For the first time ever, a chemical bond between a superheavy element and a carbon atom was demonstrated

The research findings pave new ways to study the implications of Einstein's theory of relativity regarding the structure of the periodic table.

[Translation by Dr. Nachmani Moshe]
For the first time ever, a chemical bond between a superheavy element and a carbon atom was demonstrated. The research findings pave new ways to study the implications of Einstein's theory of relativity regarding the structure of the periodic table.

An international collaboration led by a research group from the cities of Mainz and Darmstadt in Germany, led to the synthesis of a new family of chemical compounds based on superheavy elements at a Japanese research institute. For the first time ever, a chemical bond between a superheavy element called seaborgium (element number 106, seaborgium) and a carbon atom was demonstrated. Eighteen atoms of cyborgium were converted into the compound cyborgium hexacarbonyl, which consists of six carbon monoxide molecules attached to a common cyborgium atom.

The gaseous properties and the ability of the compounds to adsorb to the surface of silicon dioxide were studied and compared to similar compounds of neighboring elements in the same group of elements in the periodic table. The study paves the way for conducting more detailed studies regarding the chemical behavior of elements located at the end of the periodic table, for which the effect of relativity on the chemical properties is the most significant.

Chemical experiments with super-heavy elements - those elements with an atomic number higher than 104 - are particularly challenging: first, the element that researchers have to prepare artificially using a particle accelerator. The maximum production rate is at the level of a few single atoms per day, at best, and is even lower for the heavier elements. Second, the resulting atoms quickly decay through radioactive processes - in the present case within 10 seconds, which increases the complexity of the experiments.

A serious motive for such demanding studies lies in the fact that the large number of positively charged protons inside the atomic nucleus accelerate electrons in the atomic shells to very high speeds - about 80% of the speed of light. According to Einstein's theory of relativity, electrons become heavier than when they are at rest.

As a result, their trajectories may differ from those of the electrons of lighter elements, where the electrons are much slower. Chemical experiments with superheavy elements are usually carried out on compounds that are already in the gaseous state at relatively low temperatures.

This condition allows for their rapid passage through the gaseous state, which provides the rapid process required in such short lifetimes. Until today, compounds containing only halogens and oxygen were chosen, for example, in the past a compound of cyborgium with two chlorine atoms and two oxygen atoms was studied - a very stable compound with high volatility. However, in such compounds all the electrons occupying the outermost orbits participate in a covalent bond, which may mask the effects of relativity. Because of this, the research continued for many years in search of more advanced systems, in which compounds with other binding properties are involved, ones that demonstrate the effects of relativity more prominently. "A big challenge in experiments of this type is the powerful acceleration beam that destroys the stable chemical compounds. In order to overcome this problem we first passed the element tungsten, the heavier neighbor of the element molybdenum, through a magnetic separator and separated it from the beam. At this stage, we performed the chemical experiments behind the separator, where the conditions are also optimal for researching new families of compounds." The focus was on the formation of hexa-carbonyl conjugates. Theoretical studies in the early 90s predicted that these compounds might be stable. In these compounds, a single atom of cyborgium is bound to six molecules of carbon monoxide through metal-carbon bonds, in the manner common in organometallic compounds, with many of them exhibiting the desired electronic bonding state that chemists dealing with superheavy elements were looking for.

The researcher responsible for the production of the compounds explains: "During the usual methods for creating super-heavy elements, large amounts of by-products usually interfere with the detection of single atoms of super-heavy elements such as cyborgium. Using the separator, we finally managed to locate signs of the element and evaluate its production rates and decay properties. In the next step, the foundation was ready for the chemical research of the next generation."

In 2013, the scientists approached an experiment whose purpose was to test whether it was even possible to synthesize a compound of the hexa-carbonyl syborgium type. During two weeks of frantic experiments, the researchers managed to locate 18 such compounds. The properties of the gas, as well as the binding ability of the compound to the silicon dioxide surfaces, were studied and found to be similar to the homologous compounds of hexa-carbonyl molybdenum/tungsten - characteristic compounds of group 6 in the periodic table, which adds confirmation to the existence of the compound hexa-carbonyl syborgium, the superheavy element which is in the same group. The measured properties were found to be in accordance with the theoretical calculations, in which the effects of relativity were also included. "Our experiment represents a milestone in chemical studies of superheavy elements, and shows that many advanced compounds are within reach in terms of practical experiments in the laboratory. The window that such experiments open for us to obtain additional insights into the nature of chemical bonds, not only for superheavy elements, is fascinating and intriguing."
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