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Oxidation of Dodecanoate Intercalated Iron(II)–Iron(III) Layered Double Hydroxide to Form 2D Iron(III) (Hydr)oxide Layers
Author(s) -
Huang LiZhi,
AyalaLuis Karina B.,
Fang Liping,
Dalby Kim N.,
Kasama Takeshi,
Bender Koch Christian,
Hansen Hans Christian B.
Publication year - 2013
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201300735
Subject(s) - chemistry , hydroxide , deprotonation , inorganic chemistry , quadrupole splitting , oxide , crystallography , mössbauer spectroscopy , ion , organic chemistry
A planar trioctahedral iron(II)–iron(III) hydroxide (green rust, GR) intercalated with dodecanoate (GR C12 ) has been oxidized by dioxygen to produce the corresponding planar iron(III) (hydr)oxide. The formulae of GR C12 and the final iron(III) product (oxGR C12 ) were determined to be Fe II 2.00 Fe III 1.00 (OH) 5.31 (C 12 H 23 O 2 ) 0.66 (SO 4 ) 0.51 and Fe III 3 O 2.18 (OH) 3.13 (C 12 H 23 O 2 ) 0.56 (SO 4 ) 0.47 , respectively. oxGR C12 has the same planar layer structure as GR C12 , as revealed by identical powder X‐ray diffraction patterns. The electrostatic interactions between the interlayer dodecanoate (C12) anions and the iron hydroxide planar layer were preserved during the oxidation, as shown by FTIR spectroscopy. The high positive charge in the hydroxide layer produced by the oxidation of iron(II) to iron(III) is partially compensated by the deprotonation of hydroxy groups, as shown by X‐ray photoelectron spectroscopy. The Mössbauer quadrupole splitting of the iron(III) doublet increased on oxidation of GR C12 , which has been attributed to the distortion of the octahedral sites caused by deprotonation and changes in the coordination site geometry. oxGR C12 is stable in air for more than 2 years. The van der Waals interactions between the alkyl chains of the intercalated dodecanoate anions play a crucial role in stabilizing the structure and hindering the collapse of the iron(II)–iron(III) (hydr)oxide structure during oxidation. This is the first report describing the formation of a stable planar layered octahedral iron(III) (hydr)oxide. oxGR C12 shows promise as a sorbent and host for hydrophobic reagents, and as a possible source of single planar layers of iron(III) (hydr)oxide.