Mass spectrometric studies of platinum(II) complexes of carbonyl-stabilized arsonium ylides

A fast atom bombardment (FAB) mass spectrometric study was carried out on the two O-coordinated carbonyl-stabilized arsonium ylide Pt(II) complexes {(dppe)PtCIOC(R)C(H)AsPh₃]}BF₄ ((dppe) = Ph₂PCH₂CH₂Ph₂; R = CH₃ (1), OCH₃ (3)) and on the two corresponding C-coordinated isomers {(dppe)PtClPh₃AsC(H)COR]}BF₄ (R = CH₃ (2), OCH₃ (4)). The mass spectral analysis of complexes 1 and 2 reveals that it is possible to distinguish the two isomeric forms mainly on the basis of the relative abundance of the protonated triphenylarsine oxide at m/z 323 while the different coordination modes of the ylide in complexes 3 and 4 are evidenced by the different fragmentation pathways of these two derivative;. Further, the reaction between (dppe)PtCl]₂(BF₄)₂ and the appropriate ylide performed under FAB conditions indicates that in both cases the first complex formed is the C-coordinated isomer, in agreement with that observed in the condensed phase.