REACTIONS OF THE LINEAR TETRANUCLEAR COMPLEX RU4(CO)10(CH3C=C(H)C(H)=N-I-PR)2 WITH OXIDIZING REAGENTS - SYNTHESES OF HALIDE-BRIDGED [RU(CO)2X(CH3C=C(H)C(H)=N-I-PR)]2 AND FAC-RU(CO)3X(CH3C=C(H)C(H)=N-I-PR)1

The linear tetranuclear complex Ru4(CO)10(CH3C = C(H)C(H) = N-iota-Pr)2 (1), containing two-eta5-azaruthenacyclopentadienyl systems, reacts with oxidizing reagents (I2, Br2, NBS, CCl4) at elevated temperatures (40-90-degrees-C) in heptane or benzene to give the new dimeric halide-bridged organoruthenium (II) complexes [Ru(CO)2X(CH3C = C(H)C(H) = N-iota-Pr)]2 (X = I (3a), X = Br (3b), Cl (3c); yield 30-80%) together with [Ru(CO)3X2]2. The reactions of 1 with CX4 (X = I, Br, Cl) are accelerated by CO, probably because Ru4(CO)12(CH3C = C(H)C(H) = N-iota-Pr)2 (5), which contains two unbridged metal-metal bonds, is formed prior to oxidation. The halide-bridged dimers 3a-c are obtained as mixtures of four isomers, the configurations of which are discussed. Splitting of the halide bridges takes place when a solution of 3a-c is saturated with CO, whereby mononuclear fac-Ru(CO)3X(CH3C = C(H)C(H) = N-iota-Pr) (4a-c) is obtained. This process is reversible; i.e., passing a stream of nitrogen through a solution of 4a-c or removal of the solvent under vacuum causes the reverse reaction with reformation of 3a-c. Compounds 3a-c and 4a-c have been characterized by IR (3, 4), FD mass (3), H-1 (3, 4), and C-13{H-1} NMR (4) spectroscopy and satisfactory elemental analyses have been obtained for 3a-c. Compounds 3 and 4 are suitable percursors for the preparation of new homo- and heteronuclear transition-metal complexes.