Solvothermal Synthesis of One-dimensional Chalcogenides Containing Group 13 Elements

The new sodium tellurido manganates(II) Na2Mn2Te3, Na2Mn3Te4, Na2 AMnTe3 (A=K, Rb), and NaCsMnTe2

A series of new sodium and mixed Na/A (A = K, Rb, Cs) tellurido manganates have been synthesized from melts of the pure elements (or MnTe) at maximum temperatures of 600–1000°C. The monoclinic crystal structures of the two pure sodium salts Na2Mn2Te3 (space group C2/c, a = 1653.68(2), b = 1482.57(2), c = 773.620(10) pm, β = 117.52°, Z = 8, R1 = 0.0225) and Na2Mn3Te4 (space group C2/m, a = 1701.99(3), b = 438.741(8), c = 691.226(12) pm, β = 90.3171(8)°, Z = 2, R1 = 0.0270) are both based on a hexagonal close packed Te2− arrangement. Na2Mn2Te3 is isotypic with Na2Mn2S3 and Na2Mn2Se3 and contains layers of [MnTe4] tetrahedra, which are connected via common edges to form tetramers [Mn4Te6]. These tetramers are further connected via μ 3-Te atoms. Na2Mn3Te4 crystallizes in a new structure type, recently also reported for the selenido salt Na2Mn3Se4. Mn(2) forms ribbons of vertex-sharing dinuclear units ∞ 1 [ Te 2 / 2 MnTe 2 MnTe 2 / 2 ] $_\infty ^1[{\rm{T}}{{\rm{e}}_{2/2}}{\rm{MnT}}{{\rm{e}}_2}{\rm{MnT}}{{\rm{e}}_{2/2}}]$ running along the short b axis of the monoclinic cell. The Te atoms of these ribbons are also the ligands of edge-sharing [Mn(1)Te6] chains of octahedra. Similar to Na2Mn2Te3, the Na+ cations are octahedrally coordinated and the cations occupy tetrahedral (Mn2+) and octahedral (Na+, Mn2+) voids in the close Te2− packing. The isotypic K/Rb salts Na2 AMnTe3 crystallize in a new structure type (orthorhombic, space group Pmc21, a = 1069.70(4)/1064.34(2), b = 1350.24(5)/1350.47(3), c = 1238.82(4)/1236.94(3) pm, Z = 4, R1 = 0.0445/0.0210). In contrast to the simple formula indicating a Mn(III) compound, the complex structure contains one layer consisting of undulated chains of edge-sharing tetrahedra ∞ 1 [ Mn II Te 4 / 2 ] $_\infty ^1[{\rm{M}}{{\rm{n}}^{{\rm{II}}}}{\rm{T}}{{\rm{e}}_{4/2}}]$ separated by free ditelluride dumbbells [Te2]2− and a second layer containing a complex chain of edge- and vertex-sharing [MnIITe4] tetrahedra, in which Mn(II) is coordinated to μ 1- and μ 2-Te2− ligands and an η 1-ditellurido ligand. The cesium salt NaCsMnTe2 (orthorhombic, space group Cccm, a = 694.21(2), b = 1536.57(4), c = 664.47(2) pm, Z = 4, R1 = 0.0131) likewise forms a new structure type, which is an ordered superstructure of ThCr2Si2. Linear chains ∞ 1 [ MnTe 4 / 2 ] $_\infty ^1[{\rm{MnT}}{{\rm{e}}_{4/2}}]$ of edge-sharing tetrahedra are connected with similar chains ∞ 1 [ NaTe 4 / 2 ] $_\infty ^1[{\rm{NaT}}{{\rm{e}}_{4/2}}]$ to form [NaMnTe2] layers. The larger alkali cations Cs+ between the layers exhibit a cubic (CN = 8) coordination.

Synthesis, crystal and electronic structure of the new sodium chain sulfido cobaltates(II), Na3CoS3 and Na5[CoS2]2(Br)

The sulfido cobaltate(II) Na3CoS3 was synthesized from stoichiometric quantities of Na2S, elemental cobalt and sulfur at a maximum temperature of 1100°C. According to Na3CoS3=Na12[Co2S5(S2)][Co2S3(S2)] the orthorhombic structure of a new type (space group Cmc21, a=884.24(2), b=2177.38(5), c=1193.20(3) pm, Z=12, R1=0.0205) contains two different anions: i. dimers [Co2S5(S2)]8− of two edge-sharing [CoS4] tetrahedra with five sulfido and one η 1-disulfido ligand; ii. chains ∞ 1 [ Co 2 S 3 ( S 2 ) ] 4 − $_\infty ^1{[{\rm{C}}{{\rm{o}}_2}{{\rm{S}}_3}({{\rm{S}}_2})]^{4 - }}$ of [CoS4] tetrahedra connected via μ-sulfido (3×) besides μ-1,2-disulfido (1×) ligands. The second title compound, Na5[CoS2]2(Br), which has been likewise synthesized as a pure phase from stoichiometric quantities of Na2S, Co, S and NaBr, is isotypic to Na5[CoS2]2(S) (Na6PbO5 type; tetragonal, space group I4mm, a=914.58(7), c=625.59(5) pm; R1=0.0412). The structure contains linear chains ∞ 1 [ CoS 4 / 2 ] 2 − $_\infty ^1{[{\rm{Co}}{{\rm{S}}_{4/2}}]^{2 - }}$ running along the tetragonal c axis. In between, Br− ions are interspersed, which are coordinated by square pyramids of Na+ ions. The isotypic hydrogensulfide Na5[CoS2]2(SH) was obtained via the addition of NaSH. Several synthetic and structural arguments suggest that Na5[CoS2]2(SH) and the previously described pure sulfide are the same compound. The results of DFT band structure calculations (GGA+U, AFM spin ordering) are used to discuss and compare the chemical bonding in the new sulfido cobaltates(II) with that of the reference compound Na2[CoS2]. They also allow for obtaining insight into the superexchange path, which is responsible for the strong antiferromagnetic Co spin ordering along the chains.

Long-chain amine-templated synthesis of gallium sulfide and gallium selenide nanotubes

We describe the soft chemistry synthesis of amine-templated gallium chalcogenide nanotubes through the reaction of gallium(iii) acetylacetonate and the chalcogen (sulfur, selenium) using a mixture of long-chain amines (hexadecylamine and dodecylamine) as a solvent. Beyond their role as solvent, the amines also act as a template, directing the growth of discrete units with a one-dimensional multilayer tubular nanostructure. These new materials, which broaden the family of amine-stabilized gallium chalcogenides, can be tentatively classified as direct large band gap semiconductors. Their preliminary performance as active material for electrodes in lithium ion batteries has also been tested, demonstrating great potential in energy storage field even without optimization.

Structural complexity in indium selenides prepared using bicyclic amines as structure-directing agents

The synthesis and characterization of five new indium selenides, [C9H17N2]3[In5Se(8+x)(Se2)(1-x)] (1-2), [C6H12N2]4[C6H14N2]3[In10Se15(Se2)3] (3), [C6H14N2][(C6H12N2)2NaIn5Se9] (4) and [enH2][NH4][In7Se12] (5), are described. These materials were prepared under solvothermal conditions, using 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and 1,4-diazabicyclo[2.2.2]octane (DABCO) as structure-directing agents. Compounds 1-4 represent the first examples of ribbons in indium selenides, and 4 is the first example of incorporation of an alkali metal complex. Compounds 1, 2 and 4 contain closely related [In5Se(8+x)(Se2)(1-x)](3-) ribbons which differ only in their content of (Se2)(2-) anions. These ribbons are interspaced by organic countercations in 1 and 2, while in 4 they are linked by highly unusual [Na(DABCO)2](+) units into a three-dimensional framework. Compound 3 contains complex ribbons, with a long repeating sequence of ca. 36 Å, and 4 is a non-centrosymmetric three-dimensional framework, formed as a consequence of the decomposition of DABCO into ethylenediamine (en) and ammonia.