Alkyl-chain disorder in tetraisohexylammonium bromide

Tetraisohexylammonium bromide [systematic name: tetrakis(4-methylpentyl)azanium bromide], C24H52N+·Br−, is a powerful structure II clathrate hydrate crystal-growth inhibitor. The crystal structure, in the space groupP3221, contains one ammonium cation and one bromide anion in the asymmetric unit, both on general positions. At 100 K, the ammonium cation exhibits one ordered isohexyl chain and three disordered isohexyl chains. At 250 K, all four isohexyl chains are disordered. In an effort to reduce the disorder in the alkyl chains, the crystal was thermally cycled, but the disorder remained, indicating that it is dynamic in nature.