Preparation and Characterization of Chiral Zerovalent Organoruthenium Aqua Complexes

Enantiopure organoruthenium aqua complexes, Ru(dppe)(dmfm)2(H2O) (1) [dmfm =
dimethyl fumarate] and Ru(QUINAP)(dmfm)2(H2O) (2) [QUINAP = 1-(2-diphenylphosphino-1-naphthyl)isoquinoline], were prepared and the absolute structures were determined by
X-ray crystallography. In the crystals of these complexes, the water molecule is captured in
the chiral coordination environment assisted by two different hydrogen bonds; that is, a
chiral center is generated on the coordinated oxygen of water. The behavior of the coordinated
water in 1 and 2 was monitored by variable-temperature 1H NMR measurement. At lower
than −60 to  −70 °C, the nonequivalency of the geminal protons in the coordinated water
molecule was observed even in solution. On the basis of the VT NMR data and DFT study,
the behavior of the coordinated water was discussed. Complex 1 reacts with ammonia to
give Ru(dppe)(dmfm)2(NH3) (4), which is the first example of the isolated mononuclear
Ru(0) ammonia complex. Complex 4 was reversibly converted into 1 by the reaction with
water.