4,5-Bis(diphenylphosphino)acridine: A new type of tridentate phosporus-nitrogen-phosphorus ligands

Article abstract of DOI:10.1016/S0040-4039(97)10790-0

Reaction of 4,5-difluoroacridine (8) with two equivalents of potassium diphenylphosphide (Ph₂PK) yielded the title compound 3. Contrarily, diphenylphosphine (Ph₂PH) reacted with 8 under addition, and 4,5-difluoro-9-diphenyl-9,10-dihydroacridine (12) was obtained. Compound 8 was prepared from 2-amino-3-fluorobenzoic acid (13) in a four step synthesis. As it is shown by the preparation of the metal complexes 4,5-bis(diphenylphosphino)-acridine-palladium dichloride (16) and 4,5-bis(diphenylphosphino)acridine-molybdenum tricarbonyl (17), compound 3 is capable of acting as a tridentate PNP ligand which coordinates transition metals in an approximately 'T-shaped' planar coordination geometry. Single crystal X-ray structure analyses we reported for 3 and 17.