SYNTHESIS AND CHARACTERIZATION OF RUTHENIUM CARBONYL-COMPLEXES WITH CYCLOMETALATED LIGANDS DERIVED FROM SENECIALDIMINE

From thermal reactions of Ru-3(CO)(12) with senecialdimine, (CH3)(2)C= CHCH=NR (R = iPr (a), t-Bu (b)), in refluxing heptanes the following c omplexes have been isolated and characterised: Ru-2(CO)(6)[(CH3)(2)C(H )CC(H)NR] (2a,b), Ru-2(Co)(6)[C(H)C(CH3)C(H)C(H)=NR] (3a,b), [HRu6(CO) (18)][2-(C(H)=C(CH3)(2))-4-CH3-C5H3N] (4a), HRu3(CO)(9)[(CH3)(2)C(H)CH 2C=NR] (5a), and Ru-2(CO)(6)[C(H)C(CH3)C(H)C=N(H)R] (6b). The complexe s 3a, 4a, and 6b have been characterised by X-ray structure determinat ions. Crystals of 3a are monoclinic, space group P2(1)/n, with a = 11. 217(4)Angstrom, b = 10.991(2)Angstrom, c = 14.214(3)Angstrom, beta = 9 4.38(2)degrees, Z = 4 and R = 0.0264. Crystals of 4a are monoclinic, s pace group P2(1)/n, with a = 10.483(2)Angstrom, b = 15.910(3)Angstrom, c = 24.995(5)Angstrom, beta = 101.56(2)degrees, Z = 4 and R = 0.0279. Crystals of 6b are monoclinic, space group P2(1)/n, with a = 11.449(2 )Angstrom, b = 12.012(2)Angstrom, c = 13.561(3)Angstrom, beta = 102.69 (2)degrees, Z = 4 and R = 0.0239. The other complexes were characteris ed spectroscopically. Complex 6b contains a novel eta(4)-coordinated m etallacyclopentadiene fragment, the second of its kind reported so far . The anomalous eta(4)-coordination is attributed to the presence of a n amino substituent on one of the metallated carbon atoms causing redi stribution of electrons over the ligand skeleton. Possible formation p athways of the complexes are described.