Excited‐state reaction pathways for s‐cis buta‐1,3‐diene

The topology and energetics of the potential energy surfaces associated with the 2A1 and 1B2 valence excited states of s‐cis butadiene have been investigated via ab initio quantum chemical computations at a level of theory which includes dynamic correlation effects and extended basis sets. The results support a photochemical ring‐closure mechanism involving 1B2 and 2A1 reaction/relaxation pathways that are disrotatory. The reaction path on the 2A1 surface begins at a 1B2/2A1 conical intersection and the ground state photoproducts are produced via radiationless decay at a second 2A1/1A1 conical intersection which has been documented in a previous publication. A local Cs equilibrium structure on 1B2 potential energy surface has been optimized using the complete active space‐self‐consistent field and configuration interaction singles methods. The 1B2/2A1 conical intersection is located near this Cs equilibrium structure and offers a rationalization of the experimentally observed femtosecond lifetime of this ...

[1]  V. Vaida,et al.  Direct absorption spectroscopy of jet‐cooled polyenes. II. The 1 1B+u←1 1A−g transitions of butadienes and hexatrienes , 1984 .

[2]  W. Lugt,et al.  Symmetry control and photoinduced reactions , 1969 .

[3]  U. Manthe,et al.  Dynamics on potential energy surfaces with a conical intersection: Adiabatic, intermediate, and diabatic behavior , 1990 .

[4]  A. Bell,et al.  Fluorescence excitation spectra of the S1 states of isolated trienes , 1992 .

[5]  M. Desouter-Lecomte,et al.  Nonadiabatic interactions in unimolecular decay. IV. Transition probability as a function of the Massey parameter , 1979 .

[6]  A. Myers,et al.  Solvent effects on excited-state torsional motion and electronic relaxation of cis-1,3,5-hexatriene , 1992 .

[7]  F. Bernardi,et al.  The existence and stability of singlet tetramethylene biradicals: an ab initio MCSCF/MP2 study , 1992 .

[8]  W. Leigh.  1992 Merck-Frosst award lecture orbital symmetry and the photochemistry of cyclobutene , 1993 .

[9]  M. Trulson,et al.  Excited-state structure and dynamics of isoprene from absolute resonance Raman intensities , 1990 .

[10]  E. Grant,et al.  Molecular Dynamics Beyond the Adiabatic Approximation: New Experiments and Theory , 1985 .

[11]  Michael J. Frisch,et al.  Toward a systematic molecular orbital theory for excited states , 1992 .

[12]  G. Segal,et al.  AB INITIO SCF STUDY OF THE PHOTOCHEMICAL DISROTATORY CLOSURE OF BUTADIENE TO CYCLOBUTENE , 1976 .

[13]  R. E. Rosenberg,et al.  Butadiene. 1. A normal coordinate analysis and infrared intensities. Structure of the second rotamer , 1990 .

[14]  Peter R. Taylor,et al.  General contraction of Gaussian basis sets. I. Atomic natural orbitals for first‐ and second‐row atoms , 1987 .

[15]  Klaus Ruedenberg,et al.  Potential energy surfaces near intersections , 1991 .

[16]  K. Morokuma,et al.  The Cope Rearrangement Revisited Again. Results of Ab Initio Calculations beyond the CASSCF Level , 1994 .

[17]  M. Squillacote,et al.  Planar s-cis-1,3-butadiene , 1979 .

[18]  B. Roos,et al.  A theoretical study of the electronic spectrum of naphthalene , 1994 .

[19]  Björn O. Roos,et al.  Second-order perturbation theory with a complete active space self-consistent field reference function , 1992 .

[20]  Josef Michl,et al.  Electronic aspects of organic photochemistry , 1990 .

[21]  F. Zerbetto,et al.  Franck–Condon modeling of the structure of the S0→S2 transition of trans, trans‐, cis, trans‐, and cis, cis‐octatetraene , 1994 .

[22]  T. Semple,et al.  Photochemistry of s-cis acyclic 1,3-dienes , 1990 .

[23]  F. Bernardi,et al.  Substituent Effects in Buta-1,3-diene Photochemistry: A CAS-SCF Study of 2,3-Dimethylbutadiene and 2-Cyanobutadiene Excited-State Reaction Paths , 1994 .

[24]  M. Zgierski,et al.  Resonance Raman scattering of butadiene: Vibronic activity of a bu mode demonstrates the presence of a 1Ag symmetry excited electronic state at low energy , 1991 .

[25]  I. N. Ragazos,et al.  A new mechanistic scenario for the photochemical transformation of ergosterol: an MC-SCF and MM-VB [molecular mechanics-VB] study , 1992 .

[26]  Roland Lindh,et al.  Towards an accurate molecular orbital theory for excited states: Ethene, butadiene, and hexatriene , 1993 .

[27]  B. Roos,et al.  Theoretical study of the electronic spectra ofcis-1,3,5-hexatriene andcis-1,3-butadiene , 1994 .

[28]  F. Zerbetto,et al.  The missing fluorescence of s‐trans butadiene , 1990 .

[29]  H. Schaefer,et al.  Conrotatory and disrotatory stationary points for the electrocyclic isomerization of cyclobutene to cis-butadiene , 1984 .

[30]  O. Kikuchi,et al.  Reduced classical trajectory equations for electronically non-adiabatic transition on photochemical pericyclic reactions , 1985 .

[31]  Young S. Choi,et al.  The 2 1Ag state of trans,trans‐1,3,5,7‐octatetraene in free jet expansions , 1993 .

[32]  W. Buma,et al.  Lowest energy excited singlet state of isolated cis‐hexatriene , 1991 .

[33]  Iwao Ohmine,et al.  Mechanisms of nonadiabatic transitions in photoisomerization processes of conjugated molecules: Role of hydrogen migrations , 1985 .