Covalent Interactions in Coordination Chemistry

Covalent interactions in coordination chemistry encompass the formation and modulation of shared‐electron bonds between metal centres and ligands. Beyond the classical ionic view of metal–ligand attraction, modern studies emphasise the continuum between ionic and covalent character, recognising coordinate (dative) bonds as key contributors to structural stability and reactivity. These interactions govern electron sharing, orbital overlap and the extent of back‐bonding, influencing electronic spectra, redox potentials and catalytic activity. Non‐classical covalent motifs such as chalcogen bonding and σ-hole interactions further enrich the binding landscape, offering directional, secondary contacts that reinforce core coordination bonds. Advances in spectroscopic and computational methods have clarified how solvent polarity, ligand design and metal oxidation state tune the balance between covalent and ionic contributions. The result is a deeper understanding of how tailored ligands can direct selective activation of small molecules, enable robust frameworks for energy conversion and deliver precision in homogeneous and bioinspired catalysts. By integrating insights from real‐space bonding analyses and high‐resolution crystallography, researchers now exploit bespoke covalent interactions to engineer next‐generation functional materials and catalytic platforms with enhanced efficiency and selectivity.

Research from Nature Portfolio

A combined experimental and computational investigation has revealed that increasing solvent polarity markedly enhances the stability of covalent–dative bonds in simple amine–borane complexes. The study demonstrates that the ionic fraction of the bond is responsible for the observed stabilisation, as solvation effects preferentially stabilise charged fragments over the intact complex. This finding provides a predictive framework for tuning bond strength through solvent choice and highlights the importance of ionic–covalent contributions in determining the thermodynamic properties of coordinate bonds.

Covalent Interactions in Coordination Chemistry publication trend

The graph below shows the total number of articles in covalent interactions in coordination chemistry across all publications each year (not limited to Nature Index journals).

Technical terms

Dative bond: A coordinate covalent bond in which both electrons are donated by one atom to an empty orbital on another.

Chalcogen bond: A non-covalent interaction involving elements of group 16 acting as electrophilic sites that engage in directional contacts with nucleophiles.

σ-Hole: A region of positive electrostatic potential on a covalently bonded atom, often enabling secondary interactions beyond the primary bond.

Peri-substitution: Substitution at adjacent positions on a fused ring system that enforces close spatial proximity and through-space interactions.

Ligand: A molecule or ion that donates electron density to a central metal atom or ion to form a coordination complex.

References

1. The stability of covalent dative bond significantly increases with increasing solvent polarity. Nature Communications (2022).
2. Chalcogen-Bond-Assisted Formation of the N→C Dative Bonds in the Complexes between Chalcogenadiazoles/Chalcogenatriazoles and Fullerene C60. Molecules (2024).
3. Phosphine and Selenoether peri-Substituted Acenaphthenes and Their Transition-Metal Complexes: Structural and NMR Investigations. Inorganic Chemistry (2023).
4. Exploring the Effects of Se Basicity on a Te···Se Interaction Supported by a Rigid Indazolium Backbone. Organometallics (2024).