The stabilization of the P(CF3)(2)(-) ion by intermediary coordination to the very weak Lewis acid acetone gives access to single crystals of [18-crown-6-K]P(CF3)(2). The X-ray single crystal analysis exhibits nearly isolated P(CF3)(2)(-)ions with an unusually short P-C distance of 184(1) pm, which can be explained by negative hyperconjugation and is also found by quantum chemical hybrid DFT calculation. Coordination of the P(CF3)(2)(-) ion to pentacarbonyl tungsten has only a minor effect on electronic and geometric properties of the P(CF3)2 moiety, while a strong increase in thermal stability of the dissolved species is achieved. The hitherto unknown P(C6F5)(2)(-) ion is stabilized by coordination to pentacarbonyl tungsten and isolated as a stable 18-crown-6 potassium salt, [18-crown-6-K][W{P(C6F5)(2)}(CO)(5)], which is fully characterized. The tungstate, [W{P(C6F5)(2)}(CO)(5)](-), decomposes slowly in solution, while coordination of the phosphorus atom to a second pentacarbonyl tungsten moiety results in an enhanced thermal stability in solution. The single-crystal X-ray analysis of [18-crown-6-K][{W(CO)(5)}(2){mu-P(C6F5)(2)}].THF exhibits a very tight arrangement of the two C6F5 and two W(CO)(5) groups around the central phosphorus atom. NMR spectroscopic investigations of the [{W(CO)(5)}(2){mu-P(C6F5)(2)}](-) ion exhibit a hindered rotation of both the C6F5 and W(CO)(5) groups in solution.