(Dicyclohexylphosphino)borane, BH3PH(C6H11)2, a Precursor to Water-Soluble Phosphine Ligands

Day, Michael; Mohr, Bernhard; Grubbs, Robert H.

doi:10.1107/s0108270196010050

Cited by 4 publications

(5 citation statements)

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“…All three P−B distances are in the single-bond range (1.90−2.00 Å). The bond distances P1−B2 (1.932(2) Å) and P2−B1 (1.923(2) Å) are comparable to P−B distances found in other simple phosphine−borane adducts such as Ph 3 P·BH 3 (av 1.917 Å), (C 6 H 11 ) 2 PH·BH 3 (1.919(3) Å), or PhPH 2 ·BH 3 (1.924(4) Å, vide infra). The central P1−B1 bond distance (1.944(2) Å) is typical of a phosphorus−boron bond length found in cyclic phosphinoboranes, e.g., [Ph 2 P−BH 2 ] 3 , 2a , (av 1.948 Å) 24 or [Ph 2 P−BH 2 ] 4 , 2b , (av 1.939(5) Å, vide infra).…”

Section: Resultssupporting

confidence: 64%

Transition Metal-Catalyzed Formation of Phosphorus−Boron Bonds: A New Route to Phosphinoborane Rings, Chains, and Macromolecules

et al. 2000

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A novel catalytic dehydrocoupling route for the synthesis of linear, cyclic, and polymeric phosphinoboranes has been developed. The dehydrocoupling of neat Ph 2 PH‚BH 3 , which is otherwise very slow below 170 °C, is catalyzed by [{Rh(µ-Cl)(1,5-cod)} 2 ] or [Rh(1,5-cod) 2 ][OTf] (0.5-1 mol % Rh) to give the linear compound Ph 2 PH-BH 2 -PPh 2 -BH 3 (1) at 90 °C, and a mixture of the cyclic trimer [Ph 2 P-BH 2 ] 3 (2a) and tetramer [Ph 2 P-BH 2 ] 4 (2b) at 120 °C. In addition, the catalytic potential of other (e.g., Ti, Ru, Rh, Ir, Pd, Pt) complexes toward the dehydrocoupling of Ph 2 PH‚BH 3 was investigated and was in many cases demonstrated. The molecular structures of 1 and 2b, and of the primary phosphine-borane adduct PhPH 2 ‚ BH 3 , were determined by single-crystal X-ray analysis. The dehydrogenative coupling of PhPH 2 ‚BH 3 gave low-molecular-weight poly(phenylphosphinoborane) [PhPH-BH 2 ] n (3) when performed in toluene (110 °C) with ca. 0.5 mol % [Rh(1,5-cod) 2 ][OTf] as catalyst. The absolute weight-average molecular weight was determined by static light scattering (SLS) in THF which showed that M w ) 5600. Samples of high-molecularweight polymer 3 (M w ) 31 000 or 33 300 by SLS) were synthesized using neat conditions at 90-130 °C in the presence of [{Rh(µ-Cl)(1,5-cod)} 2 ], anhydrous RhCl 3 , or RhCl 3 hydrate (ca. 1 mol % Rh). Poly-(phosphinoborane) 3 was thereby obtained in ca. 75% yield as an air-stable, off-white solid and was structurally characterized by 1 H, 11 B, 13 C, and 31 P NMR and IR spectroscopy and elemental analysis. The hydrodynamic diameters for polymers 3 in THF were also determined by dynamic light scattering (DLS). Catalytic dehydrocoupling of the alkyl-substituted phosphine-borane adduct iBuPH 2 ‚BH 3 was also investigated and was found to be much slower than that of PhPH 2 ‚BH 3 . This produced poly(isobutylphosphinoborane) [iBuPH-BH 2 ] n (4) under neat conditions at 120 °C in the presence of [{Rh(µ-Cl)(1,5-cod)} 2 ] in 80% yield. Multinuclear NMR spectroscopy and DLS were also used to characterize polymer 4, and the latter indicated that M w ) ca. 10 000-20 000. Prolonged heating of polymers 3 and 4 at elevated temperatures in the presence of catalyst led to insoluble but solvent-swellable gels possibly due to light interchain cross-linking through P-B bonds. In the absence of rhodium catalyst thermally induced dehydrocoupling of PhPH 2 ‚BH 3 and iBuPH 2 ‚BH 3 proceeds very slowly and forms only low-molecular-weight materials with complex NMR spectra and which probably possess a branched structure.

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Section: Resultssupporting

confidence: 64%

Transition Metal-Catalyzed Formation of Phosphorus−Boron Bonds: A New Route to Phosphinoborane Rings, Chains, and Macromolecules

et al. 2000

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“…The smallest angle at phosphorus is 99.4(7)° (H1P−P1−C5), and the largest is 115.45(8)° (C1−P1−C5), while the angles at boron range from 105.4(12)° to 114.9(16)°. The P−B bond length of 1.936(2) Å is somewhat longer than those reported for, e.g., ( c Hex) 2 PH·BH 3 (1.919(3) Å) or Ph 3 P·BH 3 (av 1.917 Å), but shorter than the one in RR‘PH·BH 3 (1.944(8) Å, R = mesityl, R‘ = menthyl) which bears organic substituents of significant size 2 Molecular structure of t Bu 2 PH·BH 3 .…”

Section: Resultsmentioning

confidence: 81%

Rhodium-Catalyzed Dehydrocoupling of the Sterically Encumbered Phosphine−Borane AdducttBu₂PH·BH₃: Synthesis of the Linear DimerstBu₂PH−BH₂−tBu₂P−BH₃andtBu₂PH−BH₂−tBu₂P−BH₂Cl

et al. 2001

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The dehydrocoupling of the sterically hindered phosphine-borane adduct tBu(2)PH.BH(3) above 140 degrees C is catalyzed by the rhodium complexes [Rh(1,5-cod)(2)][OTf] or Rh(6)(CO)(16) to give the four-membered chain tBu(2)PH-BH(2)-tBu(2)P-BH(3) (1), which was isolated in 60% yield and characterized by multinuclear NMR spectroscopy, mass spectrometry, and elemental analysis. Thermolysis of 1 in the temperature range 175-180 degrees C led to partial decomposition and the formation of tBu(2)PH.BH(3). When the dehydrocoupling of tBu(2)PH.BH(3) was performed in the presence of [[Rh(mu-Cl)(1,5-cod)](2)] or RhCl(3) hydrate, the chlorinated compound tBu(2)PH-BH(2)-tBu(2)P-BH(2)Cl (2) was formed which could not be obtained free of 1. The molecular structures of tBu(2)PH.BH(3), tBu(2)PH-BH(2)-tBu(2)P-BH(3) (1), and tBu(2)PH-BH(2)-tBu(2)P-BH(2)Cl (2) together with 1 were determined by single-crystal X-ray diffraction studies.

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“…The B1-P1 bond (1.9791(18) Å) is significantly longer than those typical of BvP double bonds (1.763-1.913 Å), [42][43][44][45][46][47] and even exceeds the dative P-BH 3 bonds of secondary phosphine-boranes (1.91-1.94 Å), and is thus best described as an elongated single bond, consistent with the tetrahedral geometries at both phosphorus and boron. 4,[48][49][50][51] The C3-B1 bond (1.726(2) Å) is also elongated in comparison to the analogous γ-C-B bonds of Jones' compounds (1.680(2)-1.697(3) Å). 39 The [(C 6 F 5 ) 3 B•PPh 2 •BH 3 ] − anion, however, remains geometrically similar to that of compound 4a.…”

Section: Resultsmentioning

confidence: 95%

Phosphinoborane interception at magnesium by borane-assisted phosphine-borane dehydrogenation

et al. 2020

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(Dicyclohexylphosphino)borane, BH3PH(C6H11)2, a Precursor to Water-Soluble Phosphine Ligands

Abstract: (Dicyclohexylphosphino)borane is a precursor in the synthesis of water-soluble phosphines. The boranato group can be removed quantitatively under mild conditions.

Cited by 4 publications

References 3 publications

Transition Metal-Catalyzed Formation of Phosphorus−Boron Bonds: A New Route to Phosphinoborane Rings, Chains, and Macromolecules

Transition Metal-Catalyzed Formation of Phosphorus−Boron Bonds: A New Route to Phosphinoborane Rings, Chains, and Macromolecules

Rhodium-Catalyzed Dehydrocoupling of the Sterically Encumbered Phosphine−Borane AdducttBu₂PH·BH₃: Synthesis of the Linear DimerstBu₂PH−BH₂−tBu₂P−BH₃andtBu₂PH−BH₂−tBu₂P−BH₂Cl

Phosphinoborane interception at magnesium by borane-assisted phosphine-borane dehydrogenation

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(Dicyclohexylphosphino)borane, BH3PH(C6H11)2, a Precursor to Water-Soluble Phosphine Ligands

Abstract: (Dicyclohexylphosphino)borane is a precursor in the synthesis of water-soluble phosphines. The boranato group can be removed quantitatively under mild conditions.

Cited by 4 publications

References 3 publications

Transition Metal-Catalyzed Formation of Phosphorus−Boron Bonds: A New Route to Phosphinoborane Rings, Chains, and Macromolecules

Transition Metal-Catalyzed Formation of Phosphorus−Boron Bonds: A New Route to Phosphinoborane Rings, Chains, and Macromolecules

Rhodium-Catalyzed Dehydrocoupling of the Sterically Encumbered Phosphine−Borane AdducttBu2PH·BH3: Synthesis of the Linear DimerstBu2PH−BH2−tBu2P−BH3andtBu2PH−BH2−tBu2P−BH2Cl

Phosphinoborane interception at magnesium by borane-assisted phosphine-borane dehydrogenation

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Rhodium-Catalyzed Dehydrocoupling of the Sterically Encumbered Phosphine−Borane AdducttBu₂PH·BH₃: Synthesis of the Linear DimerstBu₂PH−BH₂−tBu₂P−BH₃andtBu₂PH−BH₂−tBu₂P−BH₂Cl