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Abstract: The crystal and magnetic structures of the hybrid organic–inorganic layer compound Fe[(CD3PO3)(D2O)] have been studied by neutron powder diffraction as a function of temperature down to 1.5K. The neutron diffraction pattern recorded at 200K shows that the fully deuterated compound crystallizes in one of the two known forms of the undeuterated Fe[(CH3PO3)(H2O)]. The crystal structure is orthorhombic, space group Pmn21, with the following unit-cell parameters: a=5.7095(1)Å, b=8.8053(3)Å and c=4.7987(1)Å; Z=2. The crystal structure remains unchanged on cooling from 200 to 1.5K. Moreover, at low temperature, Fe[(CD3PO3)(D2O)] shows a commensurate magnetic structure (k=(0,0,0)). As revealed by bulk susceptibility measurements on Fe[(CH3PO3)(H2O)], the magnetic structure corresponds to a canted antiferromagnet with a critical temperature T N=25K. Neutron powder diffraction reveals that below T N=23.5K the iron magnetic moments in Fe[(CD3PO3)(D2O)] are antiferromagnetically coupled and oriented along the b-axis, perpendicular to the inorganic layers. No ferromagnetic component is observable in the neutron powder diffraction experiment, due to its too small value (<0.1μ B). [Copyright &y& Elsevier]

The new compound MnSbS2Cl was synthesised from a mixture of MnS, MnCl2 and Sb2S3 at 500 °C. Single crystal study indicates orthorhombic symmetry, space group Pnma (No. 62), with , , , and . The refinement converged to and for 742 unique reflections and 32 parameters. The crystal structure of MnSbS2Cl is isotypic with stibnite Sb2S3 and consists of waved layers of corner-sharing MnS4Cl2 octahedra along the a axis and edge-sharing octahedra along the b axis, which are separated by antimony atoms. MnSbS2Cl susceptibility shows an antiferromagnetic behaviour below 40 K with an increase at about 23 K. [Copyright &y& Elsevier]

Abstract: The crystal structure of Pb2SbS2I3 was solved at room temperature and 100K. At 293K it crystallizes in the orthorhombic system, space group Cmcm (No. 63), with unit cell parameters a =4.3262(9), b =14.181(3), c =16.556(3)Å, V =1017.7(4)Å3, Z =4. The structure is disordered, and combines a split Pb site (s.o.f.=0.50) with one mixed (Pb,Sb) site with Pb and Sb in two distinct sub-positions. At 100K, it is monoclinic, space group P21/c, with unit cell parameters a =7.3629(6), b =16.466(3), c =8.5939(7)Å, β =107.14(2)°, V =995.6(2)Å3, Z =4. The structure is now fully ordered, without mixed sites. On the basis of bond valence calculations, new cation distributions are proposed for published structures of the Sn isotypes, Sn2SbS2I3 and Sn2SbSe2I3. A re-examination of the crystal structures of various (Pb/Sn/Sb) chalcogeno-iodides is presented according to modular analysis. All these structures can be described according to three types of 1D modules, (Pb/Sn)I4, (Sn)2I4 and (Pb/Sn/Sb)4(S/Se)2I4. Generally each type of 1D module gives one type of slab, and the final structure corresponds to a specific stacking of two or three among these slabs. A new structural model is proposed for “α-Sn2SI2”, which would have the non-stoichiometric composition (Sn5.42□0.58)S2(I6.87□0.12), ideally Sn27S10I34, with probably a narrow solid solution field on the SnS–SnI2 joint. [Copyright &y& Elsevier]

Abstract: The new oxy-chloro-sulfide (Mn1− x Pb x )Pb10+ y Sb12− y S26− y Cl4+ y O (x ∈ [0.2–0.3]; y ∈ [0.3–1.6]) was synthesized by dry way at 500–600°C. A single crystal ∼Mn0.7Pb11.0Sb11.3S25.3Cl4.7O indicates a monoclinic symmetry, space group C2/m, with a = 37.480(8), b = 4.1178(8), c = 18.167(4)Å, β = 106.37(3)°, V = 2690.2(9)Å3, Z = 2. Its crystal structure was determined by X-ray single crystal diffraction, with a final R = 5.11%. Modular analysis of the crystal structure reveals a “waffle” architecture, where complex rods with lozenge section delimitate an internal channel filled by a single chain of (Mn0.7Pb0.3)Cl6 octahedra connected by opposite edges. Minimal inter-chain distances are close to 18Å. The rod wall, two-atom thick, presents, in alternation with S atoms, Pb or (Pb,Sb) cations with prismatic coordination in the internal atom layer, while the external atom layer is constituted exclusively by Sb cations with dissymmetric square pyramidal coordination. A (Pb,Sb)2S2 fragment connects two successive rods along (201) to form a waffle-type palissadic layer. The unique O position, half filled, presents the same environment than the isolated O positions in the oxy-sulfide Pb14Sb30S54O5, or oxy-chloro-sulfides Pb18Sb20S46Cl2O and (Cu,Ag)2Pb21Sb23S55ClO. This compound belongs to a pseudo-homologous series of chalcogenides with waffle structure, ordered according to the size of their lozenge shape channel. Such a complex senary compound of the oxy-chloro-sulfide type illustrates the structural competition between three cations, on one hand, and, on the other hand, three anions. This compound is of special interest regarding the 1D distribution of magnetic Mn2+ atoms at the ∼2nm scale. [Copyright &y& Elsevier]

Abstract: 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 . 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 40.3Å. 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 50K (, ), indicating a Fe +II oxidation state, a high-spin d 6 () 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 −44K, respectively, thus suggesting the presence of Fe +II ion in the 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, , has been located by the peaks at from the ac susceptibility (χ′and χ″) vs. T plots. Below hysteresis loops recorded in the temperature region show an S-shape, while below 15K assume an ellipsoid form. They reveal that compound (2) is a weak ferromagnet. The critical temperature in these layered Fe(II) alkylphosphonates is independent of the distance between the inorganic layers. [Copyright &y& Elsevier]