The charge-assisted hydrogen-bonded organic framework (CAHOF) self-assembled from the conjugated acid of tetrakis(4-aminophenyl)methane and 2,6-naphthalenedisulfonate as a new class of recyclable Brønsted acid catalysts

The acid–base neutralization reaction of commercially available disodium 2,6-naphthalenedisulfonate (NDS, 2 equivalents) and the tetrahydrochloride salt of tetrakis(4-aminophenyl)methane (TAPM, 1 equivalent) in water gave a novel three-dimensional charge-assisted hydrogen-bonded framework (CAHOF, F-1). The framework F-1 was characterized by X-ray diffraction, TGA, elemental analysis, and 1H NMR spectroscopy. The framework was supported by hydrogen bonds between the sulfonate anions and the ammonium cations of NDS and protonated TAPM moieties, respectively. The CAHOF material functioned as a new type of catalytically active Brønsted acid in a series of reactions, including the ring opening of epoxides by water and alcohols. A Diels–Alder reaction between cyclopentadiene and methyl vinyl ketone was also catalyzed by F-1 in heptane. Depending on the polarity of the solvent mixture, the CAHOF F-1 could function as a purely heterogeneous catalyst or partly dissociate, providing some dissolved F-1 as the real catalyst. In all cases, the catalyst could easily be recovered and recycled

Cyclooctadiene iridium complexes [Cp*Ir(COD)X]+ (X = Cl, Br, I): Synthesis and application for oxidative coupling of benzoic acid with alkynes

The cyclooctadiene iridium complexes [Cp*Ir(COD)X]PF6 ([1a−c]PF6; X = Cl, Br, I) were synthesized by reactions of Cp*Ir(COD) with halogens followed by a counterion exchange. The cyclooctadiene in these complexes is a thermally labile ligand. Complex [1b]PF6 reacts with trimethylphosphite to give [Cp*Ir{P(OMe)3}2Br]PF6 ([2]PF6) as a result of the cyclooctadiene replacement. The refluxing of [1b]PF6 in 1,2-dichloroethane affords the dimeric iodide [Cp*IrI2]2. The structures of [1b]PF6, [2]PF6 and [Cp*IrI2]2 were determined by X-ray diffraction. The Ir–COD bonding in [1a−c]+ and the related non-methylated complexes was analyzed by energy decomposition analysis. In the presence of silver salts, complexes [1a−c]PF6 (at 2.0 mol % loading) catalyze the oxidative coupling of benzoic acid with 1-phenyl-1-propyne in methanol at 60 °C to selectively give 4-methyl-3-phenylisocoumarin (3) or with diphenylacetylene in o-xylene at 160 °C to afford 1,2,3,4-tetraphenylnaphthalene (4). © 2018 Elsevier B.V

Cyclooctadiene iridium complexes [Cp*Ir(COD)X]+ (X = Cl, Br, I): Synthesis and application for oxidative coupling of benzoic acid with alkynes

The cyclooctadiene iridium complexes [Cp*Ir(COD)X]PF6 ([1a−c]PF6; X = Cl, Br, I) were synthesized by reactions of Cp*Ir(COD) with halogens followed by a counterion exchange. The cyclooctadiene in these complexes is a thermally labile ligand. Complex [1b]PF6 reacts with trimethylphosphite to give [Cp*Ir{P(OMe)3}2Br]PF6 ([2]PF6) as a result of the cyclooctadiene replacement. The refluxing of [1b]PF6 in 1,2-dichloroethane affords the dimeric iodide [Cp*IrI2]2. The structures of [1b]PF6, [2]PF6 and [Cp*IrI2]2 were determined by X-ray diffraction. The Ir–COD bonding in [1a−c]+ and the related non-methylated complexes was analyzed by energy decomposition analysis. In the presence of silver salts, complexes [1a−c]PF6 (at 2.0 mol % loading) catalyze the oxidative coupling of benzoic acid with 1-phenyl-1-propyne in methanol at 60 °C to selectively give 4-methyl-3-phenylisocoumarin (3) or with diphenylacetylene in o-xylene at 160 °C to afford 1,2,3,4-tetraphenylnaphthalene (4). © 2018 Elsevier B.V

A general asymmetric synthesis of artificial aliphatic and perfluoroalkylated α-amino acids by Luche's cross-electrophile coupling reaction

Aliphatic artificial α-amino acids (α-AAs) have attracted great interest in biochemistry and pharmacy. In this context, we developed a promising practical protocol for the asymmetric synthesis of these α-AAs through the selective and efficient intermolecular cross-electrophile coupling of Belokon's chiral dehydroalanine Ni(ii) complex with different alkyl and perfluoroalkyl iodides mediated by a dual Zn/Cu system. The reaction afforded diastereomeric complexes with dr up to 21.3 : 1 in 24-95% yields (19 examples). Exemplarily, three enantiomerically pure aliphatic α-AAs were obtained through acidic decomposition of (S,S)-diastereomers of Ni(ii) complexes. Importantly, the chiral auxiliary ligand (S)-BPB((S)-2-(N-benzylprolyl)aminobenzophenone) was easily recycled by simple filtration after acidic complex decomposition and reused for the synthesis of the initial dehydroalanine Ni(ii) complex. © The Royal Society of Chemistry 2021

(Indenyl)rhodacarboranes. Electronic versus steric effects on the conformation of cyclic ligands

(Indenyl)rhodacarboranes 1,2-R2-3-(η5-indenyl)-3,1,2-RhC2B9H9 (2a: R = H; 2b: R = Me) and 3-(η5-indenyl)-4-SMe-3,1,2-RhC2B9H10 (3) were synthesized by reactions of the iodide complex [(η5-indenyl)RhI2]n (1b) with Tl[Tl(η-7,8-R2-7,8-C2B9H9)] or Tl[9-SMe2-7,8-C2B9H10]. The formation of 3 is accompanied by monodemethylation of the SMe2 substituent. The structures of rhodacarboranes 2b, 3 and the half-sandwich complex (η5-indenyl)RhBr2(dmso) were determined by X-ray diffraction. Rhodacarborane 2b has the sterically unfavorable eclipsed cisoid conformation, in which the bridgehead carbon atoms of the indenyl ligand are arranged close to the carborane cage carbon atoms. The thermal stability of conformers for 2b was analyzed by the DFT calculations. © 2018 Elsevier B.V

Black hybrid iodobismuthate containing linear anionic chains

Three hybrid 1,1′-(1,n-alkanediyl)bis(4-methylpyridinium) iodobismuthates 1-3 were prepared by a facile solution route and showed thermal stability in air up to 230 °C. The structures of solids 1 and 3 contain zero-dimensional anions, and the structure of 2 contains one-dimensional linear anionic chains [BiI5]n 2n-. Photoluminescence (PL) in the spectral range between 600 and 750 nm was observed for 1 and 2. DFT calculations and optical studies confirmed that compounds 1-3 are semiconductors with band gaps of 1.73-2.10 eV, which correspond with their intense black (for 2) or red (for 1 and 3) colors. The optical absorption of 2 in the red spectral range is primarily due to charge transfer from the I5p orbitals at the top of the valence band to the Bi6p orbitals at the bottom of the conduction band. © 2018 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique

CF3-Carbenoid functionalization of N-(pyrimidin-2-yl)indole catalyzed by cobalt complexes: Ligand control of selectivity

The carbonyl cobalt complex Cp*Co(CO)I2 catalyzes carbenoid Co alkylation of N-(pyrimidin-2-yl)indole with methyl 3,3,3-trifluoro-2-diazopropionate regioselectively giving 2-substituted indole, while the N,N’-ligated cations [CpCo(L)I]+ (L = bipy, phen) provide 3-substitution exclusively. The structure of [CpCo(phen)I]PF6 was investigated by X-ray diffraction.[Figure presented] © 201