ISSN:
0009-2940
Keywords:
Zirconium porphyrins
;
Porphyrin double-deckers
;
Special pair model system
;
ESR spectra, line width of
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Electron spin resonance spectra of the cation radicals A+ and B+ generated from a zirconium(IV) monoporphyrin, bis(acetato)(octaethylporphyrinato)zirconium(IV), Zr(OEP)(OAc)2 (A), and bis(octaethylporphyrinato)zirconium(IV), Zr(OEP)2 (B), respectively, have been measured at 293 and 77 K. [Zr(OEP*)(OAc)2]Br (A+ Br-) has been prepared in situ by oxidation of A with bromine, [Zr(OEP√/2)2]PF6 (B+ PF6-) by electrochemical oxidation of B. ESR parameters at 293 K are as follows: A+ Br-: g = 2.0025, ΔHpp = 0.57 mT; B+ PF6-: g = 2.0024, ΔHpp = 0.39 mT. The ratio of the line widths ΔHpp(A+) and ΔHpp(B+) of the ESR signals of A+ and B+ is 1.46 at room temperature, i. e. very close to the value of √2 expected for a defect electron completely delocalized between the two porphyrin π electron systems in [Zr(OEP*/2)2]+. The ESR signal of A+Br- persists on cooling to 77 K excluding any kind of π-π dimer formation. Treatment of (octaethylporphyrinato)bis(2,4-pentanedionato)zirconium(IV), Zr(OEP)(acac)2, with bromine yields bis(3-bromo-2,4-pentanedionato)(octaethylporphyrinato)zirconium(IV), Zr(OEP)(Bracac)2.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cber.19931261209
