Kurt O. Klepp

Transition metal-chalcogen systems viii: The CrTe phase diagram

Abstract The CrTe phase diagram was investigated in the composition range 30–100 at.% Te using differential thermal analysis and powder diffraction methods. Six NiAs-related phases were characterized between 52.4 and 62 at.% Te. Two of them, hexagonal Cr 1− x Te (52.4–53.5 at.% Te) and monoclinic Cr 3 Te 4 -h (53.5–59.3 at.% Te), are high temperature phases. At lower temperatures monoclinic Cr 3 Te 4 -l (56.4–59.2 at.% Te) and trigonal Cr 2 Te 3 (59.5–60.0 at.% Te) are stable. Two phases, monoclinic Cr 5 Te 8 -m (59.6–61.5 at.% Te) and trigonal Cr 5 Te 8 -tr (61.5–62.0 at.% Te), were found on the tellurium-rich side of this phase system. At 75 at.% Te monoclinic CrTe 3 , a novel polytelluride, is formed in a peritectic reaction at 753 K. There are also indications of the formation of another tellurium-rich phase at about 70 at.% Te and 734 K.

Darstellung und Kristallstrucktur von TlCu3Te2: Ein tellurocuprat mit aufgefülltem CuAl2-typ

Zusammenfassung TlCu3Te2 kristallisiert tetragonal, Raumgruppe P42/nnm mit a = 8,427(4) A , c = 14,492(6) A , Z = 8. Die Kristallstruktur wurde uber Vierkreisdiffraktometerdaten bestimmt und auf einen konventionellen R-Wert von 0,072 (405 Reflexe mit I > 3σ(I)) verfeinert. TlCu3Te2 kristallisiert in einem neuen Strukturtyp, der durch ein anionisches Netzwerk von CuTe4-Tetraedern gekennzeichnet ist. Die Tl+-Ionen befinden sich in Kanalen, die das Netzwerk in [001]-Richtung durchziehen. Sie werden von 8 Telluratomen in einer verzerrten quadratisch-antiprismatischen Anordnung koordiniert. Die Tl-Te Partialstruktur ist mit dem CuAl2-Typ verwandt. Die grundlegende Baueinheit der Tellurpackung kann als abgeplatteter Tetraederstern beschrieben werden. Sie wird von vier ausseren Tetraedern gebildet, die ein inneres Tetraeder umschreiben. In c-Richtung sind die Tetraedersterne uber Flachen zu Kolonnen verknupft. Die Kolonnen besitzen gemeinsame Kanten, so dass ein dreidimensionales Gerust aufgebaut wird, in dem die Kupferatome alternierend innere und aussere Tetraederplatze besetzen.

A copper(II) azide compound of pyrazinic acid containing a new dinuclear complex anion [Cu2(N3)6]2−. Synthesis, spectral and study of KCu2(pyrazinato) (N3)4

Abstract A new complex of copper(II) azide with pyrazinic acid, of general formula KCu2(pyrazinato)(N3)4 has been synthesized and characterized by spectroscopic and crystallographic methods. The structure of the complex consists of a new dinuclear complex anion [Cu3(N3)6]2−, potassium cations and neutral polymeric complex [Cu(pyrazinato)(N3)]. Each distorted square-planar copper centre [Cu(1)] in the complex anion is coordinated to four nitrogen atoms from two terminal and two μ-(1,1) bridging azido ligands [CuN distances 1.940(6)–2.011(5) A]. In the polymeric complex, each copper atom, Cu(2), is coordinated to N(41) of a terminal azido group and N(61), N(62) and O(31) from pyrazinato anions to form infinite, “neutral” chains of polyhedra with orientations along [010]. The potassium cations are located in broad channels which are a consequence of stacking of the copper complexes. The IR spectrum confirms the presence of different asymmetric azido ligands. The absorption frequencies of diagnostic values are given and discussed. The electronic spectrum displays three absorption bands associated with N3−CuII charge transfer transitions. The EPR spectrum of the solid complex suggests an axial structure with non-coupled copper(II) atoms.

Preparation and crystal structure of Na4Cu2S3, a thiocuprate with discrete anions

Abstract Transparent pale yellow crystals of Na 4 Cu 2 S 3 were obtained from the melt of a corresponding mixture of the binary sulphides. Na 4 Cu 2 S 3 is tetragonal, space group I4 1 /a with a = 9.468(1) A , c=36.64(2) A and Z=16 . The crystal structure was determined from four-circle diffractometer data and refined to a conventional R of 0.021 for 1682 observed reflections with F 0 2 > 3 σ ( F 0 2 ) and 83 variables. An outstanding feature of Na 4 Cu 2 S 3 is the formation of discrete V-shaped thiocuprate anions [SCuSCuS] 4− with copper in an almost linear coordination by sulphur. The bond lengths ( d CuS =2.15 A ) and angles are in good agreement with those of the infinite anionic chains of KCuS. The crystal structure is based on a cubic close-packed arrangement of sulphur atoms with sodium in the centres of the tetrahedral voids, while copper atoms are shifted from the centres towards one of the edges in order to attain a linear co-ordination.

Synthesis and crystal structure of Cu4TiS4: a novel chalcogenide with tetrahedrally coordinated titanium

Abstract Dark red single crystals of Cu 4 TiS 4 were prepared by reacting an intimate mixture of Cu 2 S, Ti and S at 500°C. Cu 4 TiS 4 is tetragonal, space group I 4 2m with a = 5.448(1) A , c = 10.565(2) A , Z = 2 . The crystal structure is of a new type. It was determined from diffractometer data and refined to a conventional R of 0.024 for 132 F 0 s and 17 variables. The crystal structure is based on a cubic close packing of chalcogen with Cu and Ti in tetrahedral interslices. This results in a three-dimensional framework of vertex sharing CuS 4 tetrahedra which are connected with the almost regular TiS 4 tetrahedra through common edges. The bond lengths are d( TiS ) = 2.278 A and d( CuS ) = 2.333 to 2.351 A .

Na7Au5S6 — A novel thioaurate(I) based on a b.c.c. chalcogen packing

Abstract Colourless transparent crystals of Na 7 Au 5 S 6 were prepared by reacting a stoichiometric mixture of Na 2 S, gold and sulphur at 1070 K. The compound is orthorhombic, oP72, space group Pbcn (number 60) with a=10.424(6) A , b=7.024(6) A , c=22.27(1) A and Z =4. The compound crystallizes with a new structure type, which was determined from single-crystal diffractometer data (Mo Kα radiation). The structure was solved by direct methods and refined to a conventional R of 0.062 ( R w =0.059) for 685 F o with F o 2 >4 σ ( F o 2 ). The outstanding feature of Na 7 Au 5 S 6 — in a partial ionic description — is the coexistence of two very different anionic species — infinite ∞ 1 (AuS) − chains and isolated (AuS 2 ) 3− dumbbells — in its structure. In both anions gold is doubly coordinated by sulphur; Au-S distances are close to 2.30 A; and S-Au-S bond angles vary from 170.3° to 180°. The Na + ions which separate the anions are in a distorted tetrahedral sulphur coordination. The crystal structure is based on a cubic body-centred packing of chalcogen atoms; the principles of this packing are discussed.

Heterobimetallic cluster of [WOS3]2− with copper(I) chloride: synthesis and structural characterization of a new dinuclear complex [Me4N]2[WOS3(CuCl)]

Abstract Orange–yellow crystals of the new dinuclear complex [Me 4 N] 2 [WOS 3 (CuCl)] were formed by the reaction of [Me 4 N] 2 [WOS 3 ] with CuCl in a mixture of 1:1 MeCN/CH 2 Cl 2 at room temperature. The new compound has been characterized by infrared and mass spectrometry. The crystal structure of the complex has been determined from single crystal diffractometer data (Mo Kα-radiation) and it is characterized as binuclear complex anions [WOS 3 (CuCl)] 2− .

Quaternary chalcogenides of the IVa metals with layered structures: preparation and crystal structures of TlCuTIVQ3 (T=Zr, Hf; Q=S, Se) and their relation to the Re3B structure type

Abstract The new compounds TlCuT IV Q 3 (T = Zr, Hf; Q = S, Se) were prepared by reacting intimate mixtures of Tl 2 S or TlSe with stoichiometric amounts of the corresponding Group IV metal, Cu and the corresponding chalcogen at 870°C. The four compounds are isostructural and crystallize in Cmcm , Z = 4 with a = 3.726(4) A , b = 13.987(9) A , c = 9.783(4) A for TlCuZrS 3 ; a = 3.847(1) A , b = 14.381(6) A , c = 10.150(1) A for TlCuZrSe 3 ; a = 3.694(1) A , b = 14.030(3) A , c = 9.750(3) A for TlCuHfS 3 ; and a = 3.831(1) A , b = 14.409(9) A , c = 10.124(2) A for TlCuHfSe 3 . Their crystal structures were determined from single crystal diffractometer data (Mo Kα radiation, ambient temperature) and refined to conventional R values of 0.016, 0.040, 0.019 and 0.031 respectively. An outstanding feature of their crystal structures is the formation of infinite anionic layers, 2 x -[CuT IV Q 3 ] − parallel to (010), which are separated by Tl 2 cations. These layers are built up by edge sharing TQ 6 octahedra and distorted CuQ 4 tetrahedra. Average T-Q distances are d ( ZrS ) = 2.586(1) A , d ( ZrSe ) = 2.707(1) A , d ( HfS ) = 2.569(2) A and d ( HfSe ) = 2.694(1) A . Cu-chalcogen distances are d ( CuS ) = 2.318(2) A and d ( CuSe ) = 2.432(3) A respectively. The thallium ions are in bicapped trigonal prismatic chalcogen coordinations. The atomic arrangement corresponds to that of KCuZrS 3 ; based on the thallium-chalcogen partial structure it can be regarded as a filled variant of an anti -Re 3 B structure type.

Preparation and crystal structure of Na7Cu12S10, a mixed valent thiocuprate with a pseudo-one-dimensional structure

Abstract The novel mixed valent thiocuprate Na 7 Cu 12 S 10 was prepared by a fusion reaction of the binary sulphides Na 2 S and Cu 2 S and sulphur at 800 °C. Na 7 Cu 12 S 10 is monoclinic, space group P 2/ m , with a = 16.074(9) A , b = 3.847(1) A , c = 16.222(8) A , β = 91.94(3)° and Z = 2. The crystal structure was determined from single-crystal data and refined to a conventional R of 0.052 for 1976 observed reflections with F o 2 ⩾ 4o(F o 2 and 178 variables. The structure is pseudo-one-dimensional, characterized by a novel type of infinite triple chains ∞ 1 -[Cu 12 S 10 ] 7− which are formed by condensation of ∞ 1 -[Cu 4 S 4 ] units via common sulphur atoms. The unit cell contains two crystallographically independent moieties. The Na ions occupy octahedral voids in the h.c.p. arrangement of the chalcogen atoms.

Darstellung und Kristallstruktur von Tl4TiS4, TI4SnS4 und Tl4TiSe4 / Preparation and Crystal Structure of Tl4TiS4, TI4SnS4 and Tl4TiSe4

Abstract The isostructural compounds Tl4TiS4, Tl4SnS4 and Tl4TiSe4 crystallize in the monoclinic system, space group P21/c with a = 8.328, b = 8.191, c = 15.248 Å, β = 104.53°; a = 8.395, b = 8.280, c = 15.398 A, ft = 103.69°, and a = 8.517, b = 8.389, c = 15.672 Å, β = 103.50°, respectively. There are four formula units in the unit cell. The crystal structures were determined and refined from single crystal diffractometer data. They are characterized by isolated tetrahedral thioanions which are connected with each other by Tl+ ions. The mean bond lengths are Ti-S = 2.26 Å, Sn-S = 2.40 Å and Ti -Se = 2.38 Å. The Tl atoms are surrounded by six and seven chalcogen atoms, respectively, in an irregular and polar arrangement, thus indicating stereochemical activity of the lone electron pair of the Tl+ ions. Tl-S distances vary from 2.93 to 3.98 Å, Tl-Se distances from 3.03 to 3.96 Å. The Tl atoms have nearest Tl neighbours at distances ranging from 3.46 to 3.65 Å. The crystal structure can be described as built from pseudotetragonal slabs oriented parallel to (001) which contain the cations and the tetrahedral anions. It is shown that a similar description is valid also for the crystal structures of Tl4GeS4 [1] and Na4SnS4 [2, 3].