Abstract
Assignments of the electronic transitions responsible for the two relatively weak visible-absorption systems in the spectra of tetragonal molybdenyl ions, MoO3+, are considered in the light of available experimental data. Solution spectra of sulfato, phosphate, and chloro molybdenyl complexes as well as studies of the low temperature polarized spectra of MoOCI− 4 in a single crystal establish that the two transitions are 2E(xz, yz) → 2B2(xy) (∼15 500 cm−1) and 2B2 (x2 -y2 ) → 2B2 (xy) (∼22500 cm−1).