1,1-dilithioethylene. A ground-state triplet olefin with nearly free rotation about the double bond

Journal Article · Wed Nov 21 00:00:00 EST 1979 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00518a010· OSTI ID:5739681

Laidig, W D; Schaefer, III, H F

Molecular electronic structure theory has been applied to the CLi/sub 2/==CH/sub 2/ molecule 1,1-dilithioethylene. Both planar and triplet structures were considered for each of the lowest singlet and triplet electronic states. Geometry optimizations were carried out at the self-consistent-field (SCF) level of theory using a basis set of better than double zeta quality: C(9s 5p 1d/4s 2p 1d), Li(9s 4p/4s 2p), H(4s/2s). The predicted C==C bond distances are 1.356 (planar singlet), 1.334 (twisted singlet), 1.322 (planar triplet), and 1.323 A (twisted triplet). The analogous Li-C-Li bond angles are 133.6, 104.1, 73.9, and 75.5/sup 0/, while the corresponding C-Li bond distances are 2.000, 1.866, 2.106, and 2.064 A. SCF theory predicts the twisted triplet to be the ground state, followed energetically by the planar triplet (1.2 kcal), twisted singlet (28.4 kcal), and planar singlet (29.3 kcal). The effects of electron correlation were investigated by configuration interaction (CI) including single and double excitations. The ordering of states is unchanged, with the relative energies being 0.0, 1.4, 14.0, and 15.5 kcal. After Davidson's correction for the effects of unlinked clusters, the same relative energies become 0.0, 1.4, 10.5, and 12.5 kcal. Qualitative features of the CLi/sub 2/CH/sub 2/ electronic structures are discussed in terms of orbital energies, Mulliken populations, and predicted dipole moments. 3 figures, 4 tables.

• Research Organization: Univ. of California, Berkeley
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 5739681
• Journal Information: J. Am. Chem. Soc.; (United States), Vol. 101:24
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
LITHIUM COMPOUNDS
ELECTRONIC STRUCTURE
ORGANOMETALLIC COMPOUNDS
ALKENES
BOND ANGLE
DOUBLE BONDS
EXCITATION
GEOMETRY
GROUND STATES
OPTIMIZATION
ALKALI METAL COMPOUNDS
CHEMICAL BONDS
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
HYDROCARBONS
MATHEMATICS
ORGANIC COMPOUNDS
400301* - Organic Chemistry- Chemical & Physicochemical Properties- (-1987)
400201 - Chemical & Physicochemical Properties