Boc-N-methyl-O-benzyl-L-threonine cyclohexyl ammonium salt

Treatment of N,N-bis-(pyridin-4-ylmeth-yl)cyclo-hexane-1,4-di-amine with hydro-chloric acid in ethanol led to the formation of the title salt, C18H26N42+·2Cl-·2H2O, which lies about a crystallographic inversion center at the center of the cyclo-hexyl ring. The asymmetric unit therefore comprises one half of the N,N-bis-(pyridin-4-ylmeth-yl)cyclo-hexane-1,4-di-ammonium dication, a chloride anion, and a solvent water mol-ecule. In the dication, the two trans-(4-pyridine)-CH2-NH2- moieties occupy equatorial sites at the 1- and 4-positions of the central cyclo-hexyl ring, which is in a chair conformation. The terminal pyridine ring is tilted by 27.98 (5)° with respect to the mean plane of the central cyclo-hexyl moiety (r.m.s. deviation = 0.2379 Å). In the crystal, dications, anions, and solvent water mol-ecules are connected via N/C/O-H⋯Cl and N-H⋯O hydrogen bonds together with C-H⋯π inter-actions, forming a three-dimensional network.

In the dication of the title salt, C(6)H(16)N(2) (2+)·2C(6)H(4)NO(2) (-), the two ammonium groups are in the equatorial positions of the chair-shaped cyclo-hexyl ring. In the crystal, the cations and anions are linked by N-H⋯O and N-H⋯N hydrogen bonds, forming a layer network parallel to the ac plane. Weak π-π inter-actions between adjacent pyridine rings with a centroid-centroid distance of 3.589 (2) Å are also present.

In the title salt, C6H14N(+)·NO3 (-), the cyclo-hexyl ring adopts a chair conformation. The ammonium group occupies an equatorial position and the crystal struture is stabilized by inter-molecular N-H⋯O hydrogen-bonding inter-actions, resulting in a three-dimensional network.