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Ionization and protonation of MgC 3 : A theoretical study
Author(s) -
Barrientos Carmen,
Redondo Pilar,
Largo Antonio
Publication year - 2001
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.1612
Subject(s) - protonation , chemistry , ionization , proton affinity , affinities , ionization energy , excitation , proton , coupled cluster , ring (chemistry) , cluster (spacecraft) , computational chemistry , atomic physics , stereochemistry , molecule , physics , ion , organic chemistry , quantum mechanics , computer science , programming language
A theoretical study of the MgC 3 + and MgC 3 H + species has been carried out. Predictions for their geometries and vibrational frequencies have been made at both second‐order Møller–Plesset (MP2) and B3LYP levels, whereas electronic energies have been computed at G2 and coupled cluster single and double excitation model augmented with a noniterative triple excitation conection (CCSD(T)) levels. The predicted global minimum for MgC 3 + is a rhombic structure ( 2 A 1 electronic state), whereas a T‐shaped structure and an open‐chain isomer lie about 10 and 12 kcal/mol, respectively, higher in energy. In the case of MgC 3 H + the predicted global minimum is also a four‐membered ring obtained upon protonation of the most stable neutral isomer. Low ionization potentials and high proton affinities are generally obtained, especially for the most stable MgC 3 + isomer. The estimated values at the CCSD(T) level for the predicted global minimum are 7.20 eV [ionization potential (IP)] and 256.5 kcal/mol [proton affinities (PA)]. Therefore, if present in the interstellar medium, MgC 3 should be easily ionized and would react quite easily to give the protonated species. © 2002 John Wiley & Sons, Inc. Int J Quantum Chem, 2001