[(R)-2,2-Bis(diphenylphosphanyl)-1,1′-binaphthyl-κ2 P,P′]{2-[(2R)-1,2-diamino-1-(4-methoxyphenyl)-3-methylbutyl]-5-methoxyphenyl-κC 1}hydridoruthenium(II) benzene monosolvate

In the title complex, [Ru(C19H25N2O2)H(C44H32P2)]·C6H6, the RuII ion is in a distorted octahedral coordination environment with the hydride H atom trans to the tertiary carbinamine N atom, giving an H—Ru—N angle of 160.8 (12)°. The equatorial sites are occupied by two P atoms, the secondary carbinamine N atom and a coordinated C atom.

In the title complex, [Ru(C 19 H 25 N 2 O 2 )H(C 44 H 32 P 2 )]ÁC 6 H 6 , the Ru II ion is in a distorted octahedral coordination environment with the hydride H atom trans to the tertiary carbinamine N atom, giving an H-Ru-N angle of 160.8 (12) . The equatorial sites are occupied by two P atoms, the secondary carbinamine N atom and a coordinated C atom.

Related literature
For the synthesis of Ru(II) hydride complexes with an RuN 2 P 2 coordination environment, see: Abdur-Rashid, Faatz et al.
There have been extensive investigations towards isolating and understanding the nature of the active catalytic species generated from RuCl 2 (diphosphine)(diamine) under the reaction conditions of added base in the presence of hydrogen gas. Our seminal papers (Abdur-Rashid, Faatz et al., 2001;Abdur-Rashid et al., 2002;Abbel et al., 2005) proved that the active catalysts are ruthenium dihydride compounds and demonstrated the role of the bifunctional cis-Ru-H···H-N motif to provide nascent, polarized dihydrogen (H δ+ ···H δ-) for the catalytic ionic hydrogenation of polar C═O and C═N bonds. Our research also resulted in the unprecedented isolation and characterization of stable hydridoamido intermediates and proved that these species are responsible for the rapid heterolytic activation and splitting of hydrogen gas (Abdur-Rashid, Faatz et al., 2001;Abdur-Rashid, et al., 2002). Recently Ohkuma and coworkers reported chlororuthenabicyclic compounds (Matsumura et al., 2011) which are derived from ruthenium complexes containing a chiral diphosphine and the chiral diamine ligand daipen. The work demonstrated that in the presence of base and hydrogen gas these ruthenabicyclic compounds are very useful for the hydrogenation of a wide variety of ketones and are capable of producing chiral alcohols with high enantioselectivities. The authors proposed a mechanism based on a hydridoruthenabicyclic catalytic species. However, their attempts to isolate and characterize this species were not successful. We previously reported the preparation and characterization of the trans-dihydride complex RuH 2 (R-binap) (R-daipen) (1) (Fig. 1), [R-Binap = (R)-bis(diphenylphosphanyl)-1,1-binaphthyl and R-Daipen = (R)-1,1-bis(4-methoxyphenyl)-3-methylbutane-1,2-diamine] and proved that this compound was an active base-free catalyst for the hydrogenation of ketones in the presence of hydrogen gas (Abdur-Rashid, Faatz et al., 2001).
The title compound (I) was readily obtained from (1) by the loss of hydrogen upon stirring a suspension of (1) in hexanes for 48 h at room temperature under an atmosphere of argon. It was demonstrated that the novel hydridoruthenabicyclic compound (I) is also a very effective base-free catalyst for the hydrogenation of ketones to alcohols. For example, a catalytic amount of (I) resulted in the complete conversion of neat acetophenone (S:C = 2000:1) to (S)-1-phenylethanol (92% e.e.) within 12 h at room temperature in the presence of hydrogen gas (3 atm.). The molecular structure of complex (I) is shown in Fig. 2. The Ru II ion is in a distorted octahedral coordination environment with the hydride H atom (H1RU) trans to the tertiary carbinamine nitrogen atom (N2) giving an H1RU-Ru1-N2 angle of 160.8 (12)°. The equatorial sites are occupied by two phosphorus atoms (P1 and P2), the secondary carbinamine nitrogen atom (N1) and a coordinated carbon atom (C11). The geometric parameters in (I) are comparable to related structures (Guo et al., 2004;Li et al., 2004).

Experimental
A solution of K-Selectride (100 ml of a 1.0 M solution in THF) was added to a solution of RuHCl(R-binap)(R-daipen) (100 mg) in THF (5 ml) and the mixture stirred under hydrogen gas at room temperature for 2 h. The mixture was filtered and the filtrate evaporated to dryness to give the bright yellow dihydride compound RuH 2 (R-binap)(R-daipen) (1) [R-Binap = (R)-bis(diphenylphosphanyl)-1,1-binaphthyl and R-Daipen = (R)-1,1-Bis(4-methoxyphenyl)-3-methylbutane-1,2diamine]. This was suspended in hexanes (5 ml) and the suspension stirred for 48 h at room temperature under argon. The solids were filtered and washed with hexanes (5 ml) and dried under vacuum to give 76 mg of the hydridoruthenabicyclic compound (I) as a bright yellow solid. X-ray diffraction quality single crystals were grown by the slow diffusion of hexanes into a solution of (I) in benzene.

Refinement
Hydrogen atoms bonded to C atoms were placed in calculated positions with C-H = 0.95-1.00 Å and were included in the refinement in a riding-model approximation with U iso (H) = 1.2U eq (C) or 1.5U eq (C) for methyl C atoms. The hydride and amine H atoms were refined independently with isotropic displacement parameters. The benzene solvent molecule was fitted as a regular hexagon with C-C = 1.39 Å using the AFIX 66 command in SHELXL (Sheldrick, 2008).    The molecular structure of (I). Displacement ellipsoids are at the 30% probability level. The benzene solvent molecule and H atoms bonded to C atoms are not shown.

Crystal data
[Ru (C 19  Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.