Rotational spectra, structures, hyperfine constants, and the nature of the bonding of KrCuF and KrCuCl

Rotational spectra of KrCuF and KrCuCl have been measured in the frequency range 8-18 GHz, using a pulsed jet cavity Fourier transform microwave spectrometer. The molecules were prepared by ablating Cu metal with a pulsed Nd:YAG laser (1064 nm) and allowing the plasma to react with appropriate precursors (Kr plus SF(6) or Cl(2)) contained in the backing gas of the jet (Ar or Kr). Rotational constants, internuclear distances, vibration frequencies, and (83)Kr, Cu, and Cl nuclear quadrupole coupling constants have all been evaluated. The Kr-Cu bonds are short and the complexes are rigid. The (83)Kr coupling constant of KrCuF is large (128.8 MHz). The Cu nuclear quadrupole coupling constants differ radically from those of uncomplexed CuF and CuCl molecules. The results are supported by those of ab initio calculations, which have also yielded Mulliken populations, MOLDEN plots of valence molecular orbitals and Laplace concentrations, and electron localization functions. The results are consistent with those reported earlier for other noble gas-noble metal halide complexes. The results have been used to assess the nature of the bonding in the complexes and have produced good evidence for weak noble gas-noble metal chemical bonding.     

Paneth,IUPAC, and the Naming of Elements

The procedure for assigning names to elements by the International Union of Pure and Applied Chemistry involves establishing priority of discovery, then inviting the discoverers to suggest a name. This protocol is in contrast with the suggestions of Friedrich A. Paneth form 1947, who believed that the discoverers of an element have the undisputed right to name it. This difference in philosophy came to light during a workshop convened 10 years ago for the purpose of naming elements 104–109, when the discoverers of these elements contended that they were solely entitled to name them. During the debate, and in support of the name seaborgium for element 106, it was argued that gadolinium, samarium, gallium, einsteinium and fermium had been named after living scientists. The history of the naming of these elements demonstrates that this is not the case; Glenn T. Seaborg is the first scientist for whom an element was named during his lifetime.     

Paneth, Kant, and the philosophy of chemistry

Immanuel Kant has built up a dualistic epistemology that seems to fit to the peculiarities of chemistry quite well. Friedrich Paneth used Kant’s concept and characterised simple and basic substances which refer to the empirical and to the transcendental world, respectively. This paper takes account of the Kantian influences in Paneth’s philosophy of chemistry, and discusses pertinent topics, like observables, atomism and realism.

An ab initio study of the structures and the harmonic and anharmonic stretching force constants of the cyanides HCN,LiCN, FCN,ClCN and isocyanides HNC,LiNC, FNC,ClNC

Equilibrium structures and both harmonic and anharmonic stretching force constants have been calculated ab initio for the four cyanides HCN, LiCN, FCN, and C1CN, and the four isocyanides HNC, LiNC, FNC, and ClNC, using several basis sets of about triple-zeta quality. The CN and NC bond lengths, as well as diagonal stretching force constants, are nearly the same throughout both series. Trends in the off-diagonal stretching force constants are discussed, and dipole moment values are correlated with the structural type, XCN and XNC, and the electronegativity of the ligand X.     

Imaging of the structure of the argon and neon dimer, trimer, and tetramer

We Coulomb explode argon and neon dimers, trimers, and tetramers by multiple ionization in an ultrashort 800 nm laser pulse. By measuring all momentum vectors of the singly charged ions in coincidence, we determine the ground state nuclear wave function of the dimer, trimer, and tetramer. Furthermore we retrieve the bond angles of the trimer in position space by applying a classical numerical simulation. For the argon and neon trimer, we find a structure close to the equilateral triangle. The width of the distribution around the equilateral triangle is considerably wider for neon than for argon.     

Synthesis and study of the properties of tetrazoles,azides, triazenes,and azo compounds of the thiadiazole series

Azo compounds and bistriazenes were obtained by diazo coupling of diazotized 5-amino-2-R-1,3,4-thiadiazoles; tetrazolo[4,5-b]-1,3,4-thiadiazoles, to which azido-tetrazole tautomerism is peculiar, were obtained by replacement of the diazo group by an azido group. The structures of the products were confirmed by their IR and UV spectra.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 933–936, July, 1980.     

A Critical Appraisal of the Experimental Data on the Molecular Structure and Spectra of Halides, Oxides, and Hydrides of the s-, d-, and f-Block Elements

Evidence for unusual shapes of simple MX(n) molecules that are not stable under normal conditions is critically appraised in this review, which assesses current knowledge of the spectra and structures of many simple binary halides, oxides, and hydrides. It emphasizes the need for more high-resolution gas-phase spectroscopic data, summarizes the current state of knowledge in many fields, and suggests key experiments that should be carried out to resolve conflicting results obtained in earlier studies.     

Electrochemical and chemical syntheses,structures, and optical properties of the zinc and cadmium complexes in the N,N,O,S-ligand environment

The chemical and electrochemical syntheses of the zinc (I) and cadmium (II) complexes are carried out on the basis of the tridentate Schiff base (H₂L), the condensation product of (2-tosylaminoaniline) N-(2-aminophenyl)-4-methylbenzenesulfunamide with 1-phenyl-3-methyl-4-formylpyrazole-5-thiol. The structures and compositions of the synthesized metallochelates are proved by the data of C, H, and N elemental analyses, IR spectroscopy, and ¹H NMR spectroscopy. X-ray absorption spectroscopy is used to determine the structure of the zinc complex. The binuclear structure of the cadmium complex is confirmed by the X-ray diffraction data (CIF file CCDC no. 1471159). The optical properties of H₂L and the zinc and cadmium complexes in dimethyl sulfoxide (DMSO) solutions are studied.     

Dissociative adsorption of oxygen and hydrogen, and the formation of hydroxyl groups on the surface of Cu, Ag, Ni, Pd and Pt

By the semi-empirical interacting bonds method, the heats of oxygen and hydrogen adsorption in a dissociative form on the (100) face of Cu, Ag, Ni, Pd and Pt have been calculated. It has been shown that most stable are the multiply bonded adsorption forms. For the different bonding states, the heat of hydroxyl group formation from O₂ and H₂ varies but slightly. The calculated values are compared with the experimental data.

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(100) Cu, Ag, Ni, Pd, Pt. , . - H₂ O₂. .

     

Isolation, purification, and study of some properties of the lysl-, phenylalanyl-, and aspartyl-tRNA synthetases from the fungus Verticillium dahliae

Conclusions Relatively highly purified preparations of lysyl-, phenylalanyl- and aspartyl-tRNA synthetases have been isolated from the 12-day mycelium of a strongly virulent form of the fungusV. dahliae and some of their physicochemical properties have been studied.Institute of Biochemistry, Academy of Sciences of the Uzbek SSR. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 229–233, March–April, 1974.     

Isolation,analysis, biosynthesis,and modification of the alkaloid cytisine

Information on methods of isolation and analysis of the alkaloid cytisine and its derivatives and questions of structure and modification over the last 25 years are generalized.Institute of Organic Synthesis and Coal Chemistry, Khazakhstan Academy of Sciences, Karaganda. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 301–313, May–June, 1991.     

Structural Chemistry,the journal,the discipline,bridge building,and our personal and professional practice

Structural Chemistry - This paper was written on the occasion of the 30th special Jubilee volume of Structural Chemistry journal in 2019. It offered us a unique opportunity to look at our common...     

Structural and energetic aspects of the protonation of phenol,catechol, resorcinol,and hydroquinone

The various protonated forms of phenol (1), catechol (2), resorcinol (3), and hydroquinone (4) were explored by ab initio quantum chemical calculations at the MP2/6-31G(d) and B3LYP/6-31G(d) levels. Proton affinities (PA) of 1-4 were calculated by the combined G2(MP2,SVP) method, and their gas-phase basicities were estimated after calculation of the change in entropy on protonation. These theoretical data were compared with the corresponding experimental values determined in a high-pressure mass spectrometer. This comparison confirmed that phenols are essentially carbon bases and that protonation generally occurs in a position para to the hydroxyl group. Resorcinol is the most effective base (PA = 856 kJ mol-1) due to the participation of both oxygen atoms in the stabilization of the protonated form. Since protonation is accompanied by a freezing of the two internal rotations, a significant decrease in entropy is observed. The basicity of catechol (PA = 823 kJ mol-1) is due to the existence of an intramolecular hydrogen bond, which is strengthened upon protonation. The lower basicity of hydroquinone (PA = 808 kJ mol-1) is a consequence of the fact that protonation necessarily occurs in a position ortho to the hydroxyl group. When the previously published data are reconsidered and a corrected protonation entropy is used, a proton affinity value of 820 kJ mol-1 is obtained for phenol.     

Catalysis in the Synthesis of S,N-Heterocycles and O,N-, S,N-, and O,S,N-Macroheterocycles

The review systemizes and generalizes published data on the catalytic syntheses of six-, seven-, and eight-membered S,N-heterocycles and O,N-, S,N-, and O,S,N-macroheterocycles.     

Scholarship, Education, and the Internet

A lecture demonstration of primary kinetic isotope effect using the bromination of acetone and acetone-d₆ is described.     

Biogeochemical migration of heavy metals, Ti, V, Mo, Ta, W, and U, in the profile of a low-laid peatbog in the country between the Ob and Tom rivers

Biogeochemical migration of heavy metals in the course of marsh formation is mainly determined by physical-chemical processes, such as the oxidation-reduction zonality of the peatbog thickness and the state of humous substances (the quality of humus adsorptive barriers). In the process of peatbog formation V, U, Ta are the weakly captured elements while Mo is captured to a relatively higher extent. Elements as Ti and W are found in separate layers. No technogenic degradation of the marsh ecosystem in the Ob and Tom has been observed.     

The structural and synthetic implications of the biosynthesis of the calycanthaceous alkaloids, the communesins, and nomofungin

A comparison is made between the calycanthaceous alkaloids, nomofungin, and the communesins using structural and biosynthetic information from studies of the former to shed light on the structural ambiguity of the two latter species. Also, a novel biosynthetic approach for the communesins is presented that involves coupling of tryptamine with the ergot alkaloid aurantioclavine that is suitable for synthetic emulation. Preliminary synthetic studies and intermediates are reported.     

Ab initio investigation of the hydration of the tetrahedral perchlorate, perbromate, selenate, arsenate, and vanadate anions

The geometries, energies, and vibrational frequencies of various isomers of XO(4)(m-)(H2O)n, x = Cl, Br, Se, As, V; n = 0-6, m = 1-3 are calculated at various levels up to MP2/6-31+G*. These properties are studied as a function of increasing cluster size. The experimental and theoretical vibrational spectra are compared where available.