Synthesis, Properties, and Crystal Structure of a Novel Anthracene-Bridged Molybdenum−Zinc Porphyrin Dimer

The synthesis and properties of novel anthracene-bridged porphyrin dimers having an oxomolybdenum(V) porphyrin unit, H₂(DPA)[Mo^VO(OMe)] (1) and (DPA)[Mo^VO(OMe)][Zn^II(MeOH)] (2), and the relevant monomer porphyrin complexes Mo^VO(MPP)OMe (3) and Zn^II(MPP) (4) are presented. An oxomolybdenum(V) unit was introduced into one of the two porphyrins in DPA to give 1, which has a free-base porphyrin unit. By introducing a zinc(II) ion to the free-base part, a mixed-metal complex of 2 was prepared and isolated. The structure of 2 was analyzed by X-ray crystallography (2·⁷/₆CH₂Cl₂, triclinic, P1̄ (no. 2), a = 15.2854(12) Å, b = 19.9640(15) Å, c = 13.6915(12) Å, α = 90.968(3)°, β = 113.108(4)°, γ = 96.501(4)°, Z = 2, R1 = 9.9, wR2 = 19.2). The structure of 2 demonstrated that a methanol is stably coordinated to the Zn(II) ion with the aid of a hydrogen bond to the methoxo ligand on the Mo(V) ion in the binding pocket of DPA. The electrochemical measurements of 2 suggested that the methanol was kept in the pocket of DPA in solution even at the reduced state of the molybdenum ion.