Acetyl­ene–ammonia–18-crown-6 (1/2/1)

The title compound, C(2)H(2)·C(12)H(24)O(6)·2NH(3), was formed by co-crystallization of 18-crown-6 and acetyl­ene in liquid ammonia. The 18-crown-6 mol­ecule has threefold rotoinversion symmetry. The acteylene mol­ecule lies on the threefold axis and the whole mol­ecule is generated by an inversion center. The two ammonia mol­ecules are also located on the threefold axis and are related by inversion symmetry. In the crystal, the ammonia mol­ecules are located below and above the crown ether plane and are connected by inter­molecular N—H⋯O hydrogen bonds. The acetyl­ene mol­ecules are additionally linked by weak C—H⋯N inter­actions into chains that propagate in the direction of the crystallographic c axis. The 18-crown-6 mol­ecule [occupancy ratio 0.830 (4):0.170 (4)] is disordered and was refined using a split model.