Acetohydrazide.

In the title compound, C(2)H(6)N(2)O, a hydrazine derivative, the asymmetric unit contains two mol-ecules with similar geom-etries. The crystal structure is stabilized by inter-molecular N-H⋯O hydrogen bonds.

Substituent effects control the self-association of molecular clips in the crystalline state.

We report the X-ray crystal structure of 11 molecular clips and analyze the influence of substituents (e.g., OMe, Me, and NO2) and their location on the observed crystal packing.