1,4-Additions of arylboron, -silicon, and -bismuth compounds to α,β-unsaturated carbonyl compounds catalyzed by dicationic palladium(II) complexes

2008 ◽  
Vol 80 (5) ◽  
pp. 807-817 ◽  
Author(s):  
Yasunori Yamamoto ◽  
Takashi Nishikata ◽  
Norio Miyaura
Keyword(s):  
Carbonyl Compounds ◽  
Density Functional ◽  
Electronic Effect ◽  
Enantioselective Synthesis ◽  
Functional Theory ◽  
X Ray ◽  
Unsaturated Ketones ◽  
Bismuth Compounds ◽  
Pd Complexes

An enantioselective synthesis of cyclic and acyclic β-aryl ketone and aldehydes via Pd(II)-catalyzed 1,4-addition of Ar-m [m = B(OH)2, BF3K, Si(OMe)3, SiF3, BiAr2] to α,β-unsaturated ketones or aldehydes is described. The catalytic cycle involves transmetallation between Ar-m and Pd complexes as a key process, the mechanism of which is discussed on the basis of characterization of the transmetallation intermediate and electronic effect of the substituents. The enantioselection mechanism and efficiency of a chiraphos ligand for structurally planar α,β-unsaturated ketones are discussed on the basis of the X-ray structure of the catalyst and results of density functional theory (DFT) computational studies on the model of coordination of the substrates to the phenylpalladium(II)/(S,S)-chiraphos intermediate.

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.

scholarly journals On the Importance of Halogen Bonding Interactions in Two X-ray Structures Containing All Four (F, Cl, Br, I) Halogen Atoms

Crystals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1406
Author(s):  
Dmitriy F. Mertsalov ◽  
Rosa M. Gomila ◽  
Vladimir P. Zaytsev ◽  
Mikhail S. Grigoriev ◽  
Eugeniya V. Nikitina ◽  
...  
Keyword(s):  
Electrostatic Potential ◽  
Density Functional ◽  
Molecular Electrostatic Potential ◽  
Halogen Bonding ◽  
Noncovalent Interaction ◽  
Functional Theory ◽  
X Ray ◽  
Halogen Atoms ◽  
Interaction Plot

This manuscript reports the synthesis and X-ray characterization of two octahydro-1H-4,6-epoxycyclopenta[c]pyridin-1-one derivatives that contain the four most abundant halogen atoms (Ha) in the structure with the aim of studying the formation of Ha···Ha halogen bonding interactions. The anisotropy of electron density at the heavier halogen atoms provokes the formation of multiple Ha···Ha contacts in the solid state. That is, the heavier Ha-atoms exhibit a region of positive electrostatic potential (σ-hole) along the C–Ha bond and a belt of negative electrostatic potential (σ-lumps) around the atoms. The halogen bonding assemblies in both compounds were analyzed using density functional theory (DFT) calculations, molecular electrostatic potential (MEP) surfaces, the quantum theory of “atom-in-molecules” (QTAIM), the noncovalent interaction plot (NCIplot), and the electron localization function (ELF).

scholarly journals Synthesis, X-ray Characterization and Density Functional Theory (DFT) Studies of Two Polymorphs of the α,α,α,α, Isomer of Tetra-p-Iodophenyl Tetramethyl Calix[4]pyrrole: On the Importance of Halogen Bonds

Molecules ◽  
2020 ◽  
Vol 25 (2) ◽  
pp. 285
Author(s):  
Dragoș Dăbuleanu ◽  
Antonio Bauzá ◽  
Joaquín Ortega-Castro ◽  
Eduardo C. Escudero-Adán ◽  
Pablo Ballester ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Single Crystals ◽  
Density Functional ◽  
Halogen Bonding ◽  
Acetonitrile Solution ◽  
Functional Theory ◽  
Crystal Lattices ◽  
Cone Conformation ◽  
X Ray

This manuscript reports the improved synthesis of the α,α,α,α isomer of tetra-p-iodophenyl tetra-methyl calix[4]pyrrole and the X-ray characterization of two solvate polymorphs. In the solid state, the calix[4]pyrrole receptor adopts the cone conformation, including one acetonitrile molecule in its aromatic cavity by establishing four convergent hydrogen bonds between its nitrogen atom and the four pyrrole NHs of the former. The inclusion complexes pack into rods, displaying a unidirectional orientation. In turn, the rods form flat 2D-layers by alternating the orientation of their p-iodo substituents. The 2D layers stack on top of another, resulting in a head-to-head and tail-to-tail orientation of the complexes or their exclusive arrangement in a head-to-tail geometry. The dissimilar stacking of the layers yields two solvate polymorphs that are simultaneously present in the structures of the single crystals. The ratio of the two polymorph phases is regulated by the amount of acetonitrile added to the chloroform solutions from which the crystals grow. Halogen bonding interactions are highly relevant in the crystal lattices of the two polymorphs. We analyzed and characterized these interactions by means of density functional theory (DFT) calculations and several computational tools. Remarkably, single crystals of a solvate containing two acetonitrile molecules per calix[4]pyrrole were obtained from pure acetonitrile solution.

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 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 The structure of ortho-(trifluoromethyl)phenol in comparison to its homologues – A combined experimental and theoretical study

2018 ◽  
Vol 16 (1) ◽  
pp. 745-756
Author(s):  
Richard Betz
Keyword(s):  
Crystal Structure ◽  
Density Functional ◽  
Theoretical Study ◽  
Functional Theory ◽  
X Ray ◽  
Iodine Compounds ◽  
Natural Bonding Orbital ◽  
Ft Ir ◽  
Reactions With Nucleophiles

AbstractThe molecular and crystal structure of commercially-availableortho-(trifluoromethyl)phenol were determined by means of single-crystal X-ray diffractometry (XRD) and represent the first structural characterization of anortho-substituted (trihalomethyl) phenol. The unexpected presence of a defined hydrate in the solid state was observed.Intermolecular contacts and hydrogen bonding were analyzed. The compound was further characterized by means of multi-nuclear nuclear magnetic resonance (NMR) spectroscopy (1H,13C{1H},19F) and Fourier-Transform infrared (FT-IR) vibrational spectroscopy. To assess the bonding situation as well as potential reaction sites for reactions with nucleophiles and electrophiles in the compound by means of natural bonding orbital (NBO) analyses, and density functional theory (DFT) calculations were performed for the title compound as well as its homologous chlorine, bromine and iodine compounds. As far as possible, experimental data were correlated to DFT data.

Synthesis, Structure, NMR Spectroscopy, and Electrochemistry of the Sterically Congested Triarylarsine Dipp3As: EPR Characterization of its Radical Cation

2013 ◽  
Vol 66 (10) ◽  
pp. 1226 ◽  
Author(s):  
Mona Taghavikish ◽  
Brock L. Price ◽  
Tracey L. Roemmele ◽  
René T. Boeré
Keyword(s):  
Nmr Spectroscopy ◽  
Density Functional ◽  
Density Functional Theory Calculation ◽  
Chemical Oxidation ◽  
Aromatic Rings ◽  
Functional Theory ◽  
X Ray ◽  
Out Of Plane ◽  
Theory Calculation

The synthesis, NMR spectroscopy, single-crystal X-ray structure, and solution electrochemistry of the new compound [2,6-{CH(CH3)}2C6H3]3 As, abbreviated as Dipp3As, is reported. The molecule, prepared by reaction of AsCl3 with a pre-formed aryl copper reagent, Dipp4Cu4, crystallizes in the hexagonal space group R3 as a racemic twin. The sum of angles around As, ∑∠{CAsC}, is 329.13(3)° in the X-ray structure and 329.17° from an R-B3LYP/6-31G(d,p) hybrid density functional theory calculation. The aromatic rings are quite distorted with both the ipso carbon and especially the As atom significantly out of plane by 0.503(3) Å. The ambient temperature NMR spectrum fits for C3 symmetry implying that inversion is slow on the NMR timescale. Cyclic voltammetry on a glassy carbon electrode in CH2Cl2 with 0.4 M [nBu4N][PF6] over scan rates of 0.05–0.8 V s–1 and temperatures of 22 ± 2°C produced one quasi-reversible process with Em1 = +0.43 V at a scan rate of 0.20 V s–1 and a second irreversible process with a peak potential of +1.45 V (v. Fc+/0). The diffusion coefficient has been measured as 3.3 ± 0.1 × 10–6 cm2 s–1 in CH2Cl2 solution containing 0.4 M [nBu4N][PF6]. Chemical oxidation with AgPF6 in CH2Cl2 in degassed solutions in sealed vessels allowed for recording of characteristic EPR spectra; at 293 K, a (75As) = 26.1 mT and g = 2.021. In frozen solution, an almost isotropic spectrum is obtained (g║ = 2.000 mT and g⊥ = 2.003 mT) and the hyperfine splitting constants are a║ = 47.9 and a⊥ = 19.0 mT, leading to an estimate for the structure being slightly pyramidal with ∑∠{CAsC} ≈ 351°.

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