Capture of Phosphorus(I) and Arsenic(I) Moieties by a 1,2-Bis(arylimino)acenaphthene (Aryl-BIAN) Ligand. A Case of Intramolecular Charge Transfer

The reaction of PCl3 with SnCl2 in THF solution, followed by treatment with dpp-BIAN (dpp = 2,6-i-Pr2C6H3), affords the phosphenium complex [(dpp-BIAN)P][SnCl5·THF]. The 31P chemical shift (δ 232.5) and the metrical parameters from a single-crystal X-ray diffraction study indicate that the oxidation state of phosphorus in this compound is +3. A similar conclusion was reached regarding the phosphorus oxidation state in [(dpp-BIAN)P][I3], which was prepared via the reaction of dpp-BIAN with PI3 in CH2Cl2 solution. The arsenium salt [(dpp-BIAN)As][SnCl5·THF] was prepared by treatment of AsCl3 with SnCl2 in THF solution, followed by the addition of dpp-BIAN. The X-ray crystal structure of this salt was determined, and the pattern of bond distances and angles indicates that arsenic is present in the +3 oxidation state.