Oxo(porphyrinato)vanadium(IV) as a standard for geoporphyrins

• The oxovanadium ([VO]2+) complex of unsubstituted porphyrin was prepared.
• Spectroscopic studies including single crystal diffraction study were carried out.
• A sombrero-shaped molecular structure was revealed and the packing motif was discussed based on Desiraju–Gavezzotti rule.

Oxo(porphyrinato)vanadium(IV), the oxovanadium [VIVO]2+ complex of unsubstituted porphyrin, was prepared and structurally characterized. Our synthetic method enabled us to obtain 1 in sufficient quantity. The paramagnetic complex was characterized by IR and mass spectroscopic measurements. The IR spectrum contained a strong absorption at 994 cm−1 (in KBr matrix) attributable to the VO stretching mode. Single-crystal diffraction study revealed that 1 was a pot lid shaped molecule, i.e., 1 exhibited a five-coordinate pseudo-square pyramidal geometry at the vanadium center. Vanadium was located above the porphyrin mean plane with a distance of 0.537(1) Å, and an oxygen atom was coordinated perpendicularly with a bond distance of 1.599(2) Å. The ligation of electropositive [VIVO]2+ induced a partial negative charge on N and a positive charge on vanadium. The resultant polarization induced an electrostatic attractive interaction, affording a dimer in the solid state with a very short interplanar distance of 3.269(2) Å. This dimer unit was packed in a herringbone manner.

A reproducible synthesis of oxo(porphyrinato)vanadium(IV) 1 was carried out and spectroscopic and single-crystal diffraction studies were performed. 1 exhibited a five-coordinate pseudo-square pyramidal geometry at the vanadium center. Ligation of the oxovanadium(IV) dication induced a partial negative charges on the ligand and a positive charge on vanadium. The resultant polarization effected an electrostatic attractive interaction that afforded a dimer in the solid state with a very short interplanar distance of 3.269(2) Å.Figure optionsDownload as PowerPoint slide