Can Immobilization of an Inactive Iron Species Switch on Catalytic Activity in the Suzuki Reaction

We examined the synthetic and catalytic claims that immobilization of an Fe-PNP pincer complex (1) on an amine-modified graphene oxide support yields a useful heterogeneous catalyst for the Suzuki biaryl cross-coupling reaction. Complex 1 is not formed under the reported conditions, rather the iron sulfate heptahydrate starting material (melanterite) undergoes partial dehydration to give iron sulfate tetrahydrate (rozenite). Neither rozenite nor melanterite are catalytically competent.