Syntheses and characterization of tetrakis(5-tert-butylpyrazole) Fe(II) and Mn(II) complexes. Molecular structure of Fe(Pz(t-Bu))(4)(OTF)(2)

Dichlorotetrakis(5-t-butylpyrazole)iron (1), dichlorotetrakis(5-t-butylpyra zole) manganese (2), and tetrakis(5-t-butylpyrazole) iron(II) bis(trifluoro methanesulfonate) (3) were prepared and characterized. The crystal structur e of 3 was determined from X-ray diffraction data. Complex 3 has a distorte d octahedral structure with the two triflate ligands at mutually trans posi tions. Complexes 1 and 2 are mild catalysts for the selective epoxidation o f styrene and norbornylene. In comparison, complex 3 is an efficient cataly st for the epoxidation of norbornylene, but promotes the oxidation of styre ne predominantly to benzaldehyde. (C) 1999 Elsevier Science Ltd. All rights reserved.