Publication
Article Metrics
Citations
Online attention
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:
Paul
Saines
(University of Cambridge)
,
Hamish
Yeung
(NIMS)
,
James
Hester
(Bragg Institute)
,
Alistair
Lennie
(Diamond Light Source)
,
Anthony
Cheetham
(The University of Cambridge)
Co-authored by industrial partner:
No
Type:
Journal Paper
Journal:
Dalton Transactions
, VOL 40 (24)
, PAGES 6401-6410
State:
Published (Approved)
Published:
March 2011
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)·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)·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.
Subject Areas:
Chemistry
Instruments:
I11-High Resolution Powder Diffraction
Added On:
04/07/2011 11:42
Discipline Tags:
Technical Tags: