Pluteus aurantipes sp. nov. from Wisconsin, United States.

Pluteus aurantipes sp. nov. was discovered in Wisconsin, United States. This agaric species is characterized by its yellowish brown pileus, reddish orange stipe, pileipellis consisting of a trichoderm and lack of pleurocystidia.

Estimation of electron transfer parameters from AM1 calculations.

The utility of AM1 calculations for estimation of the electron-transfer parameters lambda'(v) (the enthalpy part of the Marcus internal reorganization energy) and H(ab) (the electronic coupling between the charge-bearing units) is considered for some charge-localized intervalence bis(hydrazine) radical cations, for which these parameters have been experimentally determined from optical measurements. The Koopmans estimate of lambda'(v) that employs the orbital separation for the neutral compound at the radical cation geometry is far from that calculated from the enthalpies of the species involved (eq 1) and is not correct. The eq 1 lambda'(v) enthalpies estimated by AM1 are reasonably good for compounds with only alkyl substituents but are overestimated by 33-59% for aryl-substituted hydrazines. The Koopmans estimate of H(ab) as half the orbital separation for the neutral species at the transition state geometry requires adjustment for the twist angles to those of the relaxed ground state to produce useful H(ab) values. Symmetry breaking occurs for the electron-transfer transition states of the compounds with saturated bridges, and the Koopmans estimate predicts H(ab) values that are slightly less than half as large as the optical measurements.

Solvent effects on charge transfer bands of nitrogen-centered intervalence compounds.

Electron transfer parameters are extracted from the optical spectra of intervalence bis(hydrazine) radical cations. Compounds with 2-tert-butyl-3-phenyl-2,3-diazabicyclo[2.2.2]octyl-containing charge-bearing units that are doubly linked by 4-sigma-bond and by 6-sigma-bond saturated bridges are compared with ones having tert-butylisopropyl- and diphenyl-substituted charge bearing units and others having the aromatic units functioning as the bridge. Solvent effect studies show that the optical transition energy (E(op)) does not behave as dielectric continuum theory predicts but that solvent reorganization energy may be usefully separated from the vibrational reorganization energy by including linear terms in both the Pekar factor (gamma) and the Gutmann donor number (DN) in correlating the solvent effect. Solvation of the bridge for these compounds is too large to ignore, which makes dielectric continuum theory fail to properly predict solvent effects on either E(op) or the free energy for comproportionation.

Adiabatic electron transfer: comparison of modified theory with experiment.

The radical cations of properly designed bishydrazines allow comparison of observed and calculated electron transfer rate constants. These compounds have rate constants small enough to be measured by dynamic electron spin resonance spectroscopy and show charge transfer bands corresponding to vertical excitation from the energy well for the charge occurring upon one hydrazine unit to that for the electron-transferred species. Analysis of the data for all six compounds studied indicates that the shape of the adiabatic surface on which electron transfer occurs can be obtained from the charge transfer band accurately enough to successfully predict the electron transfer rate constant and that explicit tunneling corrections are not required for these compounds.