A nona-vacant Keggin-type tricarbonyl rhenium derivative {[PMo3O16][Re(CO)3]4}5− and its catalytic performance for CO2 cycloaddition reactionsElectronic supplementary information (ESI) available: Experimental section, supplementary crystal structure figures, elemental analyses, IR spectrum, XRPD patterns, thermogravimetric analysis, and computational methods. CCDC 1057225. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c5ra14201f

A nona-vacant Keggin-type tricarbonyl rhenium derivative [(NH 4 ) 5 ]{[PMo 3 O 16 ][Re(CO) 3 ] 4 }·1.5H 2 O was obtained and characterized. Its frontier orbitals were computed by density functional theory (DFT) calculations. Furthermore, it could act as a Lewis acid catalyst and promote the conversion of CO 2 to cyclic carbonate under mild reaction conditions with pyrrolidinium bromide as a co-catalyst. A nona-vacant Keggin-type tricarbonyl rhenium derivative {[PMo 3 O 16 ][Re(CO) 3 ] 4 } 5− was synthesized and its frontier orbitals were computed. Interestingly, it showed good catalytic activity for the CO 2 cycloaddition reaction.