Conformational Changes and Redox Properties of Bimetallic Single Helicates of Hexapyrrole-α,ω-dicarbaldehydes.

The hexapyrrole-α,ω-dicarbaldehydes 1 a and 1 b were metallated with Cu , Ni , and Pd to give bimetallic complexes where a pair of 3 N+O four-coordinate metal planes are helically distorted and the central 2,2'-bipyrrole subunit adopts a cis or trans conformation. X-ray crystallographic analysis of the bisCu complex revealed a closed form with a cis-2,2'-bipyrrole subunit and an open form with a trans-2,2'-bipyrrole subunit. The bisPd complexes took a closed form both in the solid state and in solution.