Open AccessESI-FTICR-MS studies on gas phase fragmentation reactions of ArPd(PPh3)2I complexes
Author(s) -
Rong Qiu,
Yuan Xi Liao,
Yin Guo,
Hao Guo
Publication year - 2006
Publication title -
journal of the american society for mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.961
H-Index - 127
eISSN - 1879-1123
pISSN - 1044-0305
DOI - 10.1016/j.jasms.2006.07.009
Subject(s) - chemistry , fourier transform ion cyclotron resonance , fragmentation (computing) , palladium , ion cyclotron resonance , collision induced dissociation , triphenylphosphine , reductive elimination , mass spectrometry , bond cleavage , dissociation (chemistry) , medicinal chemistry , phosphine , ligand (biochemistry) , ion , stereochemistry , crystallography , tandem mass spectrometry , catalysis , organic chemistry , cyclotron , biochemistry , receptor , chromatography , computer science , operating system
Gas-phase fragmentation reactions of [ArPd(PPh3)2]+ were studied by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS). The results of sustained off-resonance irradiation collision-activated dissociation (SORI-CAD) experiments provide detailed insights into mechanisms for the gas-phase fragmentation reactions of these complex ions. The PC bond cleavage mediated by palladium is investigated in the gas phase. There are two competitive fragmentation pathways for the complex ions [ArPd(PPh3)2]+ (Ar = p-OCH3-C6H4, p-CH3-C6H4, p-tBu-C6H4, p-NH2-C6H4, p-COCH3-C6H4, and p-F-C6H4) of electron-donating and electron-withdrawing aromatic iodides. Path A proceeds through reductive elimination of [ArPd(PPh3)2]+ to produce the product ion [PPh3Ar]+. Path B mostly proceeds via phenyl migration from the triphenylphosphine ligand to the palladium center by cleavage of the phosphorus-phenyl bond to give a palladium-phenyl intermediate, and subsequent reductive elimination of the intermediate to yield a product ion [PPh4]+. The result of deuterium-labeling experiments provides evidence for the phenyl shift between the palladium center and the coordinated ligand through cleavage of the PC bond. The complex ions [(o-CH3-C6H4)Pd(PPh3)2]+, [(o-2,6-Me2-C6H3)Pd(PPh3)2]+, and [(C10H7)Pd(PPh3)2]+ display more fragmentation pathways, two of which are similar to those of the ions [ArPd(PPh3)2]+ (Ar = p-OCH3-C6H4, p-CH3-C6H4, p-tBu-C6H4, p-NH2-C6H4, p-COCH3-C6H4, p-F-C6H4), and the third pathway involves loss of one molecule of benzene and one PPh3 ligand. The electronic effect and steric effect of the aryl groups also exhibit different influences on the fragmentation pathways.