Computational chemistry of molecular inorganic systems

Applied computational chemistry holds a central position as a key technique that contributes to all aspects of molecular inorganic chemistry. The last few years have seen the continued development of methodology, computer hardware and algorithms that have resulted in an ever expanding range of chemical systems and properties that are amenable to calculation. All parts of the periodic table are within reach and the size of the system and the complexity of the issues that can be studied continues to grow.

This themed issue aims to showcase the full breadth of the impact of computational methods on molecular inorganic chemistry. The issue contains papers that highlight applications in small molecule activation, organometallic reactivity, bioinorganic chemistry, the modelling of spectroscopic properties (including NMR, Mössbauer, K-edge absorption and vibrational data) and practical methodological aspects of computational chemistry. The model systems themselves range from single metal atoms through to multi-metallic systems at the core of enzyme active sites.

The very success of computational chemistry in tackling large models itself brings new challenges in ensuring that the true complexity of the real chemical system is correctly addressed. In this regard, several important recent developments in the field are represented in this issue. Density functional theory (DFT) remains the dominant technique among the papers presented. However the difficulty in describing weak interactions through this approach is being addressed through the use of dispersion-corrected functionals as seen, in particular, in the contributions from Fey, Harvey and co-workers (DOI: 10.1039/c1dt10909j) and from Ryde and co-workers (DOI: 10.1039/c1dt10867k).

The challenge of treating the broader chemical environment beyond the molecule of direct interest is increasingly being taken up. Solvent effects are routinely taken into account through continuum methods and specific solvation is being addressed. For the latter a treatment of the time-evolution of the system can be achieved through the application of molecular dynamics (MD) techniques. Examples are seen in the contributions of Bühl and Grenthe (DOI: 10.1039/c1dt10796h) and Gérard and co-workers (DOI: 10.1039/c1dt10604j). Such methods remain highly computationally intensive and alternative approaches are presented by Deeth and co-workers through their Ligand Field Molecular Mechanics method (DOI: 10.1039/c1dt10794a) and by the hybrid quantum chemical/statistical mechanics techniques of Sato and co-workers (DOI: 10.1039/c1dt10703h).

The subject matter of the papers in this themed issue reflect many of the concerns of the modern world. Prominent are papers dealing with the chemistry of lanthanide and actinide elements, on clean and efficient catalysis, as well as oxidation chemistry and the catalytic formation of dioxygen. All the papers in this issue present a computational study that is either parallel to new experimental results, or closely linked to experimental observation. The ability of computational modeling to complement and rationalise empirical data and ultimately to predict behaviour remains one of the great strengths of our discipline.

I would like to thank all those authors who have contributed to this issue and whose work has combined to make such an effective advert for the importance of computational chemistry in modern molecular inorganic chemistry.

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