caa a22 4500 475762118 CHVBK 20180406123554.0 cr unu---uuuuu 170329e20001101xx s 000 0 eng 10.1007/BF02494917 doi (NATIONALLICENCE)springer-10.1007/BF02494917 Heteroorganic betaines [Elektronische Daten] 5. A DFT study of the structure and reactivity of 6,6-dimethyl-6-silafulvene and silicon-containing organophosphorus betaine−C5H4SiMe2CH2PMe3 + [M. Nechaev, I. Borisova, N. Zemlyanskii, D. Laikov, Yu. Ustynyuk] The structures of 6,6-dimethyl-6-silafulvene C5H4SiMe2 (3), its donor-acceptor complex with ammonia. C5H4SiMe2·NH3, dimethylfulvene, a number of cyclopentadienylides, methylenetrimethylphosphorane (6), and silicon-containing organophosphorus betaine−C5H4SiMe2CH2PMe3 + (13), the product of nucleophilic addition of6 to3, were calculated using the density functional approach. For compound13, the potential energy minimum corresponds to the conformation withgauche-arrangement of the cyclopentadienyl anionie and trimethylphosphonium cationic centers and a C−Si−C−P dihedral angle of 30.5°, which is due to the Coulomb attraction between these centers. According to calculations, betaine13 is rather stable toward decomposition into3 and6 (ΔH o=42 kcal mol−1, ΔG Δ=30 kcal mol−1). The main channel of thermal decomposition of compound13 involves an intramolecular nucleophilic substitution, which proceeds with elimination of trimethylphosphine and results in 1,1-dimethyl-1-silaspiro[2,4]hepta-4,6-diene, which then undergoes a ready and irreversible isomerization into 6,6-dimethyl-6-silabicyclo[3.2.0]hepta-1,3-diene owing to the [1.5]-sigmatropic shift of the C−Si bond. Kluwer Academic/Plenum Publishers, 2000 silaolefins nationallicence silafulvene nationallicence silicon-containing organophosphorus betaines nationallicence nonempirical quantum-chemical calculations nationallicence density functional theory nationallicence Nechaev M. Department of Chemistry, M. V. Lomonosov Moscow State University, Leninskie Gory, 119899, Moscow, Russian Federation aut Borisova I. State Research Center of the Russian Federation "State Research Institute of Chemistry and Technology of Organoelement Compounds”, 38 sh. Entuziastov, 111123, Moscow, Russian Federation aut Zemlyanskii N. State Research Center of the Russian Federation "State Research Institute of Chemistry and Technology of Organoelement Compounds”, 38 sh. Entuziastov, 111123, Moscow, Russian Federation aut Laikov D. Department of Chemistry, M. V. Lomonosov Moscow State University, Leninskie Gory, 119899, Moscow, Russian Federation aut Ustynyuk Yu Department of Chemistry, M. V. Lomonosov Moscow State University, Leninskie Gory, 119899, Moscow, Russian Federation aut Russian Chemical Bulletin Kluwer Academic Publishers-Plenum Publishers 49/11(2000-11-01), 1823-1830 1066-5285 49:11<1823 2000 49 11172 https://doi.org/10.1007/BF02494917 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF02494917 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Nechaev M. Department of Chemistry, M. V. Lomonosov Moscow State University, Leninskie Gory, 119899, Moscow, Russian Federation aut NATIONALLICENCE 700 1- Borisova I. State Research Center of the Russian Federation "State Research Institute of Chemistry and Technology of Organoelement Compounds”, 38 sh. Entuziastov, 111123, Moscow, Russian Federation aut NATIONALLICENCE 700 1- Zemlyanskii N. State Research Center of the Russian Federation "State Research Institute of Chemistry and Technology of Organoelement Compounds”, 38 sh. Entuziastov, 111123, Moscow, Russian Federation aut NATIONALLICENCE 700 1- Laikov D. Department of Chemistry, M. V. Lomonosov Moscow State University, Leninskie Gory, 119899, Moscow, Russian Federation aut NATIONALLICENCE 700 1- Ustynyuk Yu Department of Chemistry, M. V. Lomonosov Moscow State University, Leninskie Gory, 119899, Moscow, Russian Federation aut NATIONALLICENCE 773 0- Russian Chemical Bulletin Kluwer Academic Publishers-Plenum Publishers 49/11(2000-11-01), 1823-1830 1066-5285 49:11<1823 2000 49 11172 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer