Synthesis and decomposition of neutral palladium(IV) complexes containing fac-PdMe2R groups, including reductive elimination by etal-propenylpalladium(IV) complexes to form eta3-propenylpalladium(II) species

Oxidative addition of ethyl iodide to PdMe2(2,2’-bipyridyl) in (CD3)2CO gives the unstable “PdIMe2Et(bpy)“, which undergoes reductive elimination to form PdIR(bpy) (R = Me, Et), ethane, and propane. Ethene and palladium metal are also formed, and are attributed to decomposition of PdIEt(bpy) via beta-elimination. Similar results are obtained with n-propyl iodide, although a palladium(IV) intermediate was not detected, but CH2=CHCH2X (X = Br, I) and PhCH=CHCH2Br give isolable complexes fac-PdXMe2(CH2CH=CHR)(L2) (R = H, Ph; L2 = bpy, phen). The propenyl complexes decompose at ambient temperature to form ethane, a trace of PdXMe(L2), and mixtures of [Pd(eta3-C3H5)(L2)]X and [Pd(eta3-C3H5)(L2)][Pd(eta3-C3H5)X2]; for fac-PdBrMe2(CH2CH=CH2)(bpy) the major palladium(II) product is [Pd(eta3-C3H5)(bpy)]Br