Synthesis and Characterization of Mono-, Bis-, and Tetrakis-Pyridyltriarylporphyrin Pd(II) and Pt(II) Supramolecular Assemblies. Molecular Structure of a Pd-Linked Bisporphyrin Complex1

Abstract

A series of mono-, bis-, and tetrakisporphyrin assemblies was synthesized from 5-(p-pyridyl)-10,15,20-triphenylporphyrin, (pyPP)H2, 5-(p-pyridyl)-10,15,20-tri(p-tolyl)porphyrin, (pyTP)H2, (pyPP)Zn, (pyTP)Zn, and Pt(II) and Pd(II) complexes. Porphyrin subunits assemble around the central metal ions through the pyridyl group. Treating trans-Pd(DMSO)2Cl2 with 2 equiv of the pyridyl porphyrins resulted in the formation of trans-bisporphyrin assemblies Pd[(pyPP)H2]2Cl, Pd[(pyTP)H2]2Cl2, Pd[(pyPP)Zn]2Cl2, and Pd[(pyTP)Zn]2Cl2. Treating cis-Pt(DMSO)2Cl2 with 1 equiv of each pyridylporphyrin produced the cis-monoporphyrin complexes Pt(DMSO)[(pyPP)H2]Cl2, Pt(DMSO)[(pyTP)H2]Cl2, Pt(DMSO)[(pyPP)Zn]Cl2, and Pt(DMSO)[(pyTP)Zn]Cl2. The treatment of Pt(DMSO)(pyPOR)Cl2 with one more equiv of pyridylporphyrin resulted in the formation of cis-bisporphyrin assemblies, Pt[(pyPP)H2]2Cl2, Pt[(pyTP)H2]2Cl2, Pt[(pyPP)Zn]2Cl2, and Pt[(pyTP)Zn]2Cl2. Also, the reaction of Pt(DMSO)(pyPOR)Cl2 and 4-pyridyl-4‘-methylpyridinium iodide (MQ+I-) afforded cis-porphyrin−Pt−viologen assemblies. Treatment of M(DPPP)(OTf)2 (M = Pt, Pd; DPPP = 1,3-bis(diphenylphosphino)propane; OTf = triflate anion) with 2 equiv of pyridylporphyrin resulted in cis-bisporphyrin assemblies [M(DPPP)[(pyPOR)H2]2](OTf)2 and [M(DPPP)[(pyPOR)Zn]2(OTf)2. Synthesis of tetrakisporphyrin assemblies [M{(pyTP)H2}4]X2 (M = Pt, Pd; X = BF4, OTf) was accomplished by the reaction of [M(CH3CN)4]X2 with (pyTP)H2. Solution 1H NMR studies show that the four porphyrins are equivalent and that the central metals have square planar geometry. The crystal structure of [Pd(DPPP){(pyTP)H2}2](OTf)2 was determined by single-crystal X-ray diffraction analysis (monoclinic, P21/n, a = 13.211(5) Å, b = 36.741(19) Å, c = 22.971(10) Å, β = 91.54(3)°, V = 11145.8(86) Å3, Z = 4, R = 8.21%, Rw = 18.44%).