Electrospray mass spectrometry of Pt(II) amidine complexes of the type cis- and trans-[PtCl2{NHC(R)NR′R″}2] and trans-[PtCl2(RCN){NHC(R)NR′R″}]

The ESI mass spectrometric behaviour of a series of Pt(II) amidine complexes of the type cis- and trans-[PtCl2{NHC(R)NR′R″}2] (R=Me, Ph; R′=H, R″=Me, Et, But, Pri; R′=R″=Me, Et) and trans-[PtCl2(RCN){NHC(R)NR′R″] (R=Me, Ph; R′=R″=Me, Et) is reported. The bis-amidine complexes have been prepared by nucleophilic attack of primary and secondary amines on acetonitrile and benzonitrile ligands coordinated to Pt(II) substrates, while the mono-amidine complexes are obtained by reaction of secondary amines with trans-[PtCl2(RCN){NHC(R)NR′R″}] (R=Me, Ph; R′=R″=Me, Et). The protonated molecular ions or cationized ions are usually observed. The fragmentation processes are extremely reduced and in any case related to the original structure. As a general feature, cis and trans compounds give rise to different ESI spectra. Additions of Na+ and/or K+ are observed. From these data, ESI mass spectrometry, due to the soft ionisation, furtherly proposes as an efficient method for the characterisation of metal complexes in solution.