The title compound, C(12)H(16)N(2)O, is a diazepane inter-mediate that can be used as an inhibitor of human nitric oxide synthesis. In the mol-ecule, the seven-membered ring has a chair-like conformation and the two rings are approximately perpendicular to one another, with a C-N-C-C torsion angle of 77.8 (4)°. Inter-molecular N-H⋯O hydrogen bonds link the mol-ecules into dimers around a centre of symmetry, with C-H⋯O inter-actions linking the dimers into infinite sheets.