SYNTHESIS OF VINYLENE-CO,N-LINKED MULTI(PORPHYRIN)S BY THE ADDITION OF FREE-BASE PORPHYRINS TO A C2H2 COMPLEX OF COBALT(III) PORPHYRIN AND THEIR OXIDATIVE REARRANGEMENT TO VINYLENE-N,N'-LINKED MULTI(PORPHYRIN)S

The nucleophilic addition reaction of a pyrrole nitrogen of free-base porphyrins to a pi-complexed acetylene ligand in a cationic Co-III por phyrin intermediate afforded good yields of vinylene-Co,N'-linked bis( porphyrin)s, (Por)Co-III-CH=CH-(N-Por)H-2. N-substituted porphyrin fre e bases are N-vinylated regioselectively at the pyrrole adjacent to th e original N-substituted pyrrole in this reaction. Tris- and tetrakis( porphyrin)s have been prepared by reacting a vinylene-N,N'-linked bis( meso-tetraarylporphyrin) with (OEP)Co-III(H2O)(2)ClO4 (OEP: octaethylp orphyrin dianion) and acetylene. The tetrakis!porphyrin) proved to be a 1:1 mixture of C-i- and C-2-symmetric regioisomers. These organometa llic Co-III complexes underwent facile oxidative migration of the Co-b ound vinyl group to a porphyrin pyrrole nitrogen when treated with Fe- III salts or HClO4 to provide moderate to good yields of Co-II vinylen e-N,N'-linked multi(porphyrin) complexes. (Vinylene-N,N')bis(porphyrin ) free bases with combinations of different porphyrins have been obtai ned by this procedure. The homobinuclear (2Co(II), 2Cu(II), and 2Zn(II )) and heterobinuclear ((CoCuII)-Cu-II and (CoZnII)-Zn-II) complexes h ave been prepared and characterized spectroscopically. The single-crys tal X-ray analysis of (CH=CH-N,N')[(OEP)(CoCl)-Cl-II][(TPP)(ZnCl)-Cl-I I] (TPP: meso-tetraphenylporphyrin dianion) showed a face-to-face stru cture with an average inter-ring separation of 4.39 Angstrom (triclini c P (1) over bar; Z = 2; a = 14.806(4), b = 18.703(10), c = 13.796(3) Angstrom, alpha = 97.69(3), beta = 99.57(2), gamma = 96.74(3)degrees).