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  • Title: Fragmentation of pentacoordinate spirobicyclic aminoacyl-phosphoranes (P-AAs) by electrospray ionization tandem mass spectrometry concerning P-O and P-N bond cleavage.
    Author: Hu X, Gao X, Zhu J, Zeng Z, Zhang X, Lin Z, Xu P, Liu Y, Zhao Y.
    Journal: Rapid Commun Mass Spectrom; 2011 Oct 30; 25(20):3151-60. PubMed ID: 21953971.
    Abstract:
    The fragmentation pathways of both protonated and sodiated pentacoordinate spirobicyclic aminoacylphosphoranes (P-AAs) have been studied by electrospray ionization multi-stage mass spectrometry (ESI-MS(n)) in positive mode. The possible pathways and their mechanisms are elucidated through the combination of ESI-MS/MS, isotope ((15)N and (2)H) labeling and high-resolution Fourier transform ion cyclotron resonance (FTICR)-MS/MS. The relative Gibbs free energies (ΔG) of the product ions and possible fragmentation pathways are estimated at the B3LYP/6-31 G(d) level of theory. The theoretical calculations show that both protonated and sodiated P-AAs would quickly fragment before Berry pseudorotation. For protonated P-AAs, they have different tendencies to P-O or P-N bond cleavage. For sodiated P-AAs, the P-N bond is easier to cleave and produces the tetracoordinated phosphorus ion H. These results to some extent may give a clue to the chemistry of the active sites of phosphoryl transfer enzymes and will enrich the gas-phase ESI-MS ion chemistry of pentacoordinate phosphoranes.
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