An unprecedented DDQ-nickel(II)Salen complex interaction and X-ray crystal structure of nickel(II)Salen.DDH co-crystal

The charge transfer interaction between DDQ and [Ni(Salen)] complex was studied in the solution and solid state. The yellow color of [Ni(Salen)] dissolved in dichloromethane or chloroform was changed to green in the presence of the DDQ. Crystallization of charge transfer solid resulted to [Ni(Salen)].DDH, in which DDH was obtained from the catalytic reduction of DDQ via the oxidation of water. The DDH combined to [Ni(Salen)] to create [Ni(Salen)].DDH co-crystal by hydrogen bonding.