Synthesis, characterization and catalytic studies of chromium(III) porphyrin complex with axial cyanate ligands

Abstract

We report the synthesis and the spectroscopic, structural and electrochemical characterization of a new chromium(III) coordination compound namely the bis(cyanato-κN)[meso-tetratolylporphyrinato]chromate(III) (cryptand-222)potassium dihydrate [K(crypt-222)][CrIII(TTP)(NCO)2]·2H2O (complex I). This compound crystallizes in the orthorhombic crystal system with the non-centrosymmetric space group C2221. The chromium and the potassium atoms are located at special positions in a two-fold axis. The crystal lattice of complex I is stabilized by O__H…O, C__H…O, C__H…N and C__H…π intermolecular contacts involving the negatively charged [CrIII(TTP)(NCO)2]− species, the [K(crypt-222)]+ counterions and the two non-coordinated water molecules. Further insights on these weak intermolecular contacts are provided by the Hirshfeld surface analysis. Molecular electrostatic potential (MEP) theoretical calculation on [K(crypt-222)][CrIII(TTP)(NCO)2]·2H2O are reported. The new Cr(III) complex was efficient as a catalyst in the decomposition of the Rhodamine B (RbH) dye by hydrogen peroxide. This coordination compound was also tested as a photocatalyst of the photodecomposition of the RbH dye by molecular oxygen.