Soluble molybdenum(V) imido phthalocyanines and pyrazinoporphyrazines: crystal structure, UV-vis and electron paramagnetic resonance spectroscopic studies.

Soluble alkyl and aryl imido phthalocyanines [Pc(#)Mo(NR)Cl] (R = tBu, Mes) with molybdenum(V) as central metal were prepared and studied by UV-vis and electron paramagnetic resonance (EPR) spectroscopy. As structural analogue to the weakly aggregating, soluble alkyl substituted Pc(#) ligand, a new, more electron deficient octaazaphthalocyanine, the pyrazinoporphyrazine ligand Ppz(#), was designed. The respective alkyl and aryl imido complexes [Ppz(#)Mo(NR)Cl] are the first examples of molybdenum pyrazinoporphyrazines. UV-vis and EPR spectra revealed unexpected differences between the alkyl and the aryl imido complexes, indicating different electronic structures depending on the nature of the axial ligand. The octahedral coordination of the molybdenum atoms by the axial NR and Cl ligands and the equatorial macrocycles could be verified by EPR spectroscopy. This result was also confirmed by the crystal structure of [Pc(#)Mo(NMes)Cl], which crystallizes from CH2Cl2 in the cubic space group Im3.