Crystal structure of cis-dichloro(1,2-R,R-diaminocyclohexane)-bis[1,3-(diphenylphosphino)propane]ruthenium(II), RuCl2(C27H26P2)(C6H14N2)

Abstract

Source of materialAll the reactions were performed using Schlenk-type flask under argon and standard high vacuum-line techniques. Solvents were of analytical grade and distilled under argon. (1R,2R)-(-)-1,2-diaminocyclohexane (0.03 g, 0.27 mmol) was dissolved in 10 ml of dichloromethane and the solution was added dropwise to a stirred solution of RuCl 2(dppp)2 (250 mg, 0.25 mmol) in 10 ml of dichloromethane within 5min. The mixture was stirred for ca. 10 -30min at room temperature while the color changed from brown to yellow. After removal of any turbidity by filtration (P 4), the volume of the solution was concentrated to about 5mlunder reduced pressure. Addition of 40 ml of diethyl ether caused precipitation of asolid, which was filtered off (P 4). After recrystallization from dichloromethane/n-hexane the title compound was obtained as ayellow-brown powder in analytically pure form ( Experimental detailsAll Hatoms were intially located in adifference Fourier map. The phenyl Ha toms were then constrained to ideal geometrical parameters with d(C-H) =0.95 Å and U iso(H) =1.5 Ueq(C). The position of the amine Hatoms was refined freely along with an isotropic displacement parameter. All other Hatoms were placed in geometrically idealised positions and constrained to ride on their parent atoms with d(C-H) in the range 0.95 -1.00 Å and U iso(H) =1.2 Ueq(C). DiscussionDiphosphines such dppp are of the most versatile ligands, since they can stablize metal-phosphorus bonds and at the same time [1-3], very different functionalization may be introduced by means of the groups bound to the phosphorus atom [4,5]. Metal complexes containing phosphorus ligands have always been important, due to their possible catalytic activity [2][3][4][5][6]. Recently, a ruthenium(II) complex system containing diphosphine and 1,2-diamine ligands of type RuCl 2/PP/NN was discovered, which in the presence of abase and 2-propanol, proved to be excellent catalysts for the hydrogenation of ketones under mild conditions [5,6]. Since that time large number of such complexes were made available for the same task [2,7]. The title complex is crystallized as solvent-free in full cis form with lost of the C 2 symmetry. The cis-[RuCl 2 (dppp)NN] thermodynamical isomer is structurally favored over the trans-[RuCl 2 (dppp)NN] kinetic isomer [3], while the opposite was observed in solution and some solid state studies [2,8]. The ruthenium center is in adistorted octahedral environment with afivemembered diamine ring coordinating in cis form via N1 and N2, a six-membered bis(phosphine) ring coordinating in cis form via P1 and P2 as well as cis-dichloro coordination ( figure, top). The six-membered ring of the dppp ligand allows ∠P-Ru-P=91.35°v ery close to ideal value, the smaller 1,2-diamine enforces ∠N-Ru-N=79.14°,that is 10.86°less than the ideal value; while the ∠Cl-Ru-Cl was found to be 90.37°,which is very close to the ideal value.

cis-[1,4-Bis(diphenylphosphanyl)butane-κ2P,P′]dichlorido(cyclohexane-1,2-diamine-κ2N,N′)ruthenium(II) dichloromethane monosolvate

“…The values of these interactions are similar to those observed in other ruthenium complexes of the same type (Warad, 2007(Warad, , 2010.…”

“…For the coordination chemistry of ruthenium complexes and their applications, see ; Noyori (1994Noyori ( , 2003; Ohkuma et al (2002); Lindner et al (2005); Noyori & Ohkuma (2001) ;. For evidence of intra-and intermolecular interactions in similar complexes, see: Warad (2007Warad ( , 2010.…”