Improved synthetic routes to Cp*Ru(Pdl) complexes (Pdl ) 2,4-dimethylpentadienyl and various oxodienyl ligands) including Cp*Ru(η 5 -2,4-Me 2 -C 4 H 3 O) (1), Cp*Ru[η 5 -2,4-(t-Bu) 2 -C 4 H 3 O] (1′), and Cp*Ru(η 5 -2,4-Me 2 -C 5 H 5 ) (1′′) have been developed, and the relative reactivities of the resulting complexes toward oxidative addition or ligand addition reactions have been examined. Thus, the oxopentadienyl complexes 1 and 1′ and the 2,4-dimethylpentadienyl complex 1′′ were found to undergo oxidative addition of SnCl 4 , Me 2 SnCl 2 , I 2 , Cl 2 (via CHCl 3 ), and O 2 , yielding Cp*Ru 5) readily, the oxodienyl products having η 3 -oxodienyl coordination occurring preferentially through an all-carbon allylic fragment, in line with ruthenium's soft nature. The O 2 reaction was of additional interest in that it also led to a product in which oxidation of the Cp* ligand to a C 5 Me 4 (CHO) ligand had occurred, giving (η 5 -C 5 Me 4 -CHO)Ru[η 5 -CH 2 C(Me)CHC(Me)O] (6). In contrast to the above, reactions of the 2,4-di(tertbutyl)oxodienyl or 2,4-dimethylpentadienyl ligand complexes were much less favorable, occurring much more slowly, if at all. For the reaction of CHCl 3 with the 2,4-dimethylpentadienyl complex, a small amount of an η 6 -toluene complex, [Cp*Ru(η 6 -C 7 H 8 )][Cp*RuCl 3 ] (11), was formed, apparently as a result of a carbon-carbon bond activation, giving a rearrangement of the dienyl ligand. The additions of Lewis bases to the oxodienyl complexes, leading to Cp*Ru[η 3 -CH 2 C(Me)CHC(Me)O]L species [L ) PPh 3 (7), PHPh 2 (8), PMe 3 (9), CO (10)], were most facile for small donors such as PMe 3 , while PPh 3 and CO additions were more reversible. Structural data have been obtained for representative examples of the above, i.e., complexes 1, 1′, 2, 5, 6, 7, and 11.
