Document Detail


Gas-phase chemistry of ionized and protonated GeF(4) : a joint experimental and theoretical study.
MedLine Citation:
PMID:  21500305     Owner:  NLM     Status:  In-Data-Review    
Abstract/OtherAbstract:
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.
Authors:
Paola Antoniotti; Elena Bottizzo; Lorenza Operti; Roberto Rabezzana; Stefano Borocci; Felice Grandinetti
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of mass spectrometry : JMS     Volume:  46     ISSN:  1096-9888     ISO Abbreviation:  J Mass Spectrom     Publication Date:  2011 May 
Date Detail:
Created Date:  2011-04-18     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9504818     Medline TA:  J Mass Spectrom     Country:  England    
Other Details:
Languages:  eng     Pagination:  465-77     Citation Subset:  IM    
Copyright Information:
Copyright © 2011 John Wiley & Sons, Ltd.
Affiliation:
Dipartimento di Chimica Generale e Chimica Organica, Università degli Studi di Torino, C.so M. d' Azeglio, 48, 10125 Torino, Italy.
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