Cyclodimers versus cyclotrimers via solvent or temperature effects on metallacyclization.

The reaction of (COD)PdCl 2 (COD = 1,5-cyclooctadiene) with bis(3-pyridyl)methylphenylsilane (L) in acetone affords single crystals consisting of cyclodimers, [PdCl 2(L)] 2, whereas the reaction in a mixture of dichloromethane and ethanol yields amorphous spheres consisting of cyclotrimers, [PdCl 2(L)] 3. The interconversion and morphology control between the crystals and the microspheres can be explained by the difference in flexibility between the cyclodimer and cyclotrimer.