Synthesis of Rh(I) diamine complexes and their exploitation for asymmetric hydrogen transfer processes

In this paper, we report the synthesis and characterisation of two novel chiral diamine ligands and three new Rh(I) complexes. The diamine ligands were prepared by reducing the Schiff base precursors using NaBH₄. Unusually, when ligand 2 was recrystallised in a methanol:acetone solution (10:1) a five membered imidazolidine ring was formed, as confirmed by X-ray crystallography, multinuclear NMR spectroscopy and mass spectrometry. The Rh(I) cationic complexes were prepared in high yields and purities and these have been exploited for the asymmetric reduction of acetophenone to 1-phenylethanol. Modest conversions (up to 88%) and enantioselectivities (up to 50%) have been achieved.     

SINGLET-TRIPLET SPIN TRANSITION IN AN IRON(II) COMPLEX OF 1,10-PHENANTHROLINE-2-CARBOTHIOAMIDE

Abstract

The ⁵⁷Fe Mössbauer effect for the solid complex FeLCl₂·H₂O (L=10-phenanthroline-2-carbothioamide) has been studied between 4.2°K and 298°K. Two overlapping doublets (I and II) are observed, their relative intensity being strongly temperature dependent. The doublets are characterized by δE_Q(I)=0.53 mm sec^?1, δ^IS(I)=+ 0.22 mm sec^?1 and δE_Q(II)=1.33 mm sec^?1, δ^IS(II)=+0.23 mm sec^?1 at 4.2°K. In conjunction with magnetic data, the Mössbauer spectra are interpreted in terms of a singlet-triplet spin transition of the central iron(II) ion. In an applied magnetic field at 4.2°K, H_int=0, V_ZZ(I)>0, and V_ZZ(II)>0. The results are consistent with optical electronic and infrared vibrational spectra.     

Rh(I) Complexes in Catalysis: A Five-Year Trend

Rhodium is one of the most used metals in catalysis both in laboratory reactions and industrial processes. Despite the extensive exploration on “classical” ligands carried out during the past decades in the field of rhodium-catalyzed reactions, such as phosphines, and other common types of ligands including N-heterocyclic carbenes, ferrocenes, cyclopentadienyl anion and pentamethylcyclopentadienyl derivatives, etc., there is still lively research activity on this topic, with considerable efforts being made toward the synthesis of new preformed rhodium catalysts that can be both efficient and selective. Although the “golden age” of homogeneous catalysis might seem over, there is still plenty of room for improvement, especially from the point of view of a more sustainable chemistry. In this review, temporally restricted to the analysis of literature during the past five years (2015–2020), the latest findings and trends in the synthesis and applications of Rh(I) complexes to catalysis will be presented. From the analysis of the most recent literature, it seems clear that rhodium-catalyzed processes still represent a stimulating challenge for the metalloorganic chemist that is far from being over.     

聚甲基异丙烯基酮和聚异亚丙基丙酮的不对称硅氢化反应

光活性高分子的合成具有重要意义，它在生物活性高分子、用于不对称合成的高分子试剂或催化剂以及不对称选择性色谱柱填料等领域具有潜在的应用价值．研究表明，不对称选择性聚合反应难以获得高光学活性的高分子［１］，而手性过渡金属络合物催化的高分子不对称反应是获得...     

Asymmetric multicomponent copper catalyzed synthesis of chiral propargylamines

A three-component stereoselective reaction between an aldehyde, an amine and phenylacetylene to afford optically active propargyl amines in good yields was developed. The reaction is catalysed by copper complexes of enantiomerically pure bis-imines. The best results were obtained with imines readily prepared in very high yields from the commercially available binaphtyl diamine.

A very simple experimental procedure at room temperature allowed to obtain optically active propargyl amines in very good yields and enantioselectivity up to 75%. The extremely simple methodology and the mild reaction conditions, as well as the possibility of a modular approach for developing new and more efficient bis-imine-based chiral ligands make the present methodology very attractive.     

含氮给体的手性膦配体及其不对称催化的研究进展

本文就近年来所出现的含氮给体的手性膦配体及其不对称催化反应的研究进展进行了较为详细的评述。     

THE CRYSTALLOGRAPHIC STRUCTURE OF THE PHOTOOXIDIZED PRODUCT OF HYPOCRELLIN A AND THE STUDY OF THE PHOTODYNAMIC ACTION MECHANISM

In attempting to study the phototherapeutic action and the photosensitized oxygenation mechanism, we have determined the crystal structure of the main oxidized product of hypocrellin A (HA). It was crystallized in monoclinic system with space group P2_1. The cell data are: a=10.030(3), b=8.877(3), c=15.764(5), β=104.50(2)°, Z=2. The crystal structure has been determined by direct method and refined to a final R of 0.055 based on the 1408 observed reflections with l>2.5σ(Ⅰ). The photooxidized product is composed of a heptacyclic aliphatic hydrocarbon connecting with two α-naphthoquinone derivatives as its skeletal molecule. No peroxidic linkage has been found. On the basis of the crystal structure determined, we have deduced part of the process of formation of the oxide, ⅰ. e. firstly, the peroxide was formed by photocycloaddition of oxygen molecule to Hypocrellin A, then thermodissociation took place to form a stable oxide.     

活性炭表面含氧基团的生成及对NO的还原作用

活性炭表面含氧基团的生成及对ＮＯ的还原作用＊高志明杨向光吴越＊＊（中国科学院长春应用化学研究所，长春１３００２２）关键词活性炭，一氧化氮，氧化铜，还原，氧化近几年，随着环保研究的开展，活性炭被用于同时脱硫脱硝反应［１］．活性炭的表面化学性质就成为需要...     

NO与Ag(110)表面的相互作用

采用Ｘ射线光电子能谱、紫外光电子能谱和原位Ｒａｍａｎ光谱研究了ＮＯ和Ｏ２在Ａｇ（１１０）表面的吸附和反应。结果表明，室温条件下，ＮＯ在银表面不发生明显的吸附和分解，氧的加入导致了ＮＯ在角表面的氧化反应生成吸附态的氮氧化物和原子态氧。     

FEATURES OF A FLEXIBLE BACKBONE IN THE COORDINATION COMPOUNDS OF A DIOXIME LIGAND: THE CHARACTERIZATION OF SUPRAMOLECULAR AND DINUCLEAR METAL COMPLEXES

Abstract

The grinding of a 2: 1 molar ratio mixture of isonitrosoacetylacetone and 1,3-diaminopropan-2-ol led to formation of the tribasic ligand (H₃L), (1) with two oxime groups and a flexible alcoholic backbone. The 1:2 molar ratio reaction of (1) with CuX₂ produced the planar dinuclear complexes LCu₂(X) nH₂O; × = acetate (2), phenylacetate (3), formate (4), monochloroacetate (5), dichloroacetate (6), trichloroacetate (7), benzoate (8), and p-hydroxybenzoate (9); n = 1 for (2) and (8); n = 2 for (3)-(7); and n = 4 for (9). The copper(II) ions are bridged by the carbox-ylate and the alcoholic oxygen. The strong antiferromagnetic interactions in (2)-(9) are impeded in (5)-(7) by the chloroacetate bridge withdrawing electron density from the carboxylate. The latter bridge is replaced by picrate in the 1:1 molar ratio reaction of (2) with picric acid (10). The 1:1 molar ratio reaction of (1) with copper(II) acetate produced the tetranuclear [HLCu]₂[LCu₂(OAc)] 5H₂O (11), whereas the 2:1 molar ratio reaction, similar to the reaction which led to (8), produced HLCu (12). The latter complex reacted (1:1 molar ratio) with either copper(ll) acetate or nickel(II) acetate to produce complexes (2) and the heterodinuclear LNi-Cu(OAc) 2H₂O (13), respectively. Similar reactions with (11) gave the same complexes (2) and (13). The acid adducts of (9) with p-hydroxybenzoic acid (14) and LCu₂(X)-HX (15); × = p-aminobenzoic acid were isolated. The cobalt(II) analogue of the mononuclear (12), HLCo 2H₂O (16) was obtained from the 1:1 molar reaction of (1) with cobalt(II) acetate. The supramolecular structure of (11), (12) and (16) took place via intermolecular hydrogen bonding of the alcoholic proton with the oximato oxygen of the adjacent molecule which mediated electron density and allowed for a magnetic exchange interaction. The suggested structures of the ligand and metal complexes are in accordance with analytical, spectral and magnetic moment data.     

THE INTERACTIONS BETWEEN PERIPHERAL AND CENTRAL UNITS IN SUPRAMOLECULAR AND METALLOSUPRAMOLECULAR STRUCTURES: THE CHARACTERIZATION OF SOME MONO-, DI- AND TRINUCLEAR COMPLEXES OF A VICINAL OXIME-IMINE LIGAND

Abstract

The 1:1 molar ratio reaction of p-phenylenediamine with isonitrosoacetylacetone in chloroform led to the formation of the half unit ligand (HL); (1). Two types of the trans octahedral (L)₂Ni 2H₂O complex were characterized; the green molecular complex (2) and the associated supramolecular dark brown complex (3). Molecular association in (3) took place via inter-molecular hydrogen bonding between the amino group of a molecule and the oxygen sites of an adjacent molecule. The 1:1 molar ratio reactions of (2) with the metal acetates M(OAc)₂ (M = divalent nickel, copper or cobalt) produced the self-assembly structure (4) whereby the metal acetate is coordinated to the amino groups of the nickel(II) complex. Reaction of the dinuclear (4) with another metal acetate (1:1 molar ratio) gave the trinuclear terminated structure (5). Similar reactions of (3) with nickel acetate (1:1 or 1:2) led to formation of complexes with metallosupramolecular structures. An antiferromagnetic interaction between the peripheral and central paramagnetic units was observed from those complexes with copper(II) at the peripheral location. In all these cases the metal ions are bridged via the aromatic Schiff-base moiety. The suggested structures of the mono-, di- and trinuclear coordination compounds are in accordance with the analytical, spectral and magnetic moment data.     

A molecular mechanics force field for rhodium(I) carbonyl phosphine complexes and its application on the oxidative addition reactions of these complexes

The main purpose of the development of an Rh(I) Carbonyl Phosphine force field was to predict the molecular structure of Rh(I) complexes as well as to compute possible intermediates or transition states during the oxidative addition of CH₃I to these complexes. © 2000 John Wiley & Sons, Inc. J Comput Chem 21: 692–703, 2000     

Homogeneous and heterogeneous asymmetric reactions. Part IX. Asymmetric transfer hydrogenation of 16-methyl-substituted steroid 17-ketones in the presence of rhodium(I) complexes

Chiral transfer hydrogenation of 16 methyl-substituted steroid 17-ketones in the presence of rhodium(I) complexes by hydrosilylation is described. During the preparation of the complex catalysts a wide variety of bidentate phosphines were used including chiral ligands, as well. The diastereoselectivity of the reduction depends strongly on the structure of the ligands. The method applied produces the hydroxy steroid products with excellent yield under very mild reaction conditions. Additionally, the procedure makes possible the preparation of 17α-OH isomers beside the easily synthesizable 17β-OH products. Part. VIII: B. T?r?k, K. Felf?ldi, G. Szakonyi, K. Balázsik and M. Bartók: Enantiodifferentiation in Asymmetric Sonochemical Hydrogenations, Catal. Letters (in press)     

NO和O2在Pt(110)面上吸附的TDS和PEEM研究

采用热脱附和光电子发射普微镜研究了Ｏ２和ＮＯ在Ｐｔ（１１０）面上的吸附和共吸附。结果表明，室温条件下，ＮＯ在Ｐｔ（１１０）面上有端式和桥式两种不同的吸附方式。Ｐｔ（１１０）表面预吸附的原子态氧占据了ＮＯ进入了桥式吸附的活性粒，从而阻遏了ＮＯ在Ｐｔ表面发生解离反应必须经过的桥式吸附中间态的形式，进而降低了ＮＯ在Ｐｔ表面直接分散的能力。     

STUDIES ON ORGANOPHOSPHORUS COMPOUNDS PART IX.1 THE ACTION OF Di-, TRIALKYL PHOSPHITES AND THIOL ACIDS ON SOME ENAMINOLACTONES

Abstract

Di-, and trimethylphosphites react with enaminolactone, 4, only in methanol to give N-benzoyl-3-phenyl-3-phosphonoalanine-trimethylester (7) in good yields. Diphenylphosphinodithioic acid also reacts with 4 to give N-benzoyl-3-phenylcysteine-methyl ester-diphenylphosphinodithioate (9). A mechanism is proposed to account for the formation of 7. Compatible analytical and spectroscopic results were obtained for the new compounds.     

吡啶与Rh(111)面相互作用的EHMO研究

吡啶作为加氢脱氮的模型化合物,与过渡金属Pt(111),Ni(100),Pd(110,111),Mo(110),Rh(111)面的吸附作用已有大量的实验研究,所采用的技术基本上是LEED,TDS,XPS,HREELS等,然而吡啶与Rh(111)面作用的理论研究尚未见报道.本文用EHMO法研究了吡啶与Rh(111)面的吸附作用,得到了最优吸附构型、结合能、集居数以及电荷分布和转移等,为新的脱氮催化剂开发提供了理论依据. 计算采用EHMO法,其中非对角矩阵元采用MWH近似:     

THE SYNTHESIS AND CHARACTERIZATION OF A NOVEL vic-DIOXIME AND ITS MONO AND TRINUCLEAR COMPLEXES CARRYING A TRIOXADITHIA MACROCYCLE

Abstract

A new vicinal dioxime, l,15-bis(hydroxyimino)-2,14-dithia-5,8,11-trioxacyclopentadecane (H₂L) was synthesized by the reaction of (E,E)-dichloroglyoxime (1) with 1,11-dithio-3.6.9-trioxaundecane (2). Mononuclear copper(II) complexes with a metal/ligand ratio of 1/2 were prepared. The two ligands coordinate to copper(II) through the deprotonated oximate oxygens which then afford the trinuclear structure bridged by the oximate groups with 1,10-phenan-throline or 2,2′-dipyridyl as the end-cap ligand.