Electron Release and Proton Acceptance Reactions of (dpp-BIAN)Mg(THF)3

(dpp-BIAN)Mg(THF)3 (1) (dpp-BIAN = 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene) and (PhCOO)2 react with splitting of the peroxide bridge and formation of the dimeric magnesium benzoate [(dpp-BIAN)MgOCOPh(THF)]2 (2). The reaction of 1 with PhCOOH yields the dimeric magnesium benzoate [(dpp-BIAN)(H)MgOCOPh(THF)]2 (3), whereas 1 and furanyl-2-carboxylic acid react with liberation of hydrogen and formation of (dpp-BIAN)Mg[OCO(2-C4H3O)]2 Mg(dpp-BIAN)(THF) (4). Compounds 2, 3, and 4 have been characterized by elemental analysis, IR spectroscopy, and X-ray structure analysis, compound 3 also by 1H NMR spectroscopy. The eightmembered metallacycles of the centrosymmetric dimers 2 and 3 are almost completely planar. The two magnesium atoms in 4 show different coordination spheres; one is surrounded by its ligands in a trigonal bipyramidal manner, the other one in a tetrahedral fashion. The Mg···Mg separations in 2, 3 and 4 are 4.236, 4.296, and 4.030 Å, respectively

Organometallic Compounds of the Lanthanides 182 [1]. Calcium and Neodymium Complexes Containing the dpp-BIAN Ligand System: Synthesis and Molecular Structure of [(dpp-BIAN)CaI(THF)2]2 and [(dpp-BIAN)NdCl(THF)2]2

Oxydation of (dpp-BIAN)Ca(THF)4 with 0.5 equiv. of I2 in THF yields [(dpp-BIAN)CaI(THF)2]2 (1). A corresponding neodymium compound [(dpp-BIAN)NdCl(THF)2]2 (2) has been obtained by reaction of (dpp-BIAN)Na2 with NdCl3 in THF. The X-ray single crystal structure analyses show 1 and 2 to be isostructural dimers containing octahedrally coordinated metal atoms bridged by the respective halides. The chelating dpp-BIAN ligand acts as a radical anion in the Ca2+ complex 1 and as a dianion in the Nd3+ complex 2, respectively.DFG, SPP 1166, Lanthanoidspezifische Funktionalitäten in Molekül und Materia

Synthesis of Unsupported Ln–Ga Bonds by Salt Metathesis and Ga–Ga Bond Reduction

Three gallyl lanthanide complexes [{(dipp-Bian)­Ga}₂Ln­(thf)₄] (Ln = Sm, Eu, Yb; dipp-Bian = 1,2-bis­[(2,6-diisopropylphenyl)­imino]­acenaphthene), in which the lanthanide atoms are coordinated by only two {(dipp-Bian)­Ga}⁻ ligands and THF, are reported. Two unsupported Ln–Ga bonds are found in each compound. The gallyl lanthanide complexes have been obtained by two synthetic pathways: (1) reductive insertion of the lanthanide metals into the Ga–Ga bond of [{(dipp-Bian)­Ga}]₂ and (2) salt metathesis of [(dipp-Bian)­GaK­(thf)₅] with LnI₂. Moreover, the samarium compound [{(dipp-Bian)­Ga}₂Sm­(thf)₄] was additionally obtained in a reductive pathway from SmI₃ and [(dipp-Bian)­GaK­(thf)₅]. The length of the Ln–Ga bond strongly depends on packing effects. The reaction of TmI₂(thf)₅ and [(dipp-Bian)­GaK­(thf)₅] gave the Tm­(III) complex [{(dipp-Bian)­Ga–Ga­(dipp-Bian)}­(C₄H₈O)­TmI­(thf)₅], in which one THF ring was opened and reduced twice, forming the formal double negative charged anion (O-CH₂-CH₂-CH₂-CH₂)^2–. This thulium compound and its dysprosium analogue [{(dipp-Bian)­Ga–Ga­(dipp-Bian)}­(C₄H₈O)­DyI­(thf)₅] were also obtained in an alternative approach by reacting LnI₂(thf)_<i>x</i> (Ln = Tm, Dy) with [(dipp-Bian)­Ga]₂ in THF. All new compounds were structurally characterized by single-crystal X-ray diffraction. The ytterbium complex shows the shortest Yb­(II)–Ga bond distances reported so far

Synthesis of Unsupported Ln–Ga Bonds by Salt Metathesis and Ga–Ga Bond Reduction

Three gallyl lanthanide complexes [{(dipp-Bian)­Ga}₂Ln­(thf)₄] (Ln = Sm, Eu, Yb; dipp-Bian = 1,2-bis­[(2,6-diisopropylphenyl)­imino]­acenaphthene), in which the lanthanide atoms are coordinated by only two {(dipp-Bian)­Ga}⁻ ligands and THF, are reported. Two unsupported Ln–Ga bonds are found in each compound. The gallyl lanthanide complexes have been obtained by two synthetic pathways: (1) reductive insertion of the lanthanide metals into the Ga–Ga bond of [{(dipp-Bian)­Ga}]₂ and (2) salt metathesis of [(dipp-Bian)­GaK­(thf)₅] with LnI₂. Moreover, the samarium compound [{(dipp-Bian)­Ga}₂Sm­(thf)₄] was additionally obtained in a reductive pathway from SmI₃ and [(dipp-Bian)­GaK­(thf)₅]. The length of the Ln–Ga bond strongly depends on packing effects. The reaction of TmI₂(thf)₅ and [(dipp-Bian)­GaK­(thf)₅] gave the Tm­(III) complex [{(dipp-Bian)­Ga–Ga­(dipp-Bian)}­(C₄H₈O)­TmI­(thf)₅], in which one THF ring was opened and reduced twice, forming the formal double negative charged anion (O-CH₂-CH₂-CH₂-CH₂)^2–. This thulium compound and its dysprosium analogue [{(dipp-Bian)­Ga–Ga­(dipp-Bian)}­(C₄H₈O)­DyI­(thf)₅] were also obtained in an alternative approach by reacting LnI₂(thf)_<i>x</i> (Ln = Tm, Dy) with [(dipp-Bian)­Ga]₂ in THF. All new compounds were structurally characterized by single-crystal X-ray diffraction. The ytterbium complex shows the shortest Yb­(II)–Ga bond distances reported so far

Ligand “Brackets” for Ga–Ga Bond

The reactivity of digallane (dpp-Bian)­Ga–Ga­(dpp-Bian) (<b>1</b>) (dpp-Bian = 1,2-bis­[(2,6-diisopropylphenyl)­imino]­acenaphthene) toward acenaphthenequinone (AcQ), sulfur dioxide, and azobenzene was investigated. The reaction of <b>1</b> with AcQ in 1:1 molar ratio proceeds via two-electron reduction of AcQ to give (dpp-Bian)­Ga­(μ₂-AcQ)­Ga­(dpp-Bian) (<b>2</b>), in which diolate [AcQ]^2– acts as “bracket” for the Ga–Ga bond. The interaction of <b>1</b> with AcQ in 1:2 molar ratio proceeds with an oxidation of the both dpp-Bian ligands as well as of the Ga–Ga bond to give (dpp-Bian)­Ga­(μ₂-AcQ)₂Ga­(dpp-Bian) (<b>3</b>). At 330 K in toluene complex <b>2</b> decomposes to give compounds <b>3</b> and <b>1</b>. The reaction of complex <b>2</b> with atmospheric oxygen results in oxidation of a Ga–Ga bond and affords (dpp-Bian)­Ga­(μ₂-AcQ)­(μ₂-O)­Ga­(dpp-Bian) (<b>4</b>). The reaction of digallane <b>1</b> with SO₂ produces, depending on the ratio (1:2 or 1:4), dithionites (dpp-Bian)­Ga­(μ₂-O₂S–SO₂)­Ga­(dpp-Bian) (<b>5</b>) and (dpp-Bian)­Ga­(μ₂-O₂S–SO₂)₂Ga­(dpp-Bian) (<b>6</b>). In compound <b>5</b> the Ga–Ga bond is preserved and supported by dithionite dianionic bracket. In compound <b>6</b> the gallium centers are bridged by two dithionite ligands. Both <b>5</b> and <b>6</b> consist of dpp-Bian radical anionic ligands. Four-electron reduction of azobenzene with 1 mol equiv of digallane <b>1</b> leads to complex (dpp-Bian)­Ga­(μ₂-NPh)₂Ga­(dpp-Bian) (<b>7</b>). Paramagnetic compounds <b>2</b>–<b>7</b> were characterized by electron spin resonance spectroscopy, and their molecular structures were established by single-crystal X-ray analysis. Magnetic behavior of compounds <b>2</b>, <b>5</b>, and <b>6</b> was investigated by superconducting quantum interference device technique in the range of 2–295 K

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

Ligand “Brackets” for Ga–Ga Bond

The reactivity of digallane (dpp-Bian)­Ga–Ga­(dpp-Bian) (<b>1</b>) (dpp-Bian = 1,2-bis­[(2,6-diisopropylphenyl)­imino]­acenaphthene) toward acenaphthenequinone (AcQ), sulfur dioxide, and azobenzene was investigated. The reaction of <b>1</b> with AcQ in 1:1 molar ratio proceeds via two-electron reduction of AcQ to give (dpp-Bian)­Ga­(μ₂-AcQ)­Ga­(dpp-Bian) (<b>2</b>), in which diolate [AcQ]^2– acts as “bracket” for the Ga–Ga bond. The interaction of <b>1</b> with AcQ in 1:2 molar ratio proceeds with an oxidation of the both dpp-Bian ligands as well as of the Ga–Ga bond to give (dpp-Bian)­Ga­(μ₂-AcQ)₂Ga­(dpp-Bian) (<b>3</b>). At 330 K in toluene complex <b>2</b> decomposes to give compounds <b>3</b> and <b>1</b>. The reaction of complex <b>2</b> with atmospheric oxygen results in oxidation of a Ga–Ga bond and affords (dpp-Bian)­Ga­(μ₂-AcQ)­(μ₂-O)­Ga­(dpp-Bian) (<b>4</b>). The reaction of digallane <b>1</b> with SO₂ produces, depending on the ratio (1:2 or 1:4), dithionites (dpp-Bian)­Ga­(μ₂-O₂S–SO₂)­Ga­(dpp-Bian) (<b>5</b>) and (dpp-Bian)­Ga­(μ₂-O₂S–SO₂)₂Ga­(dpp-Bian) (<b>6</b>). In compound <b>5</b> the Ga–Ga bond is preserved and supported by dithionite dianionic bracket. In compound <b>6</b> the gallium centers are bridged by two dithionite ligands. Both <b>5</b> and <b>6</b> consist of dpp-Bian radical anionic ligands. Four-electron reduction of azobenzene with 1 mol equiv of digallane <b>1</b> leads to complex (dpp-Bian)­Ga­(μ₂-NPh)₂Ga­(dpp-Bian) (<b>7</b>). Paramagnetic compounds <b>2</b>–<b>7</b> were characterized by electron spin resonance spectroscopy, and their molecular structures were established by single-crystal X-ray analysis. Magnetic behavior of compounds <b>2</b>, <b>5</b>, and <b>6</b> was investigated by superconducting quantum interference device technique in the range of 2–295 K

Ligand “Brackets” for Ga–Ga Bond

The reactivity of digallane (dpp-Bian)­Ga–Ga­(dpp-Bian) (<b>1</b>) (dpp-Bian = 1,2-bis­[(2,6-diisopropylphenyl)­imino]­acenaphthene) toward acenaphthenequinone (AcQ), sulfur dioxide, and azobenzene was investigated. The reaction of <b>1</b> with AcQ in 1:1 molar ratio proceeds via two-electron reduction of AcQ to give (dpp-Bian)­Ga­(μ₂-AcQ)­Ga­(dpp-Bian) (<b>2</b>), in which diolate [AcQ]^2– acts as “bracket” for the Ga–Ga bond. The interaction of <b>1</b> with AcQ in 1:2 molar ratio proceeds with an oxidation of the both dpp-Bian ligands as well as of the Ga–Ga bond to give (dpp-Bian)­Ga­(μ₂-AcQ)₂Ga­(dpp-Bian) (<b>3</b>). At 330 K in toluene complex <b>2</b> decomposes to give compounds <b>3</b> and <b>1</b>. The reaction of complex <b>2</b> with atmospheric oxygen results in oxidation of a Ga–Ga bond and affords (dpp-Bian)­Ga­(μ₂-AcQ)­(μ₂-O)­Ga­(dpp-Bian) (<b>4</b>). The reaction of digallane <b>1</b> with SO₂ produces, depending on the ratio (1:2 or 1:4), dithionites (dpp-Bian)­Ga­(μ₂-O₂S–SO₂)­Ga­(dpp-Bian) (<b>5</b>) and (dpp-Bian)­Ga­(μ₂-O₂S–SO₂)₂Ga­(dpp-Bian) (<b>6</b>). In compound <b>5</b> the Ga–Ga bond is preserved and supported by dithionite dianionic bracket. In compound <b>6</b> the gallium centers are bridged by two dithionite ligands. Both <b>5</b> and <b>6</b> consist of dpp-Bian radical anionic ligands. Four-electron reduction of azobenzene with 1 mol equiv of digallane <b>1</b> leads to complex (dpp-Bian)­Ga­(μ₂-NPh)₂Ga­(dpp-Bian) (<b>7</b>). Paramagnetic compounds <b>2</b>–<b>7</b> were characterized by electron spin resonance spectroscopy, and their molecular structures were established by single-crystal X-ray analysis. Magnetic behavior of compounds <b>2</b>, <b>5</b>, and <b>6</b> was investigated by superconducting quantum interference device technique in the range of 2–295 K