Crystal structure of 2-bromo-3-di-methyl-amino-N,N,N',N',4-penta-methyl-4-(tri-methyl-sil-yloxy)pent-2-eneamidinium bromide.

The reaction of the ortho-amide 1,1,1-tris-(di-methyl-amino)-4-methyl-4-(tri-methyl-sil-yloxy)pent-2-yne with bromine in benzene, yields the title salt, C15H33BrN3OSi(+)·Br(-). The C-N bond lengths in the amidinium unit are 1.319 (6) and 1.333 (6) Å, indicating double-bond character, pointing towards charge delocalization within the NCN plane. The C-Br bond length of 1.926 (5) Å is characteristic for a C-Br single bond. Additionally, there is a bromine-bromine inter-action [3.229 (3) Å] present involving the anion and cation. In the crystal, weak C-H⋯Br inter-actions between the methyl H atoms of the cation and the bromide ions are present.