Crystal structures of two bicyclo[5.1.0]octanes: potassium trans -bicyclo[5.1.0]octane-4-carboxylate monohydrate and cis -bicyclo[5.1.0]octan-4-yl 4-bromobenzenesulfonate

The crystal structures of the trans -fused compound potassium trans -bicyclo[5.1.0]octane-4-carboxylate monohydrate, K + ·C 9 H 13 O 2 − ·H 2 O, (I), and of cis -bicyclo[5.1.0]octan-4-yl 4-bromobenzenesulfonate, C 14 H 17 BrO 3 S, (II), have been determined. Compound (I) represents the smallest trans -fused cyclopropane structure known to date, and features the expected shortening of the bridging C—C bond relative to the other cyclopropane bond lengths, in contrast to the cis -fused system, (II), where all of the cyclopropane bond lengths are the same. The bicyclic ring system of (I) is disordered across a crystallographic mirror plane. The geometries of the cis -fused and trans -fused ring systems are compared.