Spectroscopic and magnetic studies of some copper(II) and chromium(III) complexes with dithiophosphonates as ligands

CuO-bis[4-ethoxyphenyl-O-alkyl]-dithiophosphonate and Cr(III)-tris[4-ethoxy phenyl-O-alkyl] -dithiophosphonate complexes (alkyl = methyl, ethyl, isopro pyl) were prepared and studied by magnetic measurements, and electronic, IR and EPR spectroscopic studies. The valence vibrations of the PS2 group sho w that this group coordinates isobidentate. The electronic spectra of coppe r(LI) complexes display two weak bands at 15 200 and 18 500 cm(-1), (B-2(1g ) --> (2)A(1g) and B-2(1g) --> E-2(g)) and an intense band at 23 000 cm(-1) (L --> M charge-transfer). The powder EPR spectra of Cu (II) complexes are typical for square-planar monomeric species and present hyperfine and supe rhyperfine structure. These results suggest that the copper(II) complexes h ave D-4h symmetry. Two bands were observed in the W-Vis spectra of the chro mium complexes at 14 320 and 18 640 cm(-1) ((4)A(2g)(F) --> T-4(2g)(F) and (4)A(2g)(F) --> T-4(1g)(F)). The EPR bands of the Cr(III) complexes may be attributed to isolated metallic ions in pseudoocthaedral surroundings and t o Cr(III) ions coupled by dipole-dipole interaction. (C) 1999 Elsevier Scie nce B.V. All rights reserved.