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1-3-η-Allylpalladium(II) and Platinum(II) Complexes Containing Tris(2,6-dimethoxyphenyl)phosphine Ligand

1987; Oxford University Press; Volume: 60; Issue: 10 Linguagem: Inglês

10.1246/bcsj.60.3563

1348-0634

Hideo Kurosawa, Aki Tsuboi, Yoshikane Kawasaki, Masanori Wada,

Synthetic Organic Chemistry Methods

Abstract Neutral and cationic 1-3-η-(2-methylallyl) complexes of Pd and Pt containing tris(2,6-dimethoxyphenyl)phosphine (abbreviated as P(2,6)3), M(1-3-η-CH2CMeCH2)Cl{P(2,6)3} and [M(1-3-η-CH2CMeCH2){P(2,6)3}]BF4, were prepared. The latter contained a weakly coordinated OMe group of P(2,6)3 which was readily replaced by carbon monoxide to afford [M(1-3-η-CH2CMeCH2)(CO){P(2,6)3}]BF4. Owing to large steric bulk and high nucleophilicity of P(2,6)3, addition of P(2,6)3 to these complexes did not result in coordination of the second molecule of the phosphine to the metal atom but ready attack at the metal-bound 2-methylallyl and methoxyl carbon atoms to give the corresponding (2-methylallyl)phosphonium and methylphosphonium ions. From these reactions were isolated a neutral 1-3-η-(2-methylallyl)platinum(II) complex involving chelate coordination of a tertiary phosphine ligand which was derived from the loss of methyl of one methoxyl group in P(2,6)3 and the resulting phenoxo ligand, and a cationic, binuclear Pt(I) carbonyl complex bridged by the 2-methylallyl group. Also prepared in this study were 1-3-η-(2-methylallyl)(acetylacetonato) complexes of Pd and Pt, M(1-3-η-CH2CMeCH2)(acac){P(2,6)3}. In the platinum analog, the acetylacetonato ligand was suggested to coordinate to the metal in a monodentate fashion via the central carbon atom. Both complexes afforded moderate yields of CH2=CMeCH2CH(COMe)2 upon treatment with carbon monoxide, while the reaction of M(1-3-η-CH2CMeCH2)(CO){P(2,6)3}+ with sodium acetylacetonate failed to give the same coupling product.