Synthesis of some 5,10,15,20‐tetraalkylchlorin and tetraalkylporphyrin complexes of transition metals

Metal‐assisted template syntheses of 5,10,15,20‐tetraalkylchlorin and tetraalkylporphyrin complexes of transition metals are described. With Co only the porphyrins are obtained; with Cu only the chlorins; with Ni a mixture of chlorin and porphyrin is obtained depending on alkyl and added anhydride. As opposed to the higher alkyls, (5,10,15,20‐tetramethylporphyrinato)nickel(II) dimerizes in solution, a dimerization constant of 3.9 ± 1.3 M⁻¹ being derived from ¹H nmr data.