15276-13-8Relevant academic research and scientific papers
Circular dichroism of chromium(III) complexes. 10. Circular dichroism spectra in the spin-forbidden transitions of CrIII(N)6 type complexes with chiral diamines
Kaizaki, Sumio,Ito, Mieko,Nishimura, Noriko,Matsushita, Yukie
, p. 2080 - 2088 (2008/10/08)
Room-temperature solution circular dichroism (CD) spectra were measured in the spin-forbidden 2Eg, 2T1g ← 4A2g d-d transitions of the diastereomers of [Cr(en)x(diamine)3-x]3+ (x = 0, 2), cis-[Cr(NH3)2(diamine)2]3+, and [Cr(NH3)4(diamine)]3+, where the diamines used were (R)- or (S)-propylenediamine and (1R,2R)- or (1S,2S)-1,2-trans-cyclohexanediamine. The differences in observed CD spectra between each pair of the diastereomers were accounted for by separability and additivity of the configurational and vicinal CD effects. Consistent assignments for these configurational and vicinal CD peaks to the doublet ← quartet electronic transitions were made in connection with the CD in the spin-allowed 4T2g ← 4A2g transitions on the basis of the theoretical approaches for the energy ordering and the rotational strengths between the spin-forbidden and the spin-allowed transitions; e.g., four vicinal CD peaks in the spin-forbidden transitions of the tris(diamine) complexes were assigned to the 2ā(2Eg), ē(2Eg), 2A2(2T1g), and 2E(2T1g) from the lower frequency side. This is the first demonstration by the room-temperature solution CD measurements for the 2Eg split components due to the electronic transitions to the Kramers doublets (2ā and ē) with a small spacing of less than 100 cm-1.
