Bis-cyclometalated complexes of Pd(II) and Pd(IV) from iminophosphoranes: Synthesis, structure and reactivity

Transmetallation of iminophosphoranes from [Li{C6H4(PPh2NPh)-2}]2 to chloride-bridge dimers [Pd(μ-Cl)(CˆN)]2 affords mixed bis-cyclopalladated complexes, which were obtained regioselectively as cis(C,C)-isomers. Complex [Pd{C6H4(PPh2NPh)-2}}(C6H4-(2′-NC5H4)-2)] is regioselectively oxidized to the stable Pd(IV) derivative [Pd(OAc)2{C6H4(PPh2NPh)-2}(C6H4-(2′-NC5H4)-2)] by treatment with PhI(OAc)2. This compound undergoes reductive elimination, releasing the acetoxylated phenylpyridine and keeping the orthopalladated iminophosphorane.