How big is big? Separation by conventional methods, X-ray and electronic structures of positional isomers of bis-tert-butylisocyano adduct of 2(3),9(10),16(17),23(24)-tetrachloro-3(2),10(9),17(16),24(23)-tetra(2,6-di-iso-propylphenoxy)-phthalocyaninato iron(II) complex

2016 ◽  
Vol 20 (01n04) ◽  
pp. 337-351 ◽  
Author(s):  
Derrick R. Anderson ◽  
Pavlo V. Solntsev ◽  
Hannah M. Rhoda ◽  
Victor N. Nemykin
Keyword(s):  
Electronic Structures ◽  
Density Functional ◽  
Positional Isomers ◽  
Excitation Energies ◽  
Functional Theory ◽  
X Ray ◽  
Vertical Excitation ◽  
X Ray Crystallography ◽  
Tddft Calculations ◽  
Insight Into

A presence of bulky 2,6-di-iso-propylphenoxy groups in bis-tert-butylisocyano adduct of 2(3),9(10),16(17),23(24)-tetrachloro-3(2),10(9),17(16),24(23)-tetra(2,6-di-iso-propylphenoxy)-phthalocyaninato iron(II) complex allows separation of two individual positional isomers and a mixture of the remaining two isomers using conventional chromatography. X-ray structures of “[Formula: see text]” and “[Formula: see text]” isomers were confimed by X-ray crystallography. Density functional theory (DFT) and time-dependent DFT (TDDFT) calculations of each individual positional isomer allowed insight into their electronic structures and vertical excitation energies, which were correlated with the experimental UV-vis and MCD spectra.

Organometallic pyrene-containing porphyrins: Synthesis, characterization, and non-covalent interactions with C60 fullerenes

2016 ◽  
Vol 20 (08n11) ◽  
pp. 1098-1113 ◽  
Author(s):  
Yang Li ◽  
Hannah M. Rhoda ◽  
Anthony M. Wertish ◽  
Victor N. Nemykin
Keyword(s):  
Excited States ◽  
Electronic Structures ◽  
Density Functional ◽  
Functional Theory ◽  
X Ray ◽  
X Ray Crystallography ◽  
H Nmr ◽  
Non Covalent Interactions ◽  
Covalent Interactions ◽  
C60 Fullerenes

A reaction between 5,10,15,20-tetra(4-hydroxyphenyl)porphyrin and 1-bromopyrene resulted in the formation of 5,10,15,20-tetra[4-(4-(pyrenyl-1)butoxy)phenyl]porphyrin (1), while cross-condensation between 4-(4-(pyrenyl-1)butoxy)benzaldehyde, ferrocenecaboxaldehyde, and pyrrole resulted in the formation of 5-ferrocenyl-10,15,20-tri[4-(4-(pyrenyl-1)butoxy)phenyl]porphyrin (2), 5,10-diferrocenyl-15,20-di[4-(4-(pyrenyl-1)butoxy)phenyl]porphyrin (3), and 5,15-diferrocenyl-10,20-di[4-(4-(pyrenyl-1)butoxy)phenyl]porphyrin (4). All pyrene-containing porphyrins were characterized by 1H NMR, UV-vis, MCD, and high-resolution ESI methods, while their electronic structures and the nature of the excited states were elucidated using density functional theory (DFT) and time-dependent DFT (TDDFT) calculations. The molecular structure of 1 and its fluorescence quenching upon the addition of C[Formula: see text] fullerene was also investigated using X-ray crystallography and steady-state fluorescence approaches.

X-Ray structures, Mössbauer hyperfine parameters, and molecular orbital descriptions of the phthalocyaninato iron(II) azole complexes

2020 ◽  
Vol 24 (05n07) ◽  
pp. 894-903
Author(s):  
Dustin E. Nevonen ◽  
Laura S. Ferch ◽  
Victor Y. Chernii ◽  
David E. Herbert ◽  
Johan van Lierop ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
Dft Calculations ◽  
Electronic Structures ◽  
Density Functional ◽  
Reasonable Agreement ◽  
Hyperfine Parameters ◽  
Functional Theory ◽  
X Ray ◽  
X Ray Crystallography

The electronic structures of a set of PcFe(azole)2 complexes (azole = imidazole, [Formula: see text]-methylimidazole, pyrazole, isoxazole, thiazole, 1,2,4-triazole, 3-amino-1,2,4,-triazole, and 5-amino-1,2,3,4-tetrazole) were examined by Mössbauer spectroscopy and Density Functional Theory (DFT) calculations. In addition, the geometric distortions in these compounds were elucidated by X-ray crystallography for imidazole, pyrazole, and thiazole-containing compounds. Predicted by DFT calculations, Mössbauer hyperfine parameters for all compounds are in reasonable agreement with experimental results, and the influence of the [Formula: see text]-donor and [Formula: see text]-acceptor properties of the axial azoles on the electronic structure of the PcFe(azole)2 complexes is demonstrated by comparison with the reference PcFePy2 compound.

Highly Electron-Deficient Pyridinium-Nitrones for Rapid and Tunable Inverse-Electron-Demand Strain-Promoted Alkyne-Nitrone Cycloaddition to Bicyclo[6.1.0]nonyne

2019 ◽  
Author(s):  
Praveen Gunawardene ◽  
Wilson Luo ◽  
Alexander M. Polgar ◽  
John F. Corrigan ◽  
Mark Workentin
Keyword(s):  
Density Functional Theory ◽  
Reaction Kinetics ◽  
Density Functional ◽  
Functional Theory ◽  
X Ray ◽  
Inverse Electron Demand ◽  
X Ray Crystallography ◽  
Electron Demand

<div> <div> <p>Highly accelerated inverse-electron-demand strain-promoted alkyne-nitrone cycloaddition (IED SPANC) between a sta- ble cyclooctyne (bicyclo[6.1.0]nonyne (BCN)) and nitrones delocalized into a Cα-pyridinium functionality is reported, with the most electron-deficient “pyridinium-nitrone” displaying among the most rapid cycloadditions to BCN that is currently reported. Density functional theory (DFT) and X-ray crystallography are explored to rationalize the effects of N- and Cα-substituent modifications at the nitrone on IED SPANC reaction kinetics and the overall rapid reactivity of pyridinium-delocalized nitrones.</p> </div> </div>

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 Synthesis of Chromium(II) Complexes with Chelating Bis(alkoxide) Ligand and Their Reactions with Organoazides and Diazoalkanes

Molecules ◽  
2020 ◽  
Vol 25 (2) ◽  
pp. 273 ◽  
Author(s):  
Sudheer S. Kurup ◽  
Richard J. Staples ◽  
Richard L. Lord ◽  
Stanislav Groysman
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Aryl Azides ◽  
Functional Theory ◽  
X Ray ◽  
X Ray Crystallography ◽  
Chromium Vi ◽  
Imido Complexes ◽  
Structure And Bonding

Synthesis of new chromium(II) complexes with chelating bis(alkoxide) ligand [OO]Ph (H2[OO]Ph = [1,1′:4′,1′’-terphenyl]-2,2′’-diylbis(diphenylmethanol)) and their subsequent reactivity in the context of catalytic production of carbodiimides from azides and isocyanides are described. Two different Cr(II) complexes are obtained, as a function of the crystallization solvent: mononuclear Cr[OO]Ph(THF)2 (in toluene/THF, THF = tetrahydrofuran) and dinuclear Cr2([OO]Ph)2 (in CH2Cl2/THF). The electronic structure and bonding in Cr[OO]Ph(THF)2 were probed by density functional theory calculations. Isolated Cr2([OO]Ph)2 undergoes facile reaction with 4-MeC6H4N3, 4-MeOC6H4N3, or 3,5-Me2C6H3N3 to yield diamagnetic Cr(VI) bis(imido) complexes; a structure of Cr[OO]Ph(N(4-MeC6H4))2 was confirmed by X-ray crystallography. The reaction of Cr2([OO]Ph)2 with bulkier azides N3R (MesN3, AdN3) forms paramagnetic products, formulated as Cr[OO]Ph(NR). The attempted formation of a Cr–alkylidene complex (using N2CPh2) instead forms chromium(VI) bis(diphenylmethylenehydrazido) complex Cr[OO]Ph(NNCPh2)2. Catalytic formation of carbodiimides was investigated for the azide/isocyanide mixtures containing various aryl azides and isocyanides. The formation of carbodiimides was found to depend on the nature of organoazide: whereas bulky mesitylazide led to the formation of carbodiimides with all isocyanides, no carbodiimide formation was observed for 3,5-dimethylphenylazide or 4-methylphenylazide. Treatment of Cr2([OO]Ph)2 or H2[OO]Ph with NO+ leads to the formation of [1,2-b]-dihydroindenofluorene, likely obtained via carbocation-mediated cyclization of the ligand.

Twisted Push - Pull Ethylenes

2008 ◽  
Vol 61 (10) ◽  
pp. 805 ◽  
Author(s):  
Rakesh Naduvile Veedu ◽  
Paul V. Bernhardt ◽  
Rainer Koch ◽  
Curt Wentrup
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Room Temperature ◽  
Dihedral Angles ◽  
Functional Theory ◽  
Activation Barriers ◽  
Rapid Rotation ◽  
X Ray ◽  
X Ray Crystallography ◽  
Calculated Activation

As determined by X-ray crystallography, Meldrum’s acid derivatives 5, 6, and 8 feature dihedral angles around the central C5=C7 double bond of 14–35°, whereas for the anion 9 this angle is 90°. Density functional theory and MP2 calculations are in agreement with the experimental X-ray data for compounds 5–8, but for anion 9 an angle of only ~65° is predicted. It is concluded that a part of the torsion is due to packing forces in the crystal. It is further concluded that these molecules undergo rapid rotation about the central CC bonds at room temperature (calculated activation barriers 5–14 kcal mol–1).

Different Cerium Valence Transitions Observed by Hydrogenation of the Ternary Germanides CeRhGe and CeIrGe – Structure, Physical Properties and Chemical Bonding

2008 ◽  
Vol 63 (6) ◽  
pp. 685-694 ◽  
Author(s):  
Bernard Chevalier ◽  
Etienne Gaudin ◽  
Adel F. Al Alam ◽  
Samir F. Matar ◽  
François Weill ◽  
...  
Keyword(s):  
Electronic Structures ◽  
Density Functional ◽  
Spin Fluctuation ◽  
Type Structure ◽  
Kondo Temperature ◽  
Intermediate Valence ◽  
Functional Theory ◽  
X Ray ◽  
Transmission Electron ◽  
Power Measurements

The ternary germanides CeRhGe and CeIrGe which crystallize in the orthorhombic TiNiSi-type structure, absorb hydrogen at 523 K. X-Ray powder diffraction and transmission electron microscopy indicate that the hydrides CeRhGeH1.8 and CeIrGeH1.8 adopt the hexagonal ZrBeSi-type structure. Magnetization, electrical resistivity and thermoelectric power measurements reveal that these hydrides are intermediate-valence compounds. An unusual transition from antiferromagnetic to spin fluctuation behavior occurs upon hydrogenation of CeRhGe, while on the contrary, CeIrGeH1.8 presents a Kondo temperature of 285 K smaller than that observed for CeIrGe (610 K). In order to explain these opposite valence transitions, the electronic structures of the hydrides have been selfconsistently calculated within the local spin density functional theory (LSDF). The structures are compared to those reported previously by us for CeRhGe and CeIrGe.

scholarly journals Six-fold C–H borylation of hexa-peri-hexabenzocoronene

2020 ◽  
Vol 16 ◽  
pp. 391-397 ◽  
Author(s):  
Mai Nagase ◽  
Kenta Kato ◽  
Akiko Yagi ◽  
Yasutomo Segawa ◽  
Kenichiro Itami
Keyword(s):  
Density Functional ◽  
Bathochromic Shift ◽  
Density Functional Theory Calculations ◽  
Absorption Bands ◽  
Functional Theory ◽  
X Ray ◽  
X Ray Crystallography ◽  
Polycyclic Aromatic ◽  
Direct Functionalization ◽  
Poorly Soluble

Hexa-peri-hexabenzocoronene (HBC) is known to be a poorly soluble polycyclic aromatic hydrocarbon for which direct functionalization methods have been very limited. Herein, the synthesis of hexaborylated HBC from unsubstituted HBC is described. Iridium-catalyzed six-fold C–H borylation of HBC was successfully achieved by screening solvents. The crystal structure of hexaborylated HBC was confirmed via X-ray crystallography. Optoelectronic properties of the thus-obtained hexaborylated HBC were analyzed with the support of density functional theory calculations. The spectra revealed a bathochromic shift of absorption bands compared with unsubstituted HBC under the effect of the σ-donation of boryl groups.

An amino–imino resonance study of 2-amino-4-methylpyridinium nitrate and 2-amino-5-methylpyridinium nitrate

2012 ◽  
Vol 69 (1) ◽  
pp. 61-65 ◽  
Author(s):  
Xing-Chen Yan ◽  
Yu-Hua Fan ◽  
Cai-Feng Bi ◽  
Xia Zhang ◽  
Zhong-Yu Zhang
Keyword(s):  
Density Functional Theory ◽  
Ir Spectroscopy ◽  
Ground State ◽  
Density Functional ◽  
Acta Cryst ◽  
Functional Theory ◽  
X Ray ◽  
X Ray Crystallography ◽  
Ground State Structures

The contributions of the amino and imino resonance forms to the ground-state structures of 2-amino-4-methylpyridinium nitrate, C6H9N2+·NO3−, and the previously reported 2-amino-5-methylpyridinium nitrate [Yan, Fan, Bi, Zuo & Zhang (2012).Acta Cryst.E68, o2084], were studied using a combination of IR spectroscopy, X-ray crystallography and density functional theory (DFT). The results show that the structures of 2-amino-4-methylpyridine and 2-amino-5-methylpyridine obtained upon protonation are best described as existing largely in the imino resonance forms.

scholarly journals 2-Hetaryl-1,3-tropolones based on five-membered nitrogen heterocycles: synthesis, structure and properties

2015 ◽  
Vol 11 ◽  
pp. 2179-2188 ◽  
Author(s):  
Yury A Sayapin ◽  
Inna O Tupaeva ◽  
Alexandra A Kolodina ◽  
Eugeny A Gusakov ◽  
Vitaly N Komissarov ◽  
...  
Keyword(s):  
Density Functional ◽  
Acetic Acid Solution ◽  
Intramolecular Proton Transfer ◽  
Molecular Structures ◽  
X Ray Diffraction ◽  
Dft Methods ◽  
Functional Theory ◽  
X Ray ◽  
X Ray Crystallography ◽  
Derivatives Of

A series of derivatives of 2-hetaryl-1,3-tropolone (β-tropolone) was prepared by the acid-catalyzed reaction of 2-methylbenzoxazoles, 2-methylbenzothiazoles and 2,3,3-trimethylindoline with 3,4,5,6-tetrachloro-1,2-benzoquinone. The molecular structures of the three representative compounds were determined by X-ray crystallography. In crystal and (as shown by the DFT PBE0/6-311+G** calculations) in solution, 2-hetaryl-4,5,6,7-tetrachloro- and 2-hetaryl-5,6,7-trichloro-1,3-tropolones exist in the NH-tautomeric form with a strong resonance-assisted intramolecular N–H···O hydrogen bond. The mechanism of the formation of 1,3-tropolones in the reaction of methylene-active five-membered heterocycles with o-chloranil in acetic acid solution has been studied using density functional theory (DFT) methods. The reaction of 2-(2-benzoxa(thia)zolyl)-5,6,7-trichloro(4,5,6,7-tetrachloro)-1,3-tropolones with alcohols leads to the contraction of the seven-membered tropone ring with the formation of 2-(2-benzoxa(thia)zolyl)-6-alkoxycarbonylphenols. The molecular structure of 2-(2-ethoxycarbonyl-6-hydroxy-3,4,5-trichlorophenyl)benzoxazole has been determined by X-ray diffraction. 2-(2-Benzoxa(thia)zolyl)-6-alkoxycarbonylphenols display intense green fluorescence with anomalous Stokes shifts caused by the excited state intramolecular proton transfer (ESIPT) effects.

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