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, Bu-t, Pr-t, 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) {NE = 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. (C) 2003 Elsevier B.V. All rights reserved.