Gallium Hydrides with a Radical-Anionic Ligand

The reaction of Cl₂GaH with a sodium salt of the dpp-Bian radical-anion (dpp-Bian^•–)Na (dpp-Bian = 1,2-bis­[(2,6-diisopropylphenyl)­imino]­acenaphthene) affords paramagnetic gallane (dpp-Bian^•–)­Ga­(Cl)­H (<b>1</b>). Oxidation of (dpp-Bian^2–)­Ga–Ga­(dpp-Bian^2–) (<b>2</b>) with N₂O results in the dimeric oxide (dpp-Bian^•–)­Ga­(μ²-O)₂Ga­(dpp-Bian^•–) (<b>3</b>). A treatment of the oxide <b>3</b> with phenylsilane affords paramagnetic gallium hydrides (dpp-Bian^•–)­GaH₂ (<b>4</b>) and (dpp-Bian^•–)­Ga­{OSi­(Ph)­H₂}H (<b>5</b>) depending on the reagent’s stoichiometry. The reaction of digallane <b>2</b> with benzaldehyde produces pinacolate (dpp-Bian^•–)­Ga­(O₂C₂H₂Ph₂) (<b>6</b>). In the presence of PhSiH₃, the reaction between digallane <b>2</b> and benzaldehyde (<b>2</b>: PhSiH₃: PhC­(H)­O = 1:4:4) affords compound <b>4</b>. The newly prepared complexes <b>1</b>, <b>3</b>–<b>6</b> consist of a spin-labeled diimine ligand–dpp-Bian radical-anion. The presence of the ligand-localized unpaired electron allows the use of the ESR spectroscopy for characterization of the gallium hydrides reported. The molecular structures of compounds <b>1</b>, <b>3</b>–<b>6</b> have been determined by the single-crystal X-ray analysis

Mononuclear dpp-Bian Gallium Complexes: Synthesis, Crystal Structures, and Reactivity toward Alkynes and Enones

Treatment of (dpp-Bian)­Ga–Ga­(dpp-Bian) (<b>1</b>) (dpp-Bian = 1,2-bis­[(2,6-diisopropylphenyl)­imino]­acenaphthene) with iodine gives (dpp-Bian)­Ga­(I)–Ga­(I)­(dpp-Bian) (<b>2</b>), which reacts in situ with K­(C₅H₄CH₂CH₂NMe₂) (KCp^Do) or K­(OCH₂CH₂NMe₂) (KOR^Do) to produce the monomeric species (dpp-Bian)­GaCp^Do (<b>3</b>) and (dpp-Bian)­GaOR^Do (<b>4</b>), respectively. Complex <b>3</b> reacts with PhCCH to give the paramagnetic derivative (dpp-Bian)­Ga­(CCPh)₂ (<b>5</b>), while compound <b>4</b> is inert toward this alkyne. In contrast, monomeric (dpp-Bian)­Ga­(S₂CNMe₂) (<b>6</b>) reacts with PhCCH and HCCH to give the cycloaddition products [dpp-Bian­(PhCCH)]­Ga­(S₂CNMe₂) (<b>7</b>) and [dpp-Bian­(HCCH)]­Ga­(S₂CNMe₂) (<b>8</b>). The related compounds [dpp-Bian­(MeCCC­(O)­OMe)]­Ga­(S₂CNMe₂) (<b>9</b>) and [dpp-Bian­(CH₂CHC­(Me)­O)]­Ga­(S₂CNMe₂) (<b>10</b>) have been obtained in the reactions of complex <b>6</b> with methyl 2-butynoate and methyl vinyl ketone, respectively. New complexes have been characterized by ¹H NMR (<b>3</b>, <b>4</b>, and <b>7</b>–<b>10</b>) and ESR (<b>5</b>) spectroscopy; their molecular structures have been established by single-crystal X-ray analysis. The catalytic activity of complex <b>6</b> in the hydroamination and hydroarylation of alkynes has been examined

Mononuclear dpp-Bian Gallium Complexes: Synthesis, Crystal Structures, and Reactivity toward Alkynes and Enones

Treatment of (dpp-Bian)­Ga–Ga­(dpp-Bian) (<b>1</b>) (dpp-Bian = 1,2-bis­[(2,6-diisopropylphenyl)­imino]­acenaphthene) with iodine gives (dpp-Bian)­Ga­(I)–Ga­(I)­(dpp-Bian) (<b>2</b>), which reacts in situ with K­(C₅H₄CH₂CH₂NMe₂) (KCp^Do) or K­(OCH₂CH₂NMe₂) (KOR^Do) to produce the monomeric species (dpp-Bian)­GaCp^Do (<b>3</b>) and (dpp-Bian)­GaOR^Do (<b>4</b>), respectively. Complex <b>3</b> reacts with PhCCH to give the paramagnetic derivative (dpp-Bian)­Ga­(CCPh)₂ (<b>5</b>), while compound <b>4</b> is inert toward this alkyne. In contrast, monomeric (dpp-Bian)­Ga­(S₂CNMe₂) (<b>6</b>) reacts with PhCCH and HCCH to give the cycloaddition products [dpp-Bian­(PhCCH)]­Ga­(S₂CNMe₂) (<b>7</b>) and [dpp-Bian­(HCCH)]­Ga­(S₂CNMe₂) (<b>8</b>). The related compounds [dpp-Bian­(MeCCC­(O)­OMe)]­Ga­(S₂CNMe₂) (<b>9</b>) and [dpp-Bian­(CH₂CHC­(Me)­O)]­Ga­(S₂CNMe₂) (<b>10</b>) have been obtained in the reactions of complex <b>6</b> with methyl 2-butynoate and methyl vinyl ketone, respectively. New complexes have been characterized by ¹H NMR (<b>3</b>, <b>4</b>, and <b>7</b>–<b>10</b>) and ESR (<b>5</b>) spectroscopy; their molecular structures have been established by single-crystal X-ray analysis. The catalytic activity of complex <b>6</b> in the hydroamination and hydroarylation of alkynes has been examined

Mononuclear dpp-Bian Gallium Complexes: Synthesis, Crystal Structures, and Reactivity toward Alkynes and Enones

Treatment of (dpp-Bian)­Ga–Ga­(dpp-Bian) (<b>1</b>) (dpp-Bian = 1,2-bis­[(2,6-diisopropylphenyl)­imino]­acenaphthene) with iodine gives (dpp-Bian)­Ga­(I)–Ga­(I)­(dpp-Bian) (<b>2</b>), which reacts in situ with K­(C₅H₄CH₂CH₂NMe₂) (KCp^Do) or K­(OCH₂CH₂NMe₂) (KOR^Do) to produce the monomeric species (dpp-Bian)­GaCp^Do (<b>3</b>) and (dpp-Bian)­GaOR^Do (<b>4</b>), respectively. Complex <b>3</b> reacts with PhCCH to give the paramagnetic derivative (dpp-Bian)­Ga­(CCPh)₂ (<b>5</b>), while compound <b>4</b> is inert toward this alkyne. In contrast, monomeric (dpp-Bian)­Ga­(S₂CNMe₂) (<b>6</b>) reacts with PhCCH and HCCH to give the cycloaddition products [dpp-Bian­(PhCCH)]­Ga­(S₂CNMe₂) (<b>7</b>) and [dpp-Bian­(HCCH)]­Ga­(S₂CNMe₂) (<b>8</b>). The related compounds [dpp-Bian­(MeCCC­(O)­OMe)]­Ga­(S₂CNMe₂) (<b>9</b>) and [dpp-Bian­(CH₂CHC­(Me)­O)]­Ga­(S₂CNMe₂) (<b>10</b>) have been obtained in the reactions of complex <b>6</b> with methyl 2-butynoate and methyl vinyl ketone, respectively. New complexes have been characterized by ¹H NMR (<b>3</b>, <b>4</b>, and <b>7</b>–<b>10</b>) and ESR (<b>5</b>) spectroscopy; their molecular structures have been established by single-crystal X-ray analysis. The catalytic activity of complex <b>6</b> in the hydroamination and hydroarylation of alkynes has been examined

Digallane with Redox-Active Diimine Ligand: Dualism of Electron-Transfer Reactions

The reactivity of digallane (dpp-Bian)­Ga–Ga­(dpp-Bian) (<b>1</b>), which consists of redox-active ligand 1,2-bis­[(2,6-diisopropylphenyl)­imino]­acenaphthene (dpp-Bian), has been studied. The reaction of <b>1</b> with I₂ proceeds via one-electron oxidation of each of two dpp-Bian ligands to a radical-anionic state and affords complex (dpp-Bian)­IGa–GaI­(dpp-Bian) (<b>2</b>). Dissolution of complex <b>2</b> in pyridine (Py) gives monomeric compound (dpp-Bian)­GaI­(Py) (<b>3</b>) as a result of a solvent-induced intramolecular electron transfer from the metal–metal bond to the dpp-Bian ligands. Treatment of compound <b>3</b> with B­(C₆F₅)₃ leads to removal of pyridine and restores compound <b>2</b>. The reaction of compound <b>1</b> with 3,6-di-<i>tert</i>-butyl-<i>ortho</i>-benzoquinone (3,6-Q) proceeds with oxidation of all the redox-active centers in <b>1</b> (the Ga–Ga bond and two dpp-Bian dianions) and results in mononuclear catecholate (dpp-Bian)­Ga­(Cat) (<b>4</b>) (Cat = [3,6-Q]^2–). Treatment of <b>4</b> with AgBF₄ gives a mixture of [(dpp-Bian)₂Ag]­[BF₄] (<b>5</b>) and (dpp-Bian)­GaF­(Cat) (<b>6</b>), which both consist of neutral dpp-Bian ligands. The reduction of benzylideneacetone (BA) with <b>1</b> generates the BA radical-anions, which dimerize, affording (dpp-Bian)­Ga–(BA–BA)–Ga­(dpp-Bian) (<b>7</b>). In this case the Ga–Ga bond remains unchanged. Within 10 min at 95 °C in solution compound <b>7</b> undergoes transformation to paramagnetic complex (dpp-Bian)­Ga­(BA–BA) (<b>8</b>) and metal-free compound C₃₆H₄₀N₂ (<b>9</b>). The latter is a product of intramolecular addition of the C–H bond of one of the <i>i</i>Pr groups to the CN bond in dpp-Bian. Diamagnetic compounds <b>3</b>, <b>5</b>, <b>6</b>, and <b>9</b> have been characterized by NMR spectroscopy, and paramagnetic complexes <b>2</b>, <b>4</b>, <b>7</b>, and <b>8</b> by ESR spectroscopy. Molecular structures of <b>2</b>–<b>7</b> and <b>9</b> have been established by single-crystal X-ray analysis