Die Kristallstrukturen von 1,4-Dimethylpiperazinium-tetrabromocobaltat(II) und -zinkat(II), (dmpipzH2) [MIIBr4] (M = Co, Zn) / The Crystal Structures of 1,4-Dimethylpiperazinium Tetrabromocobaltate(II) and -Zincate(II), (dmpipzH2) [MIIBr4] (M = Co, Zn)

Abstract

Abstract The compounds (dmpipzH2)[MIIBr4] (M = Co, Zn) crystallize at room temperature from equimolar solutions of 1,4-dimethylpiperazine and MBr2 · n H2O in 3M HBr. (dmpipzH2)[CoBr4] is isotypic with the homologous chlorometalates of Co and Zn and crystallizes in the mono­ clinic space group P21/m with a = 6.424(3), b = 14.588(6), c = 7.102(6) Å, β = 90.87(6)°, Z = 2. (dmpipzH2)[ZnBr4], however, crystallizes in the monoclinic space group P21/c with a = 7,605(5), b = 13,760(9), c = 13,286(7) Å, β = 93,03(6)°, Z = 4. Both structures contain centrosymmetric cations (dmpipzH2)2+ in the chair form and slightly distorted tetrahedra [MBr4]2- with a mirror plane in the case of M = Co. Several distances N···Br in both structures are interpreted in terms of N-H···Br hydrogen bonds which are favoured by the packing in the case of M = Zn.