A discrete {Co4(μ3-OH)4}4+ cluster with an oxygen-rich coordination environment as a catalyst for the epoxidation of various olefinsElectronic supplementary information (ESI) available. CCDC 1408240. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c5dt03422a

Using the sterically hindered terphenyl-based carboxylate, the tetrameric Co( ii ) complex [Co 4 (μ 3 -OH) 4 (μ-O 2 CAr 4F-Ph ) 2 (μ-OTf) 2 (Py) 4 ] ( 1 ) with an asymmetric cubane-type core has been synthesized and fully characterized by X-ray diffraction, UV-vis spectroscopy, and electron paramagnetic resonance spectroscopy. Interestingly, the cubane-type cobalt cluster 1 with 3-chloroperoxybenzoic acid as the oxidant was found to be very effective in the epoxidation of a variety of olefins, including terminal olefins which are more challenging targeting substrates. Moreover, this catalytic system showed a fast reaction rate and high epoxide yields under mild conditions. Based on product analysis and Hammett studies, the use of peroxyphenylacetic acid as a mechanistic probe, H 2 18 O-exchange experiments, and EPR studies, it has been proposed that multiple reactive cobalt-oxo species Co V &z.dbd;O and Co IV &z.dbd;O were involved in the olefin epoxidation. A tetranuclear Co( ii ) complex was active for epoxidation reactions of various olefins, and Co V &z.dbd;O and Co IV &z.dbd;O species were proposed to be the possible reactive intermediates.