4-Acetylpyridinium perchlorate

In the crystal of the title molecular salt, C7H8NO+·ClO4 −, the ions are linked by N—H⋯O hydrogen bonds, resulting in chains propagating in [010]. The packing is reinforced by C—H⋯O interactions.

In the crystal of the title molecular salt, C 7 H 8 NO + ÁClO 4 À , the ions are linked by N-HÁ Á ÁO hydrogen bonds, resulting in chains propagating in [010]. The packing is reinforced by C-HÁ Á ÁO interactions.
The author thanks the starter fund of Southeast University for financial support to buy the X-ray diffractometer.

S2. Experimental
4-Acetylpyridine was obtained according to the method described by Piner (1934) and colourless prisms of (I) were recrystallised from ethanol.

S3. Refinement
The positional parameters of all the H atoms were calculated geometrically and refined as riding with U iso (H) = 1.2U eq (carrier).  The molecular structure of (I) with displacement ellipsoids drawn at the 30% probability level (all H atoms have been omitted for clarity).

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq