Comparative structural coordination chemistry of two tricyclic bisamidines

The tricyclic bisamidines L1 and L2 are designed to be preconstrained so as to present synperiplanar donor sites for metal coordination. Their very different bite angles of 35° and 70° result from the incorporation of two five-membered instead of six-membered rings in their respective backbones. Distinct coordination preferences in a variety of metal complexes have now been confirmed by X-ray structural studies. While L1 afforded monodentate, symmetrical and unsymmetrical chelating as well as bimetallic bridging modes in its complexes, L2 has been found exclusively in a bidentate chelating mode.

Graphical abstractThese two tricyclic bisamidines have been shown to have remarkably distinct coordination preferences in their transition metal complexes.Figure optionsDownload full-size imageDownload as PowerPoint slide