Hydrosilylation of Olefins Activated on Highly Lewis-Acidic Calcium Cation.

The report introduces simple yet highly reactive calcium salt, Ca[Al(OR)] (R=C(CF)), 1, which effectively catalyses olefin hydrosilylation through an unusual mechanism involving the activation of the alkene molecule. Upon dissolution in o-difluorobenzene (oDFB), 1 forms a highly Lewis acidic [Ca(oDFB)] complex. Our DFT calculations reveal that fluoride ion affinity is comparable to SbF. Reactivity tests show that it effectively catalyses the hydrosilylation of olefins with high regioselectivity, also in reactions involving sterically demanding substrates like (iPr)SiH or tetrasubstituted olefins. Experimental and computational results point to the mechanism where the olefin molecule forms a complex with Ca, which significantly facilitates the attack of H-SiR on the C=C double bond.