Reduction of CO2 with Aluminum Hydrides Supported with Ar-BIAN Radical-Anions (Ar-BIAN = 1,2-Bis(arylimino)acenaphthene)

The reactions of H₂AlCl with [(dpp-Bian)Na(Et₂O)_n] and [(Ar^BIG-Bian)Na(THF)] produce respective aluminum hydrides supported by radical-anionic 1,2-bis(arylimino)acenaphthene ligands, [(dpp-Bian)AlH₂] (1) and [(Ar^BIG-Bian)AlH₂(THF)] (2) (dpp-Bian = 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene); Ar^BIG-Bian = 1,2-bis[(2,6-dibenzhydryl-4-methylphenyl)imino]acenaphthene). The reaction of 1 with CO₂ proceeds with reduction of both C═O bonds and results in diolate [{(dpp-Bian)Al(μ-O₂CH₂)}₂] (3). Complex 2 reacts with CO₂ to carbonate [{(Ar^BIG-Bian)Al(μ-OCH₂OCO₂)}₂] (4) that is a result of the insertion of CO₂ into the Al-O bond in diolate species formed initially. Aluminum monohydrides [(dpp-Bian)AlH(X)] (X = Cl, 5; Me, 6) react with CO₂ to form respective alumoxanes [{(dpp-Bian)AlX}₂(μ-O)] (X = Cl, 7 and X = Me, 8). Compounds 1-4, 7, and 8 have been characterized by ESR and IR spectroscopy, and their molecular structures have been determined by single-crystal X-ray analysis.

"Bulky-Yet-Flexible" α-Diimine Palladium-Catalyzed Reductive Heck Cross-Coupling: Highly Anti-Markovnikov-Selective Hydroarylation of Alkene in Air

To pursue a highly regioselective and efficient reductive Heck reaction, a series of moisture- and air-stable α-diimine palladium precatalysts were rationally designed, readily synthesized, and fully characterized. The relationship between the structures of the palladium complexes and the catalytic properties was investigated. It was revealed that the"bulky-yet-flexible"palladium complexes allowed highly anti-Markovnikov-selective hydroarylation of alkenes with (hetero)aryl bromides under aerobic conditions. Further synthetic application of the present protocol could provide rapid and straightforward access to functional and biologically active molecules.

Dinuclear Complexes of Flexidentate Pyridine-Substituted Formazanate Ligands

The utility of flexidentate pyridyl-substituted formazanate ligands for assembling dinuclear coordination complexes with iridium(III) and/or platinum(II) building blocks is demonstrated herein. The dinuclear complexes are prepared either via a stepwise strategy, adding one metal unit at a time, or via one-pot self-assembly. Eight of the new complexes, including both mononuclear precursors and dinuclear products, are structurally characterized by single-crystal X-ray diffraction and NMR spectroscopy, revealing several distinct binding modes of the formazanates. All complexes are characterized by UV/Vis absorption spectroscopy and cyclic voltammetry. The frontier orbitals are primarily localized on the formazanate ligand, and a characteristic, intense formazanate-centered π→π* absorption band is observed in the absorption spectra.

Synthesis and Characterization of Neutral Ligand α-Diimine Complexes of Aluminum with Tunable Redox Energetics

The synthesis and full characterization of a series of neutral ligand α-diimine complexes of aluminum are reported. The compounds [Al(L_Ar)₂Cl₂)][AlCl₄] [L_Ar = N, N'-bis(4-R-C₆H₄)-2,3-dimethyl-1,4-diazabutadiene] are structurally analogous, as determined by multinuclear NMR spectroscopy and solid-state X-ray diffraction, across a range of electron-donating [R = Me (2), ^tBu (3), OMe (4), and NMe₂ (5)] and electron-withdrawing [R = Cl (6), CF₃ (7), and NO₂ (8)] substituents in the aryl side arm of the ligand. UV-vis absorption spectroscopy and electrochemistry were used to access the optical and electrochemical properties, respectively, of the complexes. Both sets of properties are shown to be dependent on the R substituent. Density functional theory calculations performed on the [Al(L_Ph)₂Cl₂)][AlCl₄] complex (1) indicate primarily ligand-based frontier orbitals and were used to help support our discussion of both the spectral and electrochemical data. We also report the reaction of the L_Ph ligand with both AlBr₃ and AlI₃ and demonstrate a different reactivity profile for the heavier halide relative to the lighter members of the group.

Synthesis, characterization and mass-spectrometric analysis of [LSn(IV)F4−x]x+ salts [L = tris ((1-ethyl-benzoimidazol-2-yl)methyl)amine, x = 1–4]

A series of cationic tin fluoride complexes has been synthesized by successive fluoride abstraction from SnF₄ with TMSOTf in the presence of the tetradentate nitrogen donor BIMEt₃.

Ferrous complexes supported by sterically encumbered asymmetric bis(arylimino)acenaphthene (BIAN) ligands: synthesis, characterization and screening for catalytic hydrosilylation of carbonyl compounds

Structurally characterized Fe complexes bearing asymmetric bidentate BIAN ligands were synthesized and their use as room-temperature hydrosilylation precatalyst was reported.