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Mass‐Spectrometric Experiments together with Electronic Structure Calculations Support the Existence of the Elusive Ammonia Oxide Molecule and Its Radical Cation
Author(s) -
Brönstrup Mark,
Schröder Detlef,
Kretzschmar Ilona,
Schalley Christoph A.,
Schwarz Helmut
Publication year - 1998
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/(sici)1099-0682(199810)1998:10<1529::aid-ejic1529>3.0.co;2-y
Subject(s) - chemistry , hydroxylamine , cationic polymerization , oxide , molecule , proton affinity , ammonia , ab initio , metastability , inorganic chemistry , crystallography , ion , protonation , organic chemistry
Mass‐spectrometric experiments were combined with ab initio calculations to explore the cationic and neutral [H 3 ,N,O] ☆+/0 potential energy surfaces and relevant anionic species. The calculations predict the existence of three stable cationic and neutral [H 3 ,N,O] ☆+/0 isomers, i.e. ammonia oxide H 3 NO ☆+/0 ( 1 ☆+/0 ), hydroxylamine H 2 NOH ☆+/0 (2 ☆+/0 ) and the imine‐water complex HNOH 2 ☆+/0 ( 3 ☆+/0 ). Hydroxylamine 2 represents the most stable isomer on the neutral surface ( E rel = 0), and the metastable isomers 1 ( E rel = 24.8 kcal mol –1 ) and 3 ( E rel = 61.4 kcal mol –1 ) are separated by barriers of 49.5 kcal mol –1 and 64.2 kcal mol –1 , respectively. Adiabatic ionization of 2 ( IE a = 9.15 eV) yields 2 ☆+ , which is 21.4 kcal mol –1 more stable than 1 ☆+ and 36.4 kcal mol –1 more stable than 3 ☆+ . The barriers associated with the isomerizations of the cations are 58.6 kcal mol –1 for 2 ☆+ → 1 ☆+ and 71.4 kcal mol –1 for 2 ☆+ → 3 ☆+ . Collisional activation (CA) and unimolecular decomposition (MI) experiments allow for a clear distinction of 1 ☆+ from 2 ☆+ . Besides, neutralization/reionization (NR) experiments strongly support the gas‐phase existence of the long‐sought neutral ammonia oxide.