The treatment of achiral and chiral bis(oxazolin-2'-yl)pyridine (pybox) complexes trans-[RuCl2(eta(2)-H2C=CH2)(k(3)-N,N,N-pybox)] [pybox= 2,6-bis(dibydrooxazolin-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]pyridine] (1b) with an excess ofl triphenylphosphine in dichloromethane at 50 OC 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 generate cis-[RuCl2(Ph-3){K-3-N,N,N-(SS)-Pr-i-pybox(3). Complex 3 can be also obtained from the reaction of 1b with PPb3 in MeOH. The structure of 3 has been 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) Angstrom; final R1= 0.0565 and wR2 = 0.0944 (both for I > 2 sigma(I))]. The reaction of the achiral pybox complex 2a with 1,1-diphenyl-2-propyn-1-ol and AgBF4 in CH2Cl2 stereoselectively affords the cationic allenylidene derivative [RuCl(=C=C=CPh2)(PPh3) (K3-N,N,N-pybox)l[BEil (4a), while the methoxycarbene complex [RuCl{=C(OMe)CH=CPh2)(PPh3)(k(3)-N,N,N-py [PF6] (5) is obtained 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=CPh2)(PPh3) (K-3-N,N,N-(SS)-Pr-i-pybox}] [PF6] (4b). The X-ray crystal structure 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 the ligands around the ruthenium atom with the chloride and triphenylphosphine ligands in a trans arrangement and mutually cia with respect to the allenylidene 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 in MeOH. IR, H-1, P-81{H-1}, and C-13{H-1} NMR data of all novel compounds are also reported.