The synthesis and crystal structure of 2-(chloroselanyl)pyridine 1-oxide: The first monomeric organoselenenyl chloride stabilized by an intramolecular secondary Se⋯O interaction

The title compound, C5H4ClNOSe, is the product of the reaction of sulfuryl chloride and 2-selanyl-1-pyridine 1-oxide in dichloromethane. The molecule has an almost planar geometry (r.m.s. deviation = 0.012Å), and its molecular structure is stabilized by an intramolecular secondary Se⋯O interaction of 2.353(3)Å, closing a four-membered N - C - Se⋯O ring. The title compound represents the first monomeric organoselenenyl chloride stabilized intramolecularly by an interaction of this type. The non-valent attractive Se⋯O interaction results in a substantial distortion of the geometry of the ipso-carbon atom. The endo-cyclic N - C - Se [102.1(3)°] and exo-cyclic C - C - Se [136.9(3)°] bond angles deviate significantly from the ideal value of 120° for an sp 2-hybridized carbon atom, the former bond angle being much smaller than the latter. In the crystal, molecules are linked by C - H⋯O hydrogen bonds, forming zigzag chains propagating along [010]. The chains, which stack along the a-axis direction, are linked by offset π-π interactions [intercentroid distance = 3.960(3)Å], forming corrugated sheets parallel to the ab plane.