Dealkylation as a Strategy to Synthesize Unconventional Lithium Salts from <i>ortho</i> -Phenyl-phosphonate-boranes

Several <i>ortho</i>-phenyl-phosphonate-boranes 1-BR<sub>2</sub>-2-{P(O)(OEt)<sub>2</sub>}C<sub>6</sub>H<sub>4</sub> (R = Cy (cyclohexyl, <b>2a</b>), Ipc ((+)-isopinocampheyl, <b>2b</b>), and <sup>n</sup>Hx (<i>n</i>-hexyl, <b>2c</b>)) have been prepared and characterized. Compounds <b>2a</b>-<b>c</b> can be selectively mono-dealkylated to afford the corresponding lithium <i>ortho</i>-phenyl-boratophosphonate salts [Li(S)<sub><i>n</i></sub>][1-BR<sub>2</sub>-2-{P(O)<sub>2</sub>(OEt)}C<sub>6</sub>H<sub>4</sub>] (S = MeCN or EtOAc). All compounds were characterized by multinuclear NMR spectroscopy (<sup>1</sup>H, <sup>13</sup>C{<sup>1</sup>H}, and <sup>31</sup>P{<sup>1</sup>H}). Reactions of <b>2a</b> with NaI or KI yielded the respective [Na(MeCN)][1-BCy<sub>2</sub>-2-{P(O)<sub>2</sub>(OEt)}C<sub>6</sub>H<sub>4</sub>] ([Na(MeCN)][<b>3</b>]) and [K(MeCN)][1-BCy<sub>2</sub>-2-{P(O)<sub>2</sub>(OEt)}C<sub>6</sub>H<sub>4</sub>] ([K(MeCN)][<b>3</b>]) salts. Single-crystal X-ray diffraction studies of <b>2a</b> and [Li(MeCN)<sub>2</sub>][1-BCy<sub>2</sub>-2-{P(O)<sub>2</sub>(OEt)}C<sub>6</sub>H<sub>4</sub>] ([Li(MeCN)<sub>2</sub>][<b>3</b>]) document the presence of intramolecular P═O···B interactions that form pseudo-heterocyclic rings. In the solid state, [Li(MeCN)<sub>2</sub>][<b>3</b>] exists as a lithium-bridged dimer. Thermogravimetric analysis of [Li(MeCN)<sub>2</sub>][<b>3</b>] reveals high thermal stability with a decomposition onset above 200 °C. [Li(MeCN)<sub>2</sub>][<b>3</b>] displays good to excellent solubility in many organic solvents. Reactions of [Li(MeCN)<sub>2</sub>][<b>3</b>] with chlorotrimethylsilane, methyl triflate, and HCl·Et<sub>2</sub>O yielded the new <i>ortho</i>-phenyl-phosphonate-boranes 1-BCy<sub>2</sub>-2-{P(O)(OE)(OEt)}C<sub>6</sub>H<sub>4</sub> (E = Me<sub>3</sub>Si, Me, H). Compounds <b>2a</b> and [Li(MeCN)<sub>2</sub>][<b>3</b>] are weakly emissive in solution and in the solid state, with evidence of solvent-dependent dual emission.

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Journal
Inorganic Chemistry
Published
2026-01-13
DOI
https://doi.org/10.1021/acs.inorgchem.5c05101
Primary Topic
Coordination Chemistry and Organometallics
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article
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article

Dealkylation as a Strategy to Synthesize Unconventional Lithium Salts from ortho -Phenyl-phosphonate-boranes

John D. Protasiewicz, Judith A. Jeevarajan, Vallabha Rao Rikka, Shan M. Daniel et al.
Inorganic Chemistry
Coordination Chemistry and Organometallics
article

Dealkylation as a Strategy to Synthesize Unconventional Lithium Salts from ortho -Phenyl-phosphonate-boranes

John D. Protasiewicz, Judith A. Jeevarajan, Vallabha Rao Rikka, Shan M. Daniel, Wan Si Tang, Anthony D. Kornokovich
article en

Abstract

Several <i>ortho</i>-phenyl-phosphonate-boranes 1-BR<sub>2</sub>-2-{P(O)(OEt)<sub>2</sub>}C<sub>6</sub>H<sub>4</sub> (R = Cy (cyclohexyl, <b>2a</b>), Ipc ((+)-isopinocampheyl, <b>2b</b>), and <sup>n</sup>Hx (<i>n</i>-hexyl, <b>2c</b>)) have been prepared and characterized. Compounds <b>2a</b>-<b>c</b> can be selectively mono-dealkylated to afford the corresponding lithium <i>ortho</i>-phenyl-boratophosphonate salts [Li(S)<sub><i>n</i></sub>][1-BR<sub>2</sub>-2-{P(O)<sub>2</sub>(OEt)}C<sub>6</sub>H<sub>4</sub>] (S = MeCN or EtOAc). All compounds were characterized by multinuclear NMR spectroscopy (<sup>1</sup>H, <sup>13</sup>C{<sup>1</sup>H}, and <sup>31</sup>P{<sup>1</sup>H}). Reactions of <b>2a</b> with NaI or KI yielded the respective [Na(MeCN)][1-BCy<sub>2</sub>-2-{P(O)<sub>2</sub>(OEt)}C<sub>6</sub>H<sub>4</sub>] ([Na(MeCN)][<b>3</b>]) and [K(MeCN)][1-BCy<sub>2</sub>-2-{P(O)<sub>2</sub>(OEt)}C<sub>6</sub>H<sub>4</sub>] ([K(MeCN)][<b>3</b>]) salts. Single-crystal X-ray diffraction studies of <b>2a</b> and [Li(MeCN)<sub>2</sub>][1-BCy<sub>2</sub>-2-{P(O)<sub>2</sub>(OEt)}C<sub>6</sub>H<sub>4</sub>] ([Li(MeCN)<sub>2</sub>][<b>3</b>]) document the presence of intramolecular P═O···B interactions that form pseudo-heterocyclic rings. In the solid state, [Li(MeCN)<sub>2</sub>][<b>3</b>] exists as a lithium-bridged dimer. Thermogravimetric analysis of [Li(MeCN)<sub>2</sub>][<b>3</b>] reveals high thermal stability with a decomposition onset above 200 °C. [Li(MeCN)<sub>2</sub>][<b>3</b>] displays good to excellent solubility in many organic solvents. Reactions of [Li(MeCN)<sub>2</sub>][<b>3</b>] with chlorotrimethylsilane, methyl triflate, and HCl·Et<sub>2</sub>O yielded the new <i>ortho</i>-phenyl-phosphonate-boranes 1-BCy<sub>2</sub>-2-{P(O)(OE)(OEt)}C<sub>6</sub>H<sub>4</sub> (E = Me<sub>3</sub>Si, Me, H). Compounds <b>2a</b> and [Li(MeCN)<sub>2</sub>][<b>3</b>] are weakly emissive in solution and in the solid state, with evidence of solvent-dependent dual emission.

Inorganic ChemistryVol. 65(3)
University of California San Diego (US), Materials and Electrochemical Research (United States) (US), Case Western Reserve University (US)
Openalex Percentile: Top 90%
Coordination Chemistry and Organometallics
DOIOpen Access PDFOpenAlex
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