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

Journal Article · Wed Nov 21 04:00:00 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), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 101:24; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

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