Synthesis and Characterization of Two Novel Complexes of Cr(III) with Benzilmonoxime

The reaction of benzilmonoxime (BMOH) with CrCl 3 .6H 2 O in methanol gives the mono nuclear Cr(III) complex, [Cr(BMO)3 3 ( 1 ). Reaction of complex 1 with a methanolic solution of KOH at room temperature leads to a di‐nuclear Cr(III)‐Cr(III) complex, [Cr(BMO) 2 (OH)] 2 ( 2 ). The complexes were characterized on the basis of their elemental analysis, Mass, IR, 1 H and 13 C‐NMR and electronic spectra. The IR studies were useful in assigning the coordination mode of the benzilmonoxime ligand to the chromium(III) ion. In addition, the presence of a hydroxo bridge in the dimeric complex 2 is inferred from the IR spectral studies. The electronic spectra of the complexes revealed two bands due to d–d transitions, and one band assignable to an oxygen (p π )→Cr(eg*) LMCT transition observed in both complexes. An additional charge transfer transition, assignable to μ‐OH(p π )→Cr(eg*), was only observed for the dimeric complex 2 . The splitting energy and Racah parameter were calculated to be 18484 cm ‐1 and 560 cm ‐1 for [Cr(BMO) 3 ] ( 1 ), 17986 cm ‐1 and 545 cm ‐1 for [Cr(BMO) 2 (OH)] 2 ( 2 ) respectively.