- Palladium(II) and palladium(0) complexes of BINAP(O) (2-(diphenylphosphino)-2′-(diphenylphosphinyl)-1,1′-binaphthyl)
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The coordination organopalladium chemistry of 2-(diphenylphosphino)-2′-(diphenylphosphinyl)-1,1′-binaphthyl (BINAP(O)) was found to be totally different from that of other phosphine-phosphine oxide ligands, as well as of BINAP. The reaction of [(MeCN)2PdCl2] with BINAP(O) (1 equiv) afforded [(BINAP(O))PdCl2] (1), in which BINAP(O) is P,O-chelated to Pd in the solid state (X-ray) and in solution (NMR). Treatment of 1 with free BINAP(O) led to the reversible formation of a P,P-bonded nonchelate, [(BINAP(O))2PdCl2] (2), which could not be isolated due to the equilibrium being strongly shifted toward 1. Reduction of 1 with LiBH4 in the presence of BINAP(O) afforded a new zerovalent Pd complex [(BINAP(O))2Pd] (3), in which both BINAP(O) ligands are P-bonded to Pd and one provides η2-arene coordination via the C=C bond adjacent to the phosphinyl group (X-ray). Oxidative addition of PhI to 3 led cleanly to [(BINAP(O))Pd(Ph)I] (4; Ph trans to O; X-ray) which was also prepared by the reaction of [Pd2(dba)3] with BINAPO and PhI. The ultrasound-promoted I/F exchange reaction of [(BINAPO)Pd(Ph)I] with AgF afforded [(BINAP(O))Pd(Ph)F] (5), which was decomposed thermally to produce a mixture of P-F and C-P reductive elimination products.
- Marshall, William J.,Grushin, Vladimir V.
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