Investigation of the structure and stability of. cap alpha. -substituted cyclopropyl carbanions by semiempirical quantum-chemical methods

Journal Article · Sat Mar 01 04:00:00 EST 1986 · Theor. Exp. Chem. (Engl. Transl.); (United States)

OSTI ID:6057253

Tupitsyn, I F; Shibaev, A Yu

The cyclopropyl carbanions C/sub 3/H/sub 4/X/sup -/ (X = H (I), F (II), Cl (III), CF/sub 3/ (IV), COCH/sub 3/ (V), CN (VI), NO/sub 2/ (VII), which are formed by the removal of a proton at the ..cap alpha.. position, were calculated by the semiempirical MINDO/3 and MNDO methods with full optimization of the geometry. The MINDO/3 method, in agreement with the results from nonempirical methods and experimental data, leads to a non-planar configuration at the anionic center; the angle between the CX bond and the CCC plane was 58-62/sup 0/. In all probability conclusion about a planar structure for all the investigated carbanions except (II), which emerges from the MNDO calculations, is unreliable. By calculation of the change of energies in the isodesmic reactions C/sub 3/H/sub 5//sup -/ + C/sub 3/H/sub 5/X ..-->.. C/sub 3/H/sub 4/X/sup -/ + C/sub 3/H/sub 6/ it was found that substitution of hydrogen by the polar substituent X stabilizes the carbanion. On the basis of an analysis of the changes in the length of the cyclic and extracyclic bonds in the transition from the neutral molecule to the carbanion it was established that the introduction of substituents NO/sub 2/, COCH/sub 3/, and CN into the carbanion gives rise to predominant donation of electron density along the sigma system through the ring to the substituent while the introduction of a halogen leads to transfer of electron density from the substituent to the anionic center.

• Research Organization: State Institute of Applied Chemistry, Leningrad, USSR
• OSTI ID: 6057253
• Journal Information: Theor. Exp. Chem. (Engl. Transl.); (United States), Journal Name: Theor. Exp. Chem. (Engl. Transl.); (United States) Vol. 21:5; ISSN TEXCA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201 -- Chemical & Physicochemical Properties
640302* -- Atomic
Molecular & Chemical Physics-- Atomic & Molecular Properties & Theory
74 ATOMIC AND MOLECULAR PHYSICS
ACTIVATION ENERGY
ALKANES
ANIONS
ATOMIC MODELS
CARBANIONS
CHARGED PARTICLES
CHEMICAL REACTIONS
CHLORINATED ALIPHATIC HYDROCARBONS
CHLORINATION
COMPUTER CODES
COMPUTERIZED SIMULATION
CYCLOALKANES
DEUTERATION
DEUTERIUM COMPOUNDS
ELECTRON DENSITY
ELECTRONIC STRUCTURE
ENERGY
FLUORINATED ALIPHATIC HYDROCARBONS
FLUORINATION
HALOGENATED ALIPHATIC HYDROCARBONS
HALOGENATION
HYDROCARBONS
HYDROGEN COMPOUNDS
HYDROGEN TRANSFER
IONS
ISOTOPE EFFECTS
ISOTOPIC EXCHANGE
M CODES
MATHEMATICAL MODELS
MECHANICS
MOLECULAR MODELS
MOLECULAR STRUCTURE
ORGANIC CHLORINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC FLUORINE COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
QUANTUM MECHANICS
SIMULATION