Synthesis and reactivity of indenyl ruthenium(II) complexes containing thelabile ligand 1,5-cyclooctadiene (COD): Catalytic activity of [Ru(eta(5)-C9H7)Cl(COD)]

The treatment of [RuCl2(COD)](n) with KC9H7 in THF leads to the formation o f [Ru(eta (5)-C9H7)Cl(COD)] (1) (80% yield) in a one-pot synthesis. Complex 1 is also formed by the reaction of [RuCl2(COD)](n) with NaC9H7 in THF fol lowed by treatment of the intermediate complex [Ru(eta (5)-C9H7)(eta (2)-et a (3)-C8H11)] (2) with HCL Substitution of the labile COD ligand by bulky p hosphines PR3 (R = Cy, Pr-i(3)) can be achieved at room temperature in THF to give 16-electron species [Ru(eta (5)-C9H7)Cl(PR3)], which react with CO (1 atm) to afford complexes [Ru(eta (5)-C9H7)Cl(CO)(PR3)] (R = Cy (3a), Pr- i (3b)). Chelate complexes [Ru(eta (5)-C9H7)Cl{(kappa (2)-P,N)-o-Ph2PC6H4C( H)=(NBu)-Bu-t}] (4) and [Ru(eta (4)-C9H7){kappa (1)-(P)-Ph2PCH2C(O)Bu-t}{ka ppa (2)-(P,O)Ph2PCH= C(O)Bu-t}] (5) have been similarly prepared by reactio n with the bidentate ligands. [Ru(eta (5)-C9H7)Cl(NBD)] (NBD = norbornadien e) (6) has been prepared through an exchange reaction of 1 with NBD and cha racterized by X-ray diffraction. Neutral complexes [Ru(eta (5)-C9H7)X-(COD) ] (X = FBF3 (7), N-3 (8)) were prepared from complex 1 by metathesis reacti ons of the chloride ligand by AgBF4 and NaN3 respectively. The treatment of 7 in CH2Cl2 with an excess of pyridine and acetonitrile gives cationic com plexes [Ru(eta (5)-C9H7)(COD)L] [BF4] in good yield (L = py (9), CH3CN (10) ). The structure of complex 9 has been determined by X-ray diffraction. Com plex 1 catalyzes [2+2] and [4+2] cycloaddition reactions of norbornene and 1,5-cyclooctadiene with alkynes to give exotricyclic [4.2.1.0] coupling pro ducts and exotricyclo [4.2.2.0]dec-7-enes, respectively. These processes ta ke place with high efficiency and selectivity. Complex I is also active in the catalytic hydration of terminal alkynes to afford ketones in high yield and selectivity.