Chemistry of ruthenium(II) alkyl binap complexes: Novel bonding, cyclometalation, and P-C bond splitting

Article abstract of DOI:10.1021/om0209778

Reactions of the bis-isopropyl and bis-cyclohexyl alkyl Binap ligands, 8 and 9, respectively, with [RuCl₂(η⁶-p-cymene)]₂ afford new dinuclear chloro-bridged Ru compounds which contain the Binap ligands as six- rather than four-electron donors. A backbone double bond proximate to one of the P-donors complexes the metal atom. NMR details of the olefin bonding plus isomerization reactions involving loss of the olefin complexation are reported. Reactions of 8 or 9 with [Ru(OAc)₂(η⁶-p-cymene)] result in slow P - C bond cleavage and cyclometalation, instead of affording the anticipated [Ru(OAc)₂(Binap)] complex. The new cyclometalated complexes, 15 and 16, contain the complexed R₂P - O(C=O)CH₃ ligand and arise (presumably) via acetate attack at phosphorus with the electrons in the P - C bond moving to the ruthenium atom. The solid-state structure of one of these, the cyclohexyl analogue, 16, is reported and represents a rare structural example of a molecule with three different chelate ligands. The complexed R₂P - O(C=O)CH₃ ligand is readily hydrolyzed in wet triflic acid to afford the R₂P(OH) donor and an η⁶-arene ligand (via Ru - C protonation).