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 [RuCl2(eta(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)(eta(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 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 eta(6)-arene ligand (via Ru-C protonation).