The solvothermal synthesis of the layered compound Mn2Sb2S5·DAP (DAP = 1,3-diaminopropane) has been studied using in situ energy-dispersive X-ray diffraction. The
results clearly demonstrate that the induction time strongly depends on the reaction
temperature. At lower temperatures two crystalline intermediates could be detected. The
decay of the second intermediate and the product growth show a strong correlation. A detailed
analysis of the extent of reaction α suggests that a small fraction of the intermediate is
either dissolved or converted into an amorphous state. The experimentally determined extent
of reaction α versus time was compared with various theoretical models. The reaction
exponents indicate similar mechanisms for temperatures between 105 and 125 °C. The best
agreement is obtained with a first-order reaction and/or phase-boundary-controlled mechanisms. A rigorous analysis reveals that it is highly likely that with increasing α the
mechanism changes, suggesting consecutive and/or parallel kinetics as the reaction proceeds.
At 130 °C and α > 0.75 a three-dimensional diffusion-controlled process dominates.
The results of in-situ energy-dispersive X-ray diffraction under solvothermal conditions performed on isostructural, layered thioantimonates Mn 2 Sb 2 S 5 ·L (L = amine) demonstrate the great potential of the method. When the synthesis was carried out at low temperatures with L being 1,3-diaminopropane (DAP), two crystalline intermediate phases were detected which then grew and disappeared when product growth started. Surprisingly, when N-methyl-1,3-diaminopropane (MDAP) was used, no crystalline intermediates could be detected and the induction time was significantly shorter than for DAP. For reactions up to 100°C and for higher temperatures with α Ͻ 0.8 (α is the extent of reaction), the crystallisation is predominantly controlled by nucleation. Further progress of crystallisation (α Ͼ 0.8) leads to a change
The two new compounds Mn2(L)Sb2S5 (L = diethylenetriamine = DIEN, N-methyl-1,3- diaminopropane = MDAP) were prepared under solvothermal conditions using the elements as starting materials. Both compounds crystallise in the monoclinic space group P21/c with the lattice parameters a=10.669(7), b=12.805(2), c=12.072(1)Å , β =115.786(7)°,V =1485.1(4) Å3 for L = DIEN and a = 10.1859(7), b = 12.7806(6), c = 12.1256(8)Å , β = 110.173(8)°, V = 1481.7(2) Å3 for L = MDAP and Z = 4. The primary building units are SbS3 pyramids, MnS6 and MnS4N2 distorted octahedra. These primary building blocks are interconnected to form Mn2Sb2S4 hetero-cubane units. The hetero-cubanes share common corners, edges and faces thus forming a second heterocubane. These secondary building units are joined to form layers within the (100) plane. The connection mode yields ellipsoidal pores within the layers. The amines are exclusively bound to one of the two crystallographically independent Mn2+ cations and they point into the pores and between the layers separating the layers from each other. The interlayer separation and the size of the pores depend on the sterical requirements of the amine incorporated into the network. A pronounced distortion of the MnS4N2 octahedron results from a significant elongation of one Mn-S distance from 2.866 Å (L = methylamine, MA) to 3.185 Å for L = MDAP. The magnetic susceptibility curves are typical for low-dimensional antiferromagnetic materials and the large negative values for the Weiss constant Θ indicate strong antiferromagnetic exchange interactions. The magnetic properties are significantly influenced by the change of the Mn-S bonds introduced by the different amines. The compounds decompose at elevated temperatures with a two step reaction for L = MA and ethylenediamine and in a one step reaction for the bidentate acting amine molecules.
The two novel thioantimonate(V) compounds [Mn(C 6 H 18 N 4 )(C 6 H 19 N 4 )]SbS 4 (I) and[Mn(C 6 H 14 N 2 ) 3 ] 2 -[Mn(C 6 H 14 N 2 ) 2 (SbS 4 ) 2 ]·6H 2 O (II) were synthesized under solvothermal conditions by reacting elemental Mn, Sb and S in the stoichiometric ratio in 5 ml tris(2-aminoethyl)amine (tren) at 140°C or chxn (trans-1,2-diaminocyclohexane, aqueous solution 50 %) at 130°C. Compound I crystallises in the triclinic space group P1, a ϭ 9.578(2), b ϭ 11.541(2), c ϭ 12.297(2) Å , α ϭ 62.55(1), β ϭ 85.75(1), γ ϭ 89.44(1)°, V ϭ 1202.6(4) Å 3 , Z ϭ 2, and II in the monoclinic space group C2/c, a ϭ 32.611(2), b ϭ 13.680(1), c ϭ 19.997(1) Å , β ϭ 117.237(5)°, V ϭ 7931.7(8) Å 3 , Z ϭ 4. In I the Mn 2ϩ cation is surrounded by one tetradentate tren molecule, one
The three new thioantimonates(V) [Ni(chxn)3]3(SbS4)2·4H2O (I), [Co(chxn)3]3(SbS4)2·4H2O (II) (chxn is trans‐1,2‐diaminocyclohexane) and [Co(dien)2][Co(tren)SbS4]2·4H2O (III) (dien is diethylenetriamine and tren is tris(2‐aminoethyl)amine) were synthesized under solvothermal conditions. Compounds I and II are isostructural crystallizing in space group C2/c. The structures are composed of isolated [M(chxn)3]2+ complexes (M = Ni, Co), [SbS4]3− anions and crystal water molecules. Short S···N/S···O/O···O separations indicate hydrogen bonding interactions between the different constituents. Compound III crystallizes in space group $P{\bar 1}$ and is composed of [Co(dien)2]2+ and [Co(tren)SbS4]− anions and crystal water molecules. In the cationic complex the Co2+ ion is in an octahedral environment of two dien ligands whereas in [Co(tren)SbS4]− the Co2+ ion is in a trigonal bipyramidal coordination of four N atoms of tren and one S atom of the [SbS4]3− anion, i.e., two different coordination polyhedra around Co2+ coexist in this compound. Like in the former compounds an extended hydrogen bonding network connects the complexes and the water molecules into a three‐dimensional network.
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