Alkalimetallchalkogenidomanganate und -Indate : : Synthese, Kristallchemie und chemische Bindung

Abstract: Due to the rich structural chemistry of mixed-valent ferrates(II/III), further alkali metal chalcogenidometallates(II/III) Ax[MyQz] (A=Na, K, Rb, Cs; M=Mn, In; Q=S, Se, Te) were investigated in this work. Because the redox potential, the oxidation state +II dominates for manganese and phases
with Mn(III) or mixed-valent manganates are rare. In contrast, corresponding indates(III) again
show a comparable crystal chemistry due to the similar ionic radius of In3+ and Mn2+ , so that the
synthesis of mixed compounds with adjustable M+II/M+III ratios was possible. The synthesis was
achieved by melt reactions under inert conditions from stoichiometric samples of the elements or, if
applicable, of the A/M metal chalcogenides. The structures have been determined by means of single
crystal diffraction. Further characterisation methods included ESR, Raman and UV/Vis spectroscopy,
magnetic susceptibility measurements and DFT calculations.
Despite their high reactivity, a large number of alkali metal-rich manganese and indium compounds
were obtained by the chosen synthesis methods. The orthomanganates A6[MnQ4] (Na6[ZnO4] type)
are rare examples where the large Rb + and Cs + cations are located in the small octahedron and even tetrahedron voids of the close Q2– packing. Using a Bärnighausen tree, a group-subgroup relationship to the hexagonal close packing was established. Magnetic measurements of the three Cs-compounds (Q=S, Se, Te) revealed Curie-Weiss behavior up to a temperature of 1.9 K. The magnetic moment is reduced compared to the spin-only value of a d 5 ion, which can be attributed to a π-donation of Q-p states to the d states of the metal center by analysis of the calculated spin densities. The four salts (Na/Rb)6 [Mn(S/Te) 4 ] also show a clear spin polarisation of the Q atoms, which is necessary for the super super super exchange (AFM) via these ligands. The synthesis of the orthoindate K5[InSe4] confirmed the double salt character of the compounds K9[InSe4]2[Se] and K9[InSe4][Se2][Se] known from literature. With the chiral compounds K12[InQ4]2[Q] (Q=S, Te) as well as K54[InTe4]10[Te2]2, further salts with free chalcogenido anions or [Te2] dumbbells were obtained.
The structures of the new diindates K6[In2Q6] (Q=S, Se, Te) and Cs6[In2Te6], consisting of two
edge-sharing tetrahedra, were compared with further trivalent metalates(III) (Fe, Al and Ga) with the
same structure feature and classified into different classes based on geometric parameters such as
radius ratios and effective coordination numbers. E.g., the structures of K6[In2Te6] and Na6[Fe2S6]
could be derived from a common aristotype (h.c.p.) via a group-subgroup relationship, since the radii
of K+/In3+/Te2- and Na+/Fe3+/S2- provide ideal conditions for the formation of a close packing of
chalcogen atoms. The isotypic K/Rb salts Na2A[MnTe3] do not contain trivalent manganese, although suggested by the formula. They crystallise in an unusual new structure type due to the ordering of the alkali metals.
Between undulated chains of edge-sharing 1∞[MnIITe4/2] tetrahedra there are [Te2]2– dumbbells. A
second chain consisting of vertex- and edge-sharing [MnIITe4] tetrahedra exhibits μ1- and μ2-tellurido-
as well as η1-dumbbell-ligands.
Na2[Mn2Te3] is isotypic to the analogous sulfur and selenium compounds and contains layers
of [MnTe4] tetrahedra which are condensed via common vertices to [Mn4Te6] tetramers. These
tetramers are connected to layers by μ3-Te atoms. With Na2[Mn3Te4] the isotypic compound to the known selenide was obtained. Ribbons of vertex-sharing [MnTe4] tetrahedra and edge-sharing
[MnTe6] octahedra are linked to form layers.
In the manganates NaK[MnQ2] (Q=S, Se) (new structure type), an edge-sharing [Mn2Q6] dimer
is linked with four other dimers via common vertices to form layers. The two alkali metal cations
lie on crystallographically different positions and exhibit a five- or sixfold coordination according
to their size. The Cs manganate NaCs[MnTe2], also with a A:M:Q ratio of 2:1:2, contains linear
chains of [MnTe4] tetrahedra. Together with the |:AABB:| stacking of the 4 4 -nets of Te atoms and the
ordering of small Na+/Mn2+ and large Cs+ cations in tetrahedral or cubic voids, an order variant of
the ThCr2Si2-type structure results.
The Na-rich sulfido and selenido metallates Na12[MnIn2Q10 ] (Q=S, Se) contain in addition to
the orthoanion [InIIIQ4]5– the hetero-bimetallic dimer [MnIIInIIIQ6]7– consisting of edge-sharing
[MQ4] tetrahedra. The total arrangement of the chalcogen atoms corresponds to a hexagonal close
packing, in which intermediate layers the tetrahedron and octahedron voids are alternately occupied
by Mn2+/In3+ or Na+ . This structure relation was also verified by a Bärnighausen group-subgroup
tree.
The mixed chalcogenidometallates A3[MnInQ4 ] (A=Na, K, Rb, Cs; Q=S, Se, Te) contain MnII and
InIII in a 1:1 ratio. As with almost all Na salts in this thesis, the structural chemistry of Na3[MnInQ4]
(Q=S, Se) is based on a close packing of chalcogenide ions in which the small Na+ cations occupy octahedra or tetrahedra voids and thus differ from the analogous sodium ferrates. The sulfide compound is isotypic to β-Ca3Ga2N4 and is derived from the close cubic packing. The filling of the tetrahedral voids with Mn2+/In3+ leads to vertex-sharing supertetrahedra, which form two interpenetrating diamond-like three-dimensional networks. The selenido salt is isotypic to Na2[Mn3Te4] and consists of edge-linked [M2Se6]-dimers, which are linked by four common vertices to form ribbons. Salts withheavy alkali metals (K-Cs) crystallise in the orthorhombic Na3Fe2S4-type structure and are similar to the mixed-valent ferrates A3[Fe2Q4], both electronically and structurally. In almost all compounds with A=K, Rb, Cs, the large A + cations prevent the formation of close Q packings. Instead, there are undulated chains of edge-sharing [MQ4] tetrahedra, which are arranged to a pseudo-hexagonal rod packing. The alkali metals are located in the pseudo-trigonal channels between the chains, whose undulation depends on the size of the cations. The structural chemistry of the new Mn/In metallates is compared and discussed with the mixed-valent ferrates A3[FeII/III2Q4] and the alkaline earth metal trielates AII3[(Al/Ga/In)2(N/P/As)4] using a structure map.
The obtained results inspire the investigation of the new family of mixed melates(II/III) with other
metals like e.g. M(II)=Zn,Cd und M(III)=Al, Ga)

Angaben zum Objekt

• Standort: Deutsche Nationalbibliothek Frankfurt am Main
• Umfang: Online-Ressource
• Sprache: Deutsch
• Anmerkungen: Universität Freiburg, Dissertation, 2020

Klassifikation und Themen

• Schlagwort: Indate ; Manganate ; Kristallchemie ; Mangan ; Quantenchemie ; Kation ; Kristallchemie ; Manganate ; Kristallstruktur ; Quantenchemie ; Indate ; Mangan

Beteiligte, Orts- und Zeitangaben

• Ereignis: Veröffentlichung
• (wo): Freiburg
• (wer): Universität
• (wann): 2020
• Urheber: Langenmaier, Michael
• Beteiligte Personen und Organisationen: Röhr, Caroline ; Albert-Ludwigs-Universität Freiburg. Fakultät für Chemie und Pharmazie

Weitere Informationen

• DOI: 10.6094/UNIFR/174553
• URN: urn:nbn:de:bsz:25-freidok-1745533
• Rechteinformation: Der Zugriff auf das Objekt ist unbeschränkt möglich.
• Letzte Aktualisierung: 25.03.2025, 13:43 MEZ