The selectivity between inner C-cyanation and alkylation in cobalt(II) complexes of N-confused porphyrin with an axial NCS− ligand

Some inner C-cyanation and C-alkylation complexes have been described. Reactions of 2-N-substituted N-confused tetraphenylporphyrin (2-NCH2YNCTPPH) with Co(SCN)2 afford C-alkylation (14) and C-cyanation (15–17) complexes. The crystal structures for the inner C-alkylation product of thiocyanato(2-aza-2-[p-methylbenzyl]-5,10,15,20-tetraphenyl-21-benzyl-21-carbaporphyrinato-N,N′,N″)cobalt(II)·0.5 octane solvate [Co(2-NCH2-p-CH3C6H4-21-CH2C6H5NCTPP)(NCS)·0.5C8H18; 14·0.5C8H18] and the inner C-cyanation products of thiocyanato(2-aza-2-ethoxycarbonylmethyl-5,10,15,20-tetraphenyl-21-cyano-21-carbaporphyrinato-N,N′,N″)cobalt(II) [Co(2-NCH2COOCH2CH3-21-CN NCTPP) (NCS); 15], thiocyanato(2-aza-2-methyl-5,10,15,20-tetraphenyl-21-cyano-21-carbaporphyrinato-N,N′,N″)cobalt(II)[Co(2-NCH3-21-CNNCTPP) (NCS); 16], and thiocyanato(2-aza-2-benzyl-5,10,15,20-tetraphenyl-21-cyano-21-carbaporphyrinato-N,N′,N″)cobalt(II) [Co(2-NCH2C6H5-21-CNNCTPP) (NCS); 17] have been reported. The geometry around Co2+ ion in these four complexes is a distorted tetrahedron with a C2v symmetry. Two possible mechanisms were proposed to explain the formation of inner C-alkylation (14·0.5C8H18) versus C-cyanation (15–17) products in these complexes with an axial *NCS− ligand.