Preparation and spectra of the complexes of the first series transition metals with diphenic acid]

The ligand diphenic acid has been synthesized and the corresponding complexes of transition metal Co, Ni and Mn with diphenic acid have been prepared and characterized by the elementary analysis, IR spectra and ultraviolet-visible spectra. The results of IR show that the nu(as) and nu(s) of -CO2- in the complexes are lower than those of ligand diphenic acid, which can be explained by the coordinating between metal and ligand. In addition, compared with the complex IR spectra, the IR spectra of ligand became complicated due to the ligand polymerization through hydrogen bond. The UV-Vis spectra show that the ligand has three absorption peaks at 288, 273 and 270 nm, respectively, and these are slightly shifted in the complexes. Because the metal d-d absorption is weak, only in Co(C14H8O4).2H(2)O there is a d-d absorption at 537 nm.