Formation of Osmium-Allylphosphinomethanide Complexes by Coupling of an Isopropenyldiisopropylphosphine and Monosubstituted Allenes

Complex [Os­(η⁵-C₅H₅)­{κ³-<i>P</i>,<i>C</i>,<i>C</i>-PⁱPr₂[C­(Me)CH₂]}­(MeCN)]­PF₆ (<b>1</b>) reacts with cyclohexylallene and ethyl carboxylate allene to give the allylphosphinomethanide derivatives [Os­(η⁵-C₅H₅)­{κ⁵-<i>P</i>,<i>C</i>^a,<i>C</i>^b,<i>C</i>^c,<i>C</i>^d-PⁱPr₂[C^a(Me)­CH₂C^b(C^cH₂)­C^dHR]}]­PF₆ (R = Cy (<b>2</b>), CO₂Et (<b>3</b>)). In fluorobenzene at 95 °C, complexes <b>2</b> and <b>3</b> evolve into the corresponding γ-allyl-α-alkenyldiisopropylphosphine compounds [OsH­(η⁵-C₅H₅)­{κ⁴-<i>P</i>,<i>C</i>^a,<i>C</i>^b,<i>C</i>^c-PⁱPr₂[C­(CH₂)­CH₂C^a(C^bH₂)­C^cHR]}]­PF₆ (R = Cy (<b>4</b>), CO₂Et (<b>5</b>)). Complexes <b>2</b> and <b>4</b> have been characterized by X-ray diffraction analysis

Formation of Osmium-Allylphosphinomethanide Complexes by Coupling of an Isopropenyldiisopropylphosphine and Monosubstituted Allenes

Complex [Os­(η⁵-C₅H₅)­{κ³-<i>P</i>,<i>C</i>,<i>C</i>-PⁱPr₂[C­(Me)CH₂]}­(MeCN)]­PF₆ (<b>1</b>) reacts with cyclohexylallene and ethyl carboxylate allene to give the allylphosphinomethanide derivatives [Os­(η⁵-C₅H₅)­{κ⁵-<i>P</i>,<i>C</i>^a,<i>C</i>^b,<i>C</i>^c,<i>C</i>^d-PⁱPr₂[C^a(Me)­CH₂C^b(C^cH₂)­C^dHR]}]­PF₆ (R = Cy (<b>2</b>), CO₂Et (<b>3</b>)). In fluorobenzene at 95 °C, complexes <b>2</b> and <b>3</b> evolve into the corresponding γ-allyl-α-alkenyldiisopropylphosphine compounds [OsH­(η⁵-C₅H₅)­{κ⁴-<i>P</i>,<i>C</i>^a,<i>C</i>^b,<i>C</i>^c-PⁱPr₂[C­(CH₂)­CH₂C^a(C^bH₂)­C^cHR]}]­PF₆ (R = Cy (<b>4</b>), CO₂Et (<b>5</b>)). Complexes <b>2</b> and <b>4</b> have been characterized by X-ray diffraction analysis

Aryldihydroborane Coordination to Iridium and Osmium Hydrido Complexes

A series of iridium dihydroborate complexes [(^tBuPOCOP)­IrH­(κ²-H₂BHR)] (^tBuPOCOP = κ³-C₆H₃-1,3-[OP^tBu₂]₂; R = Mes = 2,4,6-Me₃C₆H₂; R = Dur = 2,3,5,6-Me₄C₆H) and [LIrH­(κ²-H₂BHDur)] (L = ^tBuPCP = κ³-C₆H₃-1,3-[CH₂P^tBu₂]₂, L = η⁵-C₅Me₅) and an osmium dihydroborate compound [OsH­(κ²-H₂BHDur)­(CO)­(PⁱPr₃)₂] have been prepared by using two different synthetic strategies. The first approach is based on direct borane coordination to the metal center, whereas the second is based on a salt-elimination protocol using the lithium salts Li­[H₃BR] (R = Mes or Dur) and the corresponding metal halides. The compounds have been characterized by multinuclear NMR and IR spectroscopy and X-ray diffraction analysis. The results constitute the first syntheses of κ²-σ:σ-dihydroborate complexes featuring bulky aryl groups

Osmium Models of Intermediates Involved in Catalytic Reactions of Alkylidenecyclopropanes

The complex [OsCp­{κ³-<i>P</i>,<i>C</i>,<i>C</i>-PⁱPr₂[C­(CH₃)CH₂]}­(CH₃CN)]­PF₆ (<b>1</b>) reacts with (2-pyridyl)­methylenecyclopropane, at room temperature, to give initially the cyclobutylidene derivative [Os­(η⁵-C₅H₅)­(CCH₂CH₂CH-<i>o</i>-C₅H₄N)­{PⁱPr₂[C­(Me)CH₂]}]­PF₆ (<b>2</b>), as a result of the ring expansion of the alkylidenecyclopropane unit. Over time complex <b>2</b> rearranges into the cyclobutene derivative [Os­(η⁵-C₅H₅)­{η²-C­(CHCH₂CH₂)-<i>o</i>-C₅H₄N}­{PⁱPr₂[C­(Me)CH₂]}]­PF₆ (<b>3</b>). The reaction of <b>1</b> with (2-pyridyl)­methylenecyclopropane at room temperature also affords the phosphinomethanide metallacycle [Os­(η⁵-C₅H₅)­{κ⁴-<i>P</i>,<i>C</i>^a,<i>C</i>^b,<i>N</i>-PⁱPr₂[C^a(Me)­CH₂CH)­(C^bCH₂CH₂-<i>o</i>-C₅H₄N]}]­PF₆ (<b>4</b>) as a minor product, which becomes the major product of the reaction at 45 °C. This osmacyclopentane results from the C–C coupling of the isopropenyl substituent of the phosphine ligand and the organic substrate. In acetone at 75 °C, the reaction of <b>1</b> with (2-pyridyl)­methylenecyclopropane leads to the 2-alkylidene-1-osmacyclobutane [Os­(η⁵-C₅H₅)­{κ³-<i>N</i>,<i>C</i>^a,<i>C</i>^b-C^a(CH₂C^bH₂)­(CH-<i>o</i>-C₅H₄N)}­{PⁱPr₂[C­(Me)CH₂]}]­PF₆ (<b>5</b>), as a consequence of the oxidative addition of one of the C­(sp²)–C­(sp³) bonds of the cyclopropane unit of the substrate to the osmium atom, along with <b>6</b>, a diastereomer of <b>4</b>. Complexes <b>3</b>–<b>5</b> have been characterized by X-ray diffraction analysis. DFT calculations suggest that all of the reaction products are derived from a common key 1-osma-2-azacyclopent-3-ene intermediate (<b>D</b>)

Osmium Models of Intermediates Involved in Catalytic Reactions of Alkylidenecyclopropanes

The complex [OsCp­{κ³-<i>P</i>,<i>C</i>,<i>C</i>-PⁱPr₂[C­(CH₃)CH₂]}­(CH₃CN)]­PF₆ (<b>1</b>) reacts with (2-pyridyl)­methylenecyclopropane, at room temperature, to give initially the cyclobutylidene derivative [Os­(η⁵-C₅H₅)­(CCH₂CH₂CH-<i>o</i>-C₅H₄N)­{PⁱPr₂[C­(Me)CH₂]}]­PF₆ (<b>2</b>), as a result of the ring expansion of the alkylidenecyclopropane unit. Over time complex <b>2</b> rearranges into the cyclobutene derivative [Os­(η⁵-C₅H₅)­{η²-C­(CHCH₂CH₂)-<i>o</i>-C₅H₄N}­{PⁱPr₂[C­(Me)CH₂]}]­PF₆ (<b>3</b>). The reaction of <b>1</b> with (2-pyridyl)­methylenecyclopropane at room temperature also affords the phosphinomethanide metallacycle [Os­(η⁵-C₅H₅)­{κ⁴-<i>P</i>,<i>C</i>^a,<i>C</i>^b,<i>N</i>-PⁱPr₂[C^a(Me)­CH₂CH)­(C^bCH₂CH₂-<i>o</i>-C₅H₄N]}]­PF₆ (<b>4</b>) as a minor product, which becomes the major product of the reaction at 45 °C. This osmacyclopentane results from the C–C coupling of the isopropenyl substituent of the phosphine ligand and the organic substrate. In acetone at 75 °C, the reaction of <b>1</b> with (2-pyridyl)­methylenecyclopropane leads to the 2-alkylidene-1-osmacyclobutane [Os­(η⁵-C₅H₅)­{κ³-<i>N</i>,<i>C</i>^a,<i>C</i>^b-C^a(CH₂C^bH₂)­(CH-<i>o</i>-C₅H₄N)}­{PⁱPr₂[C­(Me)CH₂]}]­PF₆ (<b>5</b>), as a consequence of the oxidative addition of one of the C­(sp²)–C­(sp³) bonds of the cyclopropane unit of the substrate to the osmium atom, along with <b>6</b>, a diastereomer of <b>4</b>. Complexes <b>3</b>–<b>5</b> have been characterized by X-ray diffraction analysis. DFT calculations suggest that all of the reaction products are derived from a common key 1-osma-2-azacyclopent-3-ene intermediate (<b>D</b>)