Electrochemistry and spectral characterization of arsenic porphyrins with σ-bonded axial ligands: X-ray crystallographic analysis of [(OEP)As(F)₂]⁺PF₆⁻, [(OEP)As(CH₃)(OCH₃)]⁺ClO₄⁻ and [(OEP)As(C₂H₅)₂]⁺PF₆⁻

Abstract

The electrochemistry of nine arsenic(V) octaethylporphyrins is reported in benzonitrile or dichloromethane containing 0.1 M tetra-n-butylammonium perchlorate as supporting electrolyte and the results compared to data for phosphorus and antimony porphyrins containing a similar set of σ-bonded and/or anionic axial ligands. The investigated compounds are divided into three groups based on the nature of the axial ligands and are represented as [( OEP ) As ( R )( R ')] + (group I), [( OEP ) As ( R )( X )] + (group II) and [( OEP ) As ( F ) 2 ] + (group III) where R and R’ = CH 3 or C 2 H 5 , X = OH − , OCH 3 − , OC 2 H 5 − , OC 3 H 7 − or NHC 4 H 9 − and OEP = the dianion of octaethylporphyrin. Each compound was characterized in its neutral, oxidized and reduced form by UV-visible and ESR spectroscopy. An X-ray crystallographic analysis of [( OEP ) As ( F ) 2 ] + PF 6 − , [( OEP ) As ( CH 3 )( OCH 3 )] + ClO 4 − and [( OEP ) As ( C 2 H 5 ) 2 ] + PF 6 − is also presented.