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The use of Bu(3)SnH and Me(3)SnH in the synthesis of HP(CF(3))(2) and HP(C(6)F(5))(2) from the corresponding bromides leads to a high-yield synthesis, which additionally provides these compounds in large quantities. The pentacarbonyl tungsten complexes [W(CO)(5)PH(CF(3))(2)] and [W(CO)(5)PH(C(6)F(5))(2)] were synthesized reacting the corresponding phosphanes with [W(CO)(5)THF] and characterized by X-ray and elemental analysis as well as multinuclear NMR and mass spectroscopy. The vibrational analyses of HP(CF(3))(2) and HP(C(6)F(5))(2) and their tungsten pentacarbonyl complexes were achieved in combination with hybrid DFT calculations. The optimized structures of [W(CO)(5)PH(CF(3))(2)] and [W(CO)(5)PH(C(6)F(5))(2)] at the B3PW91 level of theory using a LanL2DZ basis and ECP at the tungsten atom and a 6-311G(3d,p) and 6-311G(d,p) basis set for the nonmetal atoms, respectively, yield an impressively good agreement between experimental and theoretical geometric parameters. An increased pi-acidity of HP(CF(3))(2) in comparison with HP(C(6)F(5))(2) and HPPh(2) is discussed in the context of vibrational analysis, X-ray structural investigations, and theoretical calculations.

The bis(trifluoromethyl)phosphanide ion, P(CF(3))(2)(-), decomposes slowly above -30 degrees C in CH(2)Cl(2) and THF solution. An increase of the thermal stability of the P(CF(3))(2)(-) moiety is observed if excess CS(2) is added. The P(CF(3))(2)(-) moiety is stabilized because of the formation of the bis(trifluoromethyl)phosphanodithioformate anion. Solutions of a [P(CF(3))(2)CS(2)](-) salt still act as a source of P(CF(3))(2)(-), even in the presence of excess of CS(2). The stable compound [18-crown-6-K][P(CF(3))(2)CS(2)] was characterized by multinuclear NMR spectroscopy, elemental analysis, and vibrational spectroscopy in combination with quantum chemical calculations. The thermally unstable P(C(6)F(5))(2)(-) ion decomposes even at -78 degrees C in solution giving polymeric material. The intermediate formation of the bis(pentafluorophenyl)phosphanide anion in the presence of excess of CS(2) allows the isolation of [18-crown-6-K][P(C(6)F(5))(2)CS(2)]. The novel compound crystallizes with one solvent molecule CH(2)Cl(2) in the monoclinic space group P2(1)/n with a = 1151.8(1) pm, b = 1498.1(2) pm, c = 2018.2(2) pm, beta = 102.58(1) degrees, and Z = 4. Optimized geometric parameters of the [P(C(6)F(5))(2)CS(2)](-) ion at the B3PW91/6-311G(d) level of theory are in excellent agreement with the experimental values.

The stabilization of the P(CF(3))(2)(-) ion by intermediary coordination to the very weak Lewis acid acetone gives access to single crystals of [18-crown-6-K]P(CF(3))(2). The X-ray single crystal analysis exhibits nearly isolated P(CF(3))(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(CF(3))(2)(-) ion to pentacarbonyl tungsten has only a minor effect on electronic and geometric properties of the P(CF(3))(2) moiety, while a strong increase in thermal stability of the dissolved species is achieved. The hitherto unknown P(C(6)F(5))(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(C(6)F(5))(2)](CO)(5)], which is fully characterized. The tungstate, [W[P(C(6)F(5))(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(C(6)F(5))(2)]].THF exhibits a very tight arrangement of the two C(6)F(5) and two W(CO)(5) groups around the central phosphorus atom. NMR spectroscopic investigations of the [[W(CO)(5)](2)[mu-P(C(6)F(5))(2)]](-) ion exhibit a hindered rotation of both the C(6)F(5) and W(CO)(5) groups in solution.