Matrix Isolation Infrared and ab Initio Study of the 1:1 Complexes of Bromocyclopropane with NH3 and (CH3)3N: Evidence for a Novel C−H···N Hydrogen Bond

Autor:	Cindy Samet, Andrew Maynard, Brooke L. Bedell, Erin R. Mysak, Leah Goldfarb
Rok vydání:	1999
Předmět:	Alkane chemistry.chemical_classification Hydrogen bond Low-barrier hydrogen bond Substituent Matrix isolation Ab initio Photochemistry Cyclopropane chemistry.chemical_compound Crystallography chemistry Ab initio quantum chemistry methods Physical and Theoretical Chemistry
Zdroj:	The Journal of Physical Chemistry A. 103:4572-4579
ISSN:	1520-5215 1089-5639
DOI:	10.1021/jp990493y
Popis:	Hydrogen-bonded complexes of bromocyclopropane with the strong bases ammonia and trimethylamine have been isolated and characterized for the first time in argon matrices at 16 K. Coordination of the proton adjacent to the Br substituent on the cyclopropane ring to the nitrogen of the base was evidenced by distinct blue shifts of the C−H(Br) bending modes in the infrared spectrum. These shifts (∼12 cm-1 for the in-plane bend and ∼6 cm-1 for the out-of-plane bend) are much smaller than those observed for alkenes and alkynes, suggesting a distinct but extremely weak interaction. Ab initio calculations yield an essentially linear BrC−H···NH3 hydrogen bond with a C−H···N distance of 2.301 A and a hydrogen bond energy of 2.35 kcal/mol, thus supporting that this hydrogen bond is one of the weakest observed thus far in a matrix. This study represents the first example of a (substituted) cyclopropane acting as a proton donor and only the second example of an alkane taking part in a C−H···N hydrogen bond.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::6ae66a10ce6fd0df0a1fab2ab27bd264 https://doi.org/10.1021/jp990493y Zobrazit plný text záznamu