Pr₆C₂‐Doppeltetraeder in Pr₆C₂Cl₁₀ und Pr₆C₂Cl₅Br₅

Abstract

Pr6C2‐Bitetrahedra in Pr6C2Cl10 and Pr6C2Cl5Br5 The compounds Pr6C2Cl10 and Pr6C2Cl5Br5 are prepared by heating stoichiometric mixtures of Pr, PrCl3, PrBr3 and C in sealed Ta capsules at 810 − 820 °C. They form bulky transparent yellow to green and moisture sensitive crystals which have different structures: space groups C2/c, (a = 13.687(3) Å, b = 8.638(2) Å, c = 15.690(3) Å, β = 97.67(3)° for Pr6C2Cl10 and a = 13.689(1) Å, b = 10.383(1) Å, c = 14.089(1) Å, β = 106.49(1)° for Pr6C2Cl5Br5). Both crystal structures contain C‐centered Pr6C2 bitetrahedra, linked via halogen atoms above edges and corners in different ways. The site selective occupation of the halogen positions in Pr6C2Cl5Br5 is refined in a split model and analysed with the bond length‐bond strength formalism. The compound is further characterized via TEM investigations and magnetic measurements (μeff = 3.66 μB).

The First Structure with Isolated Carbon‐Centered Tetrahedra of Rare‐Earth Metals – the New Compound Ce4CCl8

“…Each tetrahedral center is occupied by a single C 4Ϫ ion, hence, the compound is electron precise which rationalizes the transparency of the yellow crystals. Furthermore, Ln 6 C 2 Cl 10 (Ln ϭ Ce, Pr) was synthesized crystallizing in the same space group type but in a different structure [16,17].1023 structure contains C-centered Ce 4 C single tetrahedra, linked by chlorine atoms above edges and corners in different ways. The compound is further characterized by HRTEM, electrondiffraction investigations and magnetic measurements.…”

“…Each tetrahedral center is occupied by a single C 4Ϫ ion, hence, the compound is electron precise which rationalizes the transparency of the yellow crystals. Furthermore, Ln 6 C 2 Cl 10 (Ln ϭ Ce, Pr) was synthesized crystallizing in the same space group type but in a different structure [16,17].…”