Detalle de: Diastereoselective Synthesis of the Indenylruthenium(II) Complexes [Ru(η 5 -C 9 H 7 ){κ 3 ( P,C,C ) - Ph 2 P(CH 2 CRCH 2 )}(PPh 3 )][PF 6 ] (R = H, Me): Enantiofacial Coordination, Hemilabile Properties, and Diastereoselective Nucleophilic Additions to κ 3 ( P,C,C )-Allylphosphine Ligands

The mixed-phosphine complexes [Ru(η 5 -C 9 H 7 )Cl{κ 1 ( P )-Ph 2 P(CH 2 CR CH 2 )}(PPh 3 )] (R = H ( 1a ), Me ( 1b )) are prepared by phosphine exchange reactions (1:1 molar ratio) of [Ru(η 5 -C 9 H 7 )Cl(PPh 3 ) 2 ] with the corresponding allylphosphines Ph 2 P(CH 2 CR CH 2 ) in refluxing THF. The reaction of 1a with sodium methoxide in methanol yields the hydride derivative [Ru(η 5 -C 9 H 7 )H{κ 1 ( P )-Ph 2 P(CH 2 CH CH 2 )}(PPh 3 )] ( 1c ). The treatment of complexes 1a and 1b with NaPF 6 in methanol diastereoselectively affords the cationic complexes [Ru(η 5 -C 9 H 7 ){κ 3 ( P,C,C ) - Ph 2 P(CH 2 CR CH 2 )}(PPh 3 )][PF 6 ] (R = H ( 2a ), Me ( 2b )) in good yield. An X-ray crystal structure determination of complex 2a shows that the si enantiofacial coordination of the olefin group accompanies the R relative configuration of the metal center. No epimerization process has been observed. Olefin exchange substitution reactions of complex 2a with MeCN and BzCN (1:1.5 molar ratio) in refluxing CH 2 Cl 2 yield the cationic complexes [Ru(η 5 -C 9 H 7 )(NCR){κ 1 ( P ) - Ph 2 P(CH 2 CH CH 2 )}(PPh 3 )][PF 6 ] (R = Me ( 3a ), Bz ( 3b )). Similarly, the neutral complexes [Ru(η 5 -C 9 H 7 )(N 3 ){κ 1 ( P ) - Ph 2 P(CH 2 CR CH 2 )}(PPh 3 )] (R = H ( 4a ), Me ( 4b )) are obtained by the treatment of complexes 2a, b with sodium azide in THF/MeOH at room temperature. The addition of lithium carbanions LiR‘ (R‘ = Me, n Bu) to solutions of complexes 2a, b in tetrahydrofuran results in regio- and stereoselective exo addition at the C β atom of the coordinated allylic group, affording the ruthenacyclopentane complexes [Ru(η 5 -C 9 H 7 ){κ 2 ( P,C ) - Ph 2 P{CH 2 C(R)(R‘)CH 2 }}(PPh 3 )] (R = H, R‘ = Me ( 5a ), n Bu ( 5b ); R = Me, R‘ = Me ( 6a ), n Bu ( 6b )) in 80−95% yield. Similarly, the complexes [Ru(η 5 -C 9 H 7 ){κ 2 ( P,C ) - Ph 2 P{CH 2 CH(R)CH 2 }}(PPh 3 )] (R = H ( 5c ), Me ( 6c )) are formed by the reaction of equimolar mixtures of complexes 2a, b with Li[B(C 2 H 5 ) 3 H]. The molecular structure and relative configurations R Ru S / S Ru R of the new stereogenic atoms of complex 5b have been determined by X-ray diffraction. Kinetic studies on the substitution reaction of complex 2a with CD 3 CN in CDCl 3 indicate that the olefin exchange occurs via parallel first-order (dissociative) and second-order (associative) pathways and highlight the intermediacy of a transient coordinatively unsaturated species, formed by olefin dissociation before attack of the nitrile.