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Progressive displacement of acac from [Pd(acac)2] occurs on reaction with different tetramic acids (HL � /Hata, Habta) to give [Pd(acac)(h 2 -L)] and [Pd(h 2 -L)2] but, when HL� /Haceta, only [Pd(acac)(h 2 -L)] is formed, even when the ratio of Pd � /HL is 1:4; reaction of all these tetramic acids with an aqueous solution of K2[PdCl4 ]g ives [Pd(h 2 -L)2]. In solution, NMR studies in non polar solvents show that there is only one isomer of [Pd(acac)(h 2 -L)] whereas there are usually two isomers of [Pd(h 2 -L)2] which are probably due to the presence of cis - and trans -isomers of the complex as a result of both the enolate ligands adopting a O,O?-mode of coordination via the functionalities associated with C 4 and the acyl group at C 3 in the pyrrolidine ring. In pyridine solution, [Pd(h 2 -abta)2] forms a Lewis base adduct, [Pd(py)4](abta)2, which has been characterised by X-ray analysis and shown to contain a |
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