Selective Carbon−Carbon Bond Forming Reductive Elimination fromCycloplatinated(IV) Complexes

Oxidative addition involves the attachment of two groups A−B to a metal complex ofrelatively low oxidation state. This produces a new complex with an oxidation state two unitshigher than before.Reductive eliminationreaction is exactly the opposite of the oxidativeadditionreaction during which A and B are removed from metal center, during this process theoxidation number of the central metal decreases by two units.Since oxidative addition andreduction-elimination reactions are among the basic steps in many catalytic cycles,mechanisticinvestigations need to be studied more in depth to provide a useful basis for furtherdevelopments.In the present work, complex[Pt(bhq)(p-Me-C۶H۴)(H۲O)(OAc)۲], ۲, in which bhq =deprotonated benzo[h]quinolineis prepared through the reactionof [Pt(bhq)(p-Me-C۶H۴)(SMe۲)],۱with ۱ equiv of PhI(OAc)۲ via anoxidative addition (OA) reaction.Complex ۲ was fullycharacterized by means of۱H, ۱۳C, ۱۹۵Pt NMR and ESI-Mass spectroscopic techniques. Densityfunctional theory (DFT) calculationssignify that the OA reaction initiated by a nucleophilicattack of the platinum(II) central atom of ۱, on the Iodine(III) atom of PhI(OAc)۲while ithadcommenced by a nucleophilic substitution reaction of coordinated SMe۲with H۲O.In the nextstep ۲undergoselective C(sp۲)−C(sp۲)bond forming reductive elimination reaction at elevatedtempreture to form new Pt(II) complex ۳. DFT calculations showed that the reductiveelimination reaction occurs through three-center concertmechanism (Scheme ۱).

کلیدواژه ها:

Platinum complexes ، oxidation-addition reactions ، reductive elimination reactions