Developments in the chemistry of tris(hydroxymethyl)phosphine

Tris(hydroxymethyl)phosphine, P(CH₂OH)₃, a water-soluble compound, has been known for about 50 years but development of its coordination chemistry has been slow and relatively recent. During some collaborative studies with a pulp and paper research institute on testing water-soluble catalysts for hydrogenation of lignin in pulp and the unsaturated functionalities in lignin model compounds, with the aim of bleaching pulps, we discovered new, in situ, Ru-P(CH₂OH)₃ hydrogenation catalysts. Interest in the coordination chemistry of this phosphine thus ensued, and this review covers this topic as well as the coordination chemistry of a diphosphine analogue, bis[bis(hydroxymethyl)phosphino]ethane, (HOCH₂)₂P(CH₂)₂P(CH₂OH)₂. The applications of the water-soluble metal complexes of these two phosphines in the areas of catalysis and medicinal drugs are also described. These phosphines, in the absence of metals, were found serendipitously to be effective bleaching agents for pulps (and also brightness stabilizing agents), and some relevant organo-phosphorus chemistry from our group is also briefly presented, particularly because of its possible significance in hydroformylation and hydrogenation processes catalyzed by metal–phosphine complexes.     

Coordination Chemistry of Aluminum,Gallium, and Indium at Transition Metals

The current upswing in the interest in organoelement chemistry of Group 13 metals is attributed not least to the establishment of the coordination chemistry of R_aE fragments (E=Al, Ga, In; a=1, 2) at d-block metals (M). Recently the availability of low-valent organoelement compounds as building blocks for synthesis has substantially enriched the structure chemistry of this class of compounds. The M–E bonding conditions and the question of the significance of M(d_π)-E(p_π) backbonding as well as potential applications in materials science, for example, as single-source precursors for the deposition of thin intermetallic films by chemical vapor deposition, are discussed.     

Cu(OTf)2/NBS Promoted Cyclization of 1-Cinnamyl Alcohol-o-Carboranes: An Efficient Approach for Synthesis of o-Carboranes Substituted Oxetanes

The Cu(OTf)₂/NBS promoted cyclization of 1-cinnamyl alcohol-o-carboranes for synthesis of o-carborane substituted oxetanes has been developed. A series of substituted oxetanes has been synthesized with moderate to good yields, which would be an important synthon for design novel reactions in oxetane chemistry as well as carborane chemistry.     

f-Block Phospholyl and Arsolyl Chemistry

The f-block chemistry of phospholyl and arsolyl ligands, heavier p-block analogues of substituted cyclopentadienyls (Cp^R, C₅R₅) where one or more CR groups are replaced by P or As atoms, is less developed than for lighter isoelectronic C₅R₅ rings. Heterocyclopentadienyl complexes can exhibit properties that complement and contrast with Cp^R chemistry. Given that there has been renewed interest in phospholyl and arsolyl f-block chemistry in the last two decades, coinciding with a renaissance in f-block solution chemistry, a review of this field is timely. Here, the syntheses of all structurally characterised examples of lanthanide and actinide phospholyl and arsolyl complexes to date are covered, including benzannulated derivatives, and together with group 3 complexes for completeness. The physicochemical properties of these complexes are reviewed, with the intention of motivating further research in this field.     

Synthesis of “Clickable” Nano Metal‐organic Framework by Generic Postsynthetic Modification Route

Organic azides have been somewhat popularized due to their pivotal role in the emerging field of “click chemistry”. A simple approach has been used for the synthesis of uniform nano Fe‐MIL‐88B‐NH₂, and a generic postsynthetic modification route has been developed for the synthesis of azide‐modified nano Fe‐MIL‐88B‐N₃. The approach also has been used to synthesize the azide‐modified IRMOF‐3(‐N₃). These new azide‐modified Fe‐MIL‐88B‐N₃ nanocrystals hold promising potential for the applications in the fields of “click chemistry”, nanotechnology devices and nano composite membranes.     

Review of technetium chemistry research conducted at the University of Nevada Las Vegas

The chemistry of technetium is being explored at the University of Nevada Las Vegas. Our goal is to investigate both the applied and fundamental aspects of technetium chemistry, with a special emphasis on synthesis, separations, and materials science. The synthetic chemistry focuses on metal–metal multiple bonding, oxides and halides. Synthesis and characterizations of (n-Bu₄N)₂Tc₂X₈, Tc₂(O₂CCH3)₄X₂ (X = Cl, Br), TcO₂, Bi₂Tc₂O₇, Bi₃TcO₈, TcBr₃ and TcBr₄ have been performed. The applied chemistry is related to the behavior of Tc in the UREX process. Separation of U/Tc has been conducted using anion exchange resin and metallic Tc waste form synthesized and characterized.     

A model for the etching of silicon in SF6/O2 plasmas

A model has been developed to describe the chemistry which occurs in SF₆/O₂ plasmas and the etching of silicon in these plasmas. Emphasis is placed nn the gas-phase free radical reactions, and the predictions n( the model are compared with experimental results. Forty-seven reactions are included, although a subset of 18 reactions describes the chemistry equally well. Agreement between the calculated and measured concentrations of stable products downstream of the plasma is better than a factor of 2. The need for additional kinetic data and fàr well-characterized diagnostic studies of SF₆/O₂ plasmas is discussed.     

Continuous Flow Synthesis of a Zr Magnetic Framework Composite for Post-Combustion CO2 Capture

Metal-organic frameworks (MOFs) have an unprecedented ability to store gas molecules, however energy efficient regeneration remains challenging. Use of magnetic induction to aid this shows promise, but economical synthesis of the requisite composites is unresolved. Continuous flow chemistry has been reported as a rapid and reliable method of MOF synthesis, delivering step-change improvements in space time yields (STY). Here the scalable production of nanomaterials suitable for regeneration by magnetic induction is demonstrated. The zirconium MOF composite, MgFe₂O₄@UiO-66-NH₂ is prepared using continuous flow chemistry resulting in a material of comparable performance to its batch counterpart. Upscaling using flow chemistry gave STY >25 times that of batch synthesis. Magnetic induced regeneration using this mass produced MFC for carbon capture is then demonstrated.     

Unravelling the Complex LiOH-Based Cathode Chemistry in Lithium–Oxygen Batteries**

The LiOH-based cathode chemistry has demonstrated potential for high-energy Li−O₂ batteries. However, the understanding of such complex chemistry remains incomplete. Herein, we use the combined experimental methods with ab initio calculations to study LiOH chemistry. We provide a unified reaction mechanism for LiOH formation during discharge via net 4 e⁻ oxygen reduction, in which Li₂O₂ acts as intermediate in low water-content electrolyte but LiHO₂ as intermediate in high water-content electrolyte. Besides, LiOH decomposes via 1 e⁻ oxidation during charge, generating surface-reactive hydroxyl species that degrade organic electrolytes and generate protons. These protons lead to early removal of LiOH, followed by a new high-potential charge plateau (1 e⁻ water oxidation). At following cycles, these accumulated protons lead to a new high-potential discharge plateau, corresponding to water formation. Our findings shed light on understanding of 4 e⁻ cathode chemistries in metal–air batteries.     

Cationic Bismuth Aminotroponiminates: Charge Controls Redox Properties

The behavior of the redox-active aminotroponiminate (ATI) ligand in the coordination sphere of bismuth has been investigated in neutral and cationic compounds, [Bi(ATI)₃] and [Bi(ATI)₂L_n][A] (L=neutral ligand; n=0, 1; A=counteranion). Their coordination chemistry in solution and in the solid state has been analyzed through (variable-temperature) NMR spectroscopy, line-shape analysis, and single-crystal X-ray diffraction analyses, and their Lewis acidity has been evaluated by using the Gutmann–Beckett method (and modifications thereof). Cyclic voltammetry, in combination with DFT calculations, indicates that switching between ligand- and metal-centered redox events is possible by altering the charge of the compounds from 0 in neutral species to +1 in cationic compounds. This adds important facets to the rich redox chemistry of ATIs and to the redox chemistry of bismuth compounds, which is, so far, largely unexplored.     

Bioorganometallic chemistry of molybdocene dichloride

The study of molybdocene dichloride and related metallocenes has been dominated by their remarkable catalytic properties in organic synthesis and polymer chemistry. Interest in the aqueous, bioorganometallic chemistry of metallocene dihalides has stemmed from the potent antitumor properties of titanocene dichloride, including results from human clinical trials. This review will summarize key results reported in the last decade on the biological chemistry of molybdocene dichloride. The effect of concentration, pH and ionic strength on the rates of hydrolysis of both the cyclopentadienyl and halide ligands have established that the positively charged monoaquated species Cp₂Mo(OH)(OH₂)⁺, in equilibrium with the dipositively charged dimer Cp₂Mo(μ-OH)₂MoCp₂, is present under physiological conditions. Systematic studies of the coordination chemistry of Cp₂MoCl₂ with nucleobases, nucleotides, single-stranded and double-stranded oligonucleotides, and calf-thymus DNA have shown that while simultaneous phosphate(O) and heterocyclic(N) adducts are formed with nucleotides, negligible interaction with DNA occurs under physiological conditions. In contrast, Cp₂MoCl₂ forms strong, non-labile complexes with deprotonated thiols in amino acids. Molybdocene dichloride is able to catalyse the hydrolysis of activated phosphate esters under physiological conditions, but hydrolysis of unactivated phosphodiesters is only significant at pH 4. Limited antitumor activity results, inhibition studies with protein kinase C and topoisomerase II, structure-activity and cell-uptake studies have provided some insight into possible mechanisms of antitumor action.     

Tritiated ethylene as precursor of a free vinyl cation.

A method for the partial hydrogenation of alkynes has been optimized for the synthesis of carrier-free politritiated ethylene. This molecule provides access to the chemistry of the free C₂H₃⁺ ion in both gaseous and condensed phase.     

Singlet Oxygen during Cycling of the Aprotic Sodium–O2 Battery

Aprotic sodium–O₂ batteries require the reversible formation/dissolution of sodium superoxide (NaO₂) on cycling. Poor cycle life has been associated with parasitic chemistry caused by the reactivity of electrolyte and electrode with NaO₂, a strong nucleophile and base. Its reactivity can, however, not consistently explain the side reactions and irreversibility. Herein we show that singlet oxygen (¹O₂) forms at all stages of cycling and that it is a main driver for parasitic chemistry. It was detected in‐ and ex‐situ via a ¹O₂ trap that selectively and rapidly forms a stable adduct with ¹O₂. The ¹O₂ formation mechanism involves proton‐mediated superoxide disproportionation on discharge, rest, and charge below ca. 3.3 V, and direct electrochemical ¹O₂ evolution above ca. 3.3 V. Trace water, which is needed for high capacities also drives parasitic chemistry. Controlling the highly reactive singlet oxygen is thus crucial for achieving highly reversible cell operation.     

Peptide β-Bend and 3 10 -Helix: from 3D-Structural Studies to Applications as Templates

The 3 ₁₀-helix is a relatively common secondary structure motif in peptides and proteins. Its building block is one of various types of β-bend conformation which comprises an N ^α-acylated dipeptide alkylamide system. A complete 3D-structural characterization of this ternary helix has been achieved, thus allowing its unambiguous discrimination from the closely related α-helix. Recent applications of rigidified peptide β-bends and 3 ₁₀-helices as templates for investigations in synthetic organic chemistry (macrocyclization, catalysis), host–guest chemistry (molecular recognition), and physical chemistry (donor–acceptor interaction) will be discussed.     

New Reactivity of the Uranyl(VI) Ion

The chemistry of the uranyl ion ([UO₂]²⁺) has evolved remarkably over the past few years, with unexpected reactivity observed that challenge our understanding of this ion, and of actinides in general. This review highlights some recent advances in the field, focussing on the organometallic chemistry of the uranyl moiety, which is not well developed in comparison to lower oxidation states of uranium. The use of uranyl as a catalyst is highlighted and the newly developed supramolecular chemistry is described. The uranyl oxygen atoms have been considered as inert, but recent work has shown that is not necessarily the case and is discussed herein. Finally, reduction to the [UO₂]⁺ ion will be discussed.     

Dodecacarbonyltriruthenium

Since the pioneering work of Mond and his coworkers the metal carbonyls and their derivatives have been under active study, and, as in other areas of inorganic chemistry, research activity has greatly increased in the last twenty years. Whereas hitherto our knowledge of the carbonyls of the heavier transition metals has been seriously hampered by a lack of good methods of synthesis, new preparative methods have recently been developed for Ru₃(CO)₁₂, and many new ruthenium carbonyl complexes are being discovered as its chemistry is explored.     

铜催化芳香醛和酮的氢硼化转化合成苄基硼酸酯类化合物（英文）

有机硼化合物广泛应用于合成化学、药物化学以及材料化学等领域,开发新颖实用的方法合成有机硼化合物是重要的研究领域.在各种有机硼化合物中,苄基硼酸酯有着一些特有的性质,例如活性相对较高,可以有效地当作苄基化试剂使用.目前已有多种合成苄基硼酸酯的方法,主要集中在苄基格氏试剂或者锂试剂的硼化反应,但是该方法底物兼容性较差,而且苄基格氏试剂或者锂试剂的制备比较困难.随着催化反应的发展,过渡金属(如Pd,Cu,Ni,Fe)催化苄基卤代物的硼化反应及芳基卤代物和1,1-二硼类化合物的偶联反应能够有效地合成这类化合物.一级苄醇在钯或铜的催化作用下也可以转化为苄基硼酸酯.苄基C–H键的催化硼化是潜在的构建苄基硼酸酯的高原子经济性的方法,但目前其选择性和反应活性仍不高.在无金属催化的条件下,对甲苯磺酰腙类化合物与HBpin或B_(2pin_2)发生1,2-金属迁移是合成苄基硼酸酯的有效方法.到目前为止,虽然有很多种合成苄基硼酸酯的方法,但仍无法满足其合成需求,因此开发新型的方法合成苄基硼酸酯具有重要的意义.本文开发了一种新型的铜催化芳香醛/酮类化合物的脱氧氢硼化转化体系.使用廉价易得的铜作为催化剂,叔丁醇钠或者叔丁醇钾作为碱,醇质子作为氢源,在100℃的条件下,芳香醛和芳香酮可直接转化成一级和二级苄基硼酸酯类化合物,该反应操作简单,反应体系可以兼容多种官能团,分离产率在21%–77%之间.反应机理方面,该转化有两种可能的过程,(1)反应体系中首先生成1,1-偕二硼化合物,该化合物在碱和EtOH的作用下发生脱硼质子解,最终转化成苄基单硼化合物;(2)醇质子转化成负氢物种,并与体系中的冄-OBpin硼酸酯生成四配位硼,发生1,2-迁移后得到目标产物.为了验证上述两种反应途径的可行性,我们进行了一系列的控制试验.首先合成了苯乙酮的1,1-二硼化合物,在催化量碱与当量醇的作用下,以99%的收率得到了脱硼质子解的产物,说明1,1-二硼化合物可以在反应体系中转化成苄基单硼化合物.以苯甲醛作为原料合成了冄-OBpin硼酸酯,首先将其投入到甲醇、叔丁醇钠和B_(2pin_2)的体系中,最终得到了47%的苄基单硼;同时将冄-OBpin硼酸酯投入到HBpin与叔丁醇钠的体系中,得到了57%的苄基单硼化合物,说明第二种反应过程通过1,2-迁移得到目标产物也是可行的.在当前的实验条件下,两种反应路径都是可能的.     

Review: the multicolored coordination chemistry of violurate anions

This review provides a comprehensive overview on the coordination chemistry of violuric acid, C₄H₃N₃O₄ (= H₃Vio), and its derivatives (e.g. 1,3-diorganovioluric acids and thiovioluric acid). The most remarkable property of these colorless compounds is the formation of brightly colored (pantochromic/polychromic) salts with colorless cations such as alkali metal and alkaline earth metal ions and organoammonium ions. These magnificent colors have fascinated chemists for more than a century. Only in recent years it has been fully recognized that the structural chemistry of violurates is rather interesting and diverse. Violurate anions are excellent building blocks for new supramolecular assemblies in the crystalline state. Various organoammonium violurates and transition metal violurate complexes have been structurally characterized through single-crystal X-ray diffraction. Highly characteristic for these structures is the formation of 1D, 2D, or 3D hydrogen-bonded assemblies in the crystalline state. This review provides a comprehensive overview on the multicolored coordination chemistry of violurate anions, with the focus being on structurally characterized species.