FIRST-ROW TRANSITION-METAL COMPLEXES OF CORROLES - SYNTHESIS AND CHARACTERIZATION OF OXOTITANIUM(IV) AND OXOVANADIUM(IV) COMPLEXES OF BETA-ALKYLCORROLES

Oxotitanium and oxovanadium beta-alkylcorrolates have been synthesized by reaction of corroles H(3)L with different metal carriers. These co mplexes retain an aromatic pi-electron system and exist as mononuclear species [MO(HL)] containing a M=O double bond. Optical and NMR spectr oscopy indicated reaction with base leading to the formation of anioni c species [MOL](-). Titanyl correlates represent the first examples of diamagnetic neutral complexes where the corrole acts as a dianionic l igand. Spectral characterization reveals that the location of the prot on of HL is at the N-22 or N-23 inner nitrogen atoms and that the comp lexes are present in two tautomeric forms. In contrast to derivatives of Cr or Mo where the metals are in the +5 oxidation state, the EPR sp ectra of the vanadyl corrolates confirm the +4 oxidation state for the co-ordinated metal. These new complexes complete the series of first- row transition-metal derivatives of corrole.