MONOMERIC AND DIMERIC CHROMIUM(III) PHTHA LOCYANINES - SYNTHESIS AND PROPERTIES OF HYDROXOPYRIDINIOPHTHALOCYANINATOCHROMIUM(III) AND MU-OXODI(PYRIDINOPHTHALOCYANINATOCHROMIUM(III)

Heating of ''[Cr(OH)Pc2-]'' in pyridine (Py) gives the paramagnetic (T = 273 K) complexes [Cr(OH)(Py)Pc2-] (mu(cr) = 3.84 mu(B) and [(Cr(Py) Pc2-)2O] (mu(Cr) = 1.24 mu(B)) by consecutive substitution and condens ation reactions. The UV-VIS spectra are characterized by the typical B , Q, and N regions of the Pc2- ligand being shifted hypsochromically f or the dimer with respect to the monomer due to excitonic coupling (1. 5 kK). Regions of weak absorbance between 8 and 13 resp. 19 kK are ass igned to trip-quartet transitions for both complexes. A weak band at 8 70 cm-1 in the FIR/MIR spectra is assigned to nu(as)(Cr-O-Cr). In the resonance Raman(RR) spectra nu(Cr-O) at 514 cm-1 resp. nu(s)(Cr-O-Cr) at 426 cm-1 is selectively enhanced. Further strong RR-lines of the mu -Oxo dimer at 110 and 631 cm-1 are assigned to a (Py-Cr-O)- resp. inte rnal pyridine deformation of a1g symmetry. An assignment as 2nu(as)(Cr -O-Cr) is proposed for the remarkable RR line at 1740 cm-1.