Phosphonous Acid

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Hoge Berthold - One of the best experts on this subject based on the ideXlab platform.

  • Coordination Properties of Perfluoroethyl- and Perfluorophenyl-Substituted Phosphonous Acids, (RP)-P-f(OH)(2)
    'Wiley', 2015
    Co-Authors: Allefeld Nadine, Kurscheid Boris, Stammler Hans-georg, Neumann Beate, Ignat'ev Nikolai, Hoge Berthold
    Abstract:

    Allefeld N, Kurscheid B, Neumann B, Stammler H-G, Ignat'ev N, Hoge B. Coordination Properties of Perfluoroethyl- and Perfluorophenyl-Substituted Phosphonous Acids, (RP)-P-f(OH)(2). Chemistry - A European Journal. 2015;21(39):13666-13675.Phosphinic Acids, (RP)-P-f(O)(OH)H (R-f=CF3, C2F5, C6F5), turned out to be excellent preligands for the coordination of Phosphonous Acids, (RP)-P-f(OH)(2). Addition of C2F5P(O)(OH)H to solid PtCl2 under different reaction conditions allows the isolation and full characterization of the mononuclear complexes [ClPt{P(C2F5)(OH)O}{P(C2F5)(OH)(2)}(2)] and [Pt{P(C2F5)(OH)O}(2){P(C2F5)(OH)(2)}] containing hydrogen-bridged [(RP)-P-f(OH)O](-) and (RP)-P-f(OH)(2) units. Further deprotonation of [Pt{P(C2F5)(OH)O}(2){P(C2F5)(OH)(2)}(2)] leads to the formation of the dianionic platinate, [Pt{P(C2F5)(OH)O}(4)](2-), revealing four intramolecular hydrogen bridges. With PdCl2 the dinuclear complex [Pd-2(-Cl)(2){[P(C2F5)(OH)O](2)H}(2)] was isolated and characterized. The Cl- free complex [Pd{P(C2F5)(OH)O}(2){P(C2F5)(OH)(2)}(2)] was also prepared and deprotonated to the dianionic palladate, [Pd{P(C2F5)(OH)O}(4)](2-). Both compounds were characterized by NMR spectroscopy, IR spectroscopy, and X-ray analyses. In addition, the C6F5 derivatives [ClPt{P(C6F5)(OH)O}{P(C6F5)(OH)(2)}(2)] and [Pd-2(-Cl)(2){[P(C6F5)(OH)O](2)H}(2)] as well as the CF3 derivative [Pd-2(-Cl)(2){[P(CF3)(OH)O](2)H}(2)] were synthesized and fully characterized. Phosphonous Acid complexes are inert towards air and moisture and can be stored for several months without decomposition. The catalytic activity of the palladium complexes in the Suzuki cross-coupling reaction between 1-bromo-3-fluorobenzene and phenyl boronic Acid was demonstrated

  • Synthesis of a Water-Stable 2, 4-Bis(trifluoromethyl)phenyl-Substituted Phosphonous Acid Palladium Complex and its Catalytic Activity in Cross-Coupling Reactions
    'Wiley', 2012
    Co-Authors: Kurscheid Boris, Stammler Hans-georg, Neumann Beate, Hoge Berthold
    Abstract:

    Kurscheid B, Stammler H-G, Neumann B, Hoge B. Synthesis of a Water-Stable 2, 4-Bis(trifluoromethyl)phenyl-Substituted Phosphonous Acid Palladium Complex and its Catalytic Activity in Cross-Coupling Reactions. Zeitschrift für anorganische und allgemeine Chemie. 2012;638(3-4):534-542.This manuscript describes the selective synthesis of2, 4-bis(trifluoromethyl)phenylphosphinic Acid, (Rf)P(O)(H)OH.Reaction of chlorobis(diethylamino)phosphane with a mixture of 2, 4-(CF3)2C6H3Li and 2, 6-(CF3)2C6H3Li results in the formation of 2, 4-bis(trifluoromethyl)phenylbis(diethylamino)phosphane, (Rf)P(NEt2)2. The following in situ reaction with gaseous HBr leads to the cleavage of the phosphorus nitrogen bonds resulting in the selective formation of the corresponding dibromophosphane (Rf)PBr2.2, 4-Bis(trifluoromethyl)phenylphosphinic Acid is available via two different synthetic strategies starting from the dibromophosphane (Rf)PBr2. Reduction of the dibromophosphane with tributyltin hydride affords selectively the phosphane (Rf)PH2. The following oxidation to the phosphinic Acid (Rf)P(O)(H)OH, however, only proceeds in moderate yields. A more efficient synthesis is achieved via the hydrolysis of the dibromophosphane (Rf)PBr2 in dichloromethane solution. 2, 4-bis(trifluoromethyl)phenylphosphinic Acid, (Rf)P(O)(H)OH, is surprisingly stable towards air and water. The water soluble phosphinic Acid reacts sluggishly with a 30?% H2O2 solution, yielding only 23?% of the corresponding phosphonic Acid (Rf)P(O)(OH)2 after seven days at ambient temperature.In principle a tautomerization of the phosphinic Acid (Rf)P(O)(H)OH to the corresponding Phosphonous Acid (Rf)P(OH)2 analogously to the phosphane oxide (Rf)2P(O)H and the phosphinous Acid (Rf)2POH is conceivable. However, the Phosphonous Acid could not be detected with spectroscopic methods. The energy difference between the phosphinic Acid and the Phosphonous Acid is calculated by quantum chemical calculations at the B3LYP/6-311+G(2df, p) level of theory to 30.1 kJ.mol1. This high value explains why the Phosphonous Acid tautomer could not be detected by spectroscopic methods so far.As transition metal complexes featuring Phosphonous Acid ligands are of significant interest for the application as homogeneous catalysts we studied the coordination chemistry of the related phosphinic Acid in more detail. The preligand 2, 4-bis(trifluoromethyl)phenylphosphinic Acid reacts smoothly with palladium dichloride in THF to the dinuclear complex [Pd2(mu-Cl)2{[2, 4-(CF3)2C6H3P(OH)O]2H}2], featuring a Phosphonous Acid phosphonato unit, with a strong hydrogen bridge substantiated by an O center dot center dot center dot O distance of 247.7(3) pm. The dinuclear Phosphonous Acid palladium complex exhibits a high catalytic activity in the Suzuki cross-coupling. Alternatively, the phosphinic Acid can be used as preligand for the in situ formation of a Phosphonous Acid palladium complex. These compounds combine catalytic activity with a very high stability towards air and water

Kurscheid Boris - One of the best experts on this subject based on the ideXlab platform.

  • Coordination Properties of Perfluoroethyl- and Perfluorophenyl-Substituted Phosphonous Acids, (RP)-P-f(OH)(2)
    'Wiley', 2015
    Co-Authors: Allefeld Nadine, Kurscheid Boris, Stammler Hans-georg, Neumann Beate, Ignat'ev Nikolai, Hoge Berthold
    Abstract:

    Allefeld N, Kurscheid B, Neumann B, Stammler H-G, Ignat'ev N, Hoge B. Coordination Properties of Perfluoroethyl- and Perfluorophenyl-Substituted Phosphonous Acids, (RP)-P-f(OH)(2). Chemistry - A European Journal. 2015;21(39):13666-13675.Phosphinic Acids, (RP)-P-f(O)(OH)H (R-f=CF3, C2F5, C6F5), turned out to be excellent preligands for the coordination of Phosphonous Acids, (RP)-P-f(OH)(2). Addition of C2F5P(O)(OH)H to solid PtCl2 under different reaction conditions allows the isolation and full characterization of the mononuclear complexes [ClPt{P(C2F5)(OH)O}{P(C2F5)(OH)(2)}(2)] and [Pt{P(C2F5)(OH)O}(2){P(C2F5)(OH)(2)}] containing hydrogen-bridged [(RP)-P-f(OH)O](-) and (RP)-P-f(OH)(2) units. Further deprotonation of [Pt{P(C2F5)(OH)O}(2){P(C2F5)(OH)(2)}(2)] leads to the formation of the dianionic platinate, [Pt{P(C2F5)(OH)O}(4)](2-), revealing four intramolecular hydrogen bridges. With PdCl2 the dinuclear complex [Pd-2(-Cl)(2){[P(C2F5)(OH)O](2)H}(2)] was isolated and characterized. The Cl- free complex [Pd{P(C2F5)(OH)O}(2){P(C2F5)(OH)(2)}(2)] was also prepared and deprotonated to the dianionic palladate, [Pd{P(C2F5)(OH)O}(4)](2-). Both compounds were characterized by NMR spectroscopy, IR spectroscopy, and X-ray analyses. In addition, the C6F5 derivatives [ClPt{P(C6F5)(OH)O}{P(C6F5)(OH)(2)}(2)] and [Pd-2(-Cl)(2){[P(C6F5)(OH)O](2)H}(2)] as well as the CF3 derivative [Pd-2(-Cl)(2){[P(CF3)(OH)O](2)H}(2)] were synthesized and fully characterized. Phosphonous Acid complexes are inert towards air and moisture and can be stored for several months without decomposition. The catalytic activity of the palladium complexes in the Suzuki cross-coupling reaction between 1-bromo-3-fluorobenzene and phenyl boronic Acid was demonstrated

  • Synthesis of a Water-Stable 2, 4-Bis(trifluoromethyl)phenyl-Substituted Phosphonous Acid Palladium Complex and its Catalytic Activity in Cross-Coupling Reactions
    'Wiley', 2012
    Co-Authors: Kurscheid Boris, Stammler Hans-georg, Neumann Beate, Hoge Berthold
    Abstract:

    Kurscheid B, Stammler H-G, Neumann B, Hoge B. Synthesis of a Water-Stable 2, 4-Bis(trifluoromethyl)phenyl-Substituted Phosphonous Acid Palladium Complex and its Catalytic Activity in Cross-Coupling Reactions. Zeitschrift für anorganische und allgemeine Chemie. 2012;638(3-4):534-542.This manuscript describes the selective synthesis of2, 4-bis(trifluoromethyl)phenylphosphinic Acid, (Rf)P(O)(H)OH.Reaction of chlorobis(diethylamino)phosphane with a mixture of 2, 4-(CF3)2C6H3Li and 2, 6-(CF3)2C6H3Li results in the formation of 2, 4-bis(trifluoromethyl)phenylbis(diethylamino)phosphane, (Rf)P(NEt2)2. The following in situ reaction with gaseous HBr leads to the cleavage of the phosphorus nitrogen bonds resulting in the selective formation of the corresponding dibromophosphane (Rf)PBr2.2, 4-Bis(trifluoromethyl)phenylphosphinic Acid is available via two different synthetic strategies starting from the dibromophosphane (Rf)PBr2. Reduction of the dibromophosphane with tributyltin hydride affords selectively the phosphane (Rf)PH2. The following oxidation to the phosphinic Acid (Rf)P(O)(H)OH, however, only proceeds in moderate yields. A more efficient synthesis is achieved via the hydrolysis of the dibromophosphane (Rf)PBr2 in dichloromethane solution. 2, 4-bis(trifluoromethyl)phenylphosphinic Acid, (Rf)P(O)(H)OH, is surprisingly stable towards air and water. The water soluble phosphinic Acid reacts sluggishly with a 30?% H2O2 solution, yielding only 23?% of the corresponding phosphonic Acid (Rf)P(O)(OH)2 after seven days at ambient temperature.In principle a tautomerization of the phosphinic Acid (Rf)P(O)(H)OH to the corresponding Phosphonous Acid (Rf)P(OH)2 analogously to the phosphane oxide (Rf)2P(O)H and the phosphinous Acid (Rf)2POH is conceivable. However, the Phosphonous Acid could not be detected with spectroscopic methods. The energy difference between the phosphinic Acid and the Phosphonous Acid is calculated by quantum chemical calculations at the B3LYP/6-311+G(2df, p) level of theory to 30.1 kJ.mol1. This high value explains why the Phosphonous Acid tautomer could not be detected by spectroscopic methods so far.As transition metal complexes featuring Phosphonous Acid ligands are of significant interest for the application as homogeneous catalysts we studied the coordination chemistry of the related phosphinic Acid in more detail. The preligand 2, 4-bis(trifluoromethyl)phenylphosphinic Acid reacts smoothly with palladium dichloride in THF to the dinuclear complex [Pd2(mu-Cl)2{[2, 4-(CF3)2C6H3P(OH)O]2H}2], featuring a Phosphonous Acid phosphonato unit, with a strong hydrogen bridge substantiated by an O center dot center dot center dot O distance of 247.7(3) pm. The dinuclear Phosphonous Acid palladium complex exhibits a high catalytic activity in the Suzuki cross-coupling. Alternatively, the phosphinic Acid can be used as preligand for the in situ formation of a Phosphonous Acid palladium complex. These compounds combine catalytic activity with a very high stability towards air and water

Berthold Hoge - One of the best experts on this subject based on the ideXlab platform.

  • synthesis of a water stable 2 4 bis trifluoromethyl phenyl substituted Phosphonous Acid palladium complex and its catalytic activity in cross coupling reactions
    Zeitschrift für anorganische und allgemeine Chemie, 2012
    Co-Authors: Boris Kurscheid, Hansgeorg Stammler, Beate Neumann, Berthold Hoge
    Abstract:

    This manuscript describes the selective synthesis of2, 4-bis(trifluoromethyl)phenylphosphinic Acid, (Rf)P(O)(H)OH.Reaction of chlorobis(diethylamino)phosphane with a mixture of 2, 4-(CF3)2C6H3Li and 2, 6-(CF3)2C6H3Li results in the formation of 2, 4-bis(trifluoromethyl)phenylbis(diethylamino)phosphane, (Rf)P(NEt2)2. The following in situ reaction with gaseous HBr leads to the cleavage of the phosphorus nitrogen bonds resulting in the selective formation of the corresponding dibromophosphane (Rf)PBr2.2, 4-Bis(trifluoromethyl)phenylphosphinic Acid is available via two different synthetic strategies starting from the dibromophosphane (Rf)PBr2. Reduction of the dibromophosphane with tributyltin hydride affords selectively the phosphane (Rf)PH2. The following oxidation to the phosphinic Acid (Rf)P(O)(H)OH, however, only proceeds in moderate yields. A more efficient synthesis is achieved via the hydrolysis of the dibromophosphane (Rf)PBr2 in dichloromethane solution. 2, 4-bis(trifluoromethyl)phenylphosphinic Acid, (Rf)P(O)(H)OH, is surprisingly stable towards air and water. The water soluble phosphinic Acid reacts sluggishly with a 30?% H2O2 solution, yielding only 23?% of the corresponding phosphonic Acid (Rf)P(O)(OH)2 after seven days at ambient temperature.In principle a tautomerization of the phosphinic Acid (Rf)P(O)(H)OH to the corresponding Phosphonous Acid (Rf)P(OH)2 analogously to the phosphane oxide (Rf)2P(O)H and the phosphinous Acid (Rf)2POH is conceivable. However, the Phosphonous Acid could not be detected with spectroscopic methods. The energy difference between the phosphinic Acid and the Phosphonous Acid is calculated by quantum chemical calculations at the B3LYP/6-311+G(2df, p) level of theory to 30.1 kJ.mol1. This high value explains why the Phosphonous Acid tautomer could not be detected by spectroscopic methods so far.As transition metal complexes featuring Phosphonous Acid ligands are of significant interest for the application as homogeneous catalysts we studied the coordination chemistry of the related phosphinic Acid in more detail. The preligand 2, 4-bis(trifluoromethyl)phenylphosphinic Acid reacts smoothly with palladium dichloride in THF to the dinuclear complex [Pd2(mu-Cl)2{[2, 4-(CF3)2C6H3P(OH)O]2H}2], featuring a Phosphonous Acid phosphonato unit, with a strong hydrogen bridge substantiated by an O center dot center dot center dot O distance of 247.7(3) pm. The dinuclear Phosphonous Acid palladium complex exhibits a high catalytic activity in the Suzuki cross-coupling. Alternatively, the phosphinic Acid can be used as preligand for the in situ formation of a Phosphonous Acid palladium complex. These compounds combine catalytic activity with a very high stability towards air and water.

Stammler Hans-georg - One of the best experts on this subject based on the ideXlab platform.

  • Coordination Properties of Perfluoroethyl- and Perfluorophenyl-Substituted Phosphonous Acids, (RP)-P-f(OH)(2)
    'Wiley', 2015
    Co-Authors: Allefeld Nadine, Kurscheid Boris, Stammler Hans-georg, Neumann Beate, Ignat'ev Nikolai, Hoge Berthold
    Abstract:

    Allefeld N, Kurscheid B, Neumann B, Stammler H-G, Ignat'ev N, Hoge B. Coordination Properties of Perfluoroethyl- and Perfluorophenyl-Substituted Phosphonous Acids, (RP)-P-f(OH)(2). Chemistry - A European Journal. 2015;21(39):13666-13675.Phosphinic Acids, (RP)-P-f(O)(OH)H (R-f=CF3, C2F5, C6F5), turned out to be excellent preligands for the coordination of Phosphonous Acids, (RP)-P-f(OH)(2). Addition of C2F5P(O)(OH)H to solid PtCl2 under different reaction conditions allows the isolation and full characterization of the mononuclear complexes [ClPt{P(C2F5)(OH)O}{P(C2F5)(OH)(2)}(2)] and [Pt{P(C2F5)(OH)O}(2){P(C2F5)(OH)(2)}] containing hydrogen-bridged [(RP)-P-f(OH)O](-) and (RP)-P-f(OH)(2) units. Further deprotonation of [Pt{P(C2F5)(OH)O}(2){P(C2F5)(OH)(2)}(2)] leads to the formation of the dianionic platinate, [Pt{P(C2F5)(OH)O}(4)](2-), revealing four intramolecular hydrogen bridges. With PdCl2 the dinuclear complex [Pd-2(-Cl)(2){[P(C2F5)(OH)O](2)H}(2)] was isolated and characterized. The Cl- free complex [Pd{P(C2F5)(OH)O}(2){P(C2F5)(OH)(2)}(2)] was also prepared and deprotonated to the dianionic palladate, [Pd{P(C2F5)(OH)O}(4)](2-). Both compounds were characterized by NMR spectroscopy, IR spectroscopy, and X-ray analyses. In addition, the C6F5 derivatives [ClPt{P(C6F5)(OH)O}{P(C6F5)(OH)(2)}(2)] and [Pd-2(-Cl)(2){[P(C6F5)(OH)O](2)H}(2)] as well as the CF3 derivative [Pd-2(-Cl)(2){[P(CF3)(OH)O](2)H}(2)] were synthesized and fully characterized. Phosphonous Acid complexes are inert towards air and moisture and can be stored for several months without decomposition. The catalytic activity of the palladium complexes in the Suzuki cross-coupling reaction between 1-bromo-3-fluorobenzene and phenyl boronic Acid was demonstrated

  • Synthesis of a Water-Stable 2, 4-Bis(trifluoromethyl)phenyl-Substituted Phosphonous Acid Palladium Complex and its Catalytic Activity in Cross-Coupling Reactions
    'Wiley', 2012
    Co-Authors: Kurscheid Boris, Stammler Hans-georg, Neumann Beate, Hoge Berthold
    Abstract:

    Kurscheid B, Stammler H-G, Neumann B, Hoge B. Synthesis of a Water-Stable 2, 4-Bis(trifluoromethyl)phenyl-Substituted Phosphonous Acid Palladium Complex and its Catalytic Activity in Cross-Coupling Reactions. Zeitschrift für anorganische und allgemeine Chemie. 2012;638(3-4):534-542.This manuscript describes the selective synthesis of2, 4-bis(trifluoromethyl)phenylphosphinic Acid, (Rf)P(O)(H)OH.Reaction of chlorobis(diethylamino)phosphane with a mixture of 2, 4-(CF3)2C6H3Li and 2, 6-(CF3)2C6H3Li results in the formation of 2, 4-bis(trifluoromethyl)phenylbis(diethylamino)phosphane, (Rf)P(NEt2)2. The following in situ reaction with gaseous HBr leads to the cleavage of the phosphorus nitrogen bonds resulting in the selective formation of the corresponding dibromophosphane (Rf)PBr2.2, 4-Bis(trifluoromethyl)phenylphosphinic Acid is available via two different synthetic strategies starting from the dibromophosphane (Rf)PBr2. Reduction of the dibromophosphane with tributyltin hydride affords selectively the phosphane (Rf)PH2. The following oxidation to the phosphinic Acid (Rf)P(O)(H)OH, however, only proceeds in moderate yields. A more efficient synthesis is achieved via the hydrolysis of the dibromophosphane (Rf)PBr2 in dichloromethane solution. 2, 4-bis(trifluoromethyl)phenylphosphinic Acid, (Rf)P(O)(H)OH, is surprisingly stable towards air and water. The water soluble phosphinic Acid reacts sluggishly with a 30?% H2O2 solution, yielding only 23?% of the corresponding phosphonic Acid (Rf)P(O)(OH)2 after seven days at ambient temperature.In principle a tautomerization of the phosphinic Acid (Rf)P(O)(H)OH to the corresponding Phosphonous Acid (Rf)P(OH)2 analogously to the phosphane oxide (Rf)2P(O)H and the phosphinous Acid (Rf)2POH is conceivable. However, the Phosphonous Acid could not be detected with spectroscopic methods. The energy difference between the phosphinic Acid and the Phosphonous Acid is calculated by quantum chemical calculations at the B3LYP/6-311+G(2df, p) level of theory to 30.1 kJ.mol1. This high value explains why the Phosphonous Acid tautomer could not be detected by spectroscopic methods so far.As transition metal complexes featuring Phosphonous Acid ligands are of significant interest for the application as homogeneous catalysts we studied the coordination chemistry of the related phosphinic Acid in more detail. The preligand 2, 4-bis(trifluoromethyl)phenylphosphinic Acid reacts smoothly with palladium dichloride in THF to the dinuclear complex [Pd2(mu-Cl)2{[2, 4-(CF3)2C6H3P(OH)O]2H}2], featuring a Phosphonous Acid phosphonato unit, with a strong hydrogen bridge substantiated by an O center dot center dot center dot O distance of 247.7(3) pm. The dinuclear Phosphonous Acid palladium complex exhibits a high catalytic activity in the Suzuki cross-coupling. Alternatively, the phosphinic Acid can be used as preligand for the in situ formation of a Phosphonous Acid palladium complex. These compounds combine catalytic activity with a very high stability towards air and water

Neumann Beate - One of the best experts on this subject based on the ideXlab platform.

  • Coordination Properties of Perfluoroethyl- and Perfluorophenyl-Substituted Phosphonous Acids, (RP)-P-f(OH)(2)
    'Wiley', 2015
    Co-Authors: Allefeld Nadine, Kurscheid Boris, Stammler Hans-georg, Neumann Beate, Ignat'ev Nikolai, Hoge Berthold
    Abstract:

    Allefeld N, Kurscheid B, Neumann B, Stammler H-G, Ignat'ev N, Hoge B. Coordination Properties of Perfluoroethyl- and Perfluorophenyl-Substituted Phosphonous Acids, (RP)-P-f(OH)(2). Chemistry - A European Journal. 2015;21(39):13666-13675.Phosphinic Acids, (RP)-P-f(O)(OH)H (R-f=CF3, C2F5, C6F5), turned out to be excellent preligands for the coordination of Phosphonous Acids, (RP)-P-f(OH)(2). Addition of C2F5P(O)(OH)H to solid PtCl2 under different reaction conditions allows the isolation and full characterization of the mononuclear complexes [ClPt{P(C2F5)(OH)O}{P(C2F5)(OH)(2)}(2)] and [Pt{P(C2F5)(OH)O}(2){P(C2F5)(OH)(2)}] containing hydrogen-bridged [(RP)-P-f(OH)O](-) and (RP)-P-f(OH)(2) units. Further deprotonation of [Pt{P(C2F5)(OH)O}(2){P(C2F5)(OH)(2)}(2)] leads to the formation of the dianionic platinate, [Pt{P(C2F5)(OH)O}(4)](2-), revealing four intramolecular hydrogen bridges. With PdCl2 the dinuclear complex [Pd-2(-Cl)(2){[P(C2F5)(OH)O](2)H}(2)] was isolated and characterized. The Cl- free complex [Pd{P(C2F5)(OH)O}(2){P(C2F5)(OH)(2)}(2)] was also prepared and deprotonated to the dianionic palladate, [Pd{P(C2F5)(OH)O}(4)](2-). Both compounds were characterized by NMR spectroscopy, IR spectroscopy, and X-ray analyses. In addition, the C6F5 derivatives [ClPt{P(C6F5)(OH)O}{P(C6F5)(OH)(2)}(2)] and [Pd-2(-Cl)(2){[P(C6F5)(OH)O](2)H}(2)] as well as the CF3 derivative [Pd-2(-Cl)(2){[P(CF3)(OH)O](2)H}(2)] were synthesized and fully characterized. Phosphonous Acid complexes are inert towards air and moisture and can be stored for several months without decomposition. The catalytic activity of the palladium complexes in the Suzuki cross-coupling reaction between 1-bromo-3-fluorobenzene and phenyl boronic Acid was demonstrated

  • Synthesis of a Water-Stable 2, 4-Bis(trifluoromethyl)phenyl-Substituted Phosphonous Acid Palladium Complex and its Catalytic Activity in Cross-Coupling Reactions
    'Wiley', 2012
    Co-Authors: Kurscheid Boris, Stammler Hans-georg, Neumann Beate, Hoge Berthold
    Abstract:

    Kurscheid B, Stammler H-G, Neumann B, Hoge B. Synthesis of a Water-Stable 2, 4-Bis(trifluoromethyl)phenyl-Substituted Phosphonous Acid Palladium Complex and its Catalytic Activity in Cross-Coupling Reactions. Zeitschrift für anorganische und allgemeine Chemie. 2012;638(3-4):534-542.This manuscript describes the selective synthesis of2, 4-bis(trifluoromethyl)phenylphosphinic Acid, (Rf)P(O)(H)OH.Reaction of chlorobis(diethylamino)phosphane with a mixture of 2, 4-(CF3)2C6H3Li and 2, 6-(CF3)2C6H3Li results in the formation of 2, 4-bis(trifluoromethyl)phenylbis(diethylamino)phosphane, (Rf)P(NEt2)2. The following in situ reaction with gaseous HBr leads to the cleavage of the phosphorus nitrogen bonds resulting in the selective formation of the corresponding dibromophosphane (Rf)PBr2.2, 4-Bis(trifluoromethyl)phenylphosphinic Acid is available via two different synthetic strategies starting from the dibromophosphane (Rf)PBr2. Reduction of the dibromophosphane with tributyltin hydride affords selectively the phosphane (Rf)PH2. The following oxidation to the phosphinic Acid (Rf)P(O)(H)OH, however, only proceeds in moderate yields. A more efficient synthesis is achieved via the hydrolysis of the dibromophosphane (Rf)PBr2 in dichloromethane solution. 2, 4-bis(trifluoromethyl)phenylphosphinic Acid, (Rf)P(O)(H)OH, is surprisingly stable towards air and water. The water soluble phosphinic Acid reacts sluggishly with a 30?% H2O2 solution, yielding only 23?% of the corresponding phosphonic Acid (Rf)P(O)(OH)2 after seven days at ambient temperature.In principle a tautomerization of the phosphinic Acid (Rf)P(O)(H)OH to the corresponding Phosphonous Acid (Rf)P(OH)2 analogously to the phosphane oxide (Rf)2P(O)H and the phosphinous Acid (Rf)2POH is conceivable. However, the Phosphonous Acid could not be detected with spectroscopic methods. The energy difference between the phosphinic Acid and the Phosphonous Acid is calculated by quantum chemical calculations at the B3LYP/6-311+G(2df, p) level of theory to 30.1 kJ.mol1. This high value explains why the Phosphonous Acid tautomer could not be detected by spectroscopic methods so far.As transition metal complexes featuring Phosphonous Acid ligands are of significant interest for the application as homogeneous catalysts we studied the coordination chemistry of the related phosphinic Acid in more detail. The preligand 2, 4-bis(trifluoromethyl)phenylphosphinic Acid reacts smoothly with palladium dichloride in THF to the dinuclear complex [Pd2(mu-Cl)2{[2, 4-(CF3)2C6H3P(OH)O]2H}2], featuring a Phosphonous Acid phosphonato unit, with a strong hydrogen bridge substantiated by an O center dot center dot center dot O distance of 247.7(3) pm. The dinuclear Phosphonous Acid palladium complex exhibits a high catalytic activity in the Suzuki cross-coupling. Alternatively, the phosphinic Acid can be used as preligand for the in situ formation of a Phosphonous Acid palladium complex. These compounds combine catalytic activity with a very high stability towards air and water

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