Charge directed reactivity:: a simple electronic model, exhibiting site selectivity, for the dissociation of ions

Abstract A Huckel-type effective Hamiltonian is used to examine the conditions for site-selected reactivity. The example is the dissociation of a positive ion, as in mass spectrometry. Coupling to the dissociative channels is included by a rate operator. We examine the time evolution of the charge and bond order matrices and of the yield of fragments following a localized initial ionization. Dissociation is found to follow the (positive) charge. Variations in the local properties can markedly change the dissociation pattern. A more statistical limit is reached when the migration of charge is unimpeded.

[1]  R. Levine,et al.  On the unimolecular dissociation of large molecules , 1989 .

[2]  M. Newton,et al.  Quantum chemical probes of electron-transfer kinetics: the nature of donor-acceptor interactions , 1991 .

[3]  R. Levine,et al.  Quantum mechanics of molecular rate processes , 1969 .

[4]  M. Newton,et al.  Calculation of electronic coupling matrix elements for ground and excited state electron transfer reactions: Comparison of the generalized Mulliken-Hush and block diagonalization methods , 1997 .

[5]  J. C. Lorquet,et al.  Whither the statistical theory of mass spectra , 1994 .

[6]  R. Weinkauf,et al.  ELEMENTARY PROCESSES IN PEPTIDES : ELECTRON MOBILITY AND DISSOCIATION IN PEPTIDE CATIONS IN THE GAS PHASE , 1995 .

[7]  R. Weinkauf,et al.  Highly Efficient Charge Transfer in Peptide Cations in the Gas Phase: Threshold Effects and Mechanism , 1996 .

[8]  N. Hush,et al.  Electron transfer and energy transfer through bridged systems. I. Formalism , 1989 .

[9]  P. Phillips,et al.  Hopping‐to‐band transitions in disordered electronic systems , 1987 .

[10]  R. Kosloff,et al.  Superexchange-Assisted Through-Bridge Electron Transfer: Electronic and Dynamical Aspects , 1990 .

[11]  Statistical fragmentation patterns in multiphoton ionization: A comparison with experiment , 1981 .

[12]  S. Rice,et al.  A quantum ergodic theory approach to unimolecular fragmentation , 1975 .

[13]  R. Levine,et al.  Molecular Reaction Dynamics and Chemical Reactivity , 1987 .

[14]  Klaus Ruedenberg,et al.  Free‐Electron Network Model for Conjugated Systems. V. Energies and Electron Distributions in the FE MO Model and in the LCAO MO Model , 1954 .

[15]  R. Levine,et al.  Ionization, charge separation, charge recombination, and electron transfer in large systems , 1992 .

[16]  F. Remacle,et al.  Trapping in competitive decay of degenerate states , 1990 .

[17]  P. Morse,et al.  Methods of theoretical physics , 1955 .

[18]  R. Levine,et al.  On the quantum mechanical theory of unimolecular reactions through a narrow bottleneck: the prompt and delayed dissociation , 1996 .

[19]  M. Ratner.  Bridge-assisted electron transfer: effective electronic coupling , 1990 .

[20]  M. Newton.  Electronic structure analysis of electron-transfer matrix elements for transition-metal redox pairs , 1988 .