Syntheses, crystal structures and optical spectroscopy of Ln2(SO4)3·8H2O (Ln=Ho, Tm) and Pr2(SO4)3·4H2O

The lanthanide sulphate octahydrates Ln₂(SO₄)₃·8H₂O (Ln=Ho, Tm) and the respective tetrahydrate Pr₂(SO₄)₃·4H₂O were obtained by evaporation of aqueous reaction mixtures of trivalent rare earth oxides and sulphuric acid at 300 K. Ln₂(SO₄)₃·8H₂O (Ln=Ho, Tm) crystallise in space group C2/c (Z=4, a_Ho=13.4421(4) Å, b_Ho=6.6745(2) Å, c_Ho=18.1642(5) Å, β_Ho=102.006(1) Å³ and a_Tm=13.4118(14) Å, b_Tm=6.6402(6) Å, c_Tm=18.1040(16) Å, β_Tm=101.980(8) Å³), Pr₂(SO₄)₃·4H₂O adopts space group P2₁/n (a=13.051(3) Å, b=7.2047(14) Å, c=13.316(3) Å, β=92.55(3) Å³). The vibrational and optical spectra of Ho₂(SO₄)₃·8H₂O and Pr₂(SO₄)₃·4H₂O are also reported.     

Infrared spectra of (CH3)2O and (CH3)2O + H2O at low temperature

Fourier transform infrared reflection spectroscopy (incidence angle of 5°) was used to characterize thin films of dimethyl ether (DME) and of mixtures containing water and DME between 10 and 160 K under a pressure of 10⁻⁷ mbar. Solid DME has two solid phases: an amorphous phase which is obtained below 65 K and a crystalline phase >65 K. From 90 K, DME begins to sublimate with surface binding energy of 20±2 kJ mol⁻¹. Vibrational spectrum of DME trapped in water ice remains nearly unchanged from 30 to 120 K. Between 120 and 130 K, a large part of DME is released and strong changes in the frequencies and the profile of the absorptions of DME are observed. This behavior suggests the formation of clathrate hydrate. Below 120 K, the trapped DME is hydrogen-bonded to water molecules.     

Hydrothermal synthesis and structure of one-dimensional Co(dien)2(VO3)3·(H2O) (dien=diethylenetriamine)

One-dimensional Co(dien)₂(VO₃)₃·(H₂O) was prepared from the hydrothermal reaction of NH₄VO₃, Co₂O₃, diethylenetriamine (dien) and H₂O at 130 °C. The compound crystallizes in the monoclinic system, space group P2₁/c with a=16.1581(6) Å, b=8.7006(3) Å, c=13.9893(4) Å, β=103.1483(11)°, V=1915.13(11) Å³, Z=4, and R₁=0.0268 for 3060 observed reflections. Single crystal X-ray diffraction revealed that the structure is composed of infinite one-dimensional chains formed by corner-sharing VO₄ tetrahedra with Co(dien)³⁺ complex cations and crystallization water molecules occupying the interchain positions, which are held together to a three-dimensional network via extensive hydrogen-bonding interactions. The compound, with a new zig-zag conformation of metavanadate chains, is the first example of vanadium oxides incorporating trivalent transition metal coordination groups. Other characterizations by elemental analysis, IR and thermal analysis are also described.     

Electronic absorption spectrum of Ba(MnO4)2·3H2O/Ba(ClO4)2·3H2O

Polarized absorption spectra of Ba(MnO₄)₂·3H₂O/Ba(ClO₄)₂·3H₂O mixed single crystals are reported at 4.2°K. Previous ¹T₂ → ¹A₁ assignments for the 5200 Å and 3000 Å absorption bands of MnO₄⁻ are substantiated; further support is provided for the ¹T₁ → ¹A₁ assignment of the 3600 Å absorption band of MnO₄⁻. The site-splitting of the 5200 Å ¹T₂ state is E(¹E)−E(¹A) ≈ −150 cm⁻¹; that of the 3000 Å ¹T₂ state is E(¹E)−E(¹A) ≈ 300 cm⁻¹. A significant e vibronic intensity component is observed in the 5200 Å ¹T₂ state.     

A novel three-dimensional malonate-bridged complex {[Cu4(4,4′- bpy)8(mal)2(H2O)4](ClO4)2(H2O)4(CH3OH)2}n

A novel malonate-bridged copper (II) compound of formula {[Cu₄(4,4′-bpy)₈(mal)₂(H₂O)₄](ClO₄)₂(H₂O)₄(CH₃OH)₂}_n (4,4′-bpy = 4,4′-bipyridine; mal = malonate dianion) has been prepared and structurally characterized by X-ray crystallography. This compound exhibits a novel three-dimensional network being composed of Cu-4,4′-bipyridine layers which are pillared by malonate bridge ligands. The copper(II) ions has two different coordination environment.     

Synthesis and structure of a novel complex [LCo(OH)2(HCO3)CoL]2[(NC)5Cr(CN)Cr(CN)2].4H2O

A novel complex containing a (μ-bicarbonato)-bis(μ-hydroxo)dicobalt(II) cation and a (μ-cyano)dichromium(III) anion has been obtained and characterized by single crystal X-ray diffraction. The cations have a confacial bioctahedral structure and the anion contains an octahedral Cr(CN)₆³⁻ unit bridging to the second Cr which has trigomal planar geometry.     

Infrared study of νOD modes in isotopically dilute (HDO) isostructural compounds M(HCOO)2·2H2O (M=Mn,Fe,Co,Ni,Cu,Zn) with matrix-isolated guest ions (Cu in M(HCOO)2·2H2O and M in Cu(HCOO)2·2H2O)

The infrared spectra of isotopically dilute (matrix-isolated HDO molecules) isostructural compounds M(HCOO)₂·2H₂O (M=Mn,Fe,Co,Ni,Zn,Cu) are presented and discussed in the region of the OD stretching modes. According to the structural data the compounds under study are divided into two groups: in M(HCOO)₂·2H₂O (M=Mn,Ni,Zn) the H₂O(1) molecules form stronger hydrogen bonds as compared to H₂O(2); in M(HCOO)₂·2H₂O (M=Fe,Co,Cu) the H₂O(2) molecules form stronger hydrogen bonds as compared to the H₂O(1) molecules. The influence of the metal–water interactions (synergetic effect) and the unit-cell volumes (repulsion potential of the lattice) on the hydrogen bond strength within the isostructural series is discussed. The wavenumbers of the uncoupled OD stretching modes of the HDO molecules influenced by guest ions (Cu²⁺ ions matrix-isolated in M(HCOO)₂·2H₂O and M²⁺ ions matrix-isolated in Cu(HCOO)₂·2H₂O) are presented and commented. For example, the analysis of the spectra reveals that when Cu²⁺ ions are included in the structure of M(HCOO)₂·2H₂O the hydrogen bonds of the type M–OH₂OCHO–Cu are considerably weaker as compared to those of the same type formed when M²⁺ ions are included in the structure of Cu(HCOO)₂·2H₂O if the cations remain unchanged.     

One-dimensional chains in uranyl tungstates: Syntheses and structures of A8[(UO2)4(WO4)4(WO5)2] (A=Rb, Cs) and Rb6[(UO2)2O(WO4)4]

Three new uranyl tungstates, A₈[(UO₂)₄(WO₄)₄(WO₅)₂] (A=Rb (1), Cs (2)), and Rb₆[(UO₂)₂O(WO₄)₄] (3), were prepared by high-temperature solid-state reactions and their structures were solved by direct methods on twinned crystals, refined to R₁=0.050, 0.042, and 0.052 for 1, 2, and 3, respectively. Compounds 1 and 2 are isostructural, monoclinic P2₁/n, (1): a=11.100(7), b=13.161(9), , β=90.033(13)°, , Z=8 and (2): , , , β=89.988(2)°, , Z=8. There are four symmetrically independent U⁶⁺ sites that form linear uranyl [O=U=O]²⁺ cations with rather distorted coordination in their equatorial planes. There are six W positions: W(1) and W(2) have square-pyramidal coordination (WO₅), whereas W(3), W(4), W(5), and W(6) are tetrahedrally coordinated. The structures are based upon a novel type of one-dimensional (1D) [(UO₂)₄(WO₄)₄(WO₅)₂]⁴⁻ chains, consisting of WU₄O₂₅ pentamers linked by WO₄ tetrahedra and WO₅ square pyramids. The chains run parallel to the a-axis and are arranged in modulated pseudo-2D-layers parallel to (0 1 0). The A⁺ cations are in the interlayer space between adjacent pseudo-layers and provide a 3D integrity of the structures. Compounds 1 and 2 are the first uranyl tungstates with 2/3 of W atoms in tetrahedral coordination. Such a high concentration of low-coordinated W⁶⁺ cations is probably responsible for the 1D character of the uranyl tungstate units. The compound 3 is triclinic, P1¯ a=10.188(2), b=13.110(2), , α=97.853(3), β=96.573(3), γ=103.894(3)°, , Z=4. There are four U positions in the structure with a typical coordination of a pentagonal bipyramid that contain uranyl ions, UO₂²⁺, as apical axes. Among eight W sites, the W(1), W(2), W(3), W(4), W(5), and W(6) atoms are tetrahedrally coordinated, whereas the W(7) and W(8) cations have distorted fivefold coordination. The structure contains chains of composition [(UO₂)₂O(WO₄)₄]⁶⁻ composed of UO₇ pentagonal bipyramids and W polyhedra. The chains involve dimers of UO₇ pentagonal bipyramids that share common O atoms. The dimers are linked into chains by sharing corners with WO₄ tetrahedra. The chains are parallel to [−101] and are arranged in layers that are parallel to (1 1 1). The Rb⁺ cations provide linkage of the chains into a 3D structure. The compound 1 has many structural and chemical similarities to its molybdate analog, Rb₆[(UO₂)₂O(MoO₄)₄]. However, the compounds are not isostructural. Due to the tendency of the W⁶⁺ cations to have higher-than-fourfold coordination, part of the W sites adopt distorted fivefold coordination, whereas all Mo atoms in the Mo compound are tetrahedrally coordinated. Distribution of the WO₅ configurations along the chain extension does not conform to its ‘typical’ periodicity. As a result, both the chain identity period and the unit-cell volume are doubled in comparison to the Mo analog, which leads to a new structure type.     

Synthesis, structural determination and magnetic properties of layered hybrid organic-inorganic, iron (II) propylphosphonate, Fe[(CH3(CH2)2PO3)(H2O)], and iron (II) octadecylphosphonate, Fe[(CH3(CH2)17PO3)(H2O)]

Fe[(CH₃(CH₂)₂PO₃)(H₂O)] (1) and Fe[(CH₃(CH₂)₁₇PO₃)(H₂O)] (2) were synthesized by reaction of FeCl₂·6H₂O and the relevant phosphonic acid in water in presence of urea and under inert atmosphere. The compounds were characterized by elemental and thermogravimetric analyses, UV-visible and IR spectroscopy. The crystal structure of (1) was determined from X-ray single crystal diffraction studies at room temperature: monoclinic symmetry, space group P2₁, , , , and β=98.62(3)°. The compound is lamellar and the structure is hybrid, made of alternating inorganic and organic layers along the c direction. The inorganic layers consist of Fe(II) ions octahedrally coordinated by five phosphonate oxygen atoms and one from the water molecule, separated by bi-layers of propyl groups. A preliminary structure characterization of compound (2) suggests a similar layered structure, but with an interlayer spacing of 40.3 Å. The magnetic properties of the compounds were both studied by a dc and ac SQUID magnetometer. Fe[(CH₃(CH₂)₂PO₃)(H₂O)] (1) obeys the Curie-Weiss law at temperatures above 50 K (, ), indicating a Fe +II oxidation state, a high-spin d⁶ (S=2) electronic configuration and an antiferromagnetic exchange couplings between the near-neighbouring Fe(II) ions. Below , Fe[(CH₃(CH₂)₂PO₃)(H₂O)] exhibits a weak ferromagnetism. The critical temperature of has been determined by ac magnetic susceptibility measurements. Compound (2) shows the same paramagnetic behaviour of the iron (II) propyl derivative. The values of C and θ were found to be and −44 K, respectively, thus suggesting the presence of Fe +II ion in the S=2 spin state and antiferromagnetic interactions between Fe(II) ions at low temperatures. Zero-field and field cooled magnetic susceptibility vs. T plots do not overlap below , suggesting the presence of an ordered magnetic state. The critical temperature, T_N, has been located by the peaks at from the ac susceptibility (χ′and χ″) vs. T plots. Below T_N hysteresis loops recorded in the temperature region show an S-shape, while below 15 K assume an ellipsoid form. They reveal that compound (2) is a weak ferromagnet. The critical temperature T_N in these layered Fe(II) alkylphosphonates is independent of the distance between the inorganic layers.     

A novel 2D layer structure constructed from sandwich-type transition metal substituted tungstates and nickel coordination fragments: {[Ni(enMe)2]2[Ni(enMe)2(H2O)]2[As2W18Ni4(enMe)2O68]}·2H3O·2H2O

A novel polyoxometalate {[Ni(enMe)₂]₂[Ni(enMe)₂(H₂O)]₂[As₂W₁₈Ni₄(enMe)₂O₆₈]}·2H₃O·2H₂O (1) (enMe = 1,2-propylenediamine) has been synthesized and characterized, which is the first high-dimensional structure constructed from sandwich-type transition metal substituted tungstates and transition metal coordination groups.     

Thermal decomposition of syngenite, K2Ca(SO4)2·H2O

The thermal decomposition of syngenite, K₂Ca(SO₄)₂·H₂O, formed during the treatment of liquid manure has been studied by thermal gravimetric analysis, differential scanning calorimetry, high temperature X-ray diffraction (XRD) and infrared emission spectroscopy (IES). Gypsum was found as a minor impurity resulting in a minor weight loss due to dehydration around 100 °C. The main endothermic dehydration and decomposition stage of syngenite to crystalline K₂Ca₂(SO₄)₃ and amorphous K₂SO₄ is observed around 200 °C. The reaction involves a solid-state re-crystallisation, while water and the K₂SO₄ diffuse out of the existing lattice. The additional weight loss steps around 250 and 350 °C are probably due to presence of larger syngenite particles, which exhibit slower decomposition due to the slower diffusion of water and K₂SO₄ out of the crystal lattice. A minor endothermic sulphate loss around 450 °C is not due to the decomposition of syngenite or its products or of the gypsum impurity. The origin of this sulphate is not clear.     

Syntheses and structures of three new scandium selenites: Sc2(SeO3)3·H2O, Sc2 (SeO3)3·3H2O and CsSc3(SeO3)4 (HSeO3)2·2H2O

Three new hydrated scandium selenites have been hydrothermally synthesized as single crystals and structurally and physically characterized. Sc₂(SeO₃)₃·H₂O crystallizes as a new structure type containing novel ScO₇ pentagonal bipyramidal and ScO₆₊₁ capped octahedral coordination polyhedra. Sc₂(SeO₃)₃·3H₂O contains typical ScO₆ octahedra and is isostructural with its M₂(SeO₃)₃·3H₂O (M=Al, Cr, Fe, Ga) congeners. CsSc₃(SeO₃)₄(HSeO₃)₂·2H₂O contains near-regular ScO₆ octahedra and has essentially the same structure as its indium-containing analogue. All three phases contain the expected pyramidal [SeO₃]^2- selenite groups. Crystal data: Sc₂(SeO₃)₃·3H₂O, M_r=524.85, trigonal, R3c (No. 161), , , , Z=6, R(F)=0.018, wR(F²)=0.036; Sc₂(SeO₃)₃·H₂O, M_r=488.82, orthorhombic, P2₁2₁2₁ (No. 19), , , , , Z=4, R(F)=0.051, wR(F²)=0.086; CsSc₃(SeO₃)₄(HSeO₃)₂·2H₂O, M_r=1067.60, orthorhombic, Pnma (No. 62), , , , , Z=4, R(F)=0.035, wR(F²)=0.070.     

Synthesis and structural behavior of the P-functional organotin chlorides [Ph2P(CH2)3]2SnCl2, Ph2P(CH2)3SnCl2Me, and Ph2P(CH2)nSnCl3 (n=2, 3)

The P-functional organotin dichloride [Ph₂P(CH₂)₃]₂SnCl₂ (3) is synthesized by reaction of Ph₂P(CH₂)₃MgCl with SnCl₄ independently of the molar ratio of the starting compounds. The corresponding organotin trichlorides Ph₂P(CH₂)_nSnCl₂R (4: n=2, R=Cl; 5: n=3, R=Cl; 6: n=3, R=Me) are formed in a cleavage reaction of Ph₂P(CH₂)_nSnCy₃ (n=2, 3) with SnCl₄ or MeSnCl₃, respectively. The main features of the crystal structures of 3–6 are both intra- and intermolecular PSn coordinations and the existence of intermolecular Sn---ClSn bridges. For further characterization of the title compounds, the adducts 4(Ph₃PO)₂ (7) and 5(Ph₃PO) (8), as well as the P-oxides and P-sulfides of 3–6 (9–15), are synthesized. The results of crystal structure analyses of 7, 11, 12, and 14 are reported. The structures of 9–15 are characterized by intramolecular P=XSn interactions (X=O, S). A first insight into the structural behavior of the compounds 3–15 in solution is discussed on the basis of multinuclear NMR data.     

Hydrothermal synthesis, crystal structure and characterization of [Zn(H2O)4]2 [H2As6V15O42(H2O)]·2H2O

The compound [Zn(H₂O)₄]₂[H₂As₆V₁₅O₄₂(H₂O)]·2H₂O (1) has been synthesized and characterized by elemental analysis, IR, ESR, magnetic measurement, third-order nonlinear property study and single crystal X-ray diffraction analysis. The compound 1 crystallizes in trigonal space group R3, a=b=12.0601(17) Å, c=33.970(7) Å, γ=120°, V=4278.8(12) Å³, Z=3 and R1(wR2)=0.0512 (0.1171). The crystal structure is constructed from [H₂As₆V₁₅O₄₂(H₂O)]⁴⁻ anions and [Zn(H₂O)₄]²⁺ cations linked through hydrogen bonds into a network. The [H₂As₆V₁₅O₄₂(H₂O)]⁶⁻ cluster consists of 15 VO₅ square pyramids linked by three As₂O₅ handle-like units.     

Co3{CH3C(NH3)(PO3H)(PO3)}2 {CH3C(NH3)(PO3H)2}2(H2O)4·2H2O: A cobalt 1-aminoethylidenediphosphonate with a layer structure

This paper describes the structure and magnetic properties of a novel cobalt 1-aminoethylidenediphosphonate compound, namely Co₃{CH₃C(NH₃)(PO₃H)(PO₃)}₂{CH₃C(NH₃)(PO₃H)₂}₂(H₂O)₄·2H₂O (1). The structure contains a trimer unit of Co₃{CH₃C(NH₃)(PO₃H)(PO₃)}₂ in which two equivalent phosphonate ligands chelate and bridge the three cobalt ions. Each trimer unit is further linked to its four equivalent neighbors through corner-sharing of CoO₆ octahedra and CPO₃ tetrahedra, forming a two-dimensional layer in the bc-plane which contains 12-membered rings. These layers are connected to each other by extensive hydrogen bonds. Magnetic studies show that weak antiferromagnetic interactions are mediated between the cobalt ions. Crystal data for 1: monoclinic, space group C2/c, a=27.727(4), b=7.1091(11), , β=118.488(3), , Z=2.     

Syntheses and characterization of Co(pydc)(H2O)2 and Ni(pydc)(H2O) (pydc = 3,5-pyridinedicarboxylate)

The hydrothermal reaction of 3,5-pyridinedicarboxylic acid (pydcH₂) and Co(NO₃)₂ or Ni(NO₃)₂ in the presence of 4,4′-bipyridine results in two novel compounds Co(pydc)(H₂O)₂ (1) and Ni(pydc)(H₂O) (2). Crystal data: 1, monoclinic, C2/c, a=9.900(2), b=11.984(2), c=7.3748(15) Å, β=105.37(3)°, V=843.7(3) Å³, Z=4; 2, monoclinic, P2₁/c, a=7.7496(6), b=15.0496(11), c=6.4224(5) Å, β=108.437(1)°, V=710.59(9) Å³, Z=4. The structure of 1 is composed of honeycomb layers built up from {CoO₄N} trigonal bipyramids and 3,5-pyridinedicarboxylate bridges. The structure of 2 adopts a three-dimensional framework structure in which the Ni atoms are coordinated by the pydc bridges both within the honeycomb layer and between the layers. The magnetic properties of 1 and 2 have been investigated.     

(2,2′-bipy)[In2(OH)2(H2O)](SO4)2: The first indium sulfate with a layer structure

The first indium sulfate coordination complex, (2,2′-bipy)[In₂(OH)₂(H₂O)](SO₄)₂ (2,2′-bipy=2,2′-bipyridyl) was hydrothermally synthesized and characterized by single-crystal X-ray diffraction (XRD), the powder XRD, elemental analysis, inductively coupled plasma (ICP) analysis, thermogravimetric analysis (TGA), IR spectroscopy and fluorescent spectroscopy. It is noteworthy that this compound exhibits a novel two-dimensional layer structure, which is built up from two distinct motifs, a butlerite-type chain and a single 4-ring (S4R) unit. The adjacent layers are stably packed together and extended into three-dimensional supramolecular arrays via π-π stacking interactions of the 2,2′-bipy ligands. Additionally, this compound shows strong fluorescent property at room temperature, which may be assigned to ligand-centered π*-π transitions.     

Formation of [CoCl4(H2O)2] complex in CoCl2·MgCl2·8H2O double salt: structural and energetic properties of [MCl4(H2O)2] and [M(H2O)6] (M=Mg, Co)

The crystal structure of the double salt CoCl₂·MgCl₂·8H₂O has been determined by the X-ray diffraction method. It crystallizes in the space group with a=6.0976(9), b=6.308(1), c=8.579(3) Å, α=81.99(2)°, β=88.40°, γ=84.61(1)°, Z=1, and R=0.027. The crystal consists of two kinds of well separated octahedra, [CoCl₄(H₂O)₂]²⁻ and [Mg(H₂O)₆]²⁺. The former is unique as aquachloro complexes of Co²⁺. In order to elucidate the reason prepared as such unique complexes in the double salts, formation energies for [MCl₄(H₂O)₂]²⁻ and [M(H₂O)₆]²⁺ (M=Co, Mg) have been calculated by using the density functional methods, and it has been revealed that the formation energies of the first coordination sphere for the metal ions and the Cl⁻?H₂O hydrogen bond networks around [CoCl₄(H₂O)₂]²⁻ play a decisive role in forming [CoCl₄(H₂O)₂]²⁻ with the regular octahedral geometry in the double salt.     

Noncentrosymmetric K2Mn3(SO4)3F2·4H2O and Rb2Mn3(SO4)3F2·2H2O with pseudo-KTP structures

Two fluoride sulfates,K₂Mn₃(SO₄)₃F₂·4H₂O(Ⅰ) and Rb₂Mn₃(SO₄)₃F₂·2H₂O (Ⅱ) are obtained by water solution method.Single-crystal X-ray diffraction analysis indicated that they crystallize in space groups of Cmc2_1.Their structures feature a pseudo-KTP structure consisting of interconnecting[Mn₃(SO₄)3F₂(H₂O)2]_∞ layers,which are further packing along the a axis with alkali metal cations balancing the charges.The structure relationships between the two compounds are discussed.Secondharmonic generation measurements manifest that Ⅰ and Ⅱ have similar second-harmonic generation responses of about 0.2 and 0.25 times that of KH₂PO₄.     

Synthesis, crystal structures, phase transition characterization and thermal decomposition of a new dabcodiium hexaaquairon(II) bis(sulfate): (C6H14N2)[Fe(H2O)6](SO4)2

The crystal structures of 1,4-diazabicyclo[2.2.2]octane (dabco)-templated iron sulfate, (C₆H₁₄N₂)[Fe(H₂O)₆](SO₄)₂, were determined at room temperature and at −173 °C from single-crystal X-ray diffraction. At 20 °C, it crystallises in the monoclinic symmetry, centrosymmetric space group P2₁/n, Z=2, a=7.964(5), b=9.100(5), c=12.065(5) Å, β=95.426(5)° and V=870.5(8) ų. The structure consists of [Fe(H₂O)₆]²⁺ and disordered (C₆H₁₄N₂)²⁺ cations and (SO₄)²⁻ anions connected together by an extensive three-dimensional H-bond network. The title compound undergoes a reversible phase transition of the first-order at −2.3 °C, characterized by DSC, dielectric measurement and optical observations, that suggests a relaxor–ferroelectric behavior. Below the transition temperature, the compound crystallizes in the monoclinic system, non-centrosymmetric space group Cc, with eight times the volume of the ambient phase: a=15.883(3), b=36.409(7), c=13.747(3) Å, β=120.2304(8)°, Z=16 and V=6868.7(2) ų. The organic moiety is then fully ordered within a supramolecular structure. Thermodiffractometry and thermogravimetric analyses indicate that its decomposition proceeds through three stages giving rise to the iron oxide.