Organometallic chemistry of diphosphazanes-13.¹ Palladium complexes of unsymmetrical diphosphazanes Ph₂PN(Prⁱ)PYY'

Abstract

Unsymmetrical diphosphazanes Ph₂PN(Prⁱ)PYY' [YY' = O₂C₁₂H₈ (L¹), O₂C₂₀H₁₂(L²); Y = Ph and Y' = OC₆H₄Br-4 (L³), OC₆H₄Me-4 (L₄), OC₂H₃Me₂-3,5 (L¹), N₂C₃HMe₂-3,5 (L⁶)] react with cis-[PdCl₂(COD)] (COD = cycloocta-1,5-diene) giving the chelate complexes of the type cis-[PdCl₂{η²-Ph₂PN(Prⁱ)PYY'}] [YY' = O₂C₁₂H₈ (1), O₂C₂₀H₁₂ (2); Y' = OC₆H₄Br-4 (3), OC₆H₄Me-4 (4), OC₆H₃Me₂-3,5 (5), N₂C₃HMe₂-3,5 (6)]. The P---N bond in 3 and 5 undergoes a facile cleavage in methanol solution to give cis-[PdCl₂{η¹-Ph₂P(OMe)}{η¹-PhP(NHPr ⁱ)(Y')}] [Y' = OC₆H₄Br-4 (7), OC₆H₃Me₂-3,5 (8)]. Reactions of Pd₂(dba)·CHCl₃ (dba = dibenzylideneacetone) with the diphosphazanes Ph₂PN(Prⁱ)PPhY' [Y' = OC₆H₄Me-4 (L⁴), N₂C₃HMe₂-3,5, (L⁶), N₂C₃H₃ (L⁷) in the presence of MeI yields cis-[PdI₂{η²-Ph₂PN(Prⁱ)PPhMe}] (9); the P---O or P---N (pyrazolyl) bond of the starting ligands is cleaved and a P---C(Me) bond is formed. An analogous oxidative addition reaction in the presence of Ph₂PN(Prⁱ)PPh₂ (L⁸) yields cis-[PdI(Me)(η²-L⁸)] (11) and cis-[PdI₂(η²-L⁸)] (11). The structures of 8 and 9 have been determined by X-ray diffraction.