A Ni^II Phosphonate as an Efficient Catalyst for the Synthesis of Cyclic Carbonate under Ambient Conditions

The self-assembly of nickel(II) nitrate hexahydrate and a rigid tetraphosphonic acid (H8L) under hydrothermal conditions has resulted in the formation of a Ni-II phosphonate (1). In its structure, each phosphonyl group is protonated, along with the coordinated water molecules in the metal centers, endowing 1 with rich Bronsted acidic sites. The cycloaddition reaction of CO2 and epoxides was carried out under ambient conditions to investigate the catalytic activity of 1, and the results show its excellent performance in the catalysis. Moreover, compound 1 can be easily separated and reused without significant reduction in the catalytic ability. The heterogeneous nature along with good catalytic performance entitles 1 as an excellent catalyst for CO2 transformation.