The kinetic instability of σ-bound aryloxide in coordinatively unsaturated or labile complexes of ruthenium

• Published in: Inorganica Chimica Acta Vol. 345; pp. 268 - 278
• Main Authors: Snelgrove, J.L., Conrad, J.C., Yap, G.P.A., Fogg, D.E.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 10.03.2003
• Subjects: Aryloxides; Decarbonylation; ortho-Metallation; Ruthenium; π-Phenoxide; π-Phenoxide; Aryloxides; Ruthenium; Decarbonylation; ortho-Metallation
• ISSN: 0020-1693; 1873-3255
• DOI: 10.1016/S0020-1693(02)01347-6

Reaction of RuCl 2(PPh 3) 3 ( 1) or RuHCl(PPh 3) 3 ( 2) with KOAr (Ar=4- tBuC 6H 4) in non-alcohol solvents affords π-aryloxide derivatives Ru(η 5-ArO)( o-C 6H 4PPh 2)(PPh 3) ( 3a) or RuH(η 5-ArO)(PPh 3) 2 ( 6a), respectively. The phenoxide analogues 3b and 6b are obtained on use of KOPh or TlOPh. Treatment of 1 with 1 equiv. KOAr in the presence of isopropanol liberates the phenol and acetone, affording clean 2 in quantitative yields. In 3:1 methanol–CH 2Cl 2, RuHCl(CO)(PPh 3) 3 ( 4) is also formed in small amounts. Reaction of 1 with 2 KOAr in 20% MeOH–CH 2Cl 2 affords a mixture of 6a and RuH 2(CO)(PPh 3) 3 ( 5). In the corresponding reaction of 2 with 1 KOAr, σ–π isomerization of the σ-aryloxide ligand dominates, affording 6a·MeOH as the principal product. Treatment of 6a with ethereal HCl gives [RuH(η 6-ArOH)(PPh 3) 2]Cl ( 7a); the corresponding reaction of 6b yields RuCl(η 5-PhO)(PPh 3) 2 ( 8b). The crystal structures of 3a, 3b, 4, 5, 7a, and 8b are reported. RuCl 2(PPh 3) 3 ( 1) reacts with KOAr in benzene– iPrOH to yield RuHCl(PPh 3) 3 ( 2); in benzene–methanol, carbonyl hydrides are formed. In non-alcohol solvents, both 1 and 2 give π-aryloxide products. A σ-aryloxide intermediate is implied, in which the basicity of the oxygen and the availability of π-electrons in the aromatic system give access to alcoholysis or σ–π isomerization pathways, respectively.