Stereochemically controlled synthesis of Ruthenium(II) complexes containing bis(oxazolin-2 '-yl)pyridine ligands. X-ray crystal structures of trans-[RuCl2(PPh3){kappa(3)-N,N,N-(S,S)-Pr-i-pybox}] and [RuCl(=C=C=CPh2)(PPh3){kappa(3)-N,N,N-(S,S)-Pr-i-pybox}][PF6] ((S,S)-Pr-i-pybox=2,6-bis[4 '-(S)-isopropyloxazolin-2 '-yl]pyridine)

The treatment of achiral and chiral bis(oxazolin-2'-yl)pyridine (pybox) com plexes trans-[RuCl2(eta(2)-H2C=CH2)(k(3)-N,N,N-pybox)] [pybox= 2,6-bis(diby drooxazolin-2'-yl)pyridine] (1a) and [RuCl2(eta(2)-H2C=CH2)(k(3)-N,N,N(SS)- Pr-i-pybox}] [(SS)-Pr-i-pybox = 2,6-bis[4'-(S)-isopropyloxazolin-2'-yl]pyri dine] (1b) with an excess ofl triphenylphosphine in dichloromethane at 50 O C leads to the formation of the first ruthenium(II) derivatives containing both bis(oxazolin-2'-yl)pyridine and phosphine ligands trans-[RuCl2(PPh3)(K -3-N,N,N-pybox)] (2a) and trans-[RuCl2(PPh3){K-3-N,N,N-(S,S)-Pr-i-pybox}] ( 2b). Chiral complex 2b slowly isomerizes in acetone at 50 degrees Cto gener ate cis-[RuCl2(Ph-3){K-3-N,N,N-(SS)-Pr-i-pybox(3). Complex 3 can be also ob tained from the reaction of 1b with PPb3 in MeOH. The structure of 3 has be en confirmed by X-ray crystallography [orthorhombic; space group P2(1)2(1)2 (1); Z = 4; a = 12.772(6) Angstrom, b = 15.208(5) Angstrom, C 19.601(7) Ang strom; final R1= 0.0565 and wR2 = 0.0944 (both for I > 2 sigma(I))]. The re action of the achiral pybox complex 2a with 1,1-diphenyl-2-propyn-1-ol and AgBF4 in CH2Cl2 stereoselectively affords the cationic allenylidene derivat ive [RuCl(=C=C=CPh2)(PPh3) (K3-N,N,N-pybox)l[BEil (4a), while the methoxyca rbene complex [RuCl{=C(OMe)CH=CPh2)(PPh3)(k(3)-N,N,N-py [PF6] (5) is obtain ed when the reaction is conducted in methanol and in the presence of NaPF6, via the addition of MeOH to the initially formed allenylidene complex 4a. In contrast, the chiral pybox complex 2b reacts with 1, 1-diphenyl-2-propyn -1-ol and NaPF6 in MeOH to give the stable alleny8dene complex [RuCl(=C=C=C Ph2)(PPh3) (K-3-N,N,N-(SS)-Pr-i-pybox}] [PF6] (4b). The X-ray crystal struc ture of 4b [orthorhombic; space group P212121; z = 4; a = 14.79(3) Angstrom , b = 16.254(8) Angstrom, c = 22.917(18) Angstrom final R1 = 0.0545 and wR2 = 0.1381 (both for I > 2 sigma(I))] shows an octahedral coordination of th e ligands around the ruthenium atom with the chloride and triphenylphosphin e ligands in a trans arrangement and mutually cia with respect to the allen ylidene moiety. The allenylidene complex 4b is also formed by the reaction of the cis dichloride complex 3 with l,l-diphenyl-Z propyn-1-oI and NaPF6 i n MeOH. IR, H-1, P-81{H-1}, and C-13{H-1} NMR data of all novel compounds a re also reported.