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Transition Metal Hydrazide‐Based Hydrogen‐Storage Materials: the First Atoms‐In‐Molecules Analysis of the Kubas Interaction
Author(s) -
Skipper Claire V. J.,
Hoang Tuan K. A.,
Antonelli David M.,
Kaltsoyannis Nikolas
Publication year - 2012
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201102715
Subject(s) - vanadium , molecule , hydrogen storage , ligand (biochemistry) , chemistry , density functional theory , hydrogen bond , hydride , atoms in molecules , metal , coordination sphere , crystallography , binding energy , acceptor , interaction energy , enthalpy , transition metal , computational chemistry , inorganic chemistry , hydrogen , thermodynamics , atomic physics , organic chemistry , physics , condensed matter physics , biochemistry , receptor , catalysis
Molecular models of the MH 2 binding sites of experimentally characterised amorphous vanadium hydrazide gels are studied computationally using gradient corrected density functional theory, to probe the coordination number of the vanadium in the material and the nature of the interaction between the metal and the H 2 molecules. The H 2 is found to bind to the vanadium through the Kubas interaction, and the first quantum theory of atoms‐in‐molecules analysis of this type of interaction is reported. Strong correlation is observed between the electron density at the HH bond critical point and the MH 2 interaction energy. Four coordinate models give the best reproduction of the experimental data, suggesting that the experimental sites are four coordinate. The VH 2 interaction is shown to be greater when the non‐hydrazine based ligand, THF, of the experimental system is altered to a poorer π‐acceptor ligand. Upon altering the metal to Ti or Cr the MH 2 interaction energy changes little but the number of H 2 which may be bound decreases from four (Ti) to two (Cr). It is proposed that changing the metal from V to Ti may increase the hydrogen storage capacity of the experimental system. A 9.9 wt % maximum storage capacity at the ideal binding enthalpy for room temperature performance is predicted when the Ti metal is combined with a coordination sphere containing 2 hydride ligands.