Dianionic Titanyl and Vanadyl (Cation+ )2 [MIV O(Pc4- )]2- Phthalocyanine Salts Containing Pc4- Macrocycles.

In this study, the titanyl and vanadyl phthalocyanine (Pc) salts (Bu4 N+ )2 [MIV O(Pc4- )]2- (M=Ti, V) and (Bu3 MeP+ )2 [MIV O(Pc4- )]2- (M=Ti, V) with [MIV O(Pc4- )]2- dianions were synthesized and characterized. Reduction of MIV O(Pc2- ) carried out with an excess of sodium fluorenone ketyl in the presence of Bu4 N+ or Bu3 MeP+ is exclusive to the phthalocyanine centers, forming Pc4- species. During reduction, the metal +4 charge did not change, implying that Pc is an non-innocent ligand. The Pc negative charge increase caused the C-N(pyr) bonds to elongate and the C-N(imine) bonds to alternate, thus increasing the distortion of Pc. Jahn-Teller effects are significant in the [eg(π*)]2 dianion ground state and can additionally distort the Pc macrocycles. Blueshifts of the Soret and Q-bands were observed in the UV/Vis/NIR when MIV O(Pc2- ) was reduced to [MIV O(Pc.3- )].- and [MIV O(Pc4- )]2- . From magnetic measurements, [TiIV O(Pc4- )]2- was found to be diamagnetic and (Bu4 N+ )2 [VIV O(Pc4- )]2- and (Bu3 MeP+ )2 [VIV O(Pc4- )]2- were found to have magnetic moments of 1.72-1.78 μB corresponding to an S=1/2 spin state owing to VIV electron spin. As a result, two latter salts show EPR signals with VIV hyperfine coupling.