Das erste Bromid mit trigonal-bipyramidalen [M5(C2)]-Clustern: [Pr5(C2)]Br9

The First Bromide with Trigonal-Bipyramidal M₅(C₂)] Clusters: Pr₅(C₂)]Br₉ The bromide Pr₅(C₂)]Br₉ is obtained via metallothermic reduction of PrBr₃ with rubidium in the presence of praseodymium and carbon in a sealed niobium container at 730°C as dark red single crystals. Pr₅(C₂)]Br₉ crystallizes in the monoclinic crystal system P2₁/n; Z = 4; a = 1 006.9(1); b = 1 886.1(1); c = 1 045.9(1) pm; β = 108.130(1)°; R_int = 0.059; R1 = 0.038; wR2 = 0.077]. One edge in the base of the trigonal bipyramid in Pr₅(C₂)]Br₉ is usually long (440 pm). It is not brigded by a Brⁱ ligand. In addition to the eight Brⁱ, the cluster is coordinated by 12 terminal ligands (Br^a). Except for the known Br^a–a–a and Br^i–a connections, Br^i–a–a brigdes are observed for the first time for trigonal-bipyramidal clusters.