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Gas‐phase chemistry of ionized and protonated GeF 4 : a joint experimental and theoretical study
Author(s) -
Antoniotti Paola,
Bottizzo Elena,
Operti Lorenza,
Rabezzana Roberto,
Borocci Stefano,
Grandinetti Felice
Publication year - 2011
Publication title -
journal of mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 1076-5174
DOI - 10.1002/jms.1913
Subject(s) - chemistry , proton affinity , thermochemistry , protonation , ion , molecule , gas phase , ammonia , ab initio quantum chemistry methods , mass spectrometry , crystallography , analytical chemistry (journal) , organic chemistry , chromatography
The gas‐phase ion chemistry of GeF 4 and of its mixtures with water, ammonia and hydrocarbons was investigated by ion trap mass spectrometry (ITMS) and ab initio calculations. Under ITMS conditions, the only fragment detected from ionized GeF 4 is GeF 3 + . This cation is a strong Lewis acid, able to react with H 2 O, NH 3 and the unsaturated C 2 H 2 , C 2 H 4 and C 6 H 6 by addition‐HF elimination reactions to form F 2 Ge(XH) + , FGe(XH) 2 + , Ge(XH) 3 + (X = OH or NH 2 ), F 2 GeC 2 H + , F 2 GeC 2 H 3 + and F 2 GeC 6 H 5 + . The structure, stability and thermochemistry of these products and the mechanistic aspects of the exemplary reactions of GeF 3 + with H 2 O, NH 3 and C 6 H 6 were investigated by MP2 and coupled cluster calculations. The experimental proton affinity (PA) and gas basicity (GB) of GeF 4 were estimated as 121.5 ± 6.0 and 117.1 ± 6.0 kcal mol −1 , respectively, and GeF 4 H + was theoretically characterized as an ion‐dipole complex between GeF 3 + and HF. Consistently, it reacts with simple inorganic and organic molecules to form GeF 3 + ‐L complexes (L = H 2 O, NH 3 , C 2 H 2 , C 2 H 4 , C 6 H 6 , CO 2 , SO 2 and GeF 4 ). The theoretical investigation of the stability of these ions with respect to GeF 3 + and L disclosed nearly linear correlations between their dissociation enthalpies and free energies and the PA and GB of L. Comparing the behavior of GeF 3 + with the previously investigated CF 3 + and SiF 3 + revealed a periodically reversed order of reactivity CF 3 + < GeF 3 + < SiF 3 + . This parallels the order of the Lewis acidities of the three cations. Copyright © 2011 John Wiley & Sons, Ltd.