Oxidative Addition of Allylic Substrates to Coordinatively Unsaturated Ruthenium Compounds, [Ru(η5-C5Me5)(η-amidinate)]: Preparation, Structure Elucidation, and Catalysis of Novel Ruthenium (IV)-η3-Allyl Complexes

Oxidative addition reactions of allylic halides, acetates, and carbonates with [Ru(η5-C5Me5)(η-amidinate)] [amidinate: iPrNC(Me)=NiPr (1a), tBuNC(Ph)=NtBu (1b)], which shows signs of coordinative unsaturation, gave novel cationic π-allyl ruthenium(IV) species. The compounds [Ru(η3-allyl)(η5-C5Me5)(η2-amidinate)]+X− were isolated by anion exchange of the products (X = PF6, BF4, BPh4), and were characterized by spectroscopic analysis. The crystallography of two of the [Ru(η3-allyl)(η5-C5Me5)(η2-amidinate)]+X− revealed a four-legged piano stool structure in which two nitrogen atoms in the amidinate ligand and two carbon atoms in the η3-allyl ligands occupy the positions of four legs; the orientation of the η3-allyl ligand was endo. Although cyclic voltammograms of the precursor, [Ru(η5-C5Me5)(η-amidinate)], indicated possible oxidative addition of organic halides other than allylic halides to [Ru(η5-C5Me5)(η-amidinate)], only allylic halides gave the corresponding Ru(IV) products. The importance of prior coo...