Bis(3-Phenyl−2,4-Pentanedionato)Copper. II. Polarized Crystal Spectra

Polarized spectra of (001) and (100) faces of the centric chelate bis(3-phenyl−2,4-pentanedionato)copper show four ``d—d'' bands, all principally y polarized. The transitions are of electric-dipole, vibronically allowed, single-molecule origin. From the polarization it is inferred that several vibrations are effective, but that the bulk of the intensity is borrowed from one charge-transfer transition, B3u←B1g in D2h. There is a subtle difference in interpretation between D2h and C2h(x) pseudosymmetry, either of which satisfactorily explains the results. From the temperature dependence of intensities, the two lowest-energy bands (∼15.4 and 16.9 kK) are inferred to be Ag(x2—y2, 3z2—r2)←B1g(xy), and the highest ones (∼19.0 and 20.6 kK) to be B2g(xz) and B3g(yz)←B1g(xy).