Macrocyclic Metal Complexes Bearing Rigid Polyaromatic Ligands: Synthesis and Catalytic Activity.

We synthesised palladium and platinum complexes possessing cyclic and acyclic pincer-type polyaromatic ligands and investigated their structural effect on the catalysis. The pincer-type bis(6-arylpyridin-2-yl)benzene skeleton was constructed via Kröhnke pyridine synthesis under transition metal-free conditions on gram-scale quantity. Ligand structure significantly influenced catalytic activity toward the platinum-catalysed hydrosilylation of diphenyl acetylenes, despite the ligand-independence of the conformations and electronic properties of these complexes.