Nitrogen Atom Transfer from a Dinitrogen-Derived Vanadium Nitride Complex to Carbon Monoxide and Isocyanide

Reduction of [(ONO)­V­(THF)] with KH under an N2 atmosphere cleaves the NN bond to afford a bis­(μ-nitride) V­(IV) dimer. This complex is oxidized to generate a V­(V) nitride. The reactions of the V­(V) nitride with carbon monoxide and isocyanide led to formation of cyanate and carbodiimide complexes. Following treatment of the cyanate complex with alkyne produces an alkyne adduct along with the release of potassium cyanate. Dissolution of the alkyne adduct in THF regenerates the starting complex [(ONO)­V­(THF)], thereby closing a synthetic cycle for conversion of N2 and CO into [NCO]−

Methylene-Linked AnilideBis(aryloxide) Ligands: Lithium, Sodium, Potassium, Chromium(III), and Vanadium(III) Ligation

The anilide–bis­(aryloxide) proligands H₃[<b>ONO</b>^<b>R</b>] (where H₃[<b>ONO</b>^<b>R</b>] = 2,6-(3-R¹-5-R²-2-hydroxybenzyl)-4-<i>tert</i>-butyl-<i>N</i>-tolyl-aniline; H₃[<b>ONO</b>^{<b><i>t</i>Bu</b>}], R¹ = ^<i>t</i>Bu, R² = Me; H₃[<b>ONO</b>^<b>Me</b>], R¹ = Me, R² = ^<i>t</i>Bu; H₃[<b>ONO</b>^<b>Me2</b>], R¹ = R² = Me) were synthesized from 2-bromo-5-<i>tert</i>-butyl-isophthalic acid dimethyl ester in three steps in multigram scale. The ligand precursor H₃[<b>ONO</b>^{<b><i>t</i>Bu</b>}] was readily doubly and triply deprotonated with alkali metal reagents to generate the related derivatives M₂[H­(<b>ONO</b>^{<b><i>t</i>Bu</b>})] and M₃[<b>ONO</b>^{<b><i>t</i>Bu</b>}] (M = Li, Na, K). The extent of ligand deprotonation is observed to depend on the choice of deprotonating reagents and solvents. Transmetalation reaction of the trilithium derivative Li₃[<b>ONO</b>^{<b><i>t</i>Bu</b>}] with MCl₃(THF)₃ (M = Cr, V; THF = tetrahydrofuran) afforded [(<b>ONO</b>^{<b><i>t</i>Bu</b>})­CrCl­(THF)­{Li­(THF)}] (<b>5</b>) and [(<b>ONO</b>^{<b><i>t</i>Bu</b>})­V­(THF)] (<b>6</b>). The vanadium complex <b>6</b> reacted readily with 2-butyne, styrene oxide, and mesityl azide, yielding [(<b>ONO</b>^{<b><i>t</i>Bu</b>})­V­(η²-MeCCMe)] (<b>7</b>), [(<b>ONO</b>^{<b><i>t</i>Bu</b>})­V­(O)] (<b>8</b>), and [(<b>ONO</b>^{<b><i>t</i>Bu</b>})­V­(NMes)] (<b>9</b>), respectively. The solid-state structures of H₃[<b>ONO</b>^{<b><i>t</i>Bu</b>}] and metal complexes were determined by X-ray crystallography. The [<b>ONO</b>^{<b><i>t</i>Bu</b>}] ligand adopts a u-shaped structure in solution and solid state

Nitrogen Atom Transfer from a Dinitrogen-Derived Vanadium Nitride Complex to Carbon Monoxide and Isocyanide

Reduction of [(ONO)­V­(THF)] with KH under an N₂ atmosphere cleaves the NN bond to afford a bis­(μ-nitride) V­(IV) dimer. This complex is oxidized to generate a V­(V) nitride. The reactions of the V­(V) nitride with carbon monoxide and isocyanide led to formation of cyanate and carbodiimide complexes. Following treatment of the cyanate complex with alkyne produces an alkyne adduct along with the release of potassium cyanate. Dissolution of the alkyne adduct in THF regenerates the starting complex [(ONO)­V­(THF)], thereby closing a synthetic cycle for conversion of N₂ and CO into [NCO]⁻

1,4,5-Trigermabicyclo[2.1.0]pent-2-en-5-ylium: The Isolable Bishomocyclopropenylium Ion Containing a Heavier Group 14 Element

The isolable bishomoaromatic cation containing a heavier Group 14 element, (2,3,5-deloc)-2-phenyl-1,4,5-tris(tri-tert-butylsilyl)-1,4,5-trigermabicyclo[2.1.0]pent-2-en-5-ylium TPFPB- (2+·TPFPB-; TPFPB- = tetrakis(pentafluorophenyl)borate) was synthesized by the reaction of 5-bromo-2-phenyl-1,4,5-tris(tri-tert-butylsilyl)-1,4,5-trigermabicyclo[2.1.0]pent-2-ene (1) with [Et3Si(benzene)]+·TPFPB- in benzene at room temperature. The characteristic bishomoaromatic structure was unambiguously determined by X-ray crystallographic analysis. NMR measurements on 2+·TPFPB- confirmed the nonclassical germyl cation structure in solution and showed strong shielding of homoconjugative carbon atoms. The bishomoaromaticity in 2+ was also investigated by theoretical calculations

1,4,5-Trigermabicyclo[2.1.0]pent-2-en-5-ylium: The Isolable Bishomocyclopropenylium Ion Containing a Heavier Group 14 Element

The isolable bishomoaromatic cation containing a heavier Group 14 element, (2,3,5-deloc)-2-phenyl-1,4,5-tris(tri-tert-butylsilyl)-1,4,5-trigermabicyclo[2.1.0]pent-2-en-5-ylium TPFPB- (2+·TPFPB-; TPFPB- = tetrakis(pentafluorophenyl)borate) was synthesized by the reaction of 5-bromo-2-phenyl-1,4,5-tris(tri-tert-butylsilyl)-1,4,5-trigermabicyclo[2.1.0]pent-2-ene (1) with [Et3Si(benzene)]+·TPFPB- in benzene at room temperature. The characteristic bishomoaromatic structure was unambiguously determined by X-ray crystallographic analysis. NMR measurements on 2+·TPFPB- confirmed the nonclassical germyl cation structure in solution and showed strong shielding of homoconjugative carbon atoms. The bishomoaromaticity in 2+ was also investigated by theoretical calculations

Zirconium Hydride Complex Supported by a Tetradentate Carbon-Centered Tripodal Tris(aryloxide) Ligand: Synthesis, Structure, and Reactivity

A dizirconium trihydride complex supported by a tetradentate carbon-centered tris­(aryloxide) ligand [{Na­(dme)}3{(O3C)­Zr}2(μ-H)3] (2; [O3C] = [(3,5-tBu2-2-O−C6H2)3C]4–) was prepared by reacting [(O3C)­Zr­(thf)3] (1) with NaBHEt3 in toluene. Exposure of 2 in THF to CO2 (1 atm) resulted in facile insertion of CO2 into Zr−H bonds, yielding a formate complex [{Na­(thf)2}3{(O3C)­Zr}2(μ-O2CH)3] (3). Treatment of 2 with P4 in toluene led to formation of [Na­(thf)5]­[{Na­(thf)2}2{(O3C)­Zr}2(μ-P3)] (4) and PH3, in which hydrogenation of P4 took place. Complex 2 reacted with Me3SiN3 to afford an azide-bridged cyclotrimer [{Na­(thf)2}­{(O3C)­ZrN3(thf)}]3 (5) with concomitant liberation of Me3SiH. The molecular structures of these complexes 2–5 have been determined by X-ray diffraction analyses

Zirconium Hydride Complex Supported by a Tetradentate Carbon-Centered Tripodal Tris(aryloxide) Ligand: Synthesis, Structure, and Reactivity

A dizirconium trihydride complex supported by a tetradentate carbon-centered tris­(aryloxide) ligand [{Na­(dme)}₃{(O₃C)­Zr}₂(μ-H)₃] (<b>2</b>; [O₃C] = [(3,5-^<i>t</i>Bu₂-2-O−C₆H₂)₃C]^4–) was prepared by reacting [(O₃C)­Zr­(thf)₃] (<b>1</b>) with NaBHEt₃ in toluene. Exposure of <b>2</b> in THF to CO₂ (1 atm) resulted in facile insertion of CO₂ into Zr−H bonds, yielding a formate complex [{Na­(thf)₂}₃{(O₃C)­Zr}₂(μ-O₂CH)₃] (<b>3</b>). Treatment of <b>2</b> with P₄ in toluene led to formation of [Na­(thf)₅]­[{Na­(thf)₂}₂{(O₃C)­Zr}₂(μ-P₃)] (<b>4</b>) and PH₃, in which hydrogenation of P₄ took place. Complex <b>2</b> reacted with Me₃SiN₃ to afford an azide-bridged cyclotrimer [{Na­(thf)₂}­{(O₃C)­ZrN₃(thf)}]₃ (<b>5</b>) with concomitant liberation of Me₃SiH. The molecular structures of these complexes <b>2</b>–<b>5</b> have been determined by X-ray diffraction analyses

Reductive Coupling of Six Carbon Monoxides by a Ditantalum Hydride Complex

Reductive Coupling of Six Carbon Monoxides by a Ditantalum Hydride Comple

1,6,7-Trigermabicyclo[4.1.0]hept-3-en-7-yl: The Isolable Bicyclic Germyl Radical

The one-electron oxidation reaction of potassium 3,4-dimethyl-1,6,7-tris(tri-tert-butylsilyl)-1,6,7-trigermabicyclo[4.1.0]hept-3-en-7-ide (2-·K+) with tris(pentafluorophenyl)borane in THF results in the formation of stable 3,4-dimethyl-1,6,7-tris(tri-tert-butylsilyl)-1,6,7-trigermabicyclo[4.1.0]hept-3-en-7-yl (3•), representing the first bicyclic germyl radical with the bicyclo[4.1.0]hept-3-ene skeleton. The germyl radical 3• was characterized by X-ray crystallographic analysis as well as ESR spectroscopy, showing that it has a near-planar Ge-radical center

Reductive Coupling of Six Carbon Monoxides by a Ditantalum Hydride Complex

Reductive Coupling of Six Carbon Monoxides by a Ditantalum Hydride Comple