Anatoli A. Korkin, Jerzy Leszczynski, Rodney J. Bartlett
{"title":"Theoretical ab Initio Study of CN2O2 Structures: Prediction of Nitryl Cyanide as a High-Energy Molecule","authors":"Anatoli A. Korkin, Jerzy Leszczynski, Rodney J. Bartlett","doi":"10.1021/jp961902i","DOIUrl":null,"url":null,"abstract":"<p >Structures, energies, and harmonic vibrational frequencies of CN<sub>2</sub>O<sub>2</sub> isomers have been investigated theoretically at the <i>ab initio</i> CCSD(T)/TZ2P//MBPT(2)/6-31G* level in search of new high-energy molecules and in a study of the mechanism of the reaction between NCO and NO radicals. Nitrosoisocyanate, ONNCO (<b>1</b>), earlier studied as a collision complex in the reaction of NCO and NO (Lin, M. C.; Melius, C. F. <i>J. Phys. Chem. </i><b>1993</b><i>, 97,</i> 9124) is the most energetically favorable CN<sub>2</sub>O<sub>2</sub> isomer, but its 18 kcal/mol unimolecular dissociation barrier is very low. Thus <b>1</b> can only be observed as a short-lived intermediate. However, nitrosofulminate, ONCNO (<b>8</b>), and nitryl cyanide, NCNO<sub>2</sub> (<b>12</b>), higher energy isomers (69 and 38 kcal/mol above <i>trans-</i><b>1a</b>, respectively), are more stable than <b>1</b> toward decomposition. This offers species <b>8 </b>and <b>12 </b>as interesting molecules for experimental study. Moreover, <b>12</b> can be a reasonably stable molecule as its C?N bond dissociation energy (59 kcal/mol) and the barrier to decomposition into N<sub>2</sub> and CO<sub>2</sub> (54 kcal/mol) are rather high, being comparable to those of nitromethane. The estimated large values of the heat of formation (Δ<i>H</i><sub>f</sub>°<sub>300</sub> = 60 kcal/mol) and of the decomposition energy of <b>12</b> (<b>12 </b>→ N<sub>2</sub> + CO<sub>2</sub>; ΔE = 150 kcal/mol) make this species potentially interesting as a high-energy molecule. Our study also includes four- (<b>2</b>) and three-membered (<b>17</b>) cyclic and bicyclic (<b>3</b>) isomers. The <i>C</i><i><sub>s</sub></i> cyclic isomers, <b>2</b> and <b>17</b>, are extremely unstable, but the bicyclic <i>C</i><sub>2</sub><i><sub>v</sub></i> form (<b>3</b>) has a 29 kcal/mol dissociation barrier and should be observable. </p>","PeriodicalId":58,"journal":{"name":"The Journal of Physical Chemistry ","volume":null,"pages":null},"PeriodicalIF":2.7810,"publicationDate":"1996-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1021/jp961902i","citationCount":"16","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"The Journal of Physical Chemistry ","FirstCategoryId":"1","ListUrlMain":"https://pubs.acs.org/doi/10.1021/jp961902i","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 16
Abstract
Structures, energies, and harmonic vibrational frequencies of CN2O2 isomers have been investigated theoretically at the ab initio CCSD(T)/TZ2P//MBPT(2)/6-31G* level in search of new high-energy molecules and in a study of the mechanism of the reaction between NCO and NO radicals. Nitrosoisocyanate, ONNCO (1), earlier studied as a collision complex in the reaction of NCO and NO (Lin, M. C.; Melius, C. F. J. Phys. Chem. 1993, 97, 9124) is the most energetically favorable CN2O2 isomer, but its 18 kcal/mol unimolecular dissociation barrier is very low. Thus 1 can only be observed as a short-lived intermediate. However, nitrosofulminate, ONCNO (8), and nitryl cyanide, NCNO2 (12), higher energy isomers (69 and 38 kcal/mol above trans-1a, respectively), are more stable than 1 toward decomposition. This offers species 8 and 12 as interesting molecules for experimental study. Moreover, 12 can be a reasonably stable molecule as its C?N bond dissociation energy (59 kcal/mol) and the barrier to decomposition into N2 and CO2 (54 kcal/mol) are rather high, being comparable to those of nitromethane. The estimated large values of the heat of formation (ΔHf°300 = 60 kcal/mol) and of the decomposition energy of 12 (12 → N2 + CO2; ΔE = 150 kcal/mol) make this species potentially interesting as a high-energy molecule. Our study also includes four- (2) and three-membered (17) cyclic and bicyclic (3) isomers. The Cs cyclic isomers, 2 and 17, are extremely unstable, but the bicyclic C2v form (3) has a 29 kcal/mol dissociation barrier and should be observable.