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 Im3̅.