Synthesis of the first chiral bidendate bis(trifluoromethyl)phosphane ligand through stabilization of the bis(trifluoromethyl)phosphanide anion in the presence of acetone.

Lewis acid/Lewis base adduct formation of the P(CF3)2- ion and acetone leads to a reduced negative hyperconjugation and, therefore, limits the C--F bond activation. The resulting increased thermal stability of the P(CF3)2- ion in the presence of acetone allows selective substitutions and enables the synthesis of the first example of a chiral, bidentate bis(trifluoromethyl)phosphane ligand: a DIOP derivative, [(2,2-dimethyl-1,3-dioxolane-4,5-diyl)bis(methylene)]bis(diphenylphosphane), in which the phenyl groups at the phosphorus atoms are replaced by strong electron-withdrawing trifluoromethyl groups. The resulting high electron-acceptor strength of the synthesized bidentate (CF3)2P ligand is demonstrated by a structural and vibrational study of the corresponding tetracarbonyl-molybdenum complex. The stabilization of the P(CF3)2- ion in the presence of acetone is based on the formation of a dynamic Lewis acid/Lewis base couple, (CF3)2PC(CH3)2O-. Although there is no spectroscopic evidence for the formation of the formulated alcoholate ion, the intermediate formation of (CF3)2PC(CH3)2O- could be proved through the reaction with (CF3)2PP(CF3)2, which yields the novel phosphane-phosphinite ligand (CF3)2PC(CH3)2OP(CF3)2. This ligand readily forms square-planar Pt(II) complexes upon treatment with solid PtCl2.

Preparation and characterization of the argentates: [Ag[P(CF(3))(2)](2)](-), [Ag[(micro-P(CF(3))(2))M(CO)(5)](2)](-) (M = Cr, W), and [Ag[(micro-P(C(6)F(5))(2))W(CO)(5)](2)](-): X-ray crystal structure of [K(18-crown-6)][Ag[(micro-P(CF(3))(2))Cr(CO)(5)](2)].

The first example of a mononuclear diphosphanidoargentate, bis[bis(trifluoromethyl)phosphanido]argentate, [Ag[P(CF(3))(2)](2)](-), is obtained via the reaction of HP(CF(3))(2) with [Ag(CN)(2)](-) and isolated as its [K(18-crown-6)] salt. When the cyclic phosphane (PCF(3))(4) is reacted with a slight excess of [K(18-crown-6)][Ag[P(CF(3))(2)](2)], selective insertion of one PCF(3) unit into each silver phosphorus bond is observed, which on the basis of NMR spectroscopic evidence suggests the [Ag[P(CF(3))P(CF(3))(2)](2)](-) ion. On treatment of the phosphane complexes [M(CO)(5)PH(CF(3))(2)] (M = Cr, W) with [K(18-crown-6)][Ag(CN)(2)], the analogous trinuclear argentates, [Ag[(micro-P(CF(3))(2))M(CO)(5)](2)](-), are formed. The chromium compound [K(18-crown-6)][Ag[(micro-P(CF(3))(2))Cr(CO)(5)](2)] crystallizes in a noncentrosymmetric space group Fdd2 (No. 43), a = 2970.2(6) pm, b = 1584.5(3) pm, c = 1787.0(4), V = 8.410(3) nm(3), Z = 8. The C(2) symmetric anion, [Ag[(micro-P(CF(3))(2))Cr(CO)(5)](2)](-), shows a nearly linear arrangement of the P-Ag-P unit. Although the bis(pentafluorophenyl)phosphanido compound [Ag[P(C(6)F(5))(2)](2)](-) has not been obtained so far, the synthesis of its trinuclear counterpart, [K(18-crown-6)][Ag[(micro-P(C(6)F(5))(2))W(CO)(5)](2)], was successful.

Preparation and characterization of [Hg[P(C6F5)2]2], [Hg[(mu-P(C6F5)2)W(CO)5]2], and [Hg[(mu-P(CF3)2)W(CO)5]2] and the X-ray crystal structure of [Hg[(mu-P(C6F5)2)W(CO)5]2].2DMF.

The thermally unstable compound [Hg[P(C(6)F(5))(2)](2)] was obtained from the reaction of mercury cyanide and bis(pentafluorophenyl)phosphane in DMF solution and characterized by multinuclear NMR spectroscopy. The thermally stable trinuclear compounds [Hg[(mu-P(CF(3))(2))W(CO)(5)](2)] and [Hg[(mu-P(C(6)F(5))(2))W(CO)(5)](2)] are isolated and completely characterized. The higher order NMR spectra exhibiting multinuclear satellite systems have been sufficiently analyzed. [Hg[(mu-P(CF(3))(2))W(CO)(5)](2)].2DMF crystallizes in the monoclinic space group C2/c with a = 2366.2(3) pm, b = 1046.9(1) pm, c = 104.0(1) pm, and beta = 104.01(1) degrees. Structural, NMR spectroscopic, and vibrational data prove a weak coordination of the two DMF molecules. Structural, vibrational, and NMR spectroscopic evidence is given for a successive weakening of the pi back-bonding effect of the W-P bond in the order [W(CO)(5)PH(R(f))(2)], [Hg[(mu-P(R(f))(2))W(CO)(5)](2)], and [W[P(R(f))(2)](CO)(5)](-) with R(f) = C(6)F(5) and CF(3). The pi back-bonding effect of the W-C bonds increases vice versa.

Bis(trifluoromethyl)phosphane and bis(pentafluorophenyl)phosphane and their pentacarbonyl tungsten complexes: improved synthesis and an experimental and density functional study.

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.

Stabilization of the P(CF3)(2)(-) and P(C6F5)(2)(-) ions by coordination to pentacarbonyl tungsten: structures of [18-crown-6-K]P(CF3)2, [18-crown-6-K][W[P(CF3)2](CO)5], and [18-crown-6-K][[W(CO)5]2[mu-P(C6F5)2]].THF.

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.

Stabilization of the P(CF(3))(2)(-) ion as a reversible CS(2) adduct, [P(CF(3))(2)CS(2)](-), and its potential use as a nucleophilic P(CF(3))(2)(-) source: synthesis and structure of [18-crown-6-K][P(C(6)F(5))(2)CS(2)].

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.