50 Years of Structure and Bonding – The Anniversary Volume

In order to understand the launching in 1966 of Structure and Bonding, it is necessary to appreciate the factors which contributed to the emergence of inorganic chemistry as an equal branch of chemistry. A variety of social and economic factors contributed to the transformation of inorganic chemistry from an essentially descriptive subject into an intellectual equal of organic and physical chemistry. The aims and distinctive features of Structure and Bonding are identified with reference to the initial preface and the composition of the editorial board. The research interests and characteristics of some of the founding editorial board members are introduced and used as a basis for highlighting the important topics which were covered in the initial 50 volumes. Subsequent changes in the character of the journal are reviewed and used to introduce the present anniversary volume.

This chapter looks at key advances in anion receptors based on organic frameworks since 2008 including the development of halogen-bonding systems, C–H hydrogen bond donors, new transmembrane anion transporters and the roles anions can play in self-assembly processes.

A personal perspective is given of progress in single-molecule magnets (SMMs) and related phenomena over the last decade. Progress is discussed under seven headings: “Lanthanide Single-Molecule Magnets”, “Organometallic and Low Coordination Number SMMs”, “Single-Chain Magnets”, “SMMs on Surfaces and on the Route to Spintronic Devices”, “Molecular Nanomagnets for Magnetic Cooling”, “Molecular Nanomagnets for Quantum Information Processing” and “Photomagnets”. In all areas, substantial progress has been made, but the proposition is made that prototype devices are now needed for the field to make further progress.

Great strides have been made in increasing performance and decreasing sensitivity in energetic materials since the first commercialization of nitroglycerine (NG) in the form of dynamite in 1867 by Alfred Nobel. However, the high energy manufacturers continue to rely on traditional chemicals to meet their needs. New energetic materials must be developed to extend their capabilities and handling capabilities. The new materials which have been prepared recently have led to new possibilities. Important advances have been made especially in the area of high-nitrogen compounds, organic difluoramine derivatives. Computational simulations have also led not only to a greater insight into the basic thermodynamics and kinetics of these materials but also their practical behavior in the field. This chapter summarizes new developments that have been achieved since Volume 126 of Structure and Bonding, which was published in 2007 and gave a comprehensive review of the field.

Layered double hydroxides (LDHs) are a class of layered materials with highly tunable composition and controllable morphology. The layered structure of LDHs enables fabrication of a large variety of intercalated, assembled, and hybrid materials which have a wide range of applications as photofunctional materials and bio-related materials, in catalysis and electrochemistry, and as multifunctional materials. The efficacy of LDHs in many applications can be attributed to the confined microenvironment of the guest species and the host–guest interactions. In this review, we will first summarize the synthetic strategies used to produce LDHs and LDH-based materials and then discuss their host–guest interactions and finally their applications.

This review is a selection of research highlights since 2010 in two main areas of rare-earth catalysis, but it is not meant to be an exhaustive treatment. Part 1 (Sect. 2) deals with advances in intra- and intermolecular hydroamination, hydrophosphination, and hydrosilylation. Part 2 (Sect. 3) covers progress in the polymerization of 1,3-dienes, and it is split into three main subsections: cis-1,4-selective and trans-1,4-selective polymerization, the 3,4-selective polymerization of isoprene, and copolymerization reactions of 1,3-dienes with alkenes.

Unconventional high-T _c superconductivity, defined both in terms of the magnitude of the superconducting transition temperature, T _c, and the key role played by electronic correlations, not only is the realm of atom-based low-dimensional layered systems such as the cuprates or the iron pnictides but is also accessible in molecular systems such as the cubic alkali fullerides with stoichiometry A₃C₆₀ (A=alkali metal). In fulleride superconductors, isotropic high-T _c superconductivity occurs in competition with electronic ground states resulting from a fine balance between electron correlations and electron–phonon coupling in an electronic phase diagram strikingly similar to those of unconventional superconductors such as the cuprates and the heavy fermions. Superconductivity at the highest T _c (38 K) known for any molecular material emerges from the antiferromagnetic insulating state solely by changing an electronic parameter – the overlap between the outer wave functions of the constituent molecules – and T _c scales universally in a structure-independent dome-like relationship with proximity to the Mott metal–insulator transition (quantified by V, the volume/C₆₀, or equivalently by (U/W), the ratio of the on-site Coulomb energy, U, to the electronic bandwidth, W), a hallmark of electron correlations characteristic of high-T _c superconductors other than fullerides. The C₆₀ molecular electronic structure plays a key role in the Mott–Jahn–Teller (MJT) insulator formed at large V, with the on-molecule dynamic Jahn–Teller (JT) effect distorting the C₆₀ ^3– units and quenching the t _1u orbital degeneracy responsible for metallicity. As V decreases, the MJT insulator transforms first into an unconventional correlated JT metal (where localised electrons coexist with metallicity and the on-molecule distortion persists) and then into a Fermi liquid with a less prominent molecular electronic signature. This normal state crossover is mirrored in the evolution of the superconducting state, with the highest T _c found at the boundary between unconventional correlated and conventional weak-coupling BCS superconductivity, where the interplay between extended and molecular aspects of the electronic structure is optimised to create the superconductivity dome.

In this chapter, we wish to review the recent progress in the application of phthalocyanines as functional molecular materials including (1) semiconducting materials for organic photovoltaic cells and organic field effect transistors, (2) functional organic dyes as photosensitizers for photodynamic therapy and dye-sensitized solar cells, and (3) single-molecule magnets. The structure–function relationship has been highlighted on the bases of selected examples since 2010, which hopefully will be informative for the future developments of phthalocyanine chemistry and related materials science.

This chapter highlights the importance of structure–property relationships in transition metal complexes for the construction of molecular- and supramolecular-based photofunctional materials and summarizes the recent advancements of this class of complexes with potential applications in the areas of energy, catalysis, materials, biology, and diagnostics.

Optical spectroscopy of transition metal complexes plays an important role in establishing excited-state electronic and nuclear structures and thus in the elucidation of the multitude of photophysical and photochemical relaxation processes. The most important advances in this area of research over the past decade are due to the development of new experimental techniques such as ultrafast spectroscopy as well as structure determination in conjunction with other methods such as high-pressure and variable temperature techniques. In this contribution, several paradigmatic systems, namely, of complexes of chromium(III), iron(II), ruthenium(II), nickel(II), platinum(II) and palladium(II), are discussed with regard to their excited electronic and nuclear structures and photophysical relaxation processes.

The treatment of the high-spin d⁵-configurated iron(III) cation in 6- and 4-coordinate ligand fields is a highly complex matter. The ⁶A₁-ground state allows only spin-forbidden transitions, here of relevance to ten spin-reduced ⁴A₁-, ⁴A₂-, ⁴E(2x)-, ⁴T₁(3x)-, ⁴T₂(3x)-states, which are not easy to handle. Though the literature offers a series of carefully prepared solids with beautifully resolved ligand field spectra, the philosophy of utilising these in terms of their binding character, particularly in respect to the d-electron cloud density between cation and the anions, diverges. Accordingly, the magnitudes of reported ligand field parameters Δ and of the Racah parameters of interelectronic repulsion B and C, which parameterise the mentioned effects, differ, and comparisons become difficult. In this review we propose a well-founded and comprehensible calculational procedure, in order to, as the main matter of concern, convince the readers that the ligand field spectra also sensibly reflect finer perturbational details of local or even cooperative binding quality. The origin of the latter effects is from the chemical environment beyond the first coordination sphere of a central, say Fe^IIIL _n -complex (n = 6,4) in an extended solid. Already subtle disturbances of this kind will modify the shade of colour. An essential point of the discussion is the symmetry analysis, which provides rigorous constraints and sets strict conditions on what can be experimentally observed. We will first discuss manganese(II) in oxidic solids. Because a divalent cation is associated with rather ionic binding properties towards oxygen, crystal field theory is the appropriate analytical instrument. Iron(III) provides a situation, which requires more sophistication and a refinement of the theory by taking also bond covalency into account. A symmetry-based reinterpretation of the additional absorptions in the d–d-spectra of Fe^III and Cr^III in corundum-type solids is presented. This treatment sheds new light on the finer roots of the impressive red-to-green colour change of Cr³⁺ in mixed crystals Al_2−x Cr _x O₃ with increasing x. Particular examples are discussed, where absorptions due to octahedral and tetrahedral iron(III) overlap in the ligand field spectra of spinel- and garnet-type solids, which model the hue in a predictable way. Finally, though not directly related to the primary topic, the charge-transfer properties of oxidic iron(III) are briefly examined. These absorptions often stray far into the visible region, with a very frequently significant influence on the apparent hue.