Chemistry of Ruthenium(II) Alkyl Binap Complexes: Novel Bonding, Cyclometalation, and P−C Bond Splitting

Reactions of the bis-isopropyl and bis-cyclohexyl alkyl Binap ligands, 8 and 9, respectively, with [RuCl 2 (η 6 - 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 (η 6 - 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 R 2 P−O(C O)CH 3 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 R 2 P−O(C O)CH 3 ligand is readily hydrolyzed in wet triflic acid to afford the R 2 P(OH) donor and an η 6 -arene ligand (via Ru−C protonation).