INVESTIGATION OF THE TRANS EFFECT IN THE FRAGMENTATION OF DINUCLEAR PLATINUM COMPLEXES BY ELECTROSPRAY-IONIZATION SURFACE-INDUCED DISSOCIATION TANDEM MASS-SPECTROMETRY

Cis and trans isomers of two dinuclear platinum complexes, [cis-{Pt(NH 3)(2)Cl}(2) mu-(NH2(CH2)(n)NH2)](NO3)(2) (1,1/c,c) and [trans-{Pt(NH3) (2)Cl}(2) mu(NH2(CH2)(n)NH2)](NO3)(2) (1,1/t,t), where the diamine was 1,4-butanediamine (n = 4) or 1,6-hexanediamine (n = 6), were studied using electrospray ionization surface-induced dissociation (ESI/SID) t andem mass spectrometry (MS/MS). The same fragment ions were observed for both the cis and trans isomers of each complex (n = 4 or 6), but t he relative intensities were dependent on the isomer studied. The ESI/ SID data and energy-resolved mass spectra show that the position of th e chloride plays a significant role in the fragmentation of these ions . Two major fragmentation pathways were detected for the complexes. Th e cleavage of the Pt-N bond trans to chloride was the most favorable p athway for both isomers of the complexes following the ion-surface col lision. The differences in the ESI/SID spectra between the cis and tra ns isomers can be explained by the trans effect, namely that the Pt-N bond trans to chloride is the most labile bond. (C) John Wiley & Sons, Ltd.