structure and hydrogen bonding
The conformation of Homopiperazine is shown below, and the N–C–C–N torsion angle of 58.2(4)° confirms that the left-hand end of the molecule has an almost ideal chair-type conformation, which is only slightly distorted by the insertion of the extra atom at the right-hand end. The two nitrogen lone pairs are aligned in opposite directions, which facilitates the formation of a hydrogen-bonded network due to interaction with the NH of adjacent molecules.
Crystal data for C5H12N2, M = 100.16 g mol-1, colorless prism, crystal dimensions 0.10 × 0.10 × 0.10 mm3, tetragonal, space group I–42d (No. 122), a = b = 7.208(2), c = 23.094(7) Å, α = β = γ = 90.00°, V = 1199.9(6) Å3, Z = 8, Dcalc = 1.109 g cm-3, T = 93 K, R1 = 0.0637, Rw2 = 0.1633 for 536 reflections with I > 2σ(I), and 37 variables, Rint 0.0374, goodness of fit on F2 1.137. Data have been deposited at the Cambridge Crystallographic Data Centre as CCDC 2049324[1].
References
[1] R. Aitken, A. Slawin, Dheirya K. Sonecha. “Homopiperazine (Hexahydro-1,4-diazepine).” Molbank 2021 1 (2021): M1200.