Pioneers and Influencers in Organometallic Chemistry: Alexander Nesmeyanov (1899–1980). Carbon and Hydrogen Are Good but What about the Other 100 Elements?

Abstract

Alexander. N. Nesmeyanov (Figure 1) became one of the founders of a new scientific discipline─the chemistry of organoelement compounds. For many years, he was a recognized leader of the entire scientific community of the Soviet Union, heading Soviet science as President of the USSR Academy of Sciences (1951–1961). During the period of the Cold War, he managed not only to preserve but to strengthen and multiply ties of Russian scientists with the international community. Figure 1. Portrait of Alexander Nesmeyanov. As a student of N. Zelinsky, (1) who was the successor of V. Markovnikov at Moscow University, (2) he created one of the largest scientific schools in Russia. He was a man of many talents, possessing a rare combination of human qualities: a quick analytical mind and developed intuition, irreconcilability in upholding basic principles and the ability to find compromises, high demands on himself and on people, strictness in assessments, and soft benevolent humor. Combined with an extraordinary capacity for work, purposefulness, and organization, these qualities formed the basis of his outstanding achievements in science (Figure 2). Figure 2. Timeline of significant events in the life of Alexander Nesmeyanov─and in chemistry. Photos used are taken by the authors or adopted from public domains (https://ineos.ac.ru/history-directors/history-nesmeyanov; https://letopis.msu.ru/peoples/3157; https://ru.freepik.com/; https://ru.wikipedia.org). Alexander Nesmeyanov was born on September 9, 1899, in Moscow into a family of teachers. In 1917, he was admitted as a student of Moscow University, at the beginning of the Russian Revolution. The postrevolutionary years were difficult. Nesmeyanov worked as a night watchman at the faculty of chemistry and lived in a closet right in Zelinsky’s laboratory. By that time, the scientific interests of Zelinsky were more concentrated on catalytic hydrocarbon chemistry. Nesmeyanov wrote later: “Of course, this was very attractive and promising, but not for me. Carbon and hydrogen are good, but what about the other 100 elements?” (3) All his further life was inextricably linked with Moscow University: 1924, assistant professor; 1930, associate professor; 1934, doctor of sciences and full professor. From 1944 to 1978, he headed the Department of Organic Chemistry at the university. In addition, from 1943 to 1948 he was dean of the Faculty of Chemistry, and from 1948 to 1951 he was rector of Moscow University. Nesmeyanov’s first critical success came in 1929 after long, hard work and many failures. (4) He discovered a synthesis of organometallic compounds by thermal decomposition of double salts of aryldiazonium halides and heavy metal halides, now known as the “Nesmeyanov diazo method” (Scheme 1). Initially, this method was used to synthesize organomercury compounds. (5,6) Next, this reaction was successfully used for the synthesis of various organometallic compounds of tin, thallium, arsenic, antimony, and bismuth. (7) Very useful application of this approach is thermolysis of stable aryldiazonium tetrafluoroborates in the presence of various metals. (8,9) The reaction with SnCl₂ opens access to diaryltin(IV) derivatives, (10−12) whereas the reaction with metallic zinc, cadmium, and aluminum gives directly the corresponding organoelement compounds (Scheme 1). (13) Nesmeyanov proposed also a convenient approach for preparation of diaryl oxonium and halogenonium salts providing up to 90% yield. Mercury was one of Nesmeyanov’s favorite elements, which encompassed his entire scientific career. Prior to 1920, there was a discussion about the nature of the mercury–carbon bond. Manchot believed the adducts of ethylene with mercury salts have the structure of π-complexes. (14) However, the classical works of Hoffmann, Scholler, Schraut, Kucherov, and their successors in the 1930s confirmed the σ-bonding nature of the Hg–C bond. Nesmeyanov further demonstrated (15) the reversible decomposition of some organomercury compounds. Before World War II, he carried out the classical work on the hydroxymercuration of conjugated and isolated dienes to show for the first time the possibility of cyclization. (16) The Nesmeyanov–Borisov Rule (1945), determining the stereochemical result of substitution reactions at the olefin carbon atom in various compounds, is still of particular importance: “Electrophilic and radical substitution at the alkene carbon atom proceeds with the retention of the configuration of the double bond.” Initially, this stereochemical feature was found in exchange reactions for alkenylmercury derivatives. (17,18) In subsequent work, (19) it was found that exchange reactions in other organoelement compounds have the same stereochemical result. This rule is one of the milestones of modern organometallic chemistry and transition-metal catalysis. Another important contribution of Nesmeyanov to theoretical organic chemistry is dual reactivity and metallotropic tautomerism. Studying the hydroxymercurization of vinyl ethers, he noted that O or C derivatives can be formed during alkylation and acylation. For example, acylation occurs at the oxygen, while the reaction with TrCl (Tr = triphenylmethyl) occurs at carbon. (20) These features have been explained on the basis of metalotropic tautomerism, which is analogous to keto–enol tautomerism. Later, other types of equilibria were demonstrated in the series of mercury derivatives of nitrosophenols, aminopyridines, and pyrazoles. (21) Similar results were obtained for derivatives of the group 14 elements Pb, Sn, Ge, and Si. (22) The pioneering work of Nesmeyanov and his co-workers opened a rapidly developing field of metallotropic rearrangements. Fast intramolecular rearrangements of η¹-organoelement derivatives of cyclopentadiene and other cyclic systems were discovered, such as 1,3-migration of boron in allyl systems, (23) migrations of metal–carbonyls, (24) inter-ring haptotropic rearrangements in metal–carbonyl complexes, (24,25) and other interesting processes. Nowadays, this is classic for organic and organometallic chemistry (26) (Scheme 2). Nesmeyanov also made a significant contribution to synthetic organic chemistry and the chemistry of heterocycles. After his group’s work, β-chlorovinyl ketones have become a useful tool in the synthesis of five- and six-membered heterocycles: pyrazoles, isoxazoles, triazoles, pyridines, benzopyrylium, flavylium, and naphtopyrylium. (27) Nesmeyanov demonstrated an addition–elimination mechanism using as a model cis- and trans-alkenyl ketones RCOCHCHX containing various leaving groups (Cl, CN, SO₃, PhSO₂-, Br, N(CH₃)₃⁺, NO₂). (28) In 1939, Nesmeyanov developed a convenient synthesis of tungsten and molybdenum hexacarbonyls by the interaction of WCl₆ and MoCl₅ with iron pentacarbonyl (29) and a method for the synthesis of mixed carbonyls with a covalent metal–metal bond. (30) Polymetallic compounds of this type having Cr–Sn, Mo–Sn, W–Sn, Mo–Pb, W–Pb, Fe–Sn, Mn–Sn, Re–Sn, and Fe–Si bonds have been obtained. It was shown that the length of the M–M bond is equal to the sum of their covalent radii. The strength of such bond is quite high, but it is broken by the action of chlorine and bromine. (31) Nesmeyanov’s work on the chemistry of metallocenes began in 1954–1956 and resulted in a long-term study of the σ and π derivatives of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Co, Ni, Pd, Au, Ag, Cu, and Ru with a wide range of ligands. Ferrocene chemistry was one of the main areas of Nesmeyanov’s research from 1954. He developed syntheses of mercury-, lithium-, and sodium-derived ferrocenes; halides; sulfur- and selenium-derivatives; and biferrocenyl and triphenylmethylferrocene (Scheme 3). (32) Direct cyanation of the ferrocenium cation has been found to proceed by the action of HCN. (33) The first obtained ferrocene boronic acids made it possible to obtain halogen, hydroxy, amino, and silver derivatives of ferrocene. (34,35) Planar-chiral 1,2- and 1,3-heterodisubstituted ferrocenes, synthesized on the basis of methods developed by Nensmeyanov, now have become an integral part of a chemist’s tools dealing with catalytic asymmetric transformations in academia as well as in industry. (36) Nesmeyanov was the first to obtain hydroxyferrocene by alkaline hydrolysis of ferrocenyl acetate. (37) The arylation of ferrocene with diazonium salts (38) has become a classic in this field. (39) Nesmeyanov and colleagues also discovered the ability of ferrocene and ruthenocene to ligand exchange of one of the cyclopentadienyl rings for an arene ligand formation of the arene-cyclopentadienyl iron cation under catalysis with AlCl₃, AlBr₃, and ZrCl₄. (40) Nesmeyanov made also a significant contribution to the chemistry of cyclopentadienyl-carbonyl derivatives of Mn, Re, V, Nb, and Ta and demonstrated their aromatic properties. (41) Metalation, acylation, mercurization, chloromethylation, phosphorylation, and deuteration of cyclopentadienyltricarbonyls of manganese and rhenium (42) were elaborated. Studying the thermal reactions of cyclopentadienyl manganese and element-substituted phenylacetylenes Ph₃E-C≡CPh (E = Si, Ge, or Sn), Nesmeyanov discovered carbene complexes having both terminal and bridging ligands (43) (Figure 3). He also studied reactions of π-cyclopentadienyl and π-allyl derivatives to demonstrate their interesting catalytic properties. (44) Figure 3. Terminal and bridging carbene complexes. (43) While all other cycles of Nesmeyanov’s work are interconnected and logically follow from one another, the study of radical telomerization, according to Nesmeyanov, (3) began to solve the industry’s request─to obtain fluorine-resistant fluids required for the separation of uranium isotopes. He proposed to use trifluoromethylated arenes prepared from trichlorometylethene. This substance was first obtained by Nesmeyanov by HCl elimination from the corresponding tetrachloropropane. As a side reaction, Nesmeyanow discovered, highly important for the industry, the telomerization process. Based on telomerization, Nesmeyanov proposed the synthesis of ω-amino (hydroxy) acids having an odd number of carbon atoms as a homologous nylon monomer and other industrially significant compounds (45) and demonstrated the fundamental reactivity of trichlorometylethene. (46) The creation of artificial food was another important area of Nesmeyanov’s research. Nesmeyanov’s idea of industrial food production without agriculture continues the works of Mendeleev and Berthelot. (47) Being a convinced vegetarian, in his youth Nesmeyanov dreamed of solving the food problem of the whole world without the need to kill animals. In the 1960s, at the Institute of Organoelement Compounds that he organized, he launched comprehensive research on the creation of food proteins, which covered a very wide range of problems: the development of methods for synthesis (chemical, microbiological, enzymatic) of food amino acids and peptides; identification of key components of smell and synthesis of flavoring substances; formation of the structure of new food forms based on mixtures of biopolymers; etc. Nesmeyanov’s artificial black caviar was the first commercial protein analogue product; (48) in the mid-1960s, artificial caviar was produced on an industrial scale. (48) In perhaps one of his most important roles, Nesmeyanov served as president of the Academy of Sciences of the Soviet Union. He headed the Academy for 10 years, with the pinnacle of these achievements being the launch of the first Earth satellite on October 4, 1957. During the period of Nesmeyanov’s leadership of the USSR Academies of Sciences, the important decision to organize a special group of scientists to create artificial Earth satellites was made, and an extensive scientific research program was launched. Furthermore, for many years (1939–1954), Nesmeyanov was head of the Zelinsky Institute of Organic Chemistry, one of the largest units of the National Academy. In 1954, on his initiative, the Institute of Organoelement Compounds was established. This institution is now named the Nesmeyanov Institute of Organoelement Chemistry, and here the Nesmeyanov museum is located. At the height of the Cold War, during the period of the most acute confrontation between the USSR and the United States, Nesmeyanov firmly defended the thesis about the internationality of science and the need to expand cooperation with other countries in the field of scientific research and education. Many prominent foreign scientists were elected at this time as members of the USSR Academy of Sciences. Nesmeyanov himself was elected an honorary member of more than 20 Academies of Sciences and the most prestigious scientific societies of different countries, as well as “honoris causa” professor at many universities worldwide. Alexander Nesmeyanov entered the history of chemistry as an outstanding scientist, one of the pioneers of organoelement chemistry, whose research results were included in textbooks and monographs. Nesmeyanov created one of the largest scientific schools in his country, and his brilliant organizational skills and wisdom allowed him, during the very difficult period of the Cold War, not only to preserve but to strengthen the ties of Soviet science with the international scientific community. The manuscript was written through contributions of all authors. All authors have given approval to the final version of the manuscript. The manuscript was prepared in terms of the State contract ot the chair of organic chemistry of the Moscow State University entitled “Synthesis and study of physical, chemical and biological properties of organic and organometallic compounds” - CITIC No-AAAA-A21-121012290046-4 This article references 48 other publications. This article has not yet been cited by other publications.