Creation and stabilisation of tuneable open metal sites in thiocyanato-bridged heterometallic coordination polymers to be used as heterogeneous catalysts.

A series of thiocyanato-bridged heterometallic coordination polymers with a 3D reticular network have been synthesised by the reaction of [PtIV(SCN)6]2- with MII ions to form {MII[PtIV(SCN)6]}n and {[MII(CH3OH)2][PtIV(SCN)6]}n (MII = MnII, FeII, CoII, NiII or CuII) in water and methanol, respectively. Single-crystal X-ray analyses revealed the absence of open metal sites in {MII[PtIV(SCN)6]}ns and the formation of potential open metal sites at the MII ions of {[MII(CH3OH)2][PtIV(SCN)6]}ns by the coordination of methanol. One of the two coordinating methanol molecules in {[CoII(CH3OH)2][PtIV(SCN)6]}n was replaced with pyridine to stabilise the open metal sites, because the methanol molecules are too labile to maintain open metal sites in water. The heterogeneous catalysis of coordination polymers with and without open metal sites was examined for organophosphate hydrolysis and photocatalytic water oxidation to clarify the requisites for heterogeneous catalysts.