Synthesis and Reactivity of an Yttrium Hydride Complex Supported by an Arene-Anchored Bis(phosphinomethylamido) Palladium (0) Metalloligand

A bis(phosphinomethylamine) ligand precursor based on a rigid arene backbone was designed that sequentially reacted with (Me₃SiCH₂)₃Y(THF)₂ and (COD)Pd(CH₂SiMe₃)₂ to afford a heterobimetallic [Y-Pd] alkyl complex. Hydrogenolysis of the [Y-Pd] alkyl complex under 1 atm of H₂ led to the isolation of the dimeric [Y-Pd] hydride complex, which showed typical insertion reactivity toward unsaturated substrates, such as diphenylacetylene, <i>N</i>,<i>N</i>'-diisopropylcarbodiimide and di(4-methylphenyl)diazomethane. Reduction of the TEMPO radical by the [Y-Pd] hydride afforded the aminoxide complex, with concomitant formation of H₂. All the complexes were characterized by multinuclear NMR spectroscopy and X-ray diffraction analysis, which disclosed that in these reactions, the Pd(0) center acts as a metalloligand to support the reactivity of the Y(III) center. On the other hand, the reaction of the [Y-Pd] hydride with iodobenzene led to the isolation of a [Y-Pd] iodide complex along with benzene, involving oxidative addition, hydride transfer, and reductive elimination steps in a synergistic pathway.