Poster

Tl2[B12H12]: Thallium(I)Dodecahydro-closo-dodecaborate withCs2[B12H12]-type Crystal Structure

Nguyen-Duc Van, Ioannis Tiritiris, Thomas Schleid*

Institut für Anorganische Chemie, Universität Stuttgart,Pfaffenwaldring 55, D-70569 Stuttgart

Keywords: Thallium; Dodecahydro-closo-dodecaborate; Crystalstructure

The preparation of thallium(I) dodecahydro-closo-dodecaborateTl2[B12H12] was studied over 40 years ago by Muetterties et al. [1],its crystal structure, however, was never determined. Colourless oc-tahedral single crystals of this title compound were obtained byneutralizing an aqueous solution of the free acid (H3O)2[B12H12]with Tl2CO3 and recrystallization of the crude product from water.The crystal structure of Tl2[B12H12] (cubic, Fm3̄, Z � 4; a �

1075.51(6) pm) is isostructural to that one of the dodecahydro-closo-dodecaborates with heavy alkali-metal cations K�, Rb� andCs� reported previously [2, 3]. It can be described as an anti-CaF2-type arrangement in which Tl� cations occupy all the tetrahedralinterstices within the cubic closest-packed host lattice of the quasi-icosahedral [B12H12]2--cluster dianions.

x/a y/b z/c Ueq/pm2

Tl 1/4 1/4 1/4 415(2)B 0 0.0830(5) 0.1360(5) 322(9)H 0 0.139(3) 0.224(3) 501(77)

The Tl� cations occupy the special Wyckoff position 8c (site sym-metry: 23.) whereas the boron and hydrogen atoms reside in 48h(site symmetry: m..). Tl� is tetrahedrally coordinated with four ne-arest neighbour [B12H12]2�-cluster dianions thus twelve hydrogenatoms belonging to four triangular faces of these clusters providean almost perfect cuboctahedral coordination sphere for each Tl�

cation (d(Tl�H) � 295.5 pm, 12�). In the [B12H12]2�-cluster di-anion itself, the icosahedral cage is formed by twelve boron atomsand each boron atom has an exopolyhedral hydrogen bond. Thecluster dianion exhibits its center of gravity at the special Wyckoffposition 4a (x/a � y/b � c/z � 0; site symmetry: m3̄) with a distan-ces of 171 pm to each of the twelve boron atoms. The interclusterbond distances are 179 pm (1�) and 181 pm (4�) for the B�Band 112 pm for the B�H bonds, a quite typical range for dodecahy-dro-closo-dodecaborate dianions [2, 3]. Within the series ofA2[B12H12]-type compounds, the lattice constant of Tl2[B12H12]ranges between K2[B12H12] (a � 1063 pm) and Rb2[B12H12] (a �

1087 pm) [2], but far below Cs2[B12H12] (a � 1128 pm) [3]. Thesame trend can be observed for the binary chlorides ACl (KCl: a �

628 pm, H.T.-TlCl: a � 632 pm, RbCl: a � 654 pm, H.T.-CsCl:a � 692 pm) with NaCl-type structure.

[1] E. L. Muetterties, J. H. Balthis, Y. T. Chia, H. C. Miller, Inorg.Chem. 1964, 3, 444.

[2] I. Tiritiris, Th. Schleid, K. Müller, W. Preetz, Z. Anorg. Allg.Chem. 2000, 626, 323.

[3] I. Tiritiris, Th. Schleid, Z. Anorg. Allg. Chem. 2003, 629, 1390.

DOI: 10.1002/zaac.200470140

1764 2004 WILEY-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim zaac.wiley-vch.de Z. Anorg. Allg. Chem. 2004, 630, 1764

Strukturverfeinerung der Seltenerd-Übergangsmetall-Carbide YCoC2 undYNiC2

Christian Vogt, Ute Ch. Rodewald, Rainer Pöttgen

Institut für Anorganische und Analytische Chemie, WestfälischeWilhelms-Universität, Correnstraße 36, D-48149 Münster;pottgen@uni-muenster.de

Keywords: Carbide; Crystal chemistry; Rare earth compounds

Die Seltenerdübergangsmetall-Carbide YCoC2 und YNiC2 [1] wur-den durch Lichtbogenschmelzen der zu Pillen gepressten Elementesynthetisiert. Zur Züchtung von Einkristallen wurden die lichtbo-gengeschmolzenen Reguli anschließend kurz unterhalb desSchmelzpunktes in wassergekühlten Quarzampullen [2] im Induk-tionsofen (Hüttinger Elektronik, Freiburg, Typ IG 10/600) für fünfStunden getempert.YCoC2 und YNiC2 wurden anhand von röntgenographischen Pul-ver- und Einkristalldaten untersucht: CeNiC2-Typ, Amm2, a �

354.19(6), b � 451.65(8), c � 602.92(10) pm, wR2 � 0.0585, 475F2-Werte (alle Daten), 15 Variable, Flack-Parameter �0.04(1) fürYCoC2 und a � 357.28(10), b � 450.87(12), c � 603.51(16) pm,wR2 � 0.0602, 959 F2-Werte (alle Daten), 15 Variable, Flack-Para-meter �0.056(8) für YNiC2.Die Strukturen (Abb. 1) sind aus zweidimensionalen [CoC2] bzw.[NiC2]-Netzwerken aufgebaut, wobei jedes Übergangsmetallatoman drei C2-Hanteln gebunden ist. Die C�C-Abstände in YCoC2

und YNiC2 betragen 139.7(9) bzw. 136.1(5) pm, nahe dem Wertvon 134 pm für C�C-Doppelbindungen.

Abb. 1 Projektion der Kristallstruktur von YNiC2 auf die yz-Ebene.Das [NiC2]-Netzwerk liegt auf x � 1/2, die Yttriumatome aufx � 0.

[1] W. Jeitschko, M. H. Gerss, J. Less-Common Met. 1986, 116,147.

[2] D. Niepmann, Yu. M. Prots, R. Pöttgen, W. Jeitschko, J. SolidState Chem. 2000, 154, 329.

DOI: 10.1002/zaac.200470141