Faraday Effect of Charge-Transfer Transitions in Fe(CN)63−, MnO4−, and CrO42−

Abstract

Measurements of the magneto-optical rotatory dispersion (MORD) and magnetic circular dichroism (MCD) through the accessible charge-transfer bands of Fe(CN)63−, MnO4−, and CrO42− in the visible and ultraviolet are described and interpreted. The apparatus employed combines a superconducting solenoid furnishing maximum fields of 45 000 G with a commercial ORD—CD instrument which covers the range 185–700 mμ. The MCD measurements are found to be more reliable and are much easier to make; they are also more useful for theoretical interpretation. However, Kramers—Kronig transforms of the MORD results agree well with the experimental MCD measurements. Comparison of the theoretically derived Faraday parameters for Fe(CN)63− with those extracted from experiment shows that the 24 000-, 33 000-, and 38 500-cm−1 bands are due, respectively, to 2T2g→2T1u, 2T2u and 2T1u, ligand-to-metal(t2g) charge-transfer transitions. A similar analysis confirms the assignment of the lowest band in MnO4− and CrO42− to a t1(π)→e(π) transition. The observed parameters for higher bands agree well with predictions based on the recent Wolfsberg—Helmholz calculation of Viste and Gray but do not unambiguously confirm their assignments.

Use of magnetic circular dichroism to study dinuclear metallohydrolases and the corresponding biomimetics

“…The selection rules governing the transitions in Fig. 2 can be found by explicitly considering the appropriate matrix elements (Schatz et al 1966). Another interpretation of this is that the lcp and rcp photons carry angular momentum of −1 and +1, respectively, so that transitions with ΔJ = +1 and ΔJ = −1 require photons of lcp and rcp, respectively, for angular momentum to be conserved.…”

Magnetic circular dichroism studies of the charge-transfer transitions in tetrachloro and tetrabromocomplexes of transition metal ions

“…provides information which is unobtainable by any other known means, the most convincing piece of evidence being the M.C.D. assignment of the potassium ferricyanide spectrum [2].…”

Photoinduced Faraday effect in a cobalt-iron polycyanide film

“…28 Band B can be assigned to the ligand-to-metal CT band from CN Ϫ to Fe III , based on the results of magnetic circular dichroism spectrum of a ͓Fe III (CN) 6 ͔ 3Ϫ aqueous solution. 29 In conclusion, we have observed the photoinduced Faraday effect in a cobalt-iron polycyanide film. In the present film, FR and FE angles changed from zero to some values upon irradiating.…”