Phosphaketenes are important versatile reagents in organophosphorus chemistry. We herein report on the synthesis of novel mono- and bis-phosphaketenes based on redox-active acenaphthene-1,2-diimine ligands (bian) and their reactions with bian-gallylene and a trityl radical. The interaction of diiodide gallium(III) (ArBIG-bian)GaI2 (ArBIG-bian = 1,2-bis(2,6-dibenzhydryl-4-methylphenyl)iminoacenaphthene) with two equivalents of sodium phosphaethynolate Na(PCO)(diox)0.5 gives the first paramagnetic phosphaketene (ArBIG-bian)Ga(PCO)2 (1). Reaction of 1 with gallylene (ArBIG-bian)Ga leads to phosphaketene (ArBIG-bian)Ga(PCO) (2). Gallium phosphaketene (ArBIG-bian)Ga(Py)(PCO) (3) is formed as a result of the interaction between diimine ArBIG-bian and excess gallium metal in the presence of gallium chloride in pyridine and a subsequent metathesis reaction with sodium phosphaethynolate. The addition of a trityl radical to 3 produces a sterically hindered alkyl complex (ArBIG-bian)Ga(CPh3) (4). New compounds 1-4 have been characterized by ESR (1) and NMR (2-4) spectroscopy; their molecular structures have been established by single-crystal X-ray analysis. The electronic structures of 1-4 and reaction thermodynamics were studied by DFT calculations.
Skatova et al. (2026) studied this question.