0181538 - UFCH-W 20020169 RIV US eng J - Článek v odborném periodiku
Hobza, Pavel
N-H...F Improper Blue-Shifting H-Bond.
International Journal of Quantum Chemistry. Roč. 90, č. 3 (2002), s. 1071-1074. ISSN 0020-7608. E-ISSN 1097-461X
Grant CEP: GA AV ČR IAA4040904
Výzkumný záměr: CEZ:AV0Z4040901
Klíčová slova: H bonds * improper blue-shifting ab initio calculations
Kód oboru RIV: CF - Fyzikální chemie a teoretická chemie
Impakt faktor: 1.514, rok: 2002

The MP2/6-31G** calculations reveal a different pattern of H-bonding in F2NH...Y (Y = FH, OH2, NH2) complexes. Whereas the blue-shifted H-bonding was found for F2NH...FH complex (the first known case of N-H...Y improper blue-shifting H-bonding), standard H-bonding exists for F2NH...OH, and F2NH...NH, complexes. A different character of H-bonding is explained by natural bond orbital analysis showing a systematic increase of electron density in the sigma* antibonding orbital of the N-H bond as well as in the lone-electron pairs of fluorine atoms of proton the acceptor. Whereas the former effect leads to elongation of the N-H bond and a red shift of N-H stretch frequency, the latter effect gives the opposite, that is, contraction of the N-H bond and a blue shift of N-H stretch frequency. Existence of a red- or blue-shifted H-bonding is explained by the dominance of the former or latter effect.
Trvalý link: http://hdl.handle.net/11104/0078093