posted on 2019-03-13, 00:00authored byArunangshu Kundu, Swagata Saikia, Manoj Majumder, Oindrila Sengupta, Biswajit Bhattacharya, Gobinda Chandra De, Sushobhan Ghosh
Three new multicomponent
crystals 1a–1c of
Zn(II), Mn(II), and Co(II), respectively, were synthesized by the
reaction of 2,6-bis(hydroxymethyl)pyridine, the respective metal salts,
and sodium benzoate in a 1:1:2 ratio. One component of these multicomponent
crystals 1a–1c is the dicationic 2,6-bis(hydroxymethyl)pyridine
metal complex and the other component is the dianionic tetrabenzoate
complex of the same metal. The complexes were fully characterized
by single-crystal X-ray structure determination. The X-ray structure
of these compounds 1a–1c reveals the formation
of 1D supramolecular chain parallel to the crystallographic b axis via H-bonding interactions between the dicationic
and dianionic parts of the respective compound. The Mn(II) (1b) and Co(II) (1c) complexes show antiferromagnetic
coupling between the two associated metal centers via the H-bonding
interaction pathway. All the three compounds 1a–1c were tested as heterogeneous catalytic systems for the successful
conversion of epoxides to cyclic carbonates in solvent-free condition
under approximately 10 bar of pressure of CO2 and temperature
ranging between 60 and 80 °C along with tetrabutyl ammonium bromide
acting as a cocatalyst. All the three compounds 1a–1c were found to have turnover number more than 1000 for the respective
epoxides except for the conversion of cyclohexene oxide to cyclohexene
carbonate.