Ligand and Metal Effects in the Gas‐Phase Fragmentation of Thiomethoxymethyl Complexes

Abstract

While the collision‐induced dissociation (CID) of the mass‐selected cation [(Ph3P)2Pt(CH2SCH3)]+ causes the selective liberation of PPh3, the diphosphine complex [(dppe)Pt(CH2SCH3)]+ (dppe=1,2‐bis(diphenylphosphino)ethane) ejects C2H4, CH2S, and (CH3)2S upon CID. The analogous palladium complexes [(Ph3P)2Pd(CH2SCH3)]+ and [(dppe)Pd(CH2SCH3)]+ show similar reactivity, except that C−H‐bond activation is completely lacking. For other bidentate diphosphine ligands such as dppm, dppv, dppp, dppb, dppbz, dppf, and xantphos, a correlation of the dominant reaction channels with the bite angle is observed. For bite angles > 90°, hydrogen‐atom transfer is favored, as evidenced by an increase in dimethyl‐sulfide loss. For smaller bite angles (< 90°), intramolecular activation of the thiomethoxymethyl ligand predominates, thus resulting in increased losses of thioformaldehyde and ethene. The results of the CID experiments are compared with those for [(bipy)Pt(CH2SCH3)]+, for which the loss of C2H4 is observed as the main process. DFT calculations for the complexes [(dppe)Pt(CH2SCH3)]+ and [(bipy)Pt(CH2SCH3)]+ together with the experimental findings uncover subtle differences in the underlying reaction mechanisms.