Mit Hilfe von röntgenographischen Einkristalluntersuchungen wurde bestätigt, daß die Verbindungen TlGaTe2, TlInSe2 und TlInTe2 im TISe‐Typ (B37) kristallisieren. Thallium ist darin als 1wertiges Kation von acht Chalkogenatomen umgeben, Gallium und Indium liegen 3wertig mit tetraedrischer Koordination und kovalenter Bindung vor. Dio interatomaren Abstände sowie die sich daraus ergebenden Koordinations‐ und Bindungsverhältnisse werden diskutiert.

The cation positions in dehydrated synthetic faujasite (zeolite 13Y, with a unit cell content approximately represented by NasTSiissA^Osst, Fd3m, a0 = 24.71 ± 0.02 A) and the analogous Kand Ag-exchange compounds (K57SÍ135AI57O384, 0 = 24.80 ± 0.02 A; Ag57Sii35-AI57O384, Oo = 24.85 ± 0.03 A) were determined with X-ray powder diffraction data by means of three-dimensional Fourier syntheses and the structures were refined by least squares. The cations Na+, K+, and Ag+ were found to occupy three different kinds of sites (I, II, III) on the threefold symmetry axes of the faujasite framework structure. These sites are associated with two sets of tetrahedrally arranged (Si, Al)eOe rings which with additional oxygen atoms define the "sodalite unit." Site I approaches, from outside of the sodalite unit, the center of the six-membered ring that faces the large absorption cavity of the structure; site II, from inside of the sodalite unit, approaches the second sixmembered ring which faces the center of symmetry. Site III is at the center of symmetry. A cation in site I or II has three nearest oxygen neighbors forming a regular triangle; in site III it is surrounded by six equidistant oxygens forming a moderately distorted octahedron. In all cases, site II has the smallest occupancy factor. The occupancy factor is close to unity for site I with Na+ and K+ and for site III with Ag+. For site I, the distances Na-0 2.33 A, K-0 2.72 A, and Ag-0 2.32 A were observed.

Röntgenographische Untersuchungen an Einkristallen von Fe2P2Se6 führten zu der Raumgruppe R3 mit Z = 3 in der hexagonalen Zelle, von Fe2P2S6 zu der Raumgruppe C2/m mit Z = 2. Die Verbindungen bilden Schichtgitter mit Doppelschichten von Chalkogenatomen, in deren Oktaederlücken Eisenatome und Phosphoratompaare so angeordnet sind, daß sich P2X5‐Baugruppen ergeben, die die Verbindungen eindeutig als Hexachalkogenohypodiphosphate charakterisieren. Die Strukturen unterscheiden sich durch die Anordnung der Doppelschichten, die beim Fe2P2Se6 eine annähernd hexagonal‐dichteste, beim Fe2P2S6 eine kubisch‐dichteste Packung der Chalkogenatome ergibt. Beide Verbindungen zeigen Kristallbaufehler, die auf Schraubenversetzungen und Stapelfehler zurückzuführen sind. Es werden die Bindungsverhältnisse sowie die Beziehungen der beiden Strukturen zum CdCl2‐Typ (C 19) und zum CdJ2‐Typ (C 6) diskutiert.

I n h a l t s u b e r s i c h t . TiPfi, kristallisiert orthorhombisch in der Raumgruppe Fdd? niit R = 10,842(4), b = 7,440(5), c = 41,535(6) -4 und Z = S. -411s 548 beobachteten syn~metrieunabhPugigei~ Reflexintensitiiten, die auf einem automatischen Z\izikreis-Einkristnlldiffraktometer gemessen ivurden, konnte die Kristallstruktur mit Hilfe einer direkten Methotle bcstimmt und bis R = ib.112 rerfeinert nerden. In der Kristallstruktur von TIP& trcten Y,S,-C;ruppen auf, wie sie fiir die Hexathiohypodiphosphate charakteritich sind. Jedes P-Atom ist tetraedrisch von drei S-Atonien (mittlerer Abstand 2,039 A) und einem weiteren P-Atom in Abstnncl von 2,807 A unigeben. TIP& kann daher als, Titan(1V)-hexathiohypodiphosphat interpret iert werden. Die P-P-Atompaare liegen jc-\veils parallel orientiert in Ebenen parallel zu (0 0 1). cber Ti-S-Bindungen erfolgt zunachst eine Verknupfung der P,S,-Gruppen zu Ketten, die nngefiihr in Richtung tler P-P-Achsen rerlaufen. Uber weitere Ti-S-Bindungen erfolgt eine dreidimensionale Vernetzung. Die Ti-dtonie erreichen auf diese Weise eine venerrte o k t d k c h e Koordination init Ahstiinden T i 4 ron 2,433 bis 9,454 d.TIPIS, repriisentiert einen neuen Strukturtyp, der mit den bereits bekannten Strukturtypen der Hexathiohypodiphosphate zneiwertiger Jletalle keine Verwandt sclinft nufweist. Synthesis and Crystal Structure of TiP;SsS b s t r a c t . TIP& is ort.horhombic, space group Fdd2 with a = lO.Y4'2(4), h = 7.440(5). c = 41.535(6) A and Z = 8. From 548 observed unique reflesions measured on a antomated two-circle single crystal diffractometer the crystal structure was determined by means of a direct method and refined to R = 0.112. The crystal structure of TiP,S, conta.inii P,Y, groups which are characteristic for hexathiohypodiphosphates. The P atoms are tetrahedrally surrouncled by three S ntomfi, (niean distance P-S: 2.039A) and one further P stom a t a distance of ?..107 -1. For this reasop,TiP2S, may be considered as titaninm(IV) hexathiohypodiphosphate. The P-P atom pairs are, located within planes parallel to (0 0 1) and.have parallel orientation in each of them. By Ti-S bonds the P2S6 p u p s are linked to chains running approximately in the direction of the P-P iises. By further Ti-S bonds a three-dimensional network is formed. I n this way the titanium atoms attain a distorted octahedral coordination with distances Ti-S ranging from 2.453 to 3.451 -\. TIP& represent3 a ne\v structure type unrelated to the known structure types of liesi~tl~iol~ypodip!~osphntcs of div.tlent metals.

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Copyrolysis of BzC14 and AsC1, at 330 "C leads to the forma-the products. At temperatures above 400 "C and higher tion of closo-1,2-As2B4C14 (1) and further products the mass B2C14/AsC13 ratios the formation of AszBloCllo is preferred to spectral evidence of which suggests that they are perchlorithat of smaller arsaboranes. A single-crystal X-ray study of 1 nated arsaboranes AsZB5Cl5, As4B8C16, and AszBloCllo. The confirmed that, consistent with its 14-skeletal electron count, pyrolysis temperature and the molar ratio of the reactants the arsaborane adopts a slightly distorted octahedral strucexert an essential influence on the type and distribution of ture with the arsenic atoms in adjacent cis positions.There are only very few boranes known so far containing two arsenic atoms in the polyhedral framework. They were synthesized by a reaction involving two arsenic insertions into decaborane in the presence of a base to yield clos0-1,2-As~B~~H~~['~~~. Derived thereof are closo-1 ,2-As2BloH812[3] and nido-7,8-As,B9H,['l. However, aside from l l -or 12-vertex arsaboranes there are no examples where arsenic atoms are part of frameworks deriving from smaller boron compounds.In this paper we report on the first direct method of combining arsenic and boron species starting from molecules with 2-center 2-electron bonds to yield several previously unknown small-and medium-sized polyhedral diarsaboranes with chlorine ligands attached to the boron atoms. Results and DiscussionRecently, we have reported on the thermal disproportionation of tetrahalodiboranes(4) BzX4 in the presence of the coreactants PX3, CX4, or C2X4 (X = C1, Br). Stable polyhedral heteroboranes such as clos0-1,2-P,B~C1~[~1(2), ~loso-l,2-P~B~Br~[~I, and C2BnXn+2 (n = 5-8)r6] could be obtained in case the reaction took place in the vapor phase. In order to apply this method to the preparation of heteroboranes aside from phospha-and carbaboranes we studied the copyrolyses of B2Cl4 with various other volatile main group halides.Preliminary attempts to prepare arsaboranes via copyrolysis of B2C14 with AsC13 under corresponding conditions in a single-flask reactor failed. Thereby trichloroarsane is reduced almost quantitatively by tetrachlorodiborane(4) to elemental arsenic and trichloroborane (eq. 1). This redox reaction already occurs in the mixture at room temperature. However, if B2C14 and AsCI3 are condensed into two separate flasks which are connected by a tube, and the reactants are transferred into a preheated oven immediately after sealing, simultaneous vaporization and pyrolysis partly suppress the redox reaction to give new arsaborane clusters. The reaction mixture can be sublimed fractionally. The components were identified by mass spectrometry as As2B4CI4 (I), B9C19, AS&Cl6, and -only in traces -as As2BSCIs. The remaining low-volatile residue contains As2BlDCl10 and elemental arsenic.The formation of A s~B~~C I~~ is favored compared to smaller arsaboranes when the pyrolysis is performed at higher temperatures. By increasing both the molar ratio B2Cld...

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