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

Lanthanum Complexes with a Diimine Ligand in Three Different Redox States

The reduction of 1,2-bis­[(2,6-diisopropylphenyl)­imino]­acenaphthene (dpp-Bian) with an excess of La metal in the presence of iodine (dpp-Bian/I₂ = 2/1) in tetrahydrofuran (thf) or dimethoxyethane (dme) affords lanthanum­(III) complexes of dpp-Bian dianion: deep blue [(dpp-Bian)^2–­LaI­(thf)₂]₂ (<b>1</b>, 84%) was isolated by crystallization of the product from hexane, while deep green [(dpp-Bian)­LaI­(dme)₂] (<b>2</b>, 93%) precipitated from the reaction mixture in the course of its synthesis. A treatment of complex <b>1</b> with 0.5 equiv of I₂ in thf leads to the oxidation of the dpp-Bian dianion to the radical anion and results in the complex [(dpp-Bian)^1–­LaI₂(thf)₃] (<b>3</b>). Addition of 18-crown-6 to the mixture of <b>1</b> and NaCp* (Cp* = 1,2,3,4,5-pentamethylcyclopentadienyl) in thf affords ionic complex [(dpp-Bian)^2–­La­(Cp*)­I]­[Na­(18-crown-6)­(thf)₂] (<b>4</b>, 71%). In the absence of crown ether the alkali metal salt-free complex [(dpp-Bian)^2–­LaCp*­(thf)] (<b>5</b>, 67%) was isolated from toluene. Reduction of complex <b>1</b> with an excess of potassium produces lanthanum–potassium salt of the dpp-Bian tetra-anion {[(dpp-Bian)^4–­La­(thf)]­[K­(thf)₃]}₂ (<b>6</b>, 68%). Diamagnetic compounds <b>1</b>, <b>2</b>, <b>4</b>, <b>5</b>, and <b>6</b> were characterized by NMR spectroscopy, while paramagnetic complex <b>3</b> was characterized by the electron spin resonance spectroscopy. Molecular structures of <b>2</b>–<b>6</b> were established by 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

Hydrate-based technique for natural gas processing: Experimental study of pressure-dropping and continuous modes

Gas hydrate crystallization is perspective and energy-efficient technology for gas mixtures processing, including natural gas. There were compared pressure-dropping and continuous gas hydrate crystallization methods for separation of gas mixture closed to natural gas. The studied mixture has been chosen similar to the natural gas composition: CH4 (75.68 mol.%) - С2H6 (7.41 mol.%) - C3H8 (4.53 mol.%) - н-C4H10 (2.47 mol.%) - CO2 (5.40 mol.%) - H2S (1.39 mol.%) - N2 (3.01 mol.%) - Xe (0.11 mol.%). Experiments were provided in the 4 L high pressure reactor, using water solution of SDS (0.20 wt.%). The experiment conditions were 280.15 K and pressure of 4.25 MPa. The components separation factors and recovery for two modes have been researched and compared for choosing more effective options. After comparing these characteristics, it was concluded that continuous process is more productive than pressure-dropping mode. At the stage cut (θ) of 0.9, the gas components total recovery (R) for the continuous mode have exceeded the total recovery for the pressure-dropping mode by 8.15 %, and at θ = 0.8, exceeded by 6.11 %. The recovery and separation factors have the highest values for H2S, C3H8, Xe in the continuous mode: 97.62 %, 94.90 %, 84.98 % and 8.7, 10.53, 6.36, respectively. Thus, the choosing of the more effective stage cut depends on the aim of the process: the highest purity or the largest recovery

Novel Oxidovanadium Complexes with Redox-Active R-Mian and R-Bian Ligands: Synthesis, Structure, Redox and Catalytic Properties

A new monoiminoacenaphthenone 3,5-(CF3)2C6H3-mian (complex 2) was synthesized and further exploited, along with the already known monoiminoacenaphthenone dpp-mian, to obtain oxidovanadium(IV) complexes [VOCl2(dpp-mian)(CH3CN)] (3) and [VOCl(3,5-(CF3)2C6H3-bian)(H2O)][VOCl3(3,5-(CF3)2C6H3-bian)]·2.85DME (4) from [VOCl2(CH3CN)2(H2O)] (1) or [VCl3(THF)3]. The structure of all compounds was determined using X-ray structural analysis. The vanadium atom in these structures has an octahedral coordination environment. Complex 4 has an unexpected structure. Firstly, it contains 3,5-(CF3)2C6H3-bian instead of 3,5-(CF3)2C6H3-mian. Secondly, it has a binuclear structure, in contrast to 3, in which two oxovanadium parts are linked to each other through V=O···V interaction. This interaction is non-covalent in origin, according to DFT calculations. In structures 2 and 3, non-covalent π-π staking interactions between acenaphthene moieties of the neighboring molecules (distances are 3.36–3.40 Å) with an estimated energy of 3 kcal/mol were also found. The redox properties of the obtained compounds were studied using cyclic voltammetry in solution. In all cases, the reduction processes initiated by the redox-active nature of the mian or bian ligand were identified. The paramagnetic nature of complexes 3 and 4 has been proven by EPR spectroscopy. Complexes 3 and 4 exhibited high catalytic activity in the oxidation of alkanes and alcohols with peroxides. The yields of products of cyclohexane oxidation were 43% (complex 3) and 27% (complex 4). Based on the data regarding the study of regio- and bond-selectivity, it was concluded that hydroxyl radicals play the most crucial role in the reaction. The initial products in the reactions with alkanes are alkyl hydroperoxides, which are easily reduced to their corresponding alcohols by the action of triphenylphosphine (PPh3). According to the DFT calculations, the difference in the catalytic activity of 3 and 4 is most likely associated with a different mechanism for the generation of ●OH radicals. For complex 4 with electron-withdrawing CF3 substituents at the diimine ligand, an alternative mechanism, different from Fenton’s and involving a redox-active ligand, is assumed