Abstract

The title compound, [Zn(C72H44N4O8)(C4H10N2)] or [Zn(TPBP)(pipz] (where TPBP and pipz are 5,10,15,20-tetra-kis-[4-(benzo-yloxy)phen-yl]porphyrinato and piperazine ligands respectively), features a distorted square-pyramidal coordin-ation geometry about the central Zn(II) atom. This central atom is chelated by the four N atoms of the porphyrinate anion and further coordinated by a nitro-gen atom of the piperazine axial ligand, which adopts a chair confirmation. The average Zn-N(pyrrole) bond length is 2.078 (7) Å and the Zn- N(pipz) bond length is 2.1274 (19) Å. The zinc cation is displaced by 0.4365 (4) Å from the N4C20 mean plane of the porphyrinate anion toward the piperazine axial ligand. This porphyrinate macrocycle exhibits major saddle and moderate ruffling deformations. In the crystal, the supra-molecular structure is made by parallel pairs of layers along (100), with an inter-layer distance of 4.100 Å while the distance between two pairs of layers is 4.047 Å. A region of electron density was treated with the SQUEEZE [Spek (2015 ▸). Acta Cryst. C71, 9-18] procedure in PLATON following unsuccessful attempts to model it as being part of disordered n-hexane solvent and water mol-ecules. The given chemical formula and other crystal data do not take into account these solvent mol-ecules.

Highlights

  • TPBP and pipz are 5,10,15,20-tetrakis[4-(benzoyloxy)phenyl]porphyrinato and piperazine ligands respectively), features a distorted square-pyramidal coordination geometry about the central ZnII atom. This central atom is chelated by the four N atoms of the porphyrinate anion and further coordinated by a nitrogen atom of the piperazine axial ligand, which adopts a chair confirmation

  • Zinc porphyrin complexes provide simpler systems than those of iron, cobalt, or other d transition metals to evaluate the influence of a wide range of different ligands on the spectroscopic and structural properties of complexed porphyrins

  • To date no zinc–piperazine porphyrin structure has been reported in the literature

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Summary

Chemical context

The ZnII ion is one of the most prevalent metal ions as the metal center of a metalloporphyrin. Zinc porphyrin complexes provide simpler systems than those of iron, cobalt, or other d transition metals to evaluate the influence of a wide range of different ligands on the spectroscopic and structural properties of complexed porphyrins. The metal ion is unambiguously in the +II oxidation state; in most cases, fourcoordinate (porphyrinato) zinc complexes will accept one axial ligand to form complexes with a coordination number of five for the metal (Denden et al, 2015). Zinc porphyrins with a coordination number of six for the metal have been reported (Shukla et al, 2000; Oberda et al., 2013).

Structural commentary
Synthesis and crystallization
Synthesis of the starting materials
UV-visible spectra
Refinement
VENTURE Bruker AXS
Full Text
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