Synthesis, Characterization, and Electrochemical Studies of β,β‘-Fused Metallocenoporphyrins

β,β‘-Fused monoruthenocenylporphyrins, Cp*Ru(III)[1,2-[M(II)-5,10,15,20-tetrakis(3,5-di-tert-butylphenyl)-porphyrinato]-3-methyl-cyclopentadienide] (M = Ni (20), Cu (21), Zn (22)), and bisferrocenoporphyrins, Fe(II) bis[1,2-[M(II)-5,10,15,20-tetraphenylporphyrinato]-3-methyl-cyclopentadienide] (M = Ni (24), Cu (25), Zn (26)), were synthesized and characterized. A novel synthetic approach to β,β‘-fused porphyrins through Pd(0)-catalyzed [3 + 2] cycloaddition was implemented in this work. UV−vis spectra of these compounds show largely broadened and red-shifted bands (relative to their precursors) indicating potential electronic communication between the attached organometallic moiety and the porphyrin core. The electrochemistry of these molecules suggests significant electronic interactions between the metallocene and metalloporphyrin in molecules 20 and 24. The crystal structure of the bisferrocenoporphyrin 26, Fe(II) bis[1,2-[Zn(II)-5,10,15,20-tetraphenylporphyrinato]-3-methyl-cyclopentadienide], was determined:  {Cp₂Fe[ZnTPP(THF)]₂}{Cp₂Fe[ZnTPP(THF)ZnTPP(MeOH)]}·3MeOH·6THF, M = 3804.35, monoclinic, space group P2₁/c, a = 33.327(5) Å, b = 19.145(3) Å, c = 29.603(5) Å, β = 106.309(2)°, V = 18128(5) ų, Z = 4. In this molecule, one porphyrin ring is rotated by about 72^o with respect to the other in the 5-fold axis of the Cp ring.