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Dynamic Motion in [HFe(CO) 4 ] − Ions as Observed by Mössbauer Spectroscopy—Evidence for Hydride “Tunneling”
Author(s) -
Long Gary J.,
Grandjean Fernande,
Whitmire Kenton H.
Publication year - 1992
Publication title -
angewandte chemie international edition in english
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 0570-0833
DOI - 10.1002/anie.199208841
Subject(s) - mössbauer spectroscopy , ion , chemistry , atom (system on chip) , quantum tunnelling , spectroscopy , salt (chemistry) , crystallography , displacement (psychology) , inorganic chemistry , physics , condensed matter physics , psychology , organic chemistry , quantum mechanics , computer science , psychotherapist , embedded system
The iron atom is moved by up to 0.34 Å from its original position in the anion [HFe(CO 4 ) − ] when the temperature is increased. This is suggested by the results of Mössbauer spectroscopy at temperatures from 78 to 280 K on a series of ammonium salts with this anion. The displacement is induced by a movement of the ligands and is in accord with a rapid change of position (“tunneling”) of the hydrido ligands, which makes the four carbonyl ligands equivalent. The Gibbs free energy of activation for the tunneling, determined from the temperature dependence of the displacement of the iron atom, is 29.2 kJ mol −1 for the Et 4 N + salt and only 9.7 kJ mol −1 for the Me 4 N + salt.