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)PtCI[OC(R)C(H)AsPh 3 ]}BF 4 ((dppe) = Ph 2 PCH 2 CH 2 Ph 2 ; R = CH 3 (1), OCH 3 (3)) and on the two corresponding C ‐coordinated isomers {(dppe)PtCl[Ph 3 AsC(H)COR]}BF 4 (R = CH 3 (2), OCH 3 (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 (BF 4 ) 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.