: The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields

Tetrathiafulvalenes, oligoacenenes, and their buckminsterfullerene derivatives: the brick and mortar of organic electronics.

The chemistry of heavier main-group elements such as aluminium, silicon and phosphorus is very different from that of the lighter ones such as boron, carbon and nitrogen, yet discussions of this topic have been dominated by comparisons with the light elements. Philip Power's review focuses on advances in chemistry of the heavier main-group elements that reveal them as having more in common with the transition metals than the lighter members of the main groups. The concept of heavier main-group elements as 'transition metals' is supported by recent work showing that many of the new compounds react with small molecules such as H2, NH3, C2H4 and CO under mild conditions and display potential as catalysts. The last quarter of the twentieth century and the beginning decade of the twenty-first witnessed spectacular discoveries in the chemistry of the heavier main-group elements. The new compounds that were synthesized highlighted the fundamental differences between their electronic properties and those of the lighter elements to a degree that was not previously apparent. This has led to new structural and bonding insights as well as a gradually increasing realization that the chemistry of the heavier main-group elements more resembles that of transition-metal complexes than that of their lighter main-group congeners. The similarity is underlined by recent work, which has shown that many of the new compounds react with small molecules such as H2, NH3, C2H4 or CO under mild conditions and display potential for applications in catalysis.

Main-group elements as transition metals

This review focuses on classifying different types of long wavelength absorbing BODIPY dyes based on the wide range of structural modification methods that have been adopted, and on tabulating their spectral and photophysical properties. The structure–property relationships are analyzed in depth with reference to molecular modeling calculations, so that the effectiveness of the different structural modification strategies for shifting the main BODIPY spectral bands to longer wavelengths can be readily compared, along with their effects on the fluorescence quantum yield (ΦF) values. This should facilitate the future rational design of red/NIR region BODIPY dyes for a wide range of different applications.

Structural modification strategies for the rational design of red/NIR region BODIPYs

Organophosphorus π-Conjugated Materials

Preface. List of Contributors. 1. Triarylmethyl and Related Radicals (Thomas T. Tidwell). 1.1 Introduction. 1.2 Free radical rearrangements. 1.3 Other routes to triphenylmethyl radicals. 1.4 The persistent radical effect. 1.5 Properties of triphenylmethyl radicals. 1.6 Steric effects and persistent radicals. 1.7 Substituted triphenylmethyl radicals and dimers. 1.8 Tris(heteroaryl)methyl and related triarylmethyl radicals. 1.9 Delocalized persistent radicals: analogues of triarylmethyl radicals. 1.10 Tetrathiatriarylmethyl (TAM) and related triarylmethyl radicals. 1.11 Perchlorinated triarylmethyl radicals. 1.12 Other triarylmethyl radicals. 1.13 Diradicals and polyradicals related to triphenylmethyl. 1.14 Outlook. Acknowledgements. References. 2. Polychlorotriphenylmethyl Radicals: Towards Multifunctional Molecular Materials (Jaume Veciana and Imma Ratera). 2.1 Introduction. 2.2 Functional molecular materials based on PTM radicals. 2.3 Multifunctional switchable molecular materials based on PTM radicals. 2.4 Conclusions. 3. Phenalenyls, Cyclopentadienyls, and Other Carbon-Centered Radicals (Yasushi Morita and Shinsuke Nishida). 3.1 Introduction. 3.2 Open shell graphene. 3.3 Phenalenyl. 3.4 2,5,8-Tri-tert-butylphenalenyl radical. 3.5 Perchlorophenalenyl radical. 3.6 Dithiophenalenyl radicals. 3.7 Nitrogen-containing phenalenyl systems. 3.8 Oxophenalenoxyl systems. 3.9 Phenalenyl-based zwitterionic radicals. 3.10 -Extended phenalenyl systems. 3.11 Curve-structured phenalenyl system. 3.12 Non-alternant stable radicals. 3.13 Stable triplet carbenes. 3.14 Conclusions. 4. The Nitrogen Oxides: Persistent Radicals and van der Waals Complex Dimers (D. Scott Bohle). 4.1 Introduction. 4.2 Synthetic access. 4.3 Physical properties. 4.4 Structural chemistry of the monomers and dimers. 4.5 Electronic structure of nitrogen oxides. 4.6 Reactivity of nitric oxide and nitrogen dioxide and their van der Waals complexes. 4.7 The kinetics of nitric oxide's termolecular reactions. 4.8 Biochemical and organic reactions of nitric oxide. 4.9 General reactivity patterns. 4.10 The colored species problem in nitric oxide chemistry. 4.11 Conclusions. 5. Nitroxide Radicals: Properties, Synthesis and Applications (Hakim Karoui, Franc¸ois Le Moigne, Olivier Ouari and Paul Tordoi). 5.1 Introduction. 5.2 Nitroxide structure. 5.3 Nitroxide multiradicals. 5.4 Nitronyl nitroxides (NNOs). 5.5 Synthesis of nitroxides. 5.6 Chemical properties of nitroxides. 5.7 Nitroxides in supramolecular entities. 5.8 Nitroxides for dynamic nuclear polarization (DNP) enhanced NMR. 5.9 Nitroxides as pH-sensitive spin probes. 5.10 Nitroxides as prefluorescent probes. 5.11 EPR-spin trapping technique. 5.12 Conclusions. 6. The Only Stable Organic Sigma Radicals: Di-tert-Alkyliminoxyls (Keith U. Ingold). 6.1 Introduction. 6.2 The discovery of stable iminoxyls. 6.3 Hydrogen atom abstraction by di-tert-butyliminoxyl. 6.4 Other reactions and non-reactions of di-tert-butyliminoxyl. 6.5 Di-tert-alkyliminoxyls more sterically crowded than di-tert-butyliminoxyl. 6.6 Di-(1-Adamantyl)iminoxyl: a truly stable radical. 7. Verdazyls and Related Radicals Containing the Hydrazyl [R2N NR] Group (Robin G. Hicks). 7.1 Introduction. 7.2 Verdazyl radicals. 7.3 Tetraazapentenyl radicals. 7.4 Tetrazolinyl radicals. 7.5 1,2,4-Triazolinyl radicals. 7.6 1,2,4,5-Tetrazinyl radicals. 7.7 Benzo-1,2,4-triazinyl radicals. 7.8 Summary. 8. Metal Coordinated Phenoxyl Radicals (Fabrice Thomas). 8.1 Introduction. 8.2 General properties of phenoxyl radicals. 8.3 Occurrence of tyrosyl radicals in proteins. 8.4 Complexes with coordinated phenoxyl radicals. 8.5 Conclusions. 8.6 Abbreviations. 9. The Synthesis and Characterization of Stable Radicals Containing the Thiazyl (SN) Fragment and Their Use as Building Blocks for Advanced Functional Materials (Robin G. Hicks). 9.1 Introduction. 9.2 Radicals based exclusively on sulfur and nitrogen. 9.3 "Organothiazyl" radicals. 9.4 Thiazyl radicals as "advanced materials". 9.5 Conclusions. 10. Stable Radicals of the Heavy p-Block Elements (Jari Konu and Tristram Chivers). 10.1 Introduction. 10.2 Group 13 element radicals. 10.3 Group 14 element radicals. 10.4 Group 15 element radicals. 10.5 Group 16 element radicals. 10.6 Group 17 element radicals. 10.7 Summary and future prospects. 11. Application of Stable Radicals as Mediators in Living-Radical Polymerization (Andrea R. Szkurhan, Julie Lukkarila and Michael K. Georges). 11.1 Introduction. 11.2 Living polymerizations. 11.3 Stable free radical polymerization. 11.4.1 Triazolinyl radicals. 11.5 Aqueous stable free radical polymerization processes. 11.6 The application of stable free radical polymerization to new materials. 11.7 Conclusions. List of abbreviations. 12. Nitroxide-Catalyzed Alcohol Oxidations in Organic Synthesis (Christian Bruckner). 12.1 Introduction. 12.2 Mechanism of TEMPO-catalyzed alcohol oxidations. 12.3 Nitroxides used as catalysts. 12.4 Chemoselectivity: oxidation of primary vs secondary alcohols. 12.5 Chemoselectivity: oxidation of primary vs benzylic alcohols. 12.6 Oxidation of secondary alcohols to ketones. 12.7 Oxidations of alcohols to carboxylic acids. 12.8 Stereoselective nitroxide-catalyzed oxidations. 12.9 Secondary oxidants used in nitroxide-catalyzed reactions. 12.10 Use of nitroxide-catalyzed oxidations in tandem reactions. 12.11 Predictable side reactions. 12.12 Comparison with other oxidation methods. 12.13 Nitroxide-catalyzed oxidations and green chemistry. 13. Metal Nitroxide Complexes: Synthesis and Magnetostructural Correlations (Victor Ovcharenko). 13.1 Introduction. 13.2 Two types of nitroxide for direct coordination of the metal to the nitroxyl group. 13.3 Ferro- and ferrimagnets based on metal nitroxide complexes. 13.4 Heterospin systems based on polynuclear compounds of metals with nitroxides. 13.5 Breathing crystals. 13.6 Other studies of metal nitroxides. 13.7 Conclusions. 14. Rechargeable Batteries Using Robust but Redox Active Organic Radicals (Takeo Suga and Hiroyuki Nishide). 14.1 Introduction. 14.2 Redox reaction of organic radicals. 14.3 Mechanism and performance of an organic radical battery. 14.4 Molecular design and synthesis of redox active radical polymers. 14.5 A totally organic-based radical battery. 14.6 Conclusions. 15. Spin Labeling: A Modern Perspective (Lawrence J. Berliner). 15.1 Introduction. 15.2 The early years. 15.3 Advantages of nitroxides. 15.4 Applications of spin labeling to biochemical and biological systems. 15.5 Distance measurements. 15.6 Site directed spin labeling (SDSL): how is it done? 15.7 Other spin labeling applications. 15.8 Conclusions. 16. Functional in vivo EPR Spectroscopy and Imaging Using Nitroxide and Trityl Radicals (Valery V. Khramtsov and Jay L. Zweier). 16.1 Introduction. 16.2 Nitroxyl radicals. 16.3 Triarylmethyl (trityl) radicals. 16.4 In vivo EPR oximetry using nitroxyl and trityl probes. 16.5 EPR spectroscopy and imaging of pH using nitroxyl and trityl probes. 16.6 Redox- and thiol-sensitive nitroxide probes. 16.7 Conclusions. 17. Biologically Relevant Chemistry of Nitroxides (Sara Goldstein and Amram Samuni). 17.1 Introduction. 17.2 Mechanisms of nitroxide reactions with biologically relevant small radicals. 17.3 Nitroxides as SOD mimics. 17.4 Nitroxides as catalytic antioxidants in biological systems. 17.5 Conclusions. Acknowledgements. References. Index.

Stable radicals : fundamentals and applied aspects of odd-electron compounds

Many kinds of radicals are stable enough to isolate, handle, and store without any special precautions. The diversity in molecular architectures of these stable radicals is sufficiently large that the common factors governing radical stability/persistence, geometric and electronic structure, association/dimerization preferences, and reactivity have generally not been well articulated or appreciated. This review provides a survey of the major classes of stable or persistent organic/organomain group radicals with a view to presenting a unified description of the interdependencies between radical molecular structure and properties.

What's new in stable radical chemistry?

The magnetochemistry of verdazyl radical-based materials

THE electronic and geometric properties of C60 can be perturbed by replacing one or more carbon atoms of the fullerene skeleton with an atom of a different element. Exchange of one carbon atom with nitrogen, a trivalent atom with a lone pair of electrons, produces the azafullerene radical C59N, which is isoelectronic with the C60 radical anion. The process is slightly similar to doping silicon with phosphorus1. We have previously described the synthesis of the azafullerene dimer2; here we report the bulk preparation of the simplest azafullerene, C59HN. The electronic, vibrational and 13C NMR spectroscopic features of C59HN are similar to those of the dimer2, except for the signature of the sp3 (C–H) carbon. C59HN should open the door to a new chemistry of heterofullerenes.

Synthesis of hydroazafullerene C59HN, the parent hydroheterofullerene

For over two decades there have been intense efforts aimed at the development of alternatives to conventional magnets, particularly materials comprised in part or wholly of molecular components. Such alternatives offer the prospect of realizing magnets fabricated through controlled, low-temperature, solution-based chemistry, as opposed to high-temperature metallurgical routes, and also the possibility of tuning magnetic properties through synthesis. However, examples of magnetically ordered molecular materials at or near room temperature are extremely rare, and the properties of these materials are often capricious and difficult to reproduce. Here we present a versatile solution-based route to a new class of metal-organic materials exhibiting magnetic order well above room temperature. Reactions of the metal (M) precursor complex bis(1,5-cyclooctadiene)nickel with three different organics A-TCNE (tetracyanoethylene), TCNQ (7,7,8,8-tetracyanoquinodimethane) or DDQ (2,3-dichloro-5,6-dicyano-1,4-benzoquinone)--proceed via electron transfer from nickel to A and lead to materials containing Ni(II) ions and reduced forms of A in a 2:1 Ni:A ratio--that is, opposite to that of conventional (low Curie temperature) MA(2)-type magnets. These materials also contain oxygen-based species within their architectures. Magnetic characterization of the three compounds reveals spontaneous field-dependent magnetization and hysteresis at room temperature, with ordering temperatures well above ambient. The unusual stoichiometry and striking magnetic properties highlight these three compounds as members of a class of stable magnets that are at the interface between conventional inorganic magnets and genuine molecule-based magnets.

Robin G. Hicks

Papers

Stable radicals : fundamentals and applied aspects of odd-electron compounds

What's new in stable radical chemistry?

The magnetochemistry of verdazyl radical-based materials

Synthesis of hydroazafullerene C59HN, the parent hydroheterofullerene

High-temperature metal–organic magnets