Larsen, John W. published the artcileThermodynamic stabilities of some cyclic halonium ions in magic acid, SDS of cas: 594-81-0, the publication is Journal of the American Chemical Society (1972), 94(5), 1614-19, database is CAplus.
The heats of formation of a series of methyl-substituted ethylene- and tetramethylene-bromonium ions and a chloronium ion from the appropriate dihaloalkane precursors were measured calorimetrically in 11.5 mole % SbF5-F SO3H at -60°. The tetramethylenebromonium ions are about as stable as the tert-Bu cation and are ∼10 kcal/mole more stable than a correspondingly substituted ethylenebromonium ion. The tetramethylenechloronium ion is ∼7.5 kcal/mole less stable than its bromo analog. The interaction of a Me group with a 3-membered ring is unusually favorable.
Journal of the American Chemical Society published new progress about 594-81-0. 594-81-0 belongs to bromides-buliding-blocks, auxiliary class Bromide,Aliphatic hydrocarbon chain, name is 2,3-Dibromo-2,3-dimethylbutane, and the molecular formula is C6H12Br2, SDS of cas: 594-81-0.
Referemce:
https://en.wikipedia.org/wiki/Bromide,
bromide – Wiktionary