Diane Dickie - Investigation of metal cyclam complexes as potential catalysts for the production of dimethyl carbonate.

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      Publication Details (including relevant citation   information):

      Stewart,Constantine A., Dickie,Diane A., Kemp,Richard A.,   Inorg. Chim. Acta, 2012, 392,   pp 268-276

      Abstract:

      While Zn cyclam complexes are known to readily react with CO2 and   methanol to provide carbonato complexes, we were interested in   trying to extend this chem. into a possible catalytic cycle for   the prodn. of di-Me carbonate. This route would require a   cleavage of the Zn-carbonato complex with methanol. Towards this   goal we modified the cyclam ligands by attaching various Lewis   basic donors as pendant groups on the cyclam that could   potentially act as hemilabile arms. The crystal structures of   1-(2-pyridylmethyl)-1,4,8,11-tetraazacyclotetradecane 2,   1-(3-pyridylmethyl)-1,4,8,11-tetraazacyclotetradecane 3, and   1-propionitrile-1,4,8,11-tetraazacyclotetradecane 4 are   presented. Ligand 2 was reacted with M[ClO4]2 (M = Zn, Cd) and   the resulting complexes were structurally and spectroscopically   characterized. Despite the modifications, again these complexes   did not perform as catalysts for the formation of di-Me   carbonate. Ligand 4 was found to react with methanol in the   presence of Zn[ClO4]2·6H2O to convert the nitrile group into a Me   propionimidate, forming the Me propionimidate   (1,4,8,11-tetraazacyclotetradecane) zinc perchlorate. It is   likely that the donor arms used bind too strongly to Zn or Cd to   allow complexation of CO2 or methanol. [on SciFinder(R)]

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