Synthesis, spectral, and structural studies of the first examples of porphyrins substituted at the meso positions with sterically hindered eta(5)-CpCo(eta(4)-C4Ph4) cobalt sandwich units are described. The novel dipyrromethane derived cobalt sandwich compound {eta(5)-[(C4H4N)(2)CH]C5H4}Co(eta(4)-C4Ph4) 1, as well as its parent aldehyde, eta(5)-[C5H4(CHO)]Co(eta(4)-C4Ph4), were used in the synthesis of porphyrins having one or two eta(5)-CpCo(eta(4)-C4Ph4) groups at their meso positions. 1,9-Diformyldipyrromethane derived eta(5)-CpCo(eta(4)-C4Ph4) 2 was synthesized using dipyrromethane 1 under Vilsmeier conditions. A reaction of 2 with unsubstituted dipyrromethane under basic conditions in the presence of Pd(C6H5CN)(2)Cl-2 yielded an A-type palladium coordinated porphyrin 3 [where A = eta(5)-CpCo(eta(4)-C4Ph4)]. A similar reaction of 2 with meso aryl and ferrocenyl-substituted dipyrromethanes yielded trans-AB type palladium coordinated porphyrins 4-6 [where A = eta(5)-CpCo(eta(4)-C4Ph4) and B = 4-tert-butylphenyl 4, ferrocenyl 5, and pentafluorophenyl 6]. Reactions of 2 with 5-ferrocenyl dipyrromethane under the same reaction conditions in the presence of Ni(acac)(2) and Zn(OAc)(2) gave the trimetallic nickel(II) and zinc(II) complexed trans-AB type porphyrins 7 and 8 having both cobalt and iron sandwich units at the meso positions. Crystal structure of the Pd(II) porphyrin 5 and nickel(II) porphyrin 7 showed nonplanar structures having distinct ruffle type distortion of the porphyrin ring. Demetalation of the zinc(II) trans-AB type porphyrin 8 in the presence of trifluoroacetic acid gave the metal free base porphyrin 9. Reactions of the cobalt sandwich aldehyde [(eta(5)-C5H4(CHO)]Co(eta(4)-C4Ph4) with sterically hindered dipyrromethane derivatives under acid-catalyzed condensation reactions gave trans-A(2)B(2) type porphyrins [where A = eta(5)-CpCo(eta(4)-C4Ph4) and B = pentafluorophenyl, 10 mesityl 11]. In contrast, reactions of [eta(5)-C5H4(CHO)]Co(eta(4)-C4Ph4) with sterically unhindered meso-4-tert-butylphenyl dipyrromethane resulted in both AB(3) 12 and cis-A(2)B(2) 13 type porphyrins [where A = eta(5)-CpCo(eta(4)-C4Ph4) and B = (4-tert-butylphenyl] as a result of scrambling. The new porphyrin derivatives have been structurally characterized, and their spectral and electrochemical features were determined.