Crystal structures of two bi-cyclo-[5.1.0]octa-nes: potassium trans -bi-cyclo-[5.1.0]octane-4-carboxyl-ate monohydrate and cis -bi-cyclo-[5.1.0]octan-4-yl 4-bromo-benzene-sulfonate

The crystal structures of the -fused compound potassium -bi-cyclo-[5.1.0]octane-4-carboxyl-ate monohydrate, K ·C H O ·H O, (I), and of -bi-cyclo-[5.1.0]octan-4-yl 4-bromo-benzene-sulfonate, C H BrO S, (II), have been determined. Compound (I) represents the smallest -fused cyclo-propane structure known to date, and features the expected of the bridging C-C bond relative to the other cyclo-propane bond lengths, in contrast to the -fused system, (II), where all of the cyclo-propane bond lengths are the same. The bicyclic ring system of (I) is disordered across a crystallographic mirror plane. The geometries of the -fused and -fused ring systems are compared.