Transition metal porphyrazines are a widely used class of compounds with
applications in catalysis, organic solar cells, photodynamic therapy and
nonlinear optics. The most prominent members of that family of compounds
are metallophtalocyanines that have been subject of numerous
spectroscopic and theoretical studies. In this work, the electronic
structure and X-ray absorption characteristics of three Cu-porphyrazine
derivatives are investigated by means of modern electronic structure
theory. More precisely, the experimentally observed N K-edge and Cu
L-edge features are presented and reproduced by time-dependent density
functional theory, restricted open-shell configuration interaction and a
restricted active space approach. Where possible, the calculations are
used to interpret the observed spectroscopic features in terms of
electronic transitions and furthermore connect spectral differences to
chemical variations. Part of the discussion of the computational results
concerns the impact of various parameters and approximations that enter
the calculations, e.g. the choice of active space.