4,4'-oxybispyridine and 4,4'-selenobispyridine

4,4'-Oxybispyridine, C10H8N2O, and 4,4'-selenobis-pyridine, C10H8N2Se, both adopt twist conformations, with twist angles of 69.2 (2) and 65.7 (2)degrees, respectively. In the oxy compound, the C-O bond lengths are 1.375(4) and 1.373(4) Angstrom, with the C-O-C angle 121.1(2)degrees. In the seleno compound, the C-Se bond lengths are 1.913 (3) and 1.913 (4) Angstrom, with the angle at the Se atom 100.40 (14)degrees. The asymmetric coordination to the chalcogen atom, evidenced by the dissimilar exocyclic angles at the bridgehead C atoms, is no doubt a consequence of steric interaction between the proximal H atoms ortho to the latter.