rh ions in [1(OCMe2)2] and [2(OCMe2)2] are best described as π4δ2σ2δ*2π*4 and δ2π4σ2δ*2π*4, respectively. Time-dependent DFT (TDDFT) calculations clarify the absorption band characters of [1(OCMe2)2] and [2(OCMe2)2]; the former shows the bands due to d–d and metal–to–metal-ligand charge transfer (MMLCT) excitations in the visible light region, whereas the latter shows the bands due to only d–d excitations in the same region. The electrochemical properties and thermal stabilities of [1(OCMe2)2] and [2(OCMe2)2] were also investigated in this study.

scholarly journals Hydrosilyation of CO2 using a silatrane hydride: structural characterization of a silyl formate compound

2021 ◽  
Vol 99 (2) ◽  
pp. 259-267
Author(s):  
Serge Ruccolo ◽  
Erika Amemiya ◽  
Daniel G. Shlian ◽  
Gerard Parkin
Keyword(s):  
Molecular Structure ◽  
Density Functional Theory ◽  
Oxygen Atom ◽  
Structural Characterization ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
X Ray

The silatrane hydride compound, [N(CH2CH2O)3]SiH, reacts with CO2 in the presence of the [tris(2-pyridylthio)methyl]zinc hydride complex, [Tptm]ZnH, to afford the silyl formate and methoxide derivatives, [N(CH2CH2O)3]SiO2CH and [N(CH2CH2O)3]SiOCH3. The molecular structure of [N(CH2CH2O)3]SiO2CH has been determined by X-ray diffraction, thereby demonstrating that the formate ligand adopts a distal conformation in which the uncoordinated oxygen atom resides with a trans-like disposition relative to silicon. Density functional theory calculations indicate that the atrane motif of [N(CH2CH2O)3]SiO2CH is flexible, such that the energy of the molecule changes relatively little as the Si···N distance varies over the range 2.0–3.0 Å.

scholarly journals Pressure-dependent X-ray diffraction of the multiferroics RMn2O5

2019 ◽  
Vol 75 (4) ◽  
pp. 687-696 ◽  
Author(s):  
Wei Peng ◽  
Victor Balédent ◽  
Marie-Bernadette Lepetit ◽  
Antoine Vaunat ◽  
Elisa Rebolini ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Density Functional ◽  
Room Temperature ◽  
Exchange Interactions ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
X Ray ◽  
X Ray Scattering ◽  
Pressure Evolution ◽  
Good Agreement

The room-temperature structural properties of the RMn2O5 multiferroics have been investigated under pressure, using powder X-ray scattering and density functional theory (DFT) calculations. It was possible to determine the lattice parameters and the main atomic positions as a function of pressure. Good agreement was observed between the X-ray and DFT results for most of the determined crystallographic data. From the DFT calculations, it was possible to infer the pressure evolution of the exchange interactions, and this analysis led to the conclusion that the onset of the q = (½, 0, ½) magnetic structure under pressure is related to the increase in the J 1 super-exchange terms (due to the reduction in the Mn—O distances) compared with the Mn—R exchange interactions. In addition, the 1D antiferromagnetic character of the compounds should be reinforced under pressure.

scholarly journals Synthesis and Physical Properties of Iridium-Based Sulfide Ca1−xIr4S6(S2) [x = 0.23–0.33]

2022 ◽  
Vol 3 (1) ◽  
pp. 41-52
Author(s):  
Michael Vogl ◽  
Martin Valldor ◽  
Roman Boy Piening ◽  
Dmitri V. Efremov ◽  
Bernd Büchner ◽  
...  
Keyword(s):  
Density Functional ◽  
Magnetic Measurements ◽  
X Ray Diffraction ◽  
Metallic Behavior ◽  
Functional Theory ◽  
X Ray ◽  
Lattice Constants ◽  
The Density Functional Theory ◽  
Xrd Techniques

We present the synthesis and characterization of the iridium-based sulfide Ca1−xIr4S6(S2). Quality and phase analysis were conducted by means of energy-dispersive X-ray spectroscopy (EDXS) and powder X-ray diffraction (XRD) techniques. Structure analysis reveals a monoclinic symmetry with the space group C 1 2/m 1 (No. 12), with the lattice constants a = 15.030 (3) Å, b = 3.5747 (5) Å and c = 10.4572 (18) Å. Both X-ray diffraction and EDXS suggest an off-stoichiometry of calcium, leading to the empirical composition Ca1−xIr4.0S6(S2) [x = 0.23–0.33]. Transport measurements show metallic behavior of the compound in the whole range of measured temperatures. Magnetic measurements down to 1.8 K show no long range order, and Curie–Weiss analysis yields θCW = −31.4 K, suggesting that the compound undergoes a magnetic state with short range magnetic correlations. We supplement our study with calculations of the band structure in the framework of the density functional theory.

scholarly journals Structure, DFT Calculations, and Magnetic Characterization of Coordination Polymers of Bridged Dicyanamido-Metal(II) Complexes

2019 ◽  
Vol 5 (3) ◽  
pp. 41 ◽  
Author(s):  
Franz A. Mautner ◽  
Patricia Jantscher ◽  
Roland C. Fischer ◽  
Ana Torvisco ◽  
Ramon Vicente ◽  
...  
Keyword(s):  
Coordination Polymers ◽  
Density Functional ◽  
Antiferromagnetic Coupling ◽  
Computational Studies ◽  
X Ray Diffraction ◽  
Opposite Orientation ◽  
Functional Theory ◽  
X Ray ◽  
In Trans

Three coordination polymers of metal(II)-dicyanamido (dca) complexes with 4-methoxypyridine-N-oxide (4-MOP-NO); namely, catena-[Co(µ1,5-dca)2(4-MOP-NO)2] (1), catena-[Mn(µ1,5-dca)2(4-MOP-NO)2] (2), catena-[Cd(µ1,5-dca)2(4-MOP-NO)2] (3), and the mononuclear [Cu(κ1dca)2(4-MOP-NO)2] (4), were synthesized in this research. The complexes were analyzed by single crystal X-ray diffraction as well as spectroscopic methods (UV/vis, IR). The polymeric 1-D chains in complexes 1–3 were achieved by the doubly µ1,5-bridging dca ligands and the O-donor atoms of two axial 4-MOP-NO molecules in trans configuration around the distorted M(II) octahedral. On the other hand, the two “trans-axial” pyridine-N-oxide molecules in complexes 2 and 3 display opposite orientation (s-trans). The DFT (density functional theory) computational studies on the complexes 1–3 were consistent with the experimentally observed crystal structures. Compounds 1 and 2 display weak antiferromagnetic coupling between metal ions (J = −10.8 for 1 and −0.35 for 2).

scholarly journals Synthesis and Electrochemical and Spectroscopic Characterization of 4,7-diamino-1,10-phenanthrolines and Their Precursors

Molecules ◽  
2019 ◽  
Vol 24 (22) ◽  
pp. 4102 ◽  
Author(s):  
Nycz ◽  
Wantulok ◽  
Sokolova ◽  
Pajchel ◽  
Stankevič ◽  
...  
Keyword(s):  
Density Functional ◽  
Spectroscopic Characterization ◽  
Frontier Molecular Orbitals ◽  
X Ray Diffraction ◽  
Nucleophilic Substitutions ◽  
Functional Theory ◽  
X Ray ◽  
Homo And Lumo ◽  
Cp Mas Nmr

New approaches to the synthesis of 4,7-dichloro-1,10-phenanthrolines and their corresponding 9H-carbazol-9-yl-, 10H-phenothiazin-10-yl- and pyrrolidin-1-yl derivatives were developed. Their properties have been characterized by a combination of several techniques: MS, HRMS, GC-MS, electronic absorption spectroscopy and multinuclear NMR in both solution and solid state including 15N CP/MAS NMR. The structures of 5-fluoro-2,9-dimethyl-4,7-di(pyrrolidin-1-yl)-1,10-phenanthroline (5d), 4,7-di(9H-carbazol-9-yl)-9-oxo-9,10-dihydro-1,10-phenanthroline-5-carbonitrile (6a) and 4,7-di(10H-phenothiazin-10-yl)-1,10-phenanthroline-5-carbonitrile (6b) were determined by single-crystal X-ray diffraction measurements. The nucleophilic substitutions of hydrogen followed by oxidation produced compounds 6a and 6b. The electrochemical properties of selected 1,10-phenanthrolines were investigated using cyclic voltammetry and compared with commercially available reference 1,10-phenanthrolin-5-amine (5l). The spatial distribution of frontier molecular orbitals of the selected compounds has been calculated by density functional theory (DFT). It was shown that potentials of reduction and oxidation were in consistence with the level of HOMO and LUMO energies.

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