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

Abstract

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, N,N'-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.