Nickel tetraphenylporphine

Tetraphenylporphine (1 g, 1.63 mmole) is dissolved in a minimum volume of trifluoroacetic acid (about 15 mL) and the solution is added to glacial acetic acid (200 mL) that has been heated at reflux in a 500-mL, round-bottomed flask. Nickel diacetate tetrahydrate (2 g, 8.0 mmole) is dissolved in a minimum of hot acetic acid and the resulting solution is added dropwise over a period of 5 minutes to the refluxing tetraphenylporphine solution. The mixture is allowed to heat at reflux for a further hour, and the hot solution is then filtered. The product is washed with boiling acetic acid until the filtrate is colorless and then further washed with water (3 X 25 mL) and methanol (3 X 25 mL). The purple crystalline product is dried in vacuum to give 1.05 g (96%). Anal. Calcd. for C44Hj8N4Ni C, 78.71 H, 4.20 N, 834. Found C, 79.05 H, 432 N, 8.22. 

An example of reversible intramolecular electron transfer has now been reported though not for a metal-metal system. It had previously been shown that the complexes [Ni (TPP)] (TPP =tetraphenylporphinate) when electrochemically oxidized in benzonitrile solution yield first the brown-coloured nickel(m) complex, which then decays at a measurable rate by a process of ligand-to-metal electron transfer [reaction (7), forward step (TPP )"=radical-ion] ... 

Miscellaneous Metal Ions.—Mention has been made already of a relatively slow formation reaction for the normally labile manganese(ii) ion. Incorporations of the labile bivalent metal ions zinc(ii), copper(ii), manganese(n), cobalt(ii), and nickel(n) into water-soluble porphyrin molecules such as tetrakis-(4-N-methyI-pyridyl)porphine, tetrasulphonated tetraphenylporphine, and uroporphine are also relatively slow reactions. However, by taking into account the porphyrin deformation which is necessary, an Id mechanism can be fitted to these reactions. The rates of formation and dissociation of nickel(ii), copper(n), cobalt(ii), and zinc(ii) complexes of the sterically hindered ligand 1,4,8,11-tetramethyl-1,4,8,11-tetra-azacyclotetra-decane (Meicyclam) are also 10 —10 smaller than is normal for these metal ions. ... 

---