THE [PO2F2-CENTER-DOT-2ASF(5)](-) ANION, AN EXAMPLE OF A STABLE, OXYGEN-BRIDGED, 1 2-DONOR-ACCEPTOR POLYNUCLEAR ANION/

KPO2F2 reacts at room temperature with excess AsF5 in a 1:2 mol ratio. The resulting stable white product was characterized by vibrational a nd multinuclear NMR spectroscopy in the solid state and SO2 solution, respectively. It is shown that AsF5 neither displaces PO2F from KPO2F2 , nor generates PO2+AsF6-, but forms a stable, oxygen-bridged polynucl ear [PO2F2 . 2AsF(5)](-) anion. When pyrolyzed, this anion undergoes a stepwise decomposition to KAsF6, POF3 and AsOF3, followed by the deco mposition of KAsF6 to KF and AsF5. While [PO2F2 . 2AsF(5)](-) is stabl e in SO2 solution, it decomposes in CD3CN solution to the known CD3CN . AsF5 adduct and [PO2F2 . AsF5](-) anion. The inability of AsF5 to di splace PO2F from its salts confirms that the latter is a very strong L ewis acid which is comparable in strength to AsF5. With PF5 the KPO2F2 salt forms at -78 degrees C the 1:2 adduct K[PO2F2 . 2PF(5)], which o n warm-up to room temperature loses 1 mol of PF5 to give the 1:1 adduc t, K[PO2F2 . PF5]. The 1:1 adduct is marginally stable at room tempera ture and undergoes slow POF3 evolution. An improved synthesis of POF3 from PF5 and P4O10 is reported.