| Abstrakt: |
Reaction of tris(2,4-pentanedionato)yttrium(III) with octaethylporhyrin, H2oep in refluxing 1,2,4-trichlorobenzene (TCB) produces a trace (2%) of the double-decker, Y(oep)2(3A) besides major amounts (72%) of the yttrium(III) monoporphyrinate, Y(oep)(acac) which are separated by chromatography. Appreciable yields of Y(oep)2(3A) (25%) are obtained from dilithium octaethylporphyrinate, Li2(oep), formed in situ and Y(oep)(acac) in refluxing TCB. The constitution of the double-decker 3Ais proved by UV/VIS, IR, 1H NMR, ESR, ENDOR, and mass spectra. The well-defined composition Y(oep)2requires that one of the porphyrin rings is electron-deficient, i.e. the charge of the YIIIion is compensated by the normal porphyrinate dianion and a porphyrinate monoanion radical. The magnetic moment in the solid state, μeff=1.5 B.M. (5–100 K), demonstrates the radical nature of 3Aas well. Under the time resolution of the methods used, the unpaired electron is delocalized between the two porphyrin rings. The wavenumber of the internal charge transfer absorption band in the near infrared (λCTI1175 nm) agrees well with the value expected for the ionic radius of YIIIaccording the linear relationship of the energy of the CTI band and the ionic radius which has been established for the series of lanthanoid octaethylporphyrinates, Ln(oep)2(Ln=La···Lu). 3Acan be reduced to the diamagnetic sandwich anion, [Y(oep)2]−. YIIIdouble-decker radicals Y(omp)2(3B; λCTI1100 nm) or Y(hbp)2(3C, λCTI1100 nm) containing octamethylporphyrin or hexadecahydrotetrabenzoporphyrin have also been prepared. |
