Development Of Organometallic Chemistry Research Articles

200 Years of Lithium and 100 Years of Organolithium Chemistry

The element lithium has been discovered 200 years ago. Due to its unique properties it has emerged to play a vital role in industry, esp. for energy storage, and lithium‐based products and processes support sustainable technological developments. In addition to the many uses of lithium in its inorganic forms, lithium has a rich organometallic chemistry. The development of organometallic chemistry has been hindered by synthetic problems from the start. When Wilhelm Schlenk developed the basic principles to handle and synthesize air‐ and moisture‐sensitive compounds, the road was open to further developments. After more information was available about the stability and solubility of such compounds, they started to play an essential role in other fields of chemistry as alkyl or aryl transfer reagents.

Tutorial on the Role of Cyclopentadienyl Ligands in the Discovery of Molecular Complexes of the Rare-Earth and Actinide Metals in New Oxidation States

A fundamental aspect of any element is the range of oxidation states accessible for useful chemistry. This tutorial describes the recent expansion of the number of oxidation states available to the rare-earth and actinide metals in molecular complexes that has resulted through organometallic chemistry involving the cyclopentadienyl ligand. These discoveries demonstrate that the cyclopentadienyl ligand, which has been a key component in the development of organometallic chemistry since the seminal discovery of ferrocene in the 1950s, continues to contribute to the advancement of science. Background information on the rare-earth and actinide elements is presented, as well as the sequence of events that led to these unexpected developments in the oxidation state chemistry of these metals.

Charging up the iron in ferrocene salts

Organometallics Ferrocene is the archetype of the sandwich compounds, so called because a metal atom is inserted between two carbon rings. The elucidation of ferrocene's structure was pivotal to the development of organometallic chemistry during the mid-20th century. The ease with which the iron in the center of the molecule can toggle between the +2 and +3 oxidation states has made the compound a common electrochemical standard. Malischewski et al. report the synthesis and isolation of ferrocene salts with iron in the +4 state, which they characterize crystallographically and spectroscopically. Science , this issue p. [678][1] [1]: /lookup/doi/10.1126/science.aaf6362

Covalency Trends in Group IV Metallocene Dichlorides. Chlorine K-Edge X-Ray Absorption Spectroscopy and Time Dependent-Density Functional Theory

For 3-5d transition-metal ions, the (C5R5)2MCl2 (R = H, Me for M = Ti, Zr, Hf) bent metallocenes represent a series of compounds that have been central in the development of organometallic chemistry and homogeneous catalysis. Here, we evaluate how changes in the principal quantum number for the group IV (C5H5)2MCl2 (M = Ti, Zr, Hf; 1- 3, respectively) complexes affects the covalency of M-Cl bonds through application of Cl K-edge X-ray Absorption Spectroscopy (XAS). Spectra were recorded on solid samples dispersed as a thin film and encapsulated in polystyrene matrices to reliably minimize problems associated with X-ray self-absorption. The data show that XAS pre-edge intensities can be quantitatively reproduced when analytes are encapsulated in polystyrene. Cl K-edge XAS data show that covalency in M-Cl bonding changes in the order Ti > Zr > Hf and demonstrates that covalency slightly decreases with increasing principal quantum number in 1-3. The percent Cl 3p character was experimentally determined to be 26, 23, and 18% per M-Cl bond in the thin-film samples for 1-3 respectively and was indistinguishable from the polystyrene samples, which analyzed as 25, 25, and 19% for 1-3, respectively. To aid in interpretation of Cl K-edge XAS, 1-3 were also analyzed by ground-state and time-dependent density functional theory (TD-DFT) calculations. The calculated spectra and percent chlorine character are in close agreement with the experimental observations, and show 20, 18, and 17% Cl 3p character per M-Cl bond for 1-3, respectively. Polystyrene matrix encapsulation affords a convenient method to safely contain radioactive samples to extend our studies to include actinide elements, where both 5f and 6d orbitals are expected to play a role in M-Cl bonding and where transition assignments must rely on accurate theoretical calculations.

Investigations on Butterfly Fe/S Cluster S‐Centered Anions (μ‐S‐)2Fe2(CO)6, (μ‐S‐)(μ‐RS)Fe2(CO)6, and Related Species

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Investigations on Butterfly Fe/S Cluster S-Centered Anions (μ-S-)2Fe2(CO)6, (μ-S-)(μ-RS)Fe2(CO)6, and Related Species

This Account describes the formation and chemical reactivities of the novel butterfly Fe/S cluster anions (mu-S(-))(2)Fe(2)(CO)(6) (I), (mu-S(-))(mu-RS)Fe(2)(CO)(6) (II), (mu-S(-))(mu-RS)[Fe(2)(CO)(6)](2)(mu(4)-S) (III), (mu-S(-))(mu-RS)[Fe(2)(CO)(6)](3)(mu(4)-S)(2) (IV), and {(mu-S(-))(mu(4)-S)[Fe(2)(CO)(6)](2)}(2)(mu-SZS-mu) (V). It also gives a description of the novel structures, unique properties, and wide applications of the corresponding butterfly Fe/S cluster complexes produced from these anions. Anions I-V along with their products are important in the development of organometallic chemistry, cluster chemistry, catalysis, and material and life sciences.

Henry Gilman: American Pioneer in the Rise of Organometallic Chemistry in Modern Science and Technology

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Henry Gilman: American Pioneer in the Rise of Organometallic Chemistry in Modern Science and Technology

The growth and development of organometallic chemistry from an esoteric, well-nigh alchemical art into a completely integrated and essential part of both current organic chemistry and inorganic chemistry have occurred with escalating rapidity over the last 150 years. The sesquicentennial history of organometallic chemistry falls rather naturally into three 50-year periods, each of which began with far-reaching discoveries: (1) the discovery of zinc alkyls by Frankland in 1849 and the use of such alkyls to prepare alkyls of other metals; (2) the discovery of organomagnesium halides by Grignard in 1900 and their many reactions with organic compounds; and (3) the dual discoveries of the existence and structure of ferrocene by Pauson and Miller in 1951 and of the polymerization of olefins by Ziegler and Natta in 1952−1953. The marked burgeoning of organometallic chemistry after World War I is traced to an international group of young pioneers launching their careers with high hope and vigor: Gilman, Kharasch, Ziegler, Wittig, Kipping, Pope, Grignard and his school, Nesmeyanov, and Razuvaev. The thesis of this historical review is that Henry Gilman, through the breadth and depth of his numerous, original contributions on covalent, σ-bonded organometallics, is the one pioneer of this group who has integrated and systematized the great lode of empirical observations on organometallics into correlations with the metal's position in a Mendeleevian periodic table. He has thereby transformed this field from alchemical art into chemical science. In support of this thesis of Henry Gilman as the prototypical pioneer of modern organometallic chemistry, this account traces his academic career at Iowa State and points out his scientific contributions made at successive stages: (1) his studies of the Grignard reagents, which did much to make their preparation convenient and reliable and their reactions of broad and useful scope; (2) his investigations of organolithium reagents and his discovery and key development of the lithium−hydrogen and lithium−halogen exchange processes, which reactions were studied independently by Karl Ziegler and by Georg Wittig but merit being termed the Gilman lithium−hydrogen exchange and the Gilman−Wittig lithium−halogen exchange reactions, respectively; (3) the preparation and reactions of many other organometallics, obtained by the transmetalation reaction of the appropriate metal salts with a magnesium or lithium organometallic; and (4) finally the preparation, structure, and chemical reactivity of diverse organometallics of group 14, especially those with metal−metal and metal−alkali metal bonds. It can be argued with great cogency that such a lifetime of research set the stage and drew the curtail for the dawn of the third era of organometallic chemistry: the discovery and utility of π-bonded organometallics. Because of Gilman's towering role in uncovering, developing, and systematizing the chemistry of σ-bonded organometallics, many of Gilman's colleagues and former students had thought him deserving of chemistry's highest honor.

Determination of kinetic parameters of 1,1′-diacylferrocene at a gold microdisc electrode

Ferrocene and its derivatives have been widely studied by various physical methods because of their key role in the stimulation of the development of organometallic chemistry and material science [1-6]. They are valuable in organic and organometallic syntheses, for example in asymmetric synthesis, catalytic hydrogenation peptide synthesis etc.. They are also potential aids to the understanding of biological electron transfer and the design of molecular electronic devices. Their redox potential and kinetic parameters are helpful for selecting d o n o r / a c c e p t o r couples for the establishment of biomimetic membrane system. However, the absence of straightforward and reliable procedures for the determination of kinetics of heterogeneous electron transfer reactions with rate constants above 10 -4 m s -~ has long been a problem. In recent years, microelectrodes have become popular as a means of ameliorating this difficulty, especially when used in conjunction with voltammetry [1,5,7-12]. The most striking feature of microelectrodes is their extremely small surface areas which can both enhance the effective mass transport rate and reduce the potential drop in the resistive solution. In general, they exhibit sigmoidal vol tammograms at slow scan rates, which offers a number of advantages over the more familiar transient voltammetry. In this work we synthesized the ferrocene derivatives FcX2; the substituents are generally bonded to the cyclopentadienyl ring through a n sp 3 hybridized

Arene Displacement Reactions of (η6−Arene)chromium(0) Carbonyl Compounds

Abstract The development of organometallic chemistry over the past 25 years has led to extremely selective catalytic systems and to a greater understanding of their mechanisms. One area of particular interest has been the study of hydrogenation reactions (e.g. dienes to monoenes) using (η6−arene)tricarbonylchromium(0) complexes as catalysts. 1–4 The possibility of the catalytic liberation of functionalized arenes from the chromium centers in such compounds has also attracted the attention of synthetic organic chemists.5−6 The mechanisms involved in catalytic hydrogenation by (η6−arene)tricarbonylchromium compounds are only just becoming understood despite the fact that these reactions have been investigated since the early sixties. The first step is believed to be partial (or complete) displacement of the arene ring from the chromiummetal center.1−7 Moreover, the catalytic rate is highly dependent on the nature of the arene involved, i.e. on the strength of the arene-Cr bond.2 In this Comment, the work th...

The reactions of organometallic compounds of transition metals with molecular nitrogen and carbon dioxide

A development of organometallic chemistry has revealed wide possibilities for activating various unsaturated and saturated molecules for numerous novel reactions. Many nitrogen fixating systems based on the low-valent transition metal derivatives and reducing agents have been discovered. Depending on the reaction conditions, complexed nitrogen reduction occurs to form either hydrazine derivatives or ammonia. An investigation of the nitrogen fixating systems involving Lewis acids, to regenerate the catalyst, has led to catalytic nitrogen fixation. Nitrogen activated by complex formation with transition metal compounds is capable of insertion reactions into metal—carbon bonds to form organic amines. In this connection the possibility arises of forming amines from the reaction of nitrogen with hydrocarbons in the presence of transition metal compounds. Transition metal nitrogen compounds seem to be intermediates in the 'reverse' reactions as well, i.e. decompositions of nitrogencompounds with nitrogen evolution (Sandmeyer reaction, hydrazine oxidation. etc). Unlike nitrogen, carbon dioxide is rather reactive and undergoes insertion reactions into non-transition metal-carbon boids. Carbon dioxide also appeared to be capable of direct or indirect complex formation with low-valent transition metal compounds (Ru, Rh, Pt, etc.). Investigation of the stability of such complexes permits novel synthetic and catalytic reactions to be found. Thus the formation of Me—H bonds (e.g. in the formic acid decomposition with CO2 evolution) can be utilized for catalytic reduction of olefins and other unsaturated compounds by means of formic acid. When the intermediate carbon dioxide complexes with Me—C bonds (carboxylates) are formed. the competitive reaction occurs, i.e. olefin insertion into Me—H or Me—C bonds with elimination of the respective carboxylic acid. Another interesting reaction, insertion of CO2 into Me—H or Me—C bonds, can follow either 'normal' (formation of a carbon-carbon' bond) or 'reverse' (formation of the metalloacid ester) pathways. A development of organometallic chemistry has provided unusual possibilities for activating various unsaturated and saturated molecules and introducing them into the various reactions. The present lecture deals with the problem of activation by transition 607