Intramolecular combination of vinyl, aryl and carbonyl ligands in ruthenium(II) complexes: a mechanistic study
Abstract
Complexes
[Ru(CO)
2
(CH![[double bond, length as m-dash]](https://www.rsc.org/images/entities/char_e001.gif)
CHR)(C
6
H
4
X-4)L(L
′)] [R = Ph, CMe
3
, H, Me or OEt;
X = H, Cl or OMe;
L = L′ = PMe
2
Ph,
PMe
3
, P(OMe)
2
Ph or PPh
3
;
L = PMe
3
,
L′ = PPh
3
] underwent competing isomerisation
reactions, one an intramolecular construction of a vinyl aryl ketone which
remains co-ordinated, the other a simple redistribution of the ligands
around the metal. Product ratios are determined by kinetic rather than
thermodynamic factors. For a sequence of complexes with
L = L′ = PMe
2
Ph,
electron-releasing substituents on the vinyl ligand favour formation of
ketone complexes, whereas similar substituents on the phenyl ligand have
the reverse effect. Increasing the reaction temperature disfavours ketone
complex formation. Mechanisms involving initial migration of either the
vinyl or the aryl ligand are discussed on the basis of these results and a
complementary study involving trapping of the likely acyl
intermediates.
CHR)(C
6
H
4
X-4)L(L
′)] [R = Ph, CMe
3
, H, Me or OEt;
X = H, Cl or OMe;
L = L′ = PMe
2
Ph,
PMe
3
, P(OMe)
2
Ph or PPh
3
;
L = PMe
3
,
L′ = PPh
3
] underwent competing isomerisation
reactions, one an intramolecular construction of a vinyl aryl ketone which
remains co-ordinated, the other a simple redistribution of the ligands
around the metal. Product ratios are determined by kinetic rather than
thermodynamic factors. For a sequence of complexes with
L = L′ = PMe
2
Ph,
electron-releasing substituents on the vinyl ligand favour formation of
ketone complexes, whereas similar substituents on the phenyl ligand have
the reverse effect. Increasing the reaction temperature disfavours ketone
complex formation. Mechanisms involving initial migration of either the
vinyl or the aryl ligand are discussed on the basis of these results and a
complementary study involving trapping of the likely acyl
intermediates.
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