Cadmium(II), nickel(II), and zinc(II) complexes of vacataporphyrin: A variable annulene conformation inside a standard porphyrin frame

Vacataporphyrin, which belongs to the family of core-modified porphyrins and resembles the parent 5, 10, 15, 20 tetaarylporphyrin, reveals interesting properties as a ligand. The molecule coordinates through three nitrogen atoms and due to coordination the macrocycle acquires two fundamentally different conformations affording, eventually, different modes of weak transaction between the central metal ion and the butadiene fragment.