Ru(III), Cr(III), Fe(III) complexes of Schiff base ligands bearing phenoxy Groups: Application as catalysts in the synthesis of vitamin K3

Two polydentade Schiff base ligands and their Ru(III), Cr(III) and Fe(III) complexes were synthesized and characterized by elemental analysis (C, H, N), UV/Vis, FT IR, ¹H and ¹³C NMR, LC–MS/MS, molar conductivity and magnetic susceptibility techniques. The absorption bands in the electronic spectra and magnetic moment measurements verified an octahedral environment around the metal ions in the complexes. The thermal stabilities were investigated using TGA. The synthesized complexes were used in the catalytic oxidation of 2-methyl naphthalene (2MN) to 2-methyl-1,4-naphthoquinone; vitamin K₃, menadione, 2MNQ; using hydrogen peroxide, acetic acid and sulfuric acid. L₁-Fe(III) complex showed very efficient catalytic activity with 58.54% selectivity in the conversions of 79.11%.     

Transition‐Metal π‐Ligation of a Tetrahalodiborane

The reaction of tetraiododiborane (B₂I₄) with trans‐[Pt(BI₂)I(PCy₃)₂] gives rise to the diplatinum(II) complex [{(Cy₃P)(I₂B)Pt}₂(μ₂:η³:η³‐B₂I₄)], which is supported by a bridging diboranyl dianion ligand [B₂I₄]^2?. This complex is the first transition‐metal complex of a diboranyl dianion, as well as the first example of intact coordination of a B₂X₄ (X=halide) unit of any type to a metal center.     

Palladium‐Catalyzed Intermolecular Acylation of Aryl Diazoesters with ortho‐Bromobenzaldehydes

In this work, we describe a palladium‐catalyzed intermolecular O acylation of α‐diazoesters with ortho‐bromobenzaldehydes. The C(sp²)?H bond activation of the aldehyde is enabled by migratory insertion of a palladium carbene intermediate. The diazoesters act as modular three‐atom units to build up key seven‐membered palladacycles, which are transformed into a variety of isocoumarin derivatives upon reductive elimination. Mechanistic experiments and DFT calculations provide insight into the reaction pathway.     

Selective C−H Halogenation with a Highly Fluorinated Manganese Porphyrin

The selective C?H functionalization of aliphatic molecules remains a challenge in organic synthesis. While radical chain halogenation reactions provide efficient access to many halogenated molecules, the use of typical protocols for the selective halogenation of electron‐deficient and strained aliphatic molecules is rare. Herein, we report selective C?H chlorination and fluorination reactions promoted by an electron‐deficient manganese pentafluorophenyl porphyrin catalyst, Mn(TPFPP)Cl. This catalyst displays superior properties for the aliphatic halogenation of recalcitrant, electron‐deficient, and strained substrates with unique regio‐ and stereoselectivity. UV/Vis analysis during the course of the reaction indicated that an oxo‐Mn^V species is responsible for hydrogen‐atom abstraction. The observed stereoselectivity results from steric interactions between the bulky porphyrin ligand and the intermediate substrate radical in the halogen rebound step.     

Y沸石和多级孔Y沸石封装CuPhen配合物催化性能的比较

选用常规Y沸石和经后处理法制备的多级孔Y沸石为主体,采用自由配体法将铜菲咯啉(CuPhen)配合物封装在不同Y沸石中,制备了CuPhen/Y复合催化材料。采用X射线衍射、TEM、紫外-可见光谱、N_2吸附-脱附、ICP和TG等手段对所制备复合催化材料的物化性质进行了较为详细的表征,并对封装在不同Y沸石主体中的铜配合物在不同尺寸大小反应底物中的催化氧化性能进行了比较研究。结果表明,在以双氧水为氧化剂的反应体系中,封装于多级孔Y沸石中的铜配合物在不同环烷烃氧化反应中的催化活性均高于封装在常规Y沸石中的催化活性,体现出多级孔Y沸石更为优越的主体性能。此外,同封装于常规Y沸石中的铜配合物一样,封装在多级孔Y沸石主体中的金属配合物催化剂也具有良好的稳定性。     

Synthesis and Characterization of Heteroleptic Ru(II) Complexes Based on 4,4′‐Bis((E)‐styryl)‐2,2′‐bipyridine as Ancillary Ligand and Application for Dye‐Sensitized Solar Cells

Heteroleptic Ru(II) complexes were designed based on 4,4′‐bis((E)‐styryl)‐2,2′‐bipyridine (bsbpy) as an ancillary ligand for dye‐sensitized solar cells (DSSCs), and those Ru(II) sensitizers, [Ru(L)(bsbpy)(NCS)₂][TBA] (TBA; tetrabutylammonium), were synthesized according to a typical one‐pot reaction of [RuCl₂(p‐cymene)]₂ with the corresponding anchoring ligands (where L = 4,4′‐dicarboxy‐2,2′‐bipyridine (dcbpy), 4,4′‐bis((E)‐carboxyvinyl)‐2,2′‐bipyridine (dcvbpy), 4,7‐dicarboxy‐1,10‐phenanthroline (dcphen), or 4,7‐bis((E)‐carboxyvinyl)‐1,10‐phenanthroline (dcvphen)). The new Ru(II) dyes, [Ru(L)(bsbpy)(NCS)₂][TBA] that incorporated vinyl spacer(s) into ancillary and/or anchoring ligand displayed red‐shifted bands over the overall UV/VIS region relative to the absorption spectra of N719 . A combination of bsbpy ancillary and dcphen anchoring ligand showed the best result for the overall power conversion efficiency (η); i.e., a DSSC fabricated with [Ru(dcphen)(bsbpy)(NCS)₂][TBA] exhibited a power conversion efficiency (η) of 2.98% (compare to N719 , 4.82%).     

Cationic ruthenium complex of the formula [RuCl(2,6-diacetylpyridine)(PPh3)2]BArF and its catalytic activity in the formation of enol esters

A new ruthenium 2,6-diacetylpyridine complex was synthesized and applied in the atom-economic synthesis of enol esters through Markovnikov-directed addition of carboxylic acids to terminal alkynes. The ruthenium complex [RuCl(dap)(PPh₃)₂]⁺BArF^? was synthesized from [RuCl₂(PPh₃)₂] and the corresponding ligand 2,6-diacetylpyridine (dap). The complex was characterized structurally. The new ruthenium complex was utilized under ambient conditions as a catalyst in the Markovnikov addition of carboxylic acids to terminal alkynes to afford the corresponding enol esters in 93% to 52% isolated yields (85?°C, 16?h reaction time, 1?mol% catalyst loading).     

Recent topics on catalytic transformations of aromatic molecules via η6-arene transition metal complexes

The π-complexation of an arene to a transition metal center delivers many useful reactivities to the arene moiety. Although synthetic methodologies that take advantage of such π-coordination have mostly been developed as stoichiometric processes, there have been considerable recent advances in the catalytic transformations of aromatic molecules through their activation in the form of transition metal η⁶-arene complexes. These advances include the π-coordination catalyzed transformations of aryl-heteroatom and side-chain CH and CC bonds and the palladium-catalyzed CH functionalization in pre-formed transition metal η⁶-arene complexes. This digest paper aims to provide a concise view of these recent advances in the area of transition metal η⁶-arene complexes.     

Atrane complexes chemistry as a tool for obtaining trimodal UVM-7-like porous silica

Abstract

The use of atrane complexes as hydrolytic precursors enables the homogeneous incorporation of manganese (25 ≤ Si/Mn ≤ 48) throughout the porous walls of the nanoparticles of a surfactant-templated bimodal mesoporous silica (UVM-7). The subsequent leaching of the manganese nanodomains allows adding controlled microporosity to the host silica framework. The resulting final silica material presents three pore systems structured at different length scales: interparticle textural-type macroporosity (ca. 43.2 nm), ordered intraparticle mesoporosity (ca. 2.63 nm; after template removal), and well-dispersed microporosity (< 2 nm; as consequence of the lixiviation of the Mn-rich domains). The good dispersion of the guest element (Mn) in the silica intermediate provided by the atrane route is responsible for the disordered but regular microporosity achieved.