The nucleophilic addition reaction of a pyrrole nitrogen of free-base porphyrins to a pi-complexed acetylene ligand in a cationic Co-III porphyrin intermediate afforded good yields of vinylene-Co,N'-linked bis(porphyrin)s, (Por)Co-III-CH=CH-(N-Por)H-2. N-substituted porphyrin free bases are N-vinylated regioselectively at the pyrrole adjacent to the 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 : octaethylporphyrin dianion) and acetylene. The tetrakis!porphyrin) proved to be a 1:1 mixture of C-i- and C-2-symmetric regioisomers. These organometallic Co-III complexes underwent facile oxidative migration of the Co-bound vinyl group to a porphyrin pyrrole nitrogen when treated with Fe-III salts or HClO4 to provide moderate to good yields of Co-II vinylene-N,N'-linked multi(porphyrin) complexes. (Vinylene-N,N')bis(porphyrin) free bases with combinations of different porphyrins have been obtained by this procedure. The homobinuclear (2Co(II), 2Cu(II), and 2Zn(II)) and heterobinuclear ((CoCuII)-Cu-II and (CoZnII)-Zn-II) complexes have been prepared and characterized spectroscopically. The single-crystal X-ray analysis of (CH=CH-N,N')[(OEP)(CoCl)-Cl-II][(TPP)(ZnCl)-Cl-II] (TPP : meso-tetraphenylporphyrin dianion) showed a face-to-face structure with an average inter-ring separation of 4.39 Angstrom (triclinic 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).