Giant Barocaloric Effect at the Spin Crossover Transition of a Molecular Crystal.

The first experimental evidence for a giant, conventional barocaloric effect (BCE) associated with a pressure-driven spin crossover transition near room temperature is provided. Magnetometry, neutron scattering, and calorimetry are used to explore the pressure dependence of the SCO phase transition in polycrystalline samples of protonated and partially deuterated [FeL2 ][BF4 ]2 [L = 2,6-di(pyrazol-1-yl)pyridine] at applied pressures of up to 120 MPa (1200 bar). The data indicate that, for a pressure change of only 0-300 bar (0-30 MPa), an adiabatic temperature change of 3 K is observed at 262 K or 257 K in the protonated and deuterated materials, respectively. This BCE is equivalent to the magnetocaloric effect (MCE) observed in gadolinium in a magnetic field change of 0-1 Tesla. The work confirms recent predictions that giant, conventional BCEs will be found in a wide range of SCO compounds.

A bimetallic iron(III) catalyst for CO2/epoxide coupling.

A novel di-iron(III) catalyst for the copolymerisation of cyclohexene oxide and CO(2) to yield poly(cyclohexene carbonate), under mild conditions, is reported. The catalyst selectivity was completely changed on addition of an ammonium co-catalyst to yield only the cis-isomer of the cyclic carbonate, also under mild conditions. Additionally, the catalyst was active for propylene carbonate and styrene carbonate production at 1 atm pressure.