The Experts below are selected from a list of 300 Experts worldwide ranked by ideXlab platform
Jian Xiao - One of the best experts on this subject based on the ideXlab platform.
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C(sp3)—H Bond Functionalization by Sequential Hydride Transfer/Cyclization: Electronic Effect and Steric Effect Controlled Regioselectivity.
ChemInform, 2016Co-Authors: Liang Wang, Jian XiaoAbstract:Both the electronic and Steric Effect have a dramatic impact on the title reaction of substrate (I).
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c sp3 h bond functionalization by sequential hydride transfer cyclization electronic Effect and Steric Effect controlled regioselectivity
ChemInform, 2016Co-Authors: Liang Wang, Jian XiaoAbstract:Both the electronic and Steric Effect have a dramatic impact on the title reaction of substrate (I).
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c sp3 h bond functionalization by sequential hydride transfer cyclization electronic Effect and Steric Effect controlled regioselectivity
Organic chemistry frontiers, 2016Co-Authors: Liang Wang, Jian XiaoAbstract:The electronic Effect and Steric Effect have a dramatic impact on the fascinating cascade [1,n]-hydride transfer/cyclization. The regioselectivity of two potential hydrogen donors could be perfectly tuned to construct different skeletons.
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C(sp3)–H bond functionalization by sequential hydride transfer/cyclization: electronic Effect and Steric Effect controlled regioselectivity
Organic Chemistry Frontiers, 2016Co-Authors: Liang Wang, Jian XiaoAbstract:The electronic Effect and Steric Effect have a dramatic impact on the fascinating cascade [1,n]-hydride transfer/cyclization. The regioselectivity of two potential hydrogen donors could be perfectly tuned to construct different skeletons.
Liang Wang - One of the best experts on this subject based on the ideXlab platform.
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C(sp3)—H Bond Functionalization by Sequential Hydride Transfer/Cyclization: Electronic Effect and Steric Effect Controlled Regioselectivity.
ChemInform, 2016Co-Authors: Liang Wang, Jian XiaoAbstract:Both the electronic and Steric Effect have a dramatic impact on the title reaction of substrate (I).
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c sp3 h bond functionalization by sequential hydride transfer cyclization electronic Effect and Steric Effect controlled regioselectivity
ChemInform, 2016Co-Authors: Liang Wang, Jian XiaoAbstract:Both the electronic and Steric Effect have a dramatic impact on the title reaction of substrate (I).
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c sp3 h bond functionalization by sequential hydride transfer cyclization electronic Effect and Steric Effect controlled regioselectivity
Organic chemistry frontiers, 2016Co-Authors: Liang Wang, Jian XiaoAbstract:The electronic Effect and Steric Effect have a dramatic impact on the fascinating cascade [1,n]-hydride transfer/cyclization. The regioselectivity of two potential hydrogen donors could be perfectly tuned to construct different skeletons.
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C(sp3)–H bond functionalization by sequential hydride transfer/cyclization: electronic Effect and Steric Effect controlled regioselectivity
Organic Chemistry Frontiers, 2016Co-Authors: Liang Wang, Jian XiaoAbstract:The electronic Effect and Steric Effect have a dramatic impact on the fascinating cascade [1,n]-hydride transfer/cyclization. The regioselectivity of two potential hydrogen donors could be perfectly tuned to construct different skeletons.
Toshio Kasai - One of the best experts on this subject based on the ideXlab platform.
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Alignment selection of the metastable CO(a 3Π1) molecule and the Steric Effect in the aligned CO(a 3Π1) + NO collision.
The journal of physical chemistry. A, 2013Co-Authors: Masaaki Nakamura, Dock-chil Che, Po-yu Tsai, King-chuen Lin, Toshio KasaiAbstract:The aligned metastable CO(a (3)Π1) molecular beam was generated by an electronic excitation through the Cameron band (CO a (3)Π1 ← X (1)Σ(+)) transition. Beam characterization of the aligned molecular beam of CO(a (3)Π1) was carried out by (1 + 1) REMPI detection via the b (3)Σ(+) state. The REMPI signals showed the clear dependence on the polarization of the pump laser, and the experimental result was well reproduced by the theoretical simulation. This agreement confirms that aligned metastable CO(a (3)Π1) can be generated and controlled by rotating polarization of the pump laser. By using this technique, a single quantum state of CO(a (3)Π1) can be selected as a metastable molecular beam. The Steric Effect in the energy-transfer collision of CO(a (3)Π1) with NO forming the excited NO was carried out with this aligned CO(a (3)Π1) molecular beam. We find that the sideways orientation of CO(a (3)Π1) is more favorable in the formation of the excited NO(A (2)Σ(+), B (2)Π) than that for the axial collisions. The obtained Steric Effect was discussed with the aid of the spatial distribution of CO(a (3)Π1) molecular orbitals, and we find that specific rotational motion of CO(a (3)Π1) in each state may not be a dominant factor in this energy-transfer collision.
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Steric Effect in the energy transfer reaction of N2 + Rg (3P2) (Rg = Kr, Ar).
The journal of physical chemistry. A, 2008Co-Authors: Hiroshi Ohoyama, K. Yasuda, Toshio KasaiAbstract:Steric Effect for the formation of N 2 (B, 3 Π u ) in the energy transfer reaction of Kr ( 3 P 2 ) + N 2 has been measured using an oriented Kr ( 3 P 2 , Mj = 2) beam at a collision energy of 0.07 eV. The N 2 (B, 3 Π u ) emission intensity was measured as a function of the magnetic orientation field direction in the collision frame. A significant atomic alignment Effect on the energy transfer probability was observed. This result was compared with that for the formation of N 2 (C, 3 Πg) in the Ar ( 3 P 2 ) + N 2 reaction. Despite the large difference on the energy transfer cross-section, the atomic alignment dependence for Kr ( 3 P 2 ) + N 2 is found to be analogous to that for Ar ( 3 P 2 ) + N 2 . It is revealed that the configuration of inner 4p (3p) orbital in the collision frame gives an important role for the stereoselectivity on electron transfer process via the curve-crossing mechanism.
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Steric Effect in the energy transfer reaction of Ar(P23)+N2
The Journal of chemical physics, 2006Co-Authors: D. Watanabe, Hiroshi Ohoyama, Takashi Matsumura, Toshio KasaiAbstract:Steric Effect for N2(C,Πu3) formation in the energy transfer reaction of Ar(P23)+N2 was directly measured by using an oriented Ar(P23,MJ=2) beam at a collision energy of 0.06eV. The N2(C,Πu3) chemiluminescence intensity was measured as a function of the magnetic orientation field direction in the collision frame. A significant alignment Effect on the energy transfer probability was observed. The relative reactivity for each magnetic substate in the collision frame σ∣MJ′∣ was determined to be σ∣2∣:σ∣1∣:σ0=0.50:0.60:1.00. It is suggested that the observed Steric Effect is primarily due to the favorable configuration of the 3p orbital for the efficient overlap with the 2σu molecular orbital of N2.
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Steric Effect in the endothermic Penning ionization reaction of tert-butyl bromide with Kr(3P)
The Journal of Chemical Physics, 2003Co-Authors: K. Koizumi, Seiki Okada, Hiroshi Ohoyama, Toshio KasaiAbstract:The Steric opacity function (the dependence of reaction cross section upon mutual molecular orientation) for the endothermic Penning ionization channel of Kr(3P)+(CH3)3CBr reaction was determined by using an oriented tert-butyl bromide molecular beam at 0.1 eV average collision energy. A remarkably large Steric Effect was observed in contrast with the Ar(3P)+CH3Br reaction. We find that the ionization cross section is maximum at sideways and it becomes “zero” at the tert-butyl end. The Br end is found to be unfavorable as compared with sideways approaches. The stereo selectivity observed in the present work is discussed in terms of the electron exchange mechanism, in which the shielding Effect by bulky nonreactive tert-butyl group as well as the smearing Effect in impact parameter are taken into account.
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Direct observation of the Steric Effect in Penning ionization reaction of Ar*+CHCl3→CHCl2++Cl+e−+Ar
The Journal of Chemical Physics, 2000Co-Authors: Masanori Yamato, Seiki Okada, Hiroshi Ohoyama, Toshio KasaiAbstract:Steric Effect in the Penning ionization reaction of Ar*(3P2,0)+CHCl3→Ar+CHCl2++Cl+e− was directly observed at an average collision energy of 0.13 eV using the oriented CHCl3 molecular beam. The product CHCl2+ ions are measured for the H-end, the CCl3-end, and sideways orientations. The obtained Steric opacity function reveals that the CCl3-end orientation is more favorable than the H-end orientation, and the sideways approach is found to be more favorable than the collinear approaches from both ends of the molecule. Furthermore, we confirm the good correlation between Penning ionization anisotropy and the electron density distribution of the 2a2 HOMO orbital of the CHCl3 molecule, whose electron cloud is mostly localized around the sideways. These results substantiate the electron exchange mechanism which is commonly accepted for the Penning ionization reaction, where the overlap of projectile atomic and target molecular orbital plays a key role in Penning ionization efficiency.
Shin-ichi Ishiguro - One of the best experts on this subject based on the ideXlab platform.
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thermodynamic and structural aspects on the solvation Steric Effect of lanthanide iii dependence on the ionic size
Coordination Chemistry Reviews, 2002Co-Authors: Shin-ichi Ishiguro, Yasuhiro Umebayashi, Morito KomiyaAbstract:Abstract Thermodynamic and structural aspects on the solvation Steric Effect for yttrium(III) and lanthanide(III) ions in DMF, DMA and their mixtures will be reviewed. The yttrium(III) and lanthanide(III) ions form outer- and inner-sphere bromo complexes in N , N -dimethylformamide (DMF) and N , N- dimethylacetamide (DMA), respectively, and an equilibrium geometry is established in the mixture. This is ascribed to the solvation Steric Effect of DMA, i.e. the simultaneous coordination of bulky DMA molecules around the metal ion causes a severe Steric hindrance among them, allowing replacement of the solvent molecule with the penetrating bromide ion into the first-coordination sphere. Solvation Steric Effects for the metal(III) ion bring about appreciable changes in the bond length and solvation number. The results from titration calorimetry, EXAFS, 89 Y-NMR and titration Raman spectroscopy will be discussed.
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Thermodynamic and Structural Aspects on Solvation Steric Effect in Nonaqueous Solution
Bulletin of the Chemical Society of Japan, 1997Co-Authors: Shin-ichi IshiguroAbstract:Formation thermodynamics and structure of halogeno and pseudo-halogeno complexes of transition metal(II) and lanthanide(III) ions have been studied in N,N-dimethylacetamide (DMA) and hexamethylphosphoric triamide (HMPA), and compared with those in N,N-dimethylformamide (DMF). Significant differences in the formation thermodynamics and structure among solvents has been explained in terms of a solvation Steric Effect. A structural survey by EXAFS demonstrates that solvent coordination number of a solvate metal ion is kept unchanged (weak solvation Steric Effect) or reduced (strong solvation Steric Effect) when the metal ion is transferred to DMA or HMPA, respectively, from DMF. DMA usually exhibits a weak solvation Steric Effect. It elucidates that a weak solvation Steric Effect of DMA is ascribable mainly to a distortion of the M–O–C–N dihedral angle. The solvent Effect operates for a complex with a coordination number larger than four in DMF, but it does not for a complex of four-coordination. Lanthanide(...
Hiroshi Ohoyama - One of the best experts on this subject based on the ideXlab platform.
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Steric Effect in the energy transfer reaction of N2 + Rg (3P2) (Rg = Kr, Ar).
The journal of physical chemistry. A, 2008Co-Authors: Hiroshi Ohoyama, K. Yasuda, Toshio KasaiAbstract:Steric Effect for the formation of N 2 (B, 3 Π u ) in the energy transfer reaction of Kr ( 3 P 2 ) + N 2 has been measured using an oriented Kr ( 3 P 2 , Mj = 2) beam at a collision energy of 0.07 eV. The N 2 (B, 3 Π u ) emission intensity was measured as a function of the magnetic orientation field direction in the collision frame. A significant atomic alignment Effect on the energy transfer probability was observed. This result was compared with that for the formation of N 2 (C, 3 Πg) in the Ar ( 3 P 2 ) + N 2 reaction. Despite the large difference on the energy transfer cross-section, the atomic alignment dependence for Kr ( 3 P 2 ) + N 2 is found to be analogous to that for Ar ( 3 P 2 ) + N 2 . It is revealed that the configuration of inner 4p (3p) orbital in the collision frame gives an important role for the stereoselectivity on electron transfer process via the curve-crossing mechanism.
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Steric Effect in the energy transfer reaction of Ar(P23)+N2
The Journal of chemical physics, 2006Co-Authors: D. Watanabe, Hiroshi Ohoyama, Takashi Matsumura, Toshio KasaiAbstract:Steric Effect for N2(C,Πu3) formation in the energy transfer reaction of Ar(P23)+N2 was directly measured by using an oriented Ar(P23,MJ=2) beam at a collision energy of 0.06eV. The N2(C,Πu3) chemiluminescence intensity was measured as a function of the magnetic orientation field direction in the collision frame. A significant alignment Effect on the energy transfer probability was observed. The relative reactivity for each magnetic substate in the collision frame σ∣MJ′∣ was determined to be σ∣2∣:σ∣1∣:σ0=0.50:0.60:1.00. It is suggested that the observed Steric Effect is primarily due to the favorable configuration of the 3p orbital for the efficient overlap with the 2σu molecular orbital of N2.
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Steric Effect in the endothermic Penning ionization reaction of tert-butyl bromide with Kr(3P)
The Journal of Chemical Physics, 2003Co-Authors: K. Koizumi, Seiki Okada, Hiroshi Ohoyama, Toshio KasaiAbstract:The Steric opacity function (the dependence of reaction cross section upon mutual molecular orientation) for the endothermic Penning ionization channel of Kr(3P)+(CH3)3CBr reaction was determined by using an oriented tert-butyl bromide molecular beam at 0.1 eV average collision energy. A remarkably large Steric Effect was observed in contrast with the Ar(3P)+CH3Br reaction. We find that the ionization cross section is maximum at sideways and it becomes “zero” at the tert-butyl end. The Br end is found to be unfavorable as compared with sideways approaches. The stereo selectivity observed in the present work is discussed in terms of the electron exchange mechanism, in which the shielding Effect by bulky nonreactive tert-butyl group as well as the smearing Effect in impact parameter are taken into account.
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Direct observation of the Steric Effect in Penning ionization reaction of Ar*+CHCl3→CHCl2++Cl+e−+Ar
The Journal of Chemical Physics, 2000Co-Authors: Masanori Yamato, Seiki Okada, Hiroshi Ohoyama, Toshio KasaiAbstract:Steric Effect in the Penning ionization reaction of Ar*(3P2,0)+CHCl3→Ar+CHCl2++Cl+e− was directly observed at an average collision energy of 0.13 eV using the oriented CHCl3 molecular beam. The product CHCl2+ ions are measured for the H-end, the CCl3-end, and sideways orientations. The obtained Steric opacity function reveals that the CCl3-end orientation is more favorable than the H-end orientation, and the sideways approach is found to be more favorable than the collinear approaches from both ends of the molecule. Furthermore, we confirm the good correlation between Penning ionization anisotropy and the electron density distribution of the 2a2 HOMO orbital of the CHCl3 molecule, whose electron cloud is mostly localized around the sideways. These results substantiate the electron exchange mechanism which is commonly accepted for the Penning ionization reaction, where the overlap of projectile atomic and target molecular orbital plays a key role in Penning ionization efficiency.
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direct observation of the Steric Effect in penning ionization reaction of ar chcl3 chcl2 cl e ar
Journal of Chemical Physics, 2000Co-Authors: Masanori Yamato, Seiki Okada, Hiroshi Ohoyama, Toshio KasaiAbstract:Steric Effect in the Penning ionization reaction of Ar*(3P2,0)+CHCl3→Ar+CHCl2++Cl+e− was directly observed at an average collision energy of 0.13 eV using the oriented CHCl3 molecular beam. The product CHCl2+ ions are measured for the H-end, the CCl3-end, and sideways orientations. The obtained Steric opacity function reveals that the CCl3-end orientation is more favorable than the H-end orientation, and the sideways approach is found to be more favorable than the collinear approaches from both ends of the molecule. Furthermore, we confirm the good correlation between Penning ionization anisotropy and the electron density distribution of the 2a2 HOMO orbital of the CHCl3 molecule, whose electron cloud is mostly localized around the sideways. These results substantiate the electron exchange mechanism which is commonly accepted for the Penning ionization reaction, where the overlap of projectile atomic and target molecular orbital plays a key role in Penning ionization efficiency.
