THE CRYSTAL-STRUCTURE AND VIBRATIONAL-SPECTRUM OF (C8H20N2)[INBR5(H2O)].H2O, A SALT OF THE 1,1,4,4-TETRAMETHYLPIPERAZONIUM DICATION CONTAINING THE AQUOPENTABROMOINDATE COMPLEX ANION

The preparation, crystal structure, and vibrational spectra of the title compound are reported. The compound crystallizes in the triclinic space group P1, with a = 7.386(2), b = 8.637(1), c = 16.546(2) Å, α = 97.40(1)°, β = 95.51(2)°, γ = 112.91(2)°, V = 951.6 Å3, ρobs = 2.43 g cm-3, Z = 2, ρcalcd = 2.424 g cm-3 (MoKα, = 0.71069 Å). The structure was solved by direct methods and electron density maps, and refined by full-matrix least squares to the final R = 0.038 for 3343 observed reflections. The structure consists of N,N,N′,N′-tetramethylpiperazonium cations containing a six-membered C4N2 heterocycle, InBr5(OH2)2- anions, and additional H2O solvent molecules. Infrared and Raman spectral bands of the InBr5(OH2)2- complex are assigned on the basis of C4ν skeletal symmetry, and the H2O molecule of crystallization is also detected spectroscopically.