VersatileN,C,NCoordination Behavior of a Monoanionic Aryldiamine Ligand in Ruthenium(II) Complexes: Syntheses and Crystal Structures of [RuII{C6H3(CH2NMe2)2-2,6}X(L)] (L = Norbornadiene, X = Cl, SO3CF3; L = PPh3, X = I) and [RuII{C6H3(CH2NMe2)2-2,6}(2,2‘:6‘,2‘‘-terpyridine)]Cl

The monoanionic ligand [C 6 H 3 (CH 2 NMe 2 ) 2 -2,6] -, a potentially terdentate N,C,N bonding system, has been employed to synthesize a series of new ruthenium(II) complexes [Ru{C 6 H 3 (CH 2 NMe 2 ) 2 -2,6}X(L)] (L = PPh 3, X = Cl ( 2a ), I ( 2b ); L = norbornadiene (nbd), X = Cl ( 4 ), η 1 -OSO 2 CF 3 ( 5 )) and [Ru{C 6 H 3 (CH 2 NMe 2 ) 2 -2,6}(2,2‘:6‘,2‘‘-terpyridine)]Cl ( 3 ). X-ray crystal structures of 2b and 3 − 5 have been determined, in which the N,C,N coordination geometry with respect to the metal center is found to differ considerably. In each complex the aryldiamine ligand is terdentate, η 3 - N,C,N -bonded as a six electron donor system. However, depending on the other ligands in the Ru(II) coordination sphere, this ligand demonstrates considerable flexibility in adopting coordination geometries which range from meridional in 3 through pseudomeridional in 2b to pseudofacial in 4 and 5 . In the structures of 4 and 5 significant distortions of the aryl ring, involving bending of the six-membered ring into a boatlike conformation, are found. The different combinations of the N,C,N ligand with sets of other ligands lead to a range of metal geometries, i.e . square pyramidal in 2b, octahedral in 3, and bicapped tetrahedral in 4 and 5 .