Magdolna Hargittai

• Budapest University of Technology and Economics

Olga Kennard (née Weisz, 1924–2023) was a true pioneer in crystallography. She left a lasting mark on scientific research with the establishment of the Cambridge Crystallographic Data Centre (CCDC).

There are profound expressions of remembrance of science and scientists, innovators and educators in Washington, DC. In this article, we survey the outdoor memorials and also include a few indoor memorials, if they are accessible to the public. There appears to be some predominance of physics and physicists, especially related to electricity among...

In 1962, the MRC Laboratory of Molecular Biology in Cambridge, UK, moved into a new building and continued a success story that had begun 15 before. Milestone discoveries and Nobel Prizes have followed ever since. They have led to profound changes in our basic ideas about the nature of life and the way medicine operates. Structural chemistry has pa...

The notion of symmetry brings together beauty and usefulness, science and economy, mathematics and music, architecture and human relations, and much more, as has been shown recently with many examples (Hargittai 1986, 1989; Hargittai and Hargittai 1995, 1996). There is a lot of symmetry, for example, in Béla Bartúk’s music. It is not known, however...

This guidebook introduces the reader—the scientific tourist and others—to the visible memorabilia of science and scientists in Budapest—statues, busts, plaques, buildings, and other artefacts. According to the Hungarian–American Nobel laureate Albert Szent-Györgyi, this metropolis at the crossroads of Europe has a special atmosphere of respect for...

This guidebook introduces the reader—the scientific tourist and others—to the visible memorabilia of science and scientists in Budapest—statues, busts, plaques, buildings, and other artefacts. According to the Hungarian–American Nobel laureate Albert Szent-Györgyi, this metropolis at the crossroads of Europe has a special atmosphere of respect for...

This guidebook introduces the reader—the scientific tourist and others—to the visible memorabilia of science and scientists in Budapest—statues, busts, plaques, buildings, and other artefacts. According to the Hungarian–American Nobel laureate Albert Szent-Györgyi, this metropolis at the crossroads of Europe has a special atmosphere of respect for...

This guidebook introduces the reader—the scientific tourist and others—to the visible memorabilia of science and scientists in Budapest—statues, busts, plaques, buildings, and other artefacts. According to the Hungarian–American Nobel laureate Albert Szent-Györgyi, this metropolis at the crossroads of Europe has a special atmosphere of respect for...

This guidebook introduces the reader—the scientific tourist and others—to the visible memorabilia of science and scientists in Budapest—statues, busts, plaques, buildings, and other artefacts. According to the Hungarian–American Nobel laureate Albert Szent-Györgyi, this metropolis at the crossroads of Europe has a special atmosphere of respect for...

This guidebook introduces the reader—the scientific tourist and others—to the visible memorabilia of science and scientists in Budapest—statues, busts, plaques, buildings, and other artefacts. According to the Hungarian–American Nobel laureate Albert Szent-Györgyi, this metropolis at the crossroads of Europe has a special atmosphere of respect for...

This guidebook introduces the reader—the scientific tourist and others—to the visible memorabilia of science and scientists in Budapest—statues, busts, plaques, buildings, and other artefacts. According to the Hungarian–American Nobel laureate Albert Szent-Györgyi, this metropolis at the crossroads of Europe has a special atmosphere of respect for...

This guidebook introduces the reader—the scientific tourist and others—to the visible memorabilia of science and scientists in Budapest—statues, busts, plaques, buildings, and other artefacts. According to the Hungarian–American Nobel laureate Albert Szent-Györgyi, this metropolis at the crossroads of Europe has a special atmosphere of respect for...

The vibrationally averaged structures of the iron chloride molecules may considerable differ from their equilibrium structure as a consequence of low-frequency large amplitude vibrations. Mean amplitudes of vibration and perpendicular amplitude correction terms have been calculated for FeCl2 and FeCl3. Mean amplitudes of vibration have also been ca...

Jerome Karle (1918–2013) had to overcome adversities before he acquired the education he strived to get. He did pioneering work in modernizing the gas-phase electron diffraction technique of molecular structure determination. Drawing on this experience, he and Herbert Hauptman jointly came to a seminal discovery that solved the phase problem in cry...

Trends in the structural variations of all perhalo derivatives of dicarbenes and their Group 14 analogues have been studied. This included all M2X4 molecules, where M = C, Si, Ge, Sn, or Pb, and X = F, Cl, Br, or I. Mapping the potential energy surface of all molecules has uncovered several isomers. The stability of these isomers depends on both th...

H.S.M. Coxeter has said that “the chief reason for studying regular polyhedra is still the same as in the times of the Pythagoreans, namely, that their symmetrical shapes appeal to one’s artistic sense.” The success of modern molecular chemistry affirms the validity of this statement; there is no doubt that aesthetic appeal has contributed to the r...

The molecular geometries of the complete series of aluminum trihalides, AlX3 (X = F, Cl, Br, and I), are discussed based on new gas-phase electron diffraction (GED) experiments (AlCl3 and Al2Cl6) and on the reanalysis of our previous GED data (for the rest of the series) with an improved and analogous treatment of the temperature effect on the aver...

Electron diffraction molecular intensities at two different camera ranges for AlF3, AlCl3, Al2Cl6, AlBr3, and Al2Br6 experiments; Cartesian coordinates of the calculated oligomer structures.

The structures, energetic, and vibrational properties of MDyX(4) (M = Li, Na, K, Rb, Cs; X = F, Cl, Br, I) mixed alkali halide/dysprosium halide complexes have been investigated by a joint computational and experimental, matrix-isolation Fourier-transform infrared spectroscopic (MI-IR), study. According to our DFT computations for the complexes wit...

In a recent article (Varga Z, Hargittai M, Bartell LS (2011) Struct Chem 22: 111–121), we showed with the example of lanthanide triiodide that contrary to previous claims by others, simple metal trihalide molecules do expand with increasing temperature. This sequel is meant to strengthen our argument and the validity of the method we used besides c...

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

The molecular and electronic structure of dysprosium triiodide, DyI(3), and its dimer, Dy(2)I(6), was determined by high level computations, gas-phase electron diffraction, and gas-phase infrared and matrix-isolation infrared and Raman spectroscopy. The free monomeric molecule is planar from all methods with an equilibrium bond length of 2.808(9) A...

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

The molecular structures, vibrational frequencies, and thermodynamic properties of all four monomeric and dimeric iron dihalide molecules, FeF2, FeCl2, FeBr2, and FeI2, were determined by quantum chemical calculations and the structure of iron diiodide also by gas-phase electron diffraction (ED). The earlier ED study of iron dibromide was also repe...

The molecular structure of SbI3 and BiI3 have been studied by gas-phase electron diffraction and infrared spectroscopy, BiI3 has been studied by electron diffraction, and SbI3 has been studied by infrared spectroscopy for the first time. Both molecules are pyramidal (C3v symmetry), and their geometries are characterized by the following bond length...

Experimental results for a variety of molecules have shown that their bond lengths expand appreciably when the molecules are heated, as expected from the asymmetric Morse-like potentials characterizing the bonds. However, in a series of papers on structures determined by gas-phase electron diffraction, Giricheva et al. claimed that, for very hot MX...

The molecular structures of the monomers and dimers of all iron trihalides, FeF(3), FeCl(3), FeBr(3), and FeI(3), were determined by computations, and the structure of iron trichloride monomers and dimers was determined also by gas-phase electron diffraction. The thermal-average bond length, r(g), of FeCl(3) is 2.136(5) A, and the estimated equilib...

The molecular geometries of VCl2 and VCl3 have been determined by computations and gas-phase electron diffraction (ED). The ED study is a reinvestigation of the previously published analysis for VCl2. The structure of the vanadium dichloride dimer has also been calculated. According to our joint ED and computational study, the evaporation of a soli...

Vibronic interactions have received increasing attention in modern structural chemistry. Edward Teller played a pioneering role in understanding and describing them during the “molecular physics” period of his scientific career. Very little is known about the two scientists who contributed significantly to our knowledge about these effects and whos...

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

The molecular geometry and vibrational frequencies of monomeric and dimeric dysprosium tribromide, DyBr(3) and Dy(2)Br(6), together with the electronic structure of their ground and first few excited-state molecules were determined by high-level computations, electron diffraction, gas-phase infrared, and matrix isolation infrared and Raman spectros...

Electron-vibrational (usually called “vibronic”) interactions in molecular systems with electronically degenerate, or near degenerate states produce a variety of novel properties best known as the Jahn–Teller effect, or the related Renner–Teller and pseudo-Jahn–Teller effects. These effects have been observed and described for decades by different...

Metal halides are a relatively large class of inorganic compounds that participate in many industrial processes, from halogen metallurgy to the production of semiconductors. Because most metal halides are ionic crystals at ambient conditions, the term “molecular metal halides” usually refers to vapor-phase species. These gas-phase molecules have a...

CrF2 was studied by combined application of quantum-chemical calculations and gas-phase electron diffraction. Coupled cluster and density functional computations found the ground electronic state to be a quasi-linear 5B2 state, which at linearity correlates with a 5A2 state to become a Renner-Teller 5Πg state. Several low-lying electronic states an...

A molecule is a collection of atoms kept together by interactions among those atoms. For some purposes it is better to consider the molecule as consisting of the nuclei of its constituent atoms and its electron density distribution. Generally, it is the geometry and symmetry of the arrangement of the atomic nuclei that is considered to be the geome...

Vibration is a special kind of motion: the atoms of every molecule are permanently changing their relative positions at every temperature (even at absolute zero) without changing the position of the molecular center of mass. In terms of the molecular geometry these vibrations amount to continuously changing bond lengths and bond angles.

Up to this point, structures of mostly finite objects have been discussed. Thus, point groups were applicable to their symmetries. A simplified classification of various symmetries was presented in Chapter 2 (cf., Figure 2-31 and Table 2-2). Point-group symmetries are characterized by the lack of periodicity in any direction. However, repetition is...

The simplest and most common of all symmetries is bilateral symmetry, yet at first sight, it does not appear as overwhelmingly important in chemistry as in our every-day life. The human body has bilateral symmetry, except for the asymmetric location of some internal organs.

So far our discussion has been non-mathematical. Ignoring mathematics, however, does not make things necessarily easier. Group theory is the mathematical apparatus for describing symmetry operations. It facilitates the understanding and the use of symmetries. It may not even be possible to successfully attack some complex problems without the use o...

The chemical reaction is the “most chemical" event. The first application of symmetry considerations to chemical reactions can be attributed to Wigner and Witmer [2]. The Wigner–Witmer rules are concerned with the conservation of spin and orbital angular momentum in the reaction of diatomic molecules. Although symmetry is not explicitly mentioned,...

Everything that counts in chemistry is related to the electronic structure of atoms and molecules. The formation of molecules from atoms, their behavior and reactivity all depend on the electronic structure. What is the role of symmetry in all this? In various aspects of the electronic structure, symmetry can tell us a good deal; why certain bonds...

... But I must speak again about crystals, shapes, colors. There are crystals as huge as the colonnade of a cathedral, soft as mould, prickly as thorns; pure, azure, green, like nothing else in the world, fiery black; mathematically exact, complete, like constructions by crazy, capricious scientists, or reminiscent of the liver, the heart ... There...

Connections between the structures of Group 12 dihalides in their vapor and crystal phases are sought and discussed. The molecular structures of all monomers and dimers (MX(2): M=Zn, Cd, Hg and X=F, Cl, Br, I) were calculated at the density functional B3PW91 and MP2 computational levels. All the monomers are linear, with the mercury dihalide molecu...

Hyaluronan is an unbranched polysaccharide of repeating disaccharides consisting of d-glucuronic acid and N-acetyl-d-glucosamine. Its strong water-retaining ability and visco-elastic properties have been broadly utilized in medical applications. Hyaluronan is an important constituent of the extracellular matrix whose physiological functions are man...

Chromium dichloride poses a challenge to the structural chemist. Its different forms of aggregation and association display all well-known structural distortions induced by vibronic interactions. The monomeric molecule has a Renner-Teller distorted bent geometry, the crystal exhibits strong Jahn-Teller distortion, and the oligomers have slightly di...

The molecular and electronic structure of dysprosium trichloride, DyCl(3), was calculated by high-level quantum chemical methods in order to learn about the effect of the partially filled 4f subshell and of the possible spin-orbit coupling on them. High-temperature electron diffraction studies of DyCl(3) were also carried out so that we could compa...

The molecular geometries and vibrational frequencies of aluminum oxyhalides, AlOX, and their dimers, (AlOX)2, have been calculated by MP2 and density functional methods. The monomeric molecules are linear while the dimers have a D 2h -symmetry geometry with a four-membered ring, in which the oxygen atoms serve as bridging ligands. Different thermod...

Crystallography, a scientific discipline about the properties and structure of crystals, and the arts seem to be two different areas of human endeavor. There are, indeed, many differences between them – however, there are also similarities. The concept of symmetry can be used as a bridge to recognize such similarities. Symmetry is everywhere, in th...

The molecular structure and vibrational characteristics of monomeric and dimeric tin diiodide, SnI2 and Sn2I4, were determined by high-level computational methods. For the dimer molecule two low-energy geometries were found, one with C s and the other with C 2v symmetry, the former with somewhat lower energy; their relative energy is strongly depen...

This compilation presents examples of artistic artifacts that have served as successful visual analogies to aspects of chemistry. The authors have used them in various college-level chemistry classes, outreach programs and chemistry textbooks, as well as in journals and monographs. They include ancient Chinese, Turkish and Thai sculptures, modern s...

The molecular geometries, relative stabilities, binding energies, and dissociation energies of NaDyBr4 and its molecular ion are discussed. Both the bidentate and tridentate isomers are stable for the neutral species, while only the bidentate form is stable for NaDyBr4 +.

Quantum chemical calculations have become an everyday tool in chemistry. There are commercial program packages and downloadable basis sets for most needs. However, many chemists rarely go beyond the routine use of these programs, rarely, if ever, checking the original references for basis sets. In this letter, we point out some of the pitfalls of s...

The molecular geometry of strontium dichloride has been determined by high-temperature electron diffraction (ED) and computational techniques. The computation at the MP2 level of theory yields a shallow bending potential with a barrier of about 0.1 kcal mol(-1) at the linear configuration. The experimentally determined thermal average Sr--Cl bond l...

The molecular geometry, vibrational frequencies, relative stabilities, and some thermodynamic properties of different isomers of the NaDyBr4 complex were determined by computation. We investigated, to our knowledge for the first time for such a complex, the possible effect of the partially filled 4f orbitals on the molecular properties of an MLnX4...

The molecular structure of aluminum triiodide was investigated in the gas phase by high-temperature gas-phase electron diffraction and high-level computations. The geometries of monomeric, AlI3, and dimeric, Al2I6, molecules were determined from two separate experiments carried out under carefully controlled conditions to prevent decomposition. Thi...

Symmetry considerations are all-important in studying structures. This compilation provides examples in diverse areas of structural science.1 The examples include molecular symmetry, buckminsterfullerene, the Jahn-Teller effect, chirality and dissymmetry, the double helix and other biological macromolecules, molecular packing in crystals, and quasi...

With increasing computational possibilities the question of critical comparison of computed results with experimental data gains importance. Differences in the physical meaning of parameters determined by different techniques and the uncertainties of both experimental and computed parameters need to be scrutinized in such comparisons. In view of a...

Symmetry and chemistry have been in a fruitful interplay, initially in spectroscopy and crystallography, lately in more traditional domains of chemistry, such as reactivity and conformational analysis. A simple phenomenological approach suffices to get an idea about the symmetries of molecules whereas group theoretical approach greatly facilitates...

The molecular structure of magnesium dibromide was investigated by high-level computational techniques and gas-phase electron diffraction. The vapor consisted of about 88% monomeric and 12% dimeric species at the electron diffraction experimental conditions at 1065 K. The geometrical parameters and vibrational characteristics of monomeric, dimeric,...

The molecular structure of all silver halide monomers, Ag(2)X, AgX, AgX(2), and AgX(3), (X = F, Cl, Br, I), have been calculated at the B3LYP, MP2, and CCSD(T) levels of theory by using quasirelativistic pseudopotentials for all atoms except fluorine and chlorine. All silver monohalides are stable molecules, while the relative stabilities of the su...

Gas-phase electron diffraction (GED) studies at high temperatures have several special common features that justify their separate discussion. Due to the difficulties connected with the experiment this technique has developed only in a few laboratories. Most often inorganic systems are studied; lower-valence metal halides and metal oxides. Their lo...

Scarcely any term connects art and science more closely than symmetry. This was already a theme in ancient times, as is found in Vitruvius, for example. On the beach of an unknown island, a shipwrecked traveler finds neatly arranged geometric figures. Can he conclude from this that there is an intelligent creator (perhaps even a god)?

The geometries and spectroscopic constants of the dihalosilanones, F2SiO, Cl2SiO, Br2SiO, and I2SiO, and their cis- and trans-XSiOX isomers were calculated by high-level computations. The potential energy surfaces of the isomerization reactions were investigated and the transition-state structures determined, together with the isomerization and act...

State-of-the-art experimental electron diffraction and computational information on the structure of alkaline earth dihalide molecules are in agreement for the shape of these symmetric triatomic molecules (linear/bent/quasi-linear). However, the computed and measured bond lengths show differences that are not only considerably larger than the exper...

The molecular structure of tin dibromide was investigated by high-level computational methods and gas-phase electron diffraction. The structural and vibrational characteristics of both SnBr2 and Sn2Br4 were determined by computations. To reach an agreement between computed and experimental bond lengths for SnBr2, very large bases and correlated met...

The molecular structures of SnCl2 and Sn2Cl4 have been calculated by high-level quantum chemical methods. The global minimum structure found for the tin dichloride dimer is of Cs symmetry and has two halogen bridges. This structure is very different from the one suggested earlier by Fields et al. based on their gas-phase Raman spectroscopic measure...

Systematic computational studies on the dihydrides and dihalides of group 14 elements have been performed, for their ground state and first excited state. We present equilibrium geometries of the lowest lying singlet and triplet states and singlet−triplet energy separation data on the whole series obtained by the CCSD(T) method. Scalar relativistic...

The teachings of Louis Pasteur about chirality continue to instruct and inspire.

The molecular geometry of gaseous cuprous chloride oligomers was determined by gas-phase electron diffraction at two different temperatures. Quantum chemical calculations were also performed for Cu(n)Cl(n) (n=1-4) molecules. A complex vapor composition was found in both experiments. Molecules of Cu(3)Cl(3) and Cu(4)Cl(4) were present at the lower t...

The molecular geometry of yttrium trichloride has been determined by high-temperature gas-phase electron diffraction. The vapor phase consisted of about 87% monomeric and 13% dimeric species. High-level quantum chemical calculations have also been carried out for both the monomer and dimer of yttrium trichloride, and their geometries, harmonic forc...