The (oxo)[(2,3,7,8,12,13,17,18-octachloro-5,10,15,20-tetrakis(4-tolylporphyrinato)]vanadium(IV): Synthesis, UV–visible, Cyclic voltammetry and X-ray crystal structure

Abstract

International audienceThe present work is concerned with the oxo vanadium(IV) complex of 2,3,7,8,12,13,17,18-octachloro-5,10,15,20-tetrakis(4-tolylporphyrin) with formula [V(Cl8TTP)O] (I), which was prepared by reacting the (oxo)[5,10,15,20-tetrakis(4-tolylporphyrinato)]vanadium(IV) complex ([V(TTP)O]), under aerobic atmosphere, with a large excess of thionyl chloride (SOCl2). The title compound was characterized by UV–visible spectroscopy, cyclic voltammetry and X-ray crystal structure. The electron-withdrawing chlorine substituents at the pyrrole carbons in the vanadyl-Cl8TTP derivative produce remarkable redshifts of the Soret and Q absorption bands and an important anodic shift of the porphyrin ring oxidation and reduction potentials. This is an indication that the porphyrin core of complex (I) is severely nonplanar in solution. The molecular structure of our vanadyl derivative shows a very high saddle distortion and an important ruffled deformation of the porphyrin macrocycle. The crystal structure of (I) is made by one-dimensional chains parallel to the c axis where channels are located between these chains. © 2017 Elsevier B.V

Molecular And Solid‐State Structure Of Oxovanadium(IV) Etioporphyrin‐III

“…However, a comparison with the literature data on H…O distances in various porphyrin aggregates suggests that this H‐bonding is weak [7,21,24,33] . So, the C−H…O distances in crystals of an analogous complex, namely, meso‐ substituted vanadyl porphyrin derivative reported in Ref [34] . are in the 2.42–2.54 Å range.…”

“…Besides, if a molecule incorporates a strong acceptor atom like chalcogen or halogen, the thermodynamically driven principle of “closest packing” in the van‐der‐Waals crystals can be complicated by hydrogen bonding [7,32,37,38] . Note that etioporphyrin ligand does not bear bulky side groups as do many other natural and non‐natural porphyrins, which might hinder adopting an electrostatically favorable arrangement by molecules in a solid [7,33,34,36,39] …”

“…[7,21,24,33] So, the CÀ H…O distances in crystals of an analogous complex, namely, meso-substituted vanadyl porphyrin derivative reported in Ref. [34] are in the 2.42-2.54 Å range.…”

“…[7,32,37,38] Note that etioporphyrin ligand does not bear bulky side groups as do many other natural and non-natural porphyrins, which might hinder adopting an electrostatically favorable arrangement by molecules in a solid. [7,33,34,36,39] Therefore, a question arises as to whether or not a weak hydrogen bond alone can create and maintain a stable 3D network, in which carbon atoms in the molecules approach at a distance 1.6 times smaller than the sum of their van-der-Waals radii. Most likely not, and the packing shown in Figure 2 reflects a superposition of several driving forces.…”