## Abstract

The new compounds CsUTe_{6}, CsTiUTe_{5}, Cs_{8}HfsUTe_{30.6}, and CsCuUTe_{3} have been synthesized through the reaction of the metals with a Cs_{2}Te_{n} flux. CsUTe_{6} crystallizes in space group D_{2h}^{16}-Pnma of the orthorhombic system with eight formula units in a cell of dimensions a = 30.801(7), b = 8.143(2), and c = 9.174(2) Å and V = 2301(1) Å^{3} (T = 113 K). CsTiUTe_{5} crystallizes in space group D_{2}h^{5}-Pmma of the orthorhombic system with two formula units in a cell of dimensions a = 6.130(1), b = 8.240(2), and c = 10.363(2) Å and V = 523.4(2) Å^{3} (T = 113 K). Cs_{8}Hf_{5}UTe_{30.6} crystallizes in space group C_{2H}^{5}-P2_{1/}c of the monoclinic system with four formula units in a cell of dimensions a = 12.043(3), b = 18.724(4), and c = 30.496(6) Å, β = 97.64(3)°, and V = 6816(2) Å^{3} (T= 113 K). CsCuUTe3 crystallizes in space group D_{2h}^{17}-Cmcm of the orthorhombic system with four formula units in a cell of dimensions a = 4.327(1), b = 16.661(4), and c = 11.337(3) Å, and V= 817.3(3) Å^{3} (T = 113 K). The structures of all four compounds were determined by single-crystal X-ray methods. CsUTe_{6} has a one-dimensional structure that contains pairs of U/Te chains coupled by Te-Te bonds and separated by Cs^{+} cations. There are many Te-Te distances less than 3.1 Å; if an arbitrary maximum Te-Te single bond distance is taken as 2.98 Å, then the chains may be formulated ^{1}∞[U_{2}(Te_{3})_{3}(Te_{2})(Te)^{2‒}], with U in the +IV oxidation state. The U atoms are coordinated to nine Te atoms in a tricapped trigonal-prismatic arrangement. Electrical resistivity measurements give conductivities of 1.6(4) × 10^{‒2} Ω^{‒1} cm^{‒1} (298 K) and 1.5(2) × 10^{‒3} Ω^{‒1} cm^{‒1} (77 K). CsTiUTe_{5} has a layered structure that contains UTe_{8} bicapped trigonal prisms sharing a common edge and TiTe_{6} octahedra sharing faces. Cs^{+} cations, located in pentagonal prisms of Te atoms, separate the layers. The structure contains an infinite linear Te-Te chain with a separation of 3.065(1) Å. Assignment from the structural results of formal oxidation states is difficult. Magnetic susceptibility data for CsTiUTe_{5} give a curvilinear x^{‒1} vs T plot. When fit to a modified Curie-Weiss law, the values C = 8.8(3) × 10^{‒2} emu K/mol, ⦵ = −1.5(2) K, and x_{0} = 2.11(8) × 10^{‒3} emu/mol result. The value of μ_{eff} (300 K) is 2.23(1) μ_{B} for each CsTiUTe_{5} unit. The resistivity of CsTiUTe_{5} at 77 K is beyond the detection limits of our instrument, but it is 1.2(9) × 10^{‒3} Ω^{‒1} cm^{‒1} at 298 K. Cs_{8}Hf_{5}UTe_{30.6} is a one-dimensional compound with ordered Hf and U atoms and disordered Te atoms in two unique chains that may be formulated ^{1}∞[Hf_{3}Te_{15 6}^{4_}] and ^{l}∞[Hf_{2}UTe_{15}^{4‒}]. Cs^{+} cations separate the chains. The Hf and Uatoms are coordinated to Te atoms in a distorted trigonal prismatic framework. Since there are many short Te-Te distances the assignment of formal oxidation states is not possible. CsCuUTe_{3} is a layered compound with no Te-Te bonding. Formal oxidation states are unambiguously Cs^{1}, Cu^{1}, U^{IV}, and Te^{II‒}. As expected, Cs^{+} cations separate the ^{2}∞[CuUTe^{3‒}] layers, which contain UTe_{6} octahedra and CuTe_{4} tetrahedra. This structure differs markedly from the channel structure of CsAg_{5}Te_{3} formed through an analogous synthesis with Cu replaced by Ag.

Original language | English (US) |
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Pages (from-to) | 3165-3172 |

Number of pages | 8 |

Journal | Inorganic chemistry |

Volume | 34 |

Issue number | 12 |

DOIs | |

State | Published - Jun 1 1995 |

## ASJC Scopus subject areas

- Physical and Theoretical Chemistry
- Inorganic Chemistry