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)degre es. 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. Th e asymmetric coordination to the chalcogen atom, evidenced by the diss imilar exocyclic angles at the bridgehead C atoms, is no doubt a conse quence of steric interaction between the proximal H atoms ortho to the latter.