Salen aluminum complex and its use as a catalyst

The invention is directed to an optionally substituted salen Al complex having a 3-pyridinium bridging group. Further a catalyst system is described comprising this complex according, optionally supported and a bromide salt or a iodide salt as a co-catalyst. The catalyst system was used in a process to prepare a cyclic carbonate by reacting an epoxide compound and CO₂ at a moderate pressure.