The compounds Ln2AuP3 were synthesized by reaction of the elemental components in evacuated silica tubes. Their crystal structures were determined from single-crystal diffractometer data. The compounds with Ln = La, Ce, and Pr crystallize with an orthorhombic U2NiC3 type structure (Pnma, Z = 4). The structure refinement for Ce2AuP3 resulted in a = 774.14(6) pm, b = 421.11(4) pm, c = 1612.3(1) pm, R = 0.019 for 1410 structure factors and 38 variable parameters. For Pr2AuP3 a residual of R = 0.024 was obtained. Nd2AuP3 crystallizes with a monoclinic distortion of this structure: P21/c, Z = 4, a = 416.14(4) pm, b = 768.87(6) pm, c = 1647.1(2) pm, β = 104.06(1)°, R = 0.022 for 1361 F values and 56 variables. The near-neighbor coordinations of the two structures are nearly the same. In both structures the gold and phosphorus atoms form two-dimensionally infinite nets, where the gold atoms are tetrahedrally coordinated by phosphorus atoms with Au–P distances varying between 245.8 and 284.2 pm. Two thirds of the phosphorus atoms form pairs with single-bond distances varying between 217.7 and 218.9 pm. Thus, using oxidation numbers the structures can be rationalized with the formulas (Ln+3)2[AuP3]–6 and (Ln+3)2Au+1(P2)–4P–3. Accordingly, La2AuP3 is a diamagnetic semiconductor. Pr2AuP3 is semiconducting with an antiferromagnetic ground state, showing metamagnetism with a critical field of Bc = 0.5(± 0.1) T. In contrast, the cerium compound is a metallic conductor, even though its cell volume indicates that the cerium atoms are essentially trivalent, as is also suggested by the ferro- or ferrimagnetic behavior of the compound. Der Halbleiter La2AuP3, der metallische Leiter Ce2AuP3 und andere Seltenerd-Gold-Phosphide Ln2AuP3 mit zwei nahe verwandten Kristallstrukturen Die Verbindungen Ln2AuP3 wurden durch Reaktion der Elemente in evakuierten Quarzglasampullen hergestellt und ihre Kristallstrukturen anhand von Einkristall-Diffraktometerdaten bestimmt. Die Verbindungen mit Ln = La, Ce und Pr kristallisieren in der orthorhombischen U2NiC3-Struktur (Pnma, Z = 4). Die Strukturverfeinerung von Ce2AuP3 ergab: a = 774,14(6) pm, b = 421,11(4) pm, c = 1612,3(1) pm, R = 0,019 für 1410 Strukturfaktoren und 38 variable Parameter. Für Pr2AuP3 wurde ein Restwert von R = 0,024 bestimmt. Nd2AuP3 kristallisiert in einer monoklinen Verzerrungsvariante dieser Struktur: P21/c, Z = 4, a = 416,14(4) pm, b = 768,87(6) pm, c = 1647,1(2) pm, β = 104,06(1)°, R = 0,022 für 1361 F-Werte und 56 Variable. Die Atomumgebungen in den zwei Strukturen sind nahezu identisch. In beiden Strukturen bilden die Gold- und Phosphoratome ein zweidimensional-unendliches Netz, wobei die Goldatome von Phosphoratomen tetraedrisch umgeben sind, mit Au–P-Abständen von 245,8 bis 284,2 pm. Zwei Drittel der Phosphoratome bilden jeweils Paare mit Einfachbindungsabständen zwischen 217,7 und 218,9 pm. Unter Verwendung von Oxidationszahlen können die Strukturen somit durch die Formeln (Ln+3)2[AuP3]–6 und (Ln+3)2Au+1(P2)–4P–3 beschrieben werden. Dementsprechend ist La2AuP3 ein diamagnetischer Halbleiter. Pr2AuP3 ist halbleitend mit einem antiferromagnetischen Grundzustand, welcher Metamagnetismus mit einer kritischen Feldstärke von Bc = 0,5(± 0,1) T zeigt. Im Gegensatz dazu hat die Cer-Verbindung metallische Leitfähigkeit, obwohl ihr Zellvolumen im wesentlichen dreiwertigem Cer entspricht, was auch durch das ferro- oder ferrimagnetische Verhalten der Verbindung nahegelegt wird.
CoIn3, RhIn3, and IrIn3 were synthesized by reacting the elements in sealed tantalum tubes at 1170 K and subsequent annealing at 770 K. The structures of the three compounds (FeGa3 type, space group P42/mnm) were refined from single crystal X-ray data: a = 682.82(6), c = 709.08(7) pm, wR2 = 0.0407, 397 F2 values for CoIn3, a = 698.28(8), c = 711.11(9) pm, wR2 = 0.0592, 418 F2 values for RhIn3, and a = 699.33(5), c = 719.08(5) pm, wR2 = 0.0625, 482 F2 values for IrIn3 with 16 parameters for each refinement. The structures may be considered as an intergrowth of tungsten-like building blocks of indium atoms and AlB2-like slabs of compositions In&Co, In&Rh, and In&Ir, respectively. These are compared with the related intergrowth variants found for compounds with ordered U3Si2 and Zr3Al2 type structure. Semi-empirical band structure calculations for RhIn3 reveal low density-of-states (DOS) at the Fermi level and negative Rh–Rh crystal orbital overlap populations (COOP) indicating antibonding Rh–Rh interactions. The bonding characteristics of CoIn3, RuIn3, and IrIn3 are similar to RhIn3. Magnetic susceptibility measurements of compact polycrystalline samples of CoIn3, RhIn3, and IrIn3 indicate weak Pauli paramagnetism. Struktur, Chemische Bindung und Eigenschaften von CoIn3, RhIn3 und IrIn3 CoIn3, RhIn3 und IrIn3 wurden durch Reaktion der Elemente bei 1170 K in verschweißten Tantalampullen und anschließendes Tempern bei 770 K synthetisiert. Die Kristallstrukturen der drei Verbindungen (FeGa3-Typ, Raumgruppe P42/mnm) wurden anhand von Einkristall-Diffraktometer-Daten verfeinert: a = 682,82(6); c = 709,08(7) pm; wR2 = 0,0407; 397 F2-Werte für CoIn3; a = 698,28(8); c = 711,11(9) pm; wR2 = 0,0592; 418 F2-Werte für RhIn3 und a = 699,33(5); c = 719,08(5) pm; wR2 = 0,0625; 482 F2-Werte für IrIn3 mit jeweils 16 Parametern. Die Strukturen können als Verwachsungsvarianten von Wolfram-ähnlichen Baueinheiten aus Indiumatomen und AlB2-ähnlichen Baueinheiten der Zusammensetzungen In&Co, In&Rh, und In&Ir beschrieben werden. Diese werden mit den sehr ähnlichen Verwachsungsvarianten von Verbindungen mit geordneter U3Si2- und Zr3Al2-Struktur verglichen. Semi-empirische Bandstrukturrechnungen für RhIn3 zeigen eine niedrige Zustandsdichte (DOS) an der Fermikante sowie negative Rh–Rh Kristall-Orbital-Überlappungspopulationen (COOP), was auf antibindende Rh–Rh-Wechselwirkungen hindeutet. Die Bindungscharakteristiken für CoIn3, RuIn3 und IrIn3 sind ähnlich. Magnetische Suszeptibilitätsmessungen an kompakten, polykristallinen Proben von CoIn3, RhIn3 und IrIn3 ergeben schwachen Pauli-Paramagnetismus.
Abstract New intermetallic compounds EuAgCd and YbAgCd were synthesized in quantitative yield by reaction of the elements in sealed tantalum tubes in a high-frequency furnace. Both com pounds were investigated by X-ray diffraction on powders and single crystals: KHg 2 type, Imma, a = 490.41(8), b = 771.0(1), c = 834.4(2) pm, wR2 = 0.0624, 255 F 2 values, 12 variables for EuAgCd, and MgZn 2 type, Pb 3 /mmc, a = 584.66(5), c = 946.83(9) pm, wR2 = 0.0502, 187 F 2 values, 11 variables for YbAgCd. Owing to the very small difference in scattering power, no long range ordering of the silver and cadmium atoms is evident from the X-ray data, although Ag-Cd ordering is expected. The silver and cadmium atoms randomly occupy the mercury and zinc positions of the KHg 2 and MgZn 2 type structures, respectively. In EuAgCd the [AgCd] substructure consists of strongly puckered, orthorhombically distorted Ag 3 Cd 3 hexagons, while a three-dimensional network of face-and comer-sharing tetrahedra is observed in YbAgCd. The rare earth atoms fill the space between the Ag 3 Cd 3 hexagons (EuAgCd) or within the three-dimensional tetrahedral network (YbAgCd). Magnetic susceptibility measurements in dicate Pauli paramagnetism for YbAgCd and Curie-Weiss behavior above 60 K for EuAgCd with an experimental magnetic moment of 7.82(3) μ B /Eu indicating divalent ytterbium and europium. Ferromagnetic ordering at Tc = 28.0(5) K is observed for EuAgCd. At 2 K and 5 T the saturation magnetization is 5.85(5) μ B /Eu.
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
