Already an ACS Member? Choose the membership that is right for you. Discount will be applied automatically at checkout. Your account has been created successfully, and a confirmation email is on the way. When it comes to extreme multiple bonds, the transition metals have long ruled the roost.
Quadruple bonds? Quintuple bonds? Right there in a landmark organometallic dichromium complex made in Even sextuple bonds have been found, in Mo 2 and W 2. In contrast, the main-group elements—those in the s- and p-blocks of the periodic table—have lagged behind in the multiple-bonding stakes.
But now Lai-Sheng Wang and colleagues at Brown University have defied expectations by reporting that diatomic rhodium boride RhB contains a quadruple bond J. Main-group elements are generally thought to max out at triple bonds because of the number and geometry of orbitals they can use for bonding. In , researchers calculated that diatomic C 2 could contain a quadruple bond, but the claim was controversial because it invoked a weak bonding interaction between electrons on opposite sides of the molecule in orbitals that pointed directly away from each other.
And whereas a quadruple bond should be stronger than a triple bond between the same atoms, calculations suggested that the connection in C2 was actually weaker than the triple bond in ethyne C 2 H 2. A few years ago the researchers made a compound containing a triple bond between bismuth and boron, and wondered if they could swap bismuth for a transition metal.
They started their search with rhodium, largely because it only has one naturally occurring isotope, which makes it easier to work with experimentally and computationally.
So they fired a laser at a disk containing powdered rhodium and boron to produce a stream of vaporized compounds, and separated them in a mass spectrometer. Then they studied selected compounds by photoelectron spectroscopy, which measures the kinetic energies of electrons ejected from ionized samples and serves as a fingerprint of the structure and bonding in the molecules. This process allowed the researchers to identify two curious compounds: a boronyl-coordinated rhodium boride, RhB BO - , and RhB itself.
The team also used theoretical calculations to study how the orbitals of each atom in RhB overlapped to form molecular orbitals.
This showed that the atoms were connected by two sigma bonds and two pi bonds. Taken together, Wang says, all their evidence suggests that RhB is the first diatomic molecule containing a quadruple bond to a boron atom.
RhB is not a new molecule, though. Clicking on the donut icon will load a page at altmetric. Find more information on the Altmetric Attention Score and how the score is calculated. In this paper, we investigate this problem explicitly avoiding all the points of conflict from the previous papers to show that there is no quadruple bond in C 2.
The generalized product function energy partitioning GPF-EP method has been applied to calculate the interference energy IE that accounts for the formation of covalent bonds for each bond of the molecule. We also show that the difference in force constants of C 2 and acetylene can be rationalized in terms of the amount of charge density in the internuclear region by looking at the changes in the overlaps between orbitals along the bond axis.
Theory Comput. View Author Information. Cite this: J. Article Views Altmetric -. Citations Cited By. This article is cited by 34 publications.
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Read our privacy policy. Computational research by a team in India predicts that a quadruple bond could form between iron and carbon in the compound C Fe CO 3. Multiple bonding between main group elements has been demonstrated up to a maximum of three bonds. A theoretical and experimental study by scientists in China in reported the formation of a quadruple bond between boron and iron in the B Fe CO 3 - anion.
The findings lend weight to the theory of single electron transmutation, which predicts that after gaining an electron, an atom will act like its neighbour with the same number of electrons. One chemistry professor received three months for producing the drug in a university lab, while another was acquitted. Site powered by Webvision Cloud. Skip to main content Skip to navigation.
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