Inter-Cage Orbital Interactions in [2+2] and [4+4] Dimers of Buckminsterfullerene

1994 ◽  
Vol 359 ◽  
Author(s):  
Shūichi Ōsawa ◽  
Eiji Ōsawa
Keyword(s):  
Geometry Optimization ◽  
Molecular Orbitals ◽  
Orbital Interaction ◽  
Orbital Interactions

ABSTRACTGeometry optimization of [2+2]- and [4+4]-dimers of C60 by semiempirical AMI MO method reveals usual length for the bridge bonds of the former but unusually long bonds for the latter. Perturbational analysis of molecular orbitals confirm the presence of orbital interaction through bond (OITB) between the cages in the [2+2] dimer but no interaction in the [4+4] dimer. These results contradict with previous examples of OITB wherein elongation of the mediating σ bond is usually observed.

Orbital interactions. IX. The effect of remote substituents on the electrophilic nitration of a series of 11-substituted exo-hexahydro-7,10-methanofluoranthenes

1980 ◽  
Vol 33 (4) ◽  
pp. 795 ◽  
Author(s):  
MJ Oliver ◽  
HK Patney ◽  
MN Paddon-Row
Keyword(s):  
Product Distribution ◽  
Molecular Orbitals ◽  
Orbital Interactions ◽  
Opposite Result ◽  
Field Effects ◽  
Methoxy Substituent ◽  
Salient Features ◽  
Scf Calculations

Product distribution and the relative rates of nitration (Cu(NO3)2,3H2O/Ac2O) of a series of 11-substituted exo-hexahydro-7,10- methanofluoranthenes, (8), (9b), (10) and (11b), and acenaphthene, (12), have been determined. It was observed that a syn-methoxy substituent, as in (11b), greatly enhanced the reactivity of the acenaphthene ring towards nitration compared with unsubstituted (8), the α position being activated more than the γ position. Precisely the opposite result was obtained for the nitration of the ketone (10). These results are explained in terms of the consequences of through- space orbital interactions (OITS), operating between the molecular orbitals of the 11-substituent and those of the acenaphthene ring; a PMO model is used for the nitration reaction. The results of INDO MO SCF calculations on the water-acenaphthene complex (22) and the formaldehyde-acenaphthene complex (23), which are intended to mimic the salient features of (11b) and (10) respectively, lend support to the OITS proposal. However, alternative proposals, based on field effects (in the case of (10)) and on the formation of a complex (24) for the nitration of (11b), are also discussed.

A new insight into π–π stacking involving remarkable orbital interactions

2016 ◽  
Vol 18 (36) ◽  
pp. 25452-25457 ◽  
Author(s):  
Rundong Zhao ◽  
Rui-Qin Zhang
Keyword(s):  
Orbital Interaction ◽  
Orbital Interactions ◽  
Π Interactions ◽  
Π Stacking ◽  
Unified Description ◽  
Insight Into

The importance of orbital interaction in π–π interactions is explored in detail and a unified description of π–π stacking is proposed.

Molecular orbitals from group orbitals. I. A perturbational molecular orbital treatment of the electronic structures, shapes and conformations of AHmBHn Systems

1976 ◽  
Vol 54 (6) ◽  
pp. 949-962 ◽  
Author(s):  
Myung-Hwan Whangbo ◽  
Saul Wolfe
Keyword(s):  
Molecular Orbital ◽  
Electronic Structures ◽  
Molecular Orbitals ◽  
Orbital Interaction ◽  
Molecular Systems ◽  
Group Orbitals

A procedure is proposed which allows the group orbitals of a fragment AHm—to be obtained from the molecular orbitals of the molecule AHm—H. Orbital interaction diagrams constructed from these group orbitals have been found useful in the description of the electronic structures and conformations of a variety of molecular systems of the type AHmBHn. The molecules that have been treated by this procedure include ethane, hydrazine, diphosphine, aminophosphine, aminoborane, and sulfonium and phosphonium ylids.

scholarly journals Constructing Spin-Adiabatic States for the Modeling of Spin-Crossing Reactions I. A Shared-Orbital Implementation

2019 ◽  
Author(s):  
Yunwen Tao ◽  
Zheng Pei ◽  
Nicole Bellonzi ◽  
Yuezhi Mao ◽  
zhu zou ◽  
...  
Keyword(s):  
Electron Spin ◽  
Energy Surface ◽  
Geometry Optimization ◽  
Molecular Orbitals ◽  
Orbit Coupling ◽  
Spin States ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Crossing Point ◽  
Adiabatic Energy

In the modeling of spin-crossing reactions, it has become popular to directly explore the spin-adiabatic surfaces. Specifically, through constructing spin-adiabatic states from a two-state Hamiltonian (with spin-orbit coupling matrix elements) at each geometry, one can readily employ advanced geometry optimization algorithms to acquire a “transition state" structure, where the spin crossing occurs. In this work, we report the implementation of a fully variational spin-adiabatic approach based on Kohn-Sham density functional theory spin states (sharing the same set of molecular orbitals) and the Breit-Pauli one-electron spin-orbit operator. For three model spin-crossing reactions [predissociation of N2O, singlet-triplet conversion in CH2, and CO association to Fe(CO)4], the spin-crossing points were easily obtained. Our results also indicated the Breit-Pauli one-electron spin-orbit coupling can vary significantly along the reaction pathway on the spin-adiabatic energy surface. On the other hand, due to the restriction that low-spin and high-spin states share the same set of molecular orbitals, the acquired spin-adiabatic energy surface shows a cusp (i.e. a first-order discontinuity) at the crossing point, which prevents the use of standard geometry optimization algorithms to pinpoint the crossing point. An extension with this restriction removed is being developed to achieve the smoothness of spin-adiabatic surfaces.

scholarly journals Constructing Spin-Adiabatic States for the Modeling of Spin-Crossing Reactions I. A Shared-Orbital Implementation

2019 ◽  
Author(s):  
Yunwen Tao ◽  
Zheng Pei ◽  
Nicole Bellonzi ◽  
Yuezhi Mao ◽  
zhu zou ◽  
...  
Keyword(s):  
Electron Spin ◽  
Energy Surface ◽  
Geometry Optimization ◽  
Molecular Orbitals ◽  
Orbit Coupling ◽  
Spin States ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Crossing Point ◽  
Adiabatic Energy

In the modeling of spin-crossing reactions, it has become popular to directly explore the spin-adiabatic surfaces. Specifically, through constructing spin-adiabatic states from a two-state Hamiltonian (with spin-orbit coupling matrix elements) at each geometry, one can readily employ advanced geometry optimization algorithms to acquire a “transition state" structure, where the spin crossing occurs. In this work, we report the implementation of a fully variational spin-adiabatic approach based on Kohn-Sham density functional theory spin states (sharing the same set of molecular orbitals) and the Breit-Pauli one-electron spin-orbit operator. For three model spin-crossing reactions [predissociation of N2O, singlet-triplet conversion in CH2, and CO association to Fe(CO)4], the spin-crossing points were easily obtained. Our results also indicated the Breit-Pauli one-electron spin-orbit coupling can vary significantly along the reaction pathway on the spin-adiabatic energy surface. On the other hand, due to the restriction that low-spin and high-spin states share the same set of molecular orbitals, the acquired spin-adiabatic energy surface shows a cusp (i.e. a first-order discontinuity) at the crossing point, which prevents the use of standard geometry optimization algorithms to pinpoint the crossing point. An extension with this restriction removed is being developed to achieve the smoothness of spin-adiabatic surfaces.

A Photoelectron Investigation of the Peroxide Bond

1975 ◽  
Vol 53 (22) ◽  
pp. 3439-3447 ◽  
Author(s):  
R. S. Brown
Keyword(s):  
Dihedral Angle ◽  
Ground State ◽  
Vibrational Frequencies ◽  
Molecular Orbitals ◽  
Photoelectron Spectra ◽  
Raman Spectroscopic ◽  
Orbital Interactions ◽  
Highest Occupied Molecular Orbitals ◽  
Peroxide Bond

The photoelectron spectra of several peroxides and their interpretation is presented. The effects of substituents is separated from vicinal orbital interactions using as a guideline the effect of similar substitution on the ether analogues. It is found that by comparison of Raman spectroscopic frequencies of the peroxide ground state, and vibrational frequencies for the ion (via pes), that the HOMO of peroxides is antibonding with respect to the O—O linkage. Additionally, the dependence of the splitting of the two highest occupied molecular orbitals on dihedral angle is verified by the pe spectra of several well-defined cyclic peroxides. Finally, the pe spectrum of tetramethyl-1,2-dioxacyclobutane (tetramethyl dioxetane) is presented indicating that it is not unlike other cyclic peroxides.

scholarly journals A theoretical study of the mechanism of the addition reaction between carbene and azacyclopropane

2010 ◽  
Vol 75 (5) ◽  
pp. 649-657 ◽  
Author(s):  
Xiaojun Tan ◽  
Ping Li ◽  
Weihua Wang ◽  
Gengxiu Zheng ◽  
Qiufen Wang
Keyword(s):  
Potential Barrier ◽  
Energy Surface ◽  
Addition Reaction ◽  
Exothermic Reaction ◽  
Geometry Optimization ◽  
Vibrational Analysis ◽  
Basis Set ◽  
Stationary Points ◽  
Orbital Interactions ◽  
Moller Plesset

The mechanism of the addition reaction between carbene and azacyclopropane was investigated using the second-order Moller-Plesset perturbation theory (MP2). By using the 6-311+G* basis set, geometry optimization, vibrational analysis and the energy properties of the involved stationary points on the potential energy surface were calculated. From the surface energy profile, it can be predicted that there are two reaction mechanisms. The first one (1) is carbene attack at the N atom of azacyclopropane to form an intermediate, 1a (IM1a), which is a barrierfree exothermic reaction. Then, IM1a can isomerize to IM1b via a transition state 1a (TS1a), in which the potential barrier is 30.0 kJ/mol. Subsequently, IM1b isomerizes to a product (Pro1) via TS1b with a potential barrier of 39.3 kJ/mol. The other one (2) is carbene attack at the C atom of azacyclopropane, firstly to form IM2 via TS2a, the potential barrier is 35.4 kJ/mol. Then IM2 isomerizes to a product (Pro2) via TS2b with a potential barrier of 35.1 kJ/mol. Correspondingly, the reaction energy for the reaction (1) and (2) is -478.3 and -509.9 kJ/mol, respectively. Additionally, the orbital interactions are also discussed for the leading intermediate.

scholarly journals Constructing Spin-Adiabatic States for the Modeling of Spin-Crossing Reactions I. A Shared-Orbital Implementation

2019 ◽  
Author(s):  
Yunwen Tao ◽  
Zheng Pei ◽  
Nicole Bellonzi ◽  
Yuezhi Mao ◽  
zhu zou ◽  
...  
Keyword(s):  
Electron Spin ◽  
Energy Surface ◽  
Geometry Optimization ◽  
Molecular Orbitals ◽  
Orbit Coupling ◽  
Spin States ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Crossing Point ◽  
Adiabatic Energy

In the modeling of spin-crossing reactions, it has become popular to directly explore the spin-adiabatic surfaces. Specifically, through constructing spin-adiabatic states from a two-state Hamiltonian (with spin-orbit coupling matrix elements) at each geometry, one can readily employ advanced geometry optimization algorithms to acquire a “transition state" structure, where the spin crossing occurs. In this work, we report the implementation of a fully variational spin-adiabatic approach based on Kohn-Sham density functional theory spin states (sharing the same set of molecular orbitals) and the Breit-Pauli one-electron spin-orbit operator. For three model spin-crossing reactions [predissociation of N2O, singlet-triplet conversion in CH2, and CO association to Fe(CO)4], the spin-crossing points were easily obtained. Our results also indicated the Breit-Pauli one-electron spin-orbit coupling can vary significantly along the reaction pathway on the spin-adiabatic energy surface. On the other hand, due to the restriction that low-spin and high-spin states share the same set of molecular orbitals, the acquired spin-adiabatic energy surface shows a cusp (i.e. a first-order discontinuity) at the crossing point, which prevents the use of standard geometry optimization algorithms to pinpoint the crossing point. An extension with this restriction removed is being developed to achieve the smoothness of spin-adiabatic surfaces.

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