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Please use this identifier to cite or link to this item: http://apo.ansto.gov.au/dspace/handle/10238/3955

Title: Detailed investigations of phase transitions and magnetic structure in Fe(iii), Mn(ii), Co(ii) and Ni(ii) 3,4,5-trihydroxybenzoate (gallate) dihydrates by neutron and X-ray diffraction
Authors: Saines, PJ
Yeung, HHM
Hester, JR
Lennie, AR
Cheetham, AK
Keywords: X-ray Diffraction
Neutron Diffraction
SPECTROSCOPY
Hybridization
PROTONS
DEUTERATION
Issue Date: 28-Jun-2011
Publisher: Royal Society of Chemistry
Citation: Saines, P.J., Yeung, H.H.M., Hester, J.R., Lennie, A.R., Cheetham, A.K. (2011). Detailed investigations of phase transitions and magnetic structure in Fe(III), Mn(II), Co(II) and Ni(II) 3,4,5-trihydroxybenzoate (gallate) dihydrates by neutron and X-ray diffraction. Dalton Transactions, 40(24), 6401-6410.
Abstract: The effect of cation valency on the complex structures of divalent and trivalent transition metal gallates has been examined using a combination of neutron and synchrotron X-ray powder diffraction, single-crystal X-ray diffraction and XANES spectroscopy. In the divalent frameworks, M(C7H4O5)[middle dot]2H2O (M = Mn, Co and Ni), it was found that charge balance was achieved via the presence of protons on the meta-hydroxyl groups. It was also established that these compounds undergo a discontinuous phase transition at lower temperatures, which is driven by the position of the extra-framework water molecules in these materials. By contrast, in the trivalent Fe gallate, Fe(C7H3O5)[middle dot]2H2O, it was found that the stronger bonding between the meta-hydroxy oxygen and the cations leads to a weakening of the bond between this oxygen and its proton. This is turn is thought to lead to stronger hydrogen bonding with the extra-framework water. The lattice water is disordered in the Fe(iii) case, which prevents the phase transition found in the M(ii) gallates. Refinement against the neutron diffraction patterns also revealed that the relatively mild microwave synthesis of gallate frameworks in D2O led to an extensive deuteration of the ortho-hydrogen sites on the aromatic ring, which may suggest a more versatile method of deuterating aromatic organics. The antiferromagnetic structure of Co gallate has also been determined. © 2011, Royal Society of Chemistry
URI: http://dx.doi.org/10.1039/c0dt01687j
http://apo.ansto.gov.au/dspace/handle/10238/3955
ISSN: 1477-9226
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