Charge-localized p-phenylenedihydrazine radical cations: ESR and optical studies of intramolecular electron transfer rates

被引:111
作者
Nelsen, SF
Ismagilov, RF
Powell, DR
机构
[1] Department of Chemistry, University of Wisconsin, Madison, WI 53706-1396
关键词
D O I
10.1021/ja9720321
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
1,4-Bis(2-tert-butyl-2,3-diazabicyclo[2.2.2]oct-3-yl)benzene-1,4-diyl (2) its 2,5-dimethyl and 2,3,5,6-tetramethyl derivatives (3 and 4), their radical cations, and bis-radical dications are studied. Crystal structures including those of 2(+)BPh(4)(-), 3(2+)(BPh4-)(2), 4(+)BPh(4)(-), and 4(2+)(BPh4-)(2) establish that ring methylation causes more N-lone pair, aryl pi twist without changing the N-Ar,N-Ar distance significantly and that both 2(+) and 4(+) have the charge localized in one hydrazine unit. NMR measurements show that 3(+) has about 6% of its spin at the four aryl CH and CMe carbons, while 4(+) has about 1.5% of its spin at the four CMe carbons. The average distance between the unpaired electrons of 3(2+) and 4(2+) was obtained from the dipolar splittings of their thermally excited triplet states and, as expected, is significantly smaller for 3(2+) (5.25 Angstrom) than for 4(2+) (5.63 Angstrom). Rate constants for electron transfer between the hydrazine units of 3(+) and 4(+) in CH2Cl2 and CH3CN were determined by dynamic ESR. The intervalence radical cations show charge transfer bands corresponding to vertical electron transfer between the ground state and the highly vibrationally excited electron-shifted state, allowing calculation of the parameters controlling electron transfer. Electron transfer parameters obtained from the CT bands using adiabatic energy surfaces which approximate the CT band shapes observed produce rate constants within experimental error of those extrapolated to room temperature from the ESR data for both 3(+) and 4(+) in both solvents, without using tunneling corrections. The effects of mixing of the electronic wave functions of the reduced and oxidized hydrazine units of 2(+) on d(NN), the C(t-Bu)N,NA(Ar) twist angle, and the aryl nitrogen lone pair, aryl pi twist angle which are observed by X-ray are close to those predicted from the position of the minima on the ET coordinate X of the adiabatic energy surface calculated from the CT band.
引用
收藏
页码:10213 / 10222
页数:10
相关论文
共 39 条
  • [1] Contemporary issues in electron transfer research
    Barbara, PF
    Meyer, TJ
    Ratner, MA
    [J]. JOURNAL OF PHYSICAL CHEMISTRY, 1996, 100 (31) : 13148 - 13168
  • [2] Localization versus delocalization in diamine radical cations
    Brouwer, AM
    Wiering, PG
    Zwier, JM
    Langkilde, FW
    Wilbrandt, R
    [J]. ACTA CHEMICA SCANDINAVICA, 1997, 51 (02): : 217 - 219
  • [3] SOLVENT REORGANIZATION IN OPTICAL AND THERMAL ELECTRON-TRANSFER PROCESSES
    BRUNSCHWIG, BS
    EHRENSON, S
    SUTIN, N
    [J]. JOURNAL OF PHYSICAL CHEMISTRY, 1986, 90 (16) : 3657 - 3668
  • [4] BAND-SHAPE ANALYSIS OF THE CHARGE-TRANSFER FLUORESCENCE IN BARRELENE-BASED ELECTRON DONOR-ACCEPTOR COMPOUNDS
    CORTES, J
    HEITELE, H
    JORTNER, J
    [J]. JOURNAL OF PHYSICAL CHEMISTRY, 1994, 98 (10) : 2527 - 2536
  • [5] MIXED-VALENCE COMPLEXES OF D5-D6 METAL CENTERS
    CREUTZ, C
    [J]. PROGRESS IN INORGANIC CHEMISTRY, 1983, 30 : 1 - 73
  • [6] METAL-LIGAND AND METAL-METAL COUPLING ELEMENTS
    CREUTZ, C
    NEWTON, MD
    SUTIN, N
    [J]. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY, 1994, 82 (1-3) : 47 - 59
  • [7] PATHWAYS OF PROTON-TRANSFER IN ACETAL HYDROLYSIS
    DUNN, BM
    [J]. INTERNATIONAL JOURNAL OF CHEMICAL KINETICS, 1974, 6 (01) : 143 - 159
  • [8] STABLE N,N'-DI-TERT-BUTYL-META-PHENYLENE-BISNITROXIDES - UNEXPECTED GROUND-STATE SINGLETS
    DVOLAITZKY, M
    CHIARELLI, R
    RASSAT, A
    [J]. ANGEWANDTE CHEMIE-INTERNATIONAL EDITION IN ENGLISH, 1992, 31 (02): : 180 - 181
  • [9] SPIN DISTRIBUTIONS AND GEOMETRIES OF THE RADICAL CATIONS OF SESQUINORBORNENES AND OTHER POLYCYCLIC TETRAALKYLETHENES
    GERSON, F
    GESCHEIDT, G
    NELSEN, SF
    PAQUETTE, LA
    TEASLEY, MF
    WAYKOLE, L
    [J]. JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1989, 111 (15) : 5518 - 5525
  • [10] RADIATIVE AND NONRADIATIVE ELECTRON-TRANSFER IN CONTACT RADICAL-ION PAIRS
    GOULD, IR
    NOUKAKIS, D
    GOMEZJAHN, L
    YOUNG, RH
    GOODMAN, JL
    FARID, S
    [J]. CHEMICAL PHYSICS, 1993, 176 (2-3) : 439 - 456