METALS IN ORGANIC SYNTHESIS. XIV. NMR, IR, AND REACTIVITY STUDIES ON THE OLEFIN HYDROFORMYLATION CATALYZED BY Pt-Sn COMPLEXES

Article abstract of DOI:10.1016/0022-328X(86)80399-0

Among the several hydrides formed when trans- (L=PPh3) reacts with SnCl2, only trans- rapidly inserts ethylene, at -80 deg C, to yield cis-.At -10 deg C, cis- irreversibly rearranges to the trans-isomer, thus indicating that the cis-isomer is the kinetically controlled species, and that the trans-isomer is thermodynamically more stable.At -50 deg C, a mixture of trans- and trans- reacts with ethylene to give cis- and this has been attributed to the catalytic activity of SnCl2 which dissociates from cis- at this temperature.Carbon monoxide promotes the cis-trans isomerization of cis-, which occurs rapidly even at -80 deg C.This rearrangement is followed by a slower reaction leading to the cationic complex trans-(1+)SnCl3(1-).At -80 deg C, this complex does not react further, but when it is kept at room temperature ethyl migration to coordinated carbon monoxide takes place, to give several Pt-acyl complexes, i.e. trans-, trans-, trans-, and trans-(1+)SnCl3(1-).This mixture of Pt-acyl complexes reacts with molecular hydrogen to yield n-propanal and the same complex mixture of platinum hydrides as is obtained by treating trans- with SnCl2.