Proton nuclear magnetic resonance behaviour of acetylacetonato(chloro)-2-chloromethylpyridineplatinum(II)

Abstract

The temperature dependence of the ¹H n.m.r. spectrum of the complex PtCl(acac)(2-chloromethylpyridine) indicates the presence at low temperature of a locked structure wherein the methylene protons occupy two non-equivalent positions. An averaging process of the proton sites is observed at higher temperatures. The following activation parameters for the exchange process have been calculated: ΔH^‡= 57 kJ moh^–1, ΔS^‡=–15 J K^–1 mol^–1, E_a= 60 kJ mol^–1, log A= 12·5. The results are interpreted in terms of the barrier to rotation about the Pt–N co-ordination bond.