Introduction to ‘Frontiers in Main Group Chemistry’

Liu Leo Liu

Liu Leo Liu is a professor at the Southern University of Science and Technology (SUSTech), where he leads a research team focused on ambiphilic main group compounds. He received his BSc in chemistry from Xiamen University in 2011 and PhD in organic chemistry in 2016 from a joint program with Xiamen University and the University of California, San Diego. After postdoctoral research at the University of Toronto and the University of California, Berkeley/Lawrence Berkeley National Laboratory, he joined SUSTech in 2020.

Viktoria H. Gessner

Viktoria H. Gessner is a professor at Ruhr-University Bochum (Germany). She obtained her PhD from TU Dortmund in 2009 and completed a postdoctoral stint at the University of California in Berkeley (USA). She began her independent career at the University of Würzburg and moved to Bochum in 2016. Gessner's research interests lie in the field of organometallic chemistry and catalysis, including the development of carbanionic and ylidic ligands for the stabilization of reactive main group compounds and the design of new catalysts and reagents.

Douglas W. Stephan

Doug Stephan OC FRS FRSC began his career at the University of Windsor in 1982 and moved to the University of Toronto as Professor and Canada Research Chair in 2008, where he is now a university professor and the J.C. Polanyi Chair in chemistry. He was an associate editor and Chair of the board for Chemical Society Reviews and now chairs the editorial board of Chemical Communications. His work has spanned the periodic table, working in transition metal and main group catalysis, although he is best known as the founder of the field of “frustrated Lewis pair” (FLP) chemistry.

Main group chemistry is experiencing a profound resurgence. Once framed largely in terms of classical structure, bonding, and stoichiometric reactivity, the field has evolved into a far more dynamic arena encompassing small-molecule activation, catalysis, materials synthesis, and functional molecular systems.¹ Enabled by sustained advances in ligand design, electronic-structure modulation, and kinetic stabilization, contemporary main group chemistry has moved well beyond the isolation of unusual compounds as an end in itself. Instead, increasingly refined control over geometry, frontier orbital manifolds, and bond polarization is allowing structurally unconventional species to be translated into distinctive reactivity and, ultimately, emergent function.^2–5 In this context, Frontiers in Main Group Chemistry seeks to capture a timely snapshot of a field that is simultaneously refining its conceptual foundations and extending its synthetic and functional reach.

The eight contributions collected in this themed issue reflect both the breadth and the intellectual coherence of modern main group chemistry. Although they span a diverse range of elements, molecular platforms, and target transformations, they are united by a common principle: deliberate manipulation of structure and electronics can unlock new bonding modes, noncanonical reactivity patterns, and chemically useful function. Taken together, these studies show that the current vitality of main group chemistry lies not only in the continued discovery of unprecedented species, but also in the growing ability to place those discoveries within broader mechanistic, catalytic, and materials-oriented frameworks.

A first defining theme emerging from this collection is the steadily expanding reactivity space of low-valent and electronically unusual main-group compounds. Scheschkewitz et al. report the selective activation of carbon dioxide and ethyl isocyanate at the central carbon atom by an N-heterocyclic carbene-stabilized para-silylenephenylene-bridged bis(germylene), disclosing a cooperative silagermylenation manifold and, notably, cyclic (alkyl)(amino)carbene-induced radical fragmentation of the CO₂-expanded product.⁶ In a conceptually related but mechanistically distinct direction, Inoue et al. demonstrate that neutral silicon- and germanium-based Lewis superacids are competent promoters for the catalytic reduction of relatively robust element–oxygen double bonds in phosphine oxides, sulfoxide, and amide.⁷ Together, these studies underscore a central feature of current main group chemistry: carefully orchestrated electronic unsaturation, ambiphilicity, or high electrophilicity can now be deployed with increasing precision to enable bond activation, bond cleavage, and bond construction in substrates once considered beyond the comfortable reach of p-block reactivity.

A second prominent motif is the increasingly intimate relationship between substituent patterns, electronic differentiation, and reaction outcome. Dobrovetsky et al. show that the reactivity of o-carboranes toward cyclic (alkyl)(amino)carbenes is highly sensitive to carbon substitution, giving rise to divergent pathways that include C–H insertion, B–H insertion, or nucleophilic attack with concomitant nido-cluster formation, depending on the electronic and steric character of the substituents.⁸ In a complementary study, Ye et al. elucidate the isocyanide insertion chemistry of a carborane-fused borirane, revealing a sequential coordination/insertion scenario together with markedly enhanced isocyanide affinity in the further ring-expanded α-diimine product.⁹ These contributions exemplify how subtle steric and electronic perturbations in cluster and cage architectures can be translated into sharply differentiated reaction trajectories, thereby enabling increasingly programmable control over bond activation, ring expansion, and reversible substrate capture.

A third thread running throughout the issue is the emergence of new conceptual frameworks for heavier-element bonding and reactivity. Chitnis et al. provide experimentally grounded estimates for the acidity and hydridicity of Sb–H bonds and disclose a new D_2d-symmetric group 15 metal cluster topology, thereby advancing the broader understanding of how heavy p-block element–hydrogen bonds may engage in both proton-transfer and hydride-transfer chemistry.¹⁰ Dielmann et al. expand phosphonioacetylide chemistry through isolable alkali–metal precursors that function as transferable rod-shaped carbon donor ligands, opening access to structurally distinctive and strongly donating ligand platforms.¹¹ Hemingway and Lu et al. meanwhile report a non-aqueous Li/Na perchlorate separation enabled by selective coordination with a semi-flexible hexadentate amine ligand, demonstrating that coordination principles rooted in main-group and s-block chemistry can be leveraged to address problems of wider synthetic and practical significance.¹² Collectively, these studies reinforce the point that modern main group chemistry is not merely broadening element scope; it is also redefining the conceptual vocabulary through which reactivity, bonding, and utility are interpreted.

The issue further highlights the increasingly productive dialogue between molecular main group chemistry and macromolecular or materials-directed research. In a timely Review, Wiebe and Staubitz survey transition-metal-free routes to poly(aminoboranes) and poly(phosphinoboranes), emphasizing mechanistic distinctions from metal-mediated dehydropolymerization and illustrating how control over the generation of reactive monomeric intermediates can unlock new polymerization concepts and architectures.¹³ In this regard, the present collection extends beyond discrete-molecule synthesis and reactivity per se, and points toward a broader future in which main group chemistry contributes in an increasingly integrated manner to sustainable synthesis, functional materials, and mechanism-informed molecular design.

Taken together, the contributions assembled here delineate several defining characteristics of the current main-group resurgence. Unusual bonding motifs are no longer merely synthetic curiosities but increasingly constitute enabling platforms for new chemical functions. Reactivity in main-group systems is becoming progressively more programmable through the interplay of ligand environment, substituent effects, and geometric constraint. At the same time, the field is moving beyond its traditional boundaries, engaging with questions central to catalysis, polymer chemistry, materials science, and molecular function. We hope that this themed issue will serve not only as a record of recent progress, but also as an invitation to further explore the conceptual richness, synthetic versatility, and functional promise that contemporary main group chemistry now vividly embodies.

Finally, we sincerely thank all authors for their excellent contributions to this themed issue, and all reviewers for their careful assessment and constructive comments. We are likewise grateful to the editorial and production teams of Inorganic Chemistry Frontiers for their dedicated support in bringing this collection to completion. We hope that readers will find in these contributions not only a valuable perspective on current advances, but also inspiration for future developments in this rapidly evolving field.

References

1. R. L. Melen, Science, 2019, 363, 479–484.
2. P. P. Power, Nature, 2010, 463, 171–177.
3. D. W. Stephan, Science, 2016, 354, aaf7229.
4. F. Krischer and V. H. Gessner, JACS Au, 2024, 4, 1709–1722.
5. S. Burnett, S. Miller, F. Murphy and C. E. Weetman, ACS Catal., 2026, 16, 5276–5293.
6. A.-L. Thömmes, R. Völker, B. Morgenstern, M. Zimmer, D. Munz, C. W. M. Kay and D. Scheschkewitz, Inorg. Chem. Front., 2025, 12, 4835–4843.
7. D. Franz, T. R. Frost, S. Stigler and S. Inoue, Inorg. Chem. Front., 2026, 13, 2989–2998.
8. N. Safadi, V. Kampel and R. Dobrovetsky, Inorg. Chem. Front., 2026, 13, 3869–3877.
9. L. Xiang, J. Wang, J. Bolch, A. Matler and Q. Ye, Inorg. Chem. Front., 2026, 13, 1515–1523.
10. M. A. Z. MacEachern, T. George and S. S. Chitnis, Inorg. Chem. Front., 2026, 13, 957–962.
11. F. Brylak, P. Löwe, K. Wurst, S. Hohloch and F. Dielmann, Inorg. Chem. Front., 2025, 12, 7556–7565.
12. J. M. Hemingway, X. Yang, P. G. Waddell, J. Cornelio, M. E. Lowe, J. A. Dawson, P. R. Slater, R. J. Armstrong and E. Lu, Inorg. Chem. Front., 2026, 13, 1073–1079.
13. M. A. Wiebe and A. Staubitz, Inorg. Chem. Front., 2026, 13, 1310–1323.

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