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The isolation of a crystalline radical cation carbon(I) species, generated via single-electron transfer between a carbodicarbene and a nitroaromatic compound, is reported. The resulting radical ion pair can mediate various C–O and C–C cross-coupling reactions with electron-deficient arenes bearing a leaving group.

What is the maximum number of covalent chemical bonds that two atoms can share? Six, according to the latest theoretical study — at least where just two atoms of the same element are concerned.

While chemical bonding between carbon and the d- and p-block elements is relatively well-studied, that between carbon and the f-block elements remains comparatively poorly understood. Here, the authors synthesize a series of uranium−carbone complexes in which carbon forms an unprecedented double dative bond to uranium.

Diatomic C₂ is an elusive species that has only been indirectly observed in the gas phase. It had previously been stabilized in the condensed phase using two ligands, but now a monoligated L→C₂ complex has been prepared with a bulky phosphine ligand (L) bearing two imidazolidin-2-iminato groups. Reactivity studies and theoretical quantum chemical analysis point to the C₂ moiety having a dicarbene character.

While polyhedral boron hydride complexes have found application in a number of diverse fields, the isolation of stable aluminium analogues remains highly challenging. Here, Jones and colleagues demonstrate that reduction of an amidinato-aluminum(III) hydride complex with magnesium(I) dimers affords stable aluminium(I) hydride compounds.

Stable diradicals are generally based on two s/p-localized or π-delocalized unpaired electrons (radicals). Here, the authors report a dication diradical that is based on two Se∴Se three-electron σ-bonds.

Magnesium hydride is a potential hydrogen-storage material, but its use is hampered by its high stability and slow hydrogen sorption processes. Dimeric magnesium compounds can act as models for these materials, and it is now shown that they can be easily and reversibly hydrogenated across the magnesium–magnesium bond.

N-heterocyclic carbenes have been shown to be versatile ligands for metal catalysts and even catalysts in their own right. Here, bulky N-heterocyclic carbenes are shown to stabilize paramagnetic and electron-poor species sufficiently for their crystallographic characterization.

Although several inorganic analogues of cyclopentadiene have been reported with group-15 elements, examples featuring the heavier elements Sb and Bi remain scarce. Now, a Bi₅ ring has been stabilized between two Nb(cyclopentadienyl) units, forming a triple-decker sandwich structure; the bonding analysis indicates that a Nb–Nb bond goes through the centre of the Bi₅ plane.

Boron's unusual properties inspired big advances in chemistry. A compound in which boron binds two carbon monoxide molecules reveals another oddity — the element forms bonds similar to those of transition metals. See Letter p.327

Heavy analogues of carbynes of the type R–\({{{\dot{\mathrm E:}}}}\), where E is a group 14 element, are difficult to isolate in the condensed phase due to their high reactivity. Now, a germylyne radical supported by a sterically hindered hydrindacene ligand has been prepared and structurally characterized. Theoretical calculations show that the spin density mainly resides at the germanium centre.

Aromatic Cr₅ planes, capped by Sn atoms and enclosed within a large binary main-group molecular cage, are reported. This stabilizing framework facilitates the capture of metastable Cr clusters, providing insights into Cr–Cr bonding.

The study of main group complexes remains important to our fundamental understanding of main group element bonding and properties. Here the authors isolate and spectroscopically characterize a series of 8-coordinated alkaline earth metal–dinitrogen complexes M(N₂)₈ (M=Ca, Sr, Ba) in a low-temperature neon matrix.

Carbon-free analogues of metallocene with homoleptic arsenic or antimony ligands have remained experimentally elusive, especially analogues of higher nuclearity. Now, sandwich-type clusters containing three-dimensional icosahedral metal centres and As₅^– or Sb₅^– ligands have been synthesized.

Noble gases are the least reactive elements. Chemists have created the first neutral compound containing the noble gas argon, leaving only two stable elements in the periodic table — helium and neon — for which no neutral compound exists.

Introducing main group elements into neutral and charged cyclobutadienes enables the fine-tuning of their stability and electronic structures by disrupting their aromatic and antiaromatic character. Here, the authors report the isolation and characterization of a 4π-electron tetrasilacyclobutadiene, an analogue of a 4π neutral cyclobutadiene that exhibits features of a Möbius-type aromatic ring.

Lewis’ shared electron-pair model was a stroke of genius, describing the structure and reactivity of molecules purely on the basis of his tremendous knowledge of empirical chemistry without any quantum chemistry. Unprecedented in simplicity, its success unfortunately concealed some misleading interpretations of the physical origin of chemical bonding.

This Perspective introduces energy decomposition analysis as a means of providing a quantum chemically derived bonding model that we can use to rationalize molecular geometries and bonding. The model serves as a bridge between the simple Lewis electron-pair bond and the complicated quantum theoretical nature of the chemical bond.