UNSATURATED CARBENE TRANSITION-METAL INDENYL COMPLEXES .3. SYNTHESIS AND CHARACTERIZATION OF (ALKYNYL)RUTHENIUM, (VINYLIDENE)RUTHENIUM, AND(CARBENE)RUTHENIUM INDENYL COMPLEXES - X-RAY CRYSTAL-STRUCTURE OF U(=C=CME2)(ETA-5-C9H7)(PPH3)2][CF3SO3]CENTER-DOT-1 2CH2CL2 AND EHMO CALCULATIONS/

The sigma-alkynyl complexes [Ru(C=CR1)(eta5-C9H7)L2] (L2 = 2PPh3, 1,2- bis(diphenylphosphino)ethane (dppe), R1 = Ph, (t)Bu, (n)Pr; L2 = bis(d iphenylphosphino)methane (dppm), R1 = Ph) have been prepared by reacti on of the complex [RuCl(eta5-C9H7)L2] with HC=CR1 and potassium hydrox ide in refluxing methanol. Electrophilic additions of HBF4.OEt2 and Me OSO2CF3 to the neutral sigma-alkynyl complexes yield the cationic viny lidene complexes [Ru-(=C=CR2R1)(eta5-C9H7)L2]+ (R2 = H, Me), which hav e been isolated as tetrafluoroborate or triflate salts in good yields. Reaction in refluxing dichloromethane of [RuCl(eta5-C9H7)L2] with NH4 PF6 and HC=CSiMe3 gives the cationic unsubstituted vinylidene complexe s [Ru-(=C=CH2)(eta5-C9H7)L2]+; deprotonation of these cationic unsubst ituted vinylidene species with potassium tert-butoxide yields the neut ral sigma-ethynyl complexes [Ru(C=CH)(eta5-C9H7)L2] (L2 = 2PPh3, dppe) . Methylation of these compounds leads to a mixture of the symmetrical vinylidene complexes [Ru(=C=CR2)(eta5-C9H7)L2]+ (R = H, Me). Reaction in refluxing methanol or ethanol of [RuCl(eta5-C9H7)L2] with HC=CSiMe 3 or HC=CPh and NH4-PF6 yields the alkoxycarbene derivatives [Ru{=C(OR 2)R1}(eta5-C9H7)L2][PF6](L2 = 2PPh3, dppe, R1 = Me, R2 = Me, Et; L2 = dppm, R1 = Me, R2 = Me, Et; L2 = dppm, R1 = Bz, R2 = Me). The synthesi s of the alkoxycarbenes has also been achieved by treatment of the uns ubstituted vinylidne complexes with methanol or ethanol. The aminocarb ene derivative [Ru{=C(NH2)-Me}(eta5-C9H7)(dppm)][PF6] has been prepare d by reaction of [RuCl(eta5-C9H7)(dppm)] with HC=CSiMe3 and NH4PF6 in CH2Cl2. The crystal structure of [Ru(=C=CMe2)(eta5-C9H7)(PPh3)2][CF3SO 3].1/2CH2Cl2 (monoclinic, space group P2(1)/c, Z = 4, a = 12.854(4) an gstrom, b = 14.42(1) angstrom, c = 23.98(3) angstrom, beta = 92.25(7)- degrees, R = 0.066) has been determined by X-ray diffraction methods. In the structure of the cationic complex the dimethylvinylidene ligand is almost linearly bound to the Ru atom (Ru-C(1)-C(2) = 173.7(6)-degr ees) with an Ru-C(1) distance of 1.839(7) angstrom and the ruthenium-v inylidene chain Ru=C=C lying out of the mirror molecular plane (confor mational angle (CA) = 22.2(4)-degrees). The coordination around the Ru atom is completed by two P atoms from the triphenylphosphine ligand a nd a eta5-bonded indenyl ligand with the benzo ring orientated trans t o the vinylidene group. The structure shows distortions of the five-ca rbon ring from planarity with hinge angle (HA) and fold angle (FA) val ues of 8.1(6) and 13.1(6)-degrees, respectively, and a pronounced slip -fold value of 0.197(7) angstrom. Extended Huckel molecular orbital ca lculations were used to rationalize the preferred ''trans'' orientatio n of the indenyl ligand with respect to the vinylidene group. H-1, P-3 1{H-1}, and C-13{H-1} NMR spectra are discussed. C-13]H-1} NMR data ar e used for the calculation of the indenyl distortion parameters, showi ng that the distortion of the eta5-indenyl coordination in the solid s tate is maintained in solution.