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Combined Experimental and Theoretical Study on the Formation of the Elusive 2-Methyl-1-silacycloprop-2-enylidene Molecule under Single Collision Conditions via Reactions of the Silylidyne Radical (SiH; X(2)Π) with Allene (H2CCCH2; X(1)A1) and D4-Allene (D2CCCD2; X(1)A1).
J Phys Chem A. 2015 Dec 17; 119(50):12562-78.JP

Abstract

The crossed molecular beam reactions of the ground-state silylidyne radical (SiH; X(2)Π) with allene (H2CCCH2; X(1)A1) and D4-allene (D2CCCD2; X(1)A1) were carried out at collision energies of 30 kJ mol(-1). Electronic structure calculations propose that the reaction of silylidyne with allene has no entrance barrier and is initiated by silylidyne addition to the π electron density of allene either to one carbon atom (C1/C2) or to both carbon atoms simultaneously via indirect (complex forming) reaction dynamics. The initially formed addition complexes isomerize via two distinct reaction pathways, both leading eventually to a cyclic SiC3H5 intermediate. The latter decomposes through a loose exit transition state via an atomic hydrogen loss perpendicularly to the plane of the decomposing complex (sideways scattering) in an overall exoergic reaction (experimentally: -19 ± 13 kJ mol(-1); computationally: -5 ± 3 kJ mol(-1)). This hydrogen loss yields the hitherto elusive 2-methyl-1-silacycloprop-2-enylidene molecule (c-SiC3H4), which can be derived from the closed-shell cyclopropenylidene molecule (c-C3H2) by replacing a hydrogen atom with a methyl group and the carbene carbon atom by the isovalent silicon atom. The synthesis of the 2-methyl-1-silacycloprop-2-enylidene molecule in the bimolecular gas-phase reaction of silylidyne with allene enriches our understanding toward the formation of organosilicon species in the gas phase of the interstellar medium in particular via exoergic reactions of no entrance barrier. This facile route to 2-methyl-1-silacycloprop-2-enylidene via a silylidyne radical reaction with allene opens up a versatile approach to form hitherto poorly characterized silicon-bearing species in extraterrestrial environments; this reaction class might represent the missing link, leading from silicon-bearing radicals via organosilicon chemistry eventually to silicon-carbon-rich interstellar grains even in cold molecular clouds where temperatures are as low as 10 K.

Authors+Show Affiliations

Department of Chemistry, University of Hawai'i at Manoa , Honolulu, Hawaii 96822, United States. Department of Chemistry, University of California, Berkeley , Berkeley, California 94720, United States.Department of Chemistry, University of Hawai'i at Manoa , Honolulu, Hawaii 96822, United States. Department of Chemistry, University of California, Berkeley , Berkeley, California 94720, United States.Department of Chemistry, University of Hawai'i at Manoa , Honolulu, Hawaii 96822, United States. Department of Chemistry, University of California, Berkeley , Berkeley, California 94720, United States.Department of Chemistry, University of Hawai'i at Manoa , Honolulu, Hawaii 96822, United States. Department of Chemistry, University of California, Berkeley , Berkeley, California 94720, United States.Department of Chemistry, University of Hawai'i at Manoa , Honolulu, Hawaii 96822, United States. Department of Chemistry, University of California, Berkeley , Berkeley, California 94720, United States.Department of Chemistry, University of Hawai'i at Manoa , Honolulu, Hawaii 96822, United States. Department of Chemistry, University of California, Berkeley , Berkeley, California 94720, United States.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

26535955

Citation

Yang, Tao, et al. "Combined Experimental and Theoretical Study On the Formation of the Elusive 2-Methyl-1-silacycloprop-2-enylidene Molecule Under Single Collision Conditions Via Reactions of the Silylidyne Radical (SiH; X(2)Π) With Allene (H2CCCH2; X(1)A1) and D4-Allene (D2CCCD2; X(1)A1)." The Journal of Physical Chemistry. A, vol. 119, no. 50, 2015, pp. 12562-78.
Yang T, Dangi BB, Maksyutenko P, et al. Combined Experimental and Theoretical Study on the Formation of the Elusive 2-Methyl-1-silacycloprop-2-enylidene Molecule under Single Collision Conditions via Reactions of the Silylidyne Radical (SiH; X(2)Π) with Allene (H2CCCH2; X(1)A1) and D4-Allene (D2CCCD2; X(1)A1). J Phys Chem A. 2015;119(50):12562-78.
Yang, T., Dangi, B. B., Maksyutenko, P., Kaiser, R. I., Bertels, L. W., & Head-Gordon, M. (2015). Combined Experimental and Theoretical Study on the Formation of the Elusive 2-Methyl-1-silacycloprop-2-enylidene Molecule under Single Collision Conditions via Reactions of the Silylidyne Radical (SiH; X(2)Π) with Allene (H2CCCH2; X(1)A1) and D4-Allene (D2CCCD2; X(1)A1). The Journal of Physical Chemistry. A, 119(50), 12562-78. https://doi.org/10.1021/acs.jpca.5b09773
Yang T, et al. Combined Experimental and Theoretical Study On the Formation of the Elusive 2-Methyl-1-silacycloprop-2-enylidene Molecule Under Single Collision Conditions Via Reactions of the Silylidyne Radical (SiH; X(2)Π) With Allene (H2CCCH2; X(1)A1) and D4-Allene (D2CCCD2; X(1)A1). J Phys Chem A. 2015 Dec 17;119(50):12562-78. PubMed PMID: 26535955.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Combined Experimental and Theoretical Study on the Formation of the Elusive 2-Methyl-1-silacycloprop-2-enylidene Molecule under Single Collision Conditions via Reactions of the Silylidyne Radical (SiH; X(2)Π) with Allene (H2CCCH2; X(1)A1) and D4-Allene (D2CCCD2; X(1)A1). AU - Yang,Tao, AU - Dangi,Beni B, AU - Maksyutenko,Pavlo, AU - Kaiser,Ralf I, AU - Bertels,Luke W, AU - Head-Gordon,Martin, Y1 - 2015/11/12/ PY - 2015/11/5/entrez PY - 2015/11/5/pubmed PY - 2015/11/5/medline SP - 12562 EP - 78 JF - The journal of physical chemistry. A JO - J Phys Chem A VL - 119 IS - 50 N2 - The crossed molecular beam reactions of the ground-state silylidyne radical (SiH; X(2)Π) with allene (H2CCCH2; X(1)A1) and D4-allene (D2CCCD2; X(1)A1) were carried out at collision energies of 30 kJ mol(-1). Electronic structure calculations propose that the reaction of silylidyne with allene has no entrance barrier and is initiated by silylidyne addition to the π electron density of allene either to one carbon atom (C1/C2) or to both carbon atoms simultaneously via indirect (complex forming) reaction dynamics. The initially formed addition complexes isomerize via two distinct reaction pathways, both leading eventually to a cyclic SiC3H5 intermediate. The latter decomposes through a loose exit transition state via an atomic hydrogen loss perpendicularly to the plane of the decomposing complex (sideways scattering) in an overall exoergic reaction (experimentally: -19 ± 13 kJ mol(-1); computationally: -5 ± 3 kJ mol(-1)). This hydrogen loss yields the hitherto elusive 2-methyl-1-silacycloprop-2-enylidene molecule (c-SiC3H4), which can be derived from the closed-shell cyclopropenylidene molecule (c-C3H2) by replacing a hydrogen atom with a methyl group and the carbene carbon atom by the isovalent silicon atom. The synthesis of the 2-methyl-1-silacycloprop-2-enylidene molecule in the bimolecular gas-phase reaction of silylidyne with allene enriches our understanding toward the formation of organosilicon species in the gas phase of the interstellar medium in particular via exoergic reactions of no entrance barrier. This facile route to 2-methyl-1-silacycloprop-2-enylidene via a silylidyne radical reaction with allene opens up a versatile approach to form hitherto poorly characterized silicon-bearing species in extraterrestrial environments; this reaction class might represent the missing link, leading from silicon-bearing radicals via organosilicon chemistry eventually to silicon-carbon-rich interstellar grains even in cold molecular clouds where temperatures are as low as 10 K. SN - 1520-5215 UR - https://www.unboundmedicine.com/medline/citation/26535955/Combined_Experimental_and_Theoretical_Study_on_the_Formation_of_the_Elusive_2_Methyl_1_silacycloprop_2_enylidene_Molecule_under_Single_Collision_Conditions_via_Reactions_of_the_Silylidyne_Radical__SiH L2 - https://dx.doi.org/10.1021/acs.jpca.5b09773 DB - PRIME DP - Unbound Medicine ER -
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