Publisher Summary There have been many reviews and books on electron spin resonance (ESR) and several on transition metal ions. Many of these publications have been written by physicists or theoreticians and are very comprehensive. This review is aimed at inorganic chemists, who have had no experience relating to electron spin resonance and who are becoming more and more likely either to use the technique or to need to appreciate the significance of the information available from the technique. The first part of the review gives an elementary account of the relevant theory. There are many good books for further reading for the inorganic chemist, who wishes to go deeper into the subject. The second part of the review is a comprehensive survey of the results of ESR studies on compounds of transition elements. Inevitably, there has had to be some selection of material, and the criteria for inclusion or rejection has been based upon the likely interest of an inorganic chemist might have in the species. This is particularly in the areas, where there is a lot of related work, e.g., the Mn2+ host-lattice data. In the case of copper dg complexes, there has been much duplication of work and papers devoted to the spectra of complexes where a minor substitutive change has been made to a bulky organic ligand.

Electron Spin Resonance of Transition Metal Complexes

The ruthenium (II) complex [Ru(bipy)2(dppz)]2+(bipy = 2,2′-bipyridine, dppz = dipyrido[3,2-a : 2′,3′-c]phenazine) was synthesized, characterized, and studied. Its oxidation and first reduction potentials are respectively 1.24 and –1.02 V (vs. saturated calomel electrode). The maxima of the metal-to-ligand charge-transfer absorption and emission occur respectively at 448 and 610 nm. These data suggest that [Ru(bipy)2(dppz)]2+ is made up of two electronically independent units, one behaving as a [Ru(bipy)3]2+-like chromophore, the other as a phenazine-like electron acceptor. Excited-state absorption spectra were obtained for [Ru(bipy)2(dppz)]2+ and its parent complex [Ru(bipy)3]2+. Above 500 nm the latter shows only one maximum (at 510 nm), and the former shows two maxima (around 526 and 557 nm), whereas radical anions of both bipyridine and phenazine or dipyridophenazine show two maxima (at 512 and 552 nm for phenazine). In the case of [Ru(bipy)2(dppz)]2+ these results can be interpreted in terms of a light-induced directed charge transfer from the ruthenium to the phenazine part of the dipyridophenazine ligand, and its localization on this ligand moiety. Photochemical properties of [Ru(bipy)2(dppz)]2+ were studied in ethanol. The excited state of the complex is quenched both by an electron acceptor (methylviologen, kq= 1.37 × 109 dm3 mol–1 s–1) and an electron donor (triethanolamine, kq= 4.40 × 107 dm3 mol–1s–1).

Synthesis and study of a mixed-ligand ruthenium(II) complex in its ground and excited states: bis(2,2′-bipyridine)(dipyrido[3,2-a : 2′,3′-c]phenazine-N4N5)ruthenium(II)

Bimolecular electron transfer reactions of the excited states of transition metal complexes

Publisher Summary In this chapter, one attempts to present a review giving emphasis to these new fields, and to this end as much material as possible has been subdivided under the headings of the various techniques and types of information. As a result of the chosen subdivision, certain aspects, such as the nature of the metal-to-ligand bonding are discussed in more than one section. Little mention will be made of the analytical uses of these ligands, which have recently been reviewed separately (711), of the synthesis of ring-substituted derivatives of the parent ligands, although a potentially useful method using transition-metal complexes has been reported; or of related species, such as 4,4‘-bipyridyl. The coverage of the literature is complete up to the end of 1967, and usually to the end of April 1968, and although many publications have regretfully not been mentioned, one have attempted to discuss the great majority of those papers which one believe to be of special importance.

The Chemistry of Complexes Containing 2,2′-Bipyridyl, 1, 10-Phenanthroline, or 2,2′,6′,2”-Terpyridyl as Ligands

The transition metal complexes [Ru(dmb)3]2+ and [Ru(dpb)3]2+, where dmb is 4,4‘-dimethyl-2,2‘-bipyridine and dpb is 4,4‘-diphenyl-2,2‘-bipyridine, have been studied by femtosecond visible electronic absorption spectroscopy. Spectroelectrochemical measurements in conjunction with nanosecond time-resolved absorption spectroscopy allow for the assignment of various features in the excited-state differential absorption spectra as both ligand-based π* ← π* and ligand-to-metal charge transfer (LMCT) in nature. A unique absorptive feature centered at ∼ 530 nm in [Ru(dpb)3]2+ was identified as an optical marker for the thermalized (and hence fully intraligand delocalized) excited state. Single wavelength and full spectrum transient absorption data were obtained on both molecules in CH3CN solution at room temperature following metal-to-ligand charge transfer (MLCT) excitation at 400 nm. Data on [Ru(dmb)3]2+ at 532 nm, a region of net excited-state absorption, revealed biphasic decay kinetics (∼120 fs and 5 ps) att...

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Carol Mahon

Papers

Preparation of sodium tris(2,2'-bipyridine)ferrate(-I)

Crystal structure of mercury(II) cyanide-silver nitrate dihydrate

Crystal structure of mercury(II) cyanonitrate

Crystal structure of zinc nitrate-2 mercury(II) cyanide-7 water