ARENE AND CYCLOPENTADIENYL HALF-SANDWICH COMPLEXES OF RUTHENIUM WITH OXIMATES, CARBOXYLATES, IMINES AND AZAVINYLIDENES AS LIGANDS

The reaction of [C6H6Ru((PPr3)-Pr-i)Cl-2] (1) with NaON=CRR' in the pr esence of KPF6 leads to the formation of the oximatoruthenium(II) comp lexes [C6H6Ru(eta(2)-ON=CRR')((PPr3)-Pr-i)]PF6 (2-5) in 70-90% yield. Compound 5 (R = Me, R' =(t)Bu) reacts with HN=CPh(2) via Iigand exchan ge to give [C6H6Ru(=N=CPh(2))((PPr3)-Pr-i)]PF6 (8). The azavinylidene complex 8 has also been prepared from the acetatoruthenium derivative [C6H6Ru(eta(2)-O2CCH3)((PPr3)-Pr-i)]PF6 (6) which can be obtained eith er from 1, CH3CO2Na and KPF6 or from treatment of 5 with an excess of CH3CO2H. The synthesis of the hexamethylbenzeneruthenium compounds [C( 6)Me(6)Ru(=N=CR(2)('))(PR(3))]PF6 (12-15) is achieved by the reaction of the hydrido(chloro)metal complexes [C(6)Me(6)RuH(PR(3))Cl] (10, 11) with oximes HON=CR(2)('), and AgPF6. Nucleophilic addition of H- and CH3- to the N=C carbon atom of [C(6)Me(6)Ru-(=N=CPh(2))(PMe(3))](+) af fords the uncharged imido compounds [C(6)Me(6)Ru(=NCXPh(2))(PMe(3))] ( 16, 17). The cyclopentadienylruthenium complex [C5H5Ru(=N=CPh(2))(PPh( 3))] (23) is prepared from either one of the imino derivatives [C5H5Ru -(NH=CPh(2))(PPh(3))(2)]BF4.0.5CH(2)Cl(2) (22) or [C5H5Ru(NH=CPh(2))(P Ph(3))(O2CCH3)] (25) on treatment with NaR (R = H, C5H5). Compound 25 reacts in toluene at room temperature by elimination of CH,CO,H to giv e the five-membered metallaheterocycle [C5H5Ru{NH=C(Ph)C6H4}(PPh(3))] (26) which is an isomer of 23. The X-ray structural analysis of 5 reve als the presence of a O,N-bound oximato ligand and a cis position of t he C6H6((PPr3)-Pr-i)Ru and (t)Bu units at the N=C double bond.