Anionic N-donors

Complexes with Multidentate Ligands Containing Anionic N-Donors... 

Table 2.4 Bond distances (pm) in selected complexes with multidentate ligands containing anionic N-donors.

There have been only a handful of studies on exchange coupled ruthenium dimers and yet the information available on metal-metal coupling is potentially as valuable as that obtained from mixed-valence complexes. The reason for this lack of activity has been the greater familiarity of researchers with the chemistry of Ru(II) bound to 7r-acid ligands. The synthetic pathways to complexes of this type are well explored (7) and possess the tremendous advantages of stability and ease of handling. Ru(II) complexes that incorporate anionic n donor... 

Anionic N-donor ligands comprise essentially amido (NR2 ), imides or nitrenes (NR ) amidinates or guanidinates... 

Figure 3 Ti(m) alkyl complexes supported by multidentate anionic N-donor ligands.

Treatment of a typical CA inhibitor, acetazolamide with la. yields the product as a precipitate, which was identified as a I complex 9. wherein the sulfonamide is deprotonated to coordinate with zinc(II) ions. It is o/ interest to point out that with other transition metal ions (e.g., Ni " ), acetazolamide binds to the thiazole N but not to the deprotonated sulfonamide nitrogen. This different behavior of zinc(II) best illustrates its outstanding (hard) acid nature that favors the anionic N donor over the neutral (soft) N donor. The value of 7.4 for... 

In fact, MOFs based on anionic N-donor hgands and metal clusters as nodes have been synthesized. 

Simple alkyl and aryl cr-bonded complexes are conveniently prepared by reaction of an alkylating reagent with a halocobalt(II) precursor. All-alkyl systems are rare, but the penta-methylcobaltate(II) anion is known.197 More typically, the coordination sphere of the metal contains additional co-ligands, particularly with P, S, or N donors. Some examples that reflect the style of reactions extant appear below. 

These rod-shaped ligands share a sterically efficient terminal N-donor and their divalent Co chemistry is well established. They will be discussed here only with selected examples. [Co (NCMe)6](TFPB)2 (TFPB- = tetrakis(3,5-bis(trifhioromethyl)phenyl)borate)) has been synthesized and characterized in the solid state along with a number of other divalent transition metal analogs.357 As a result of the extremely poor coordinating ability of the anion and facile loss of MeCN ligands from the cation, the salt is an excellent source of naked Co2+ ions. Thermolysis up to 100 °C leads to the loss of one MeCN and formation of a r -bound nitrile, whereas above 130 °C decomposition occurs with loss of MeCN and abstraction of fluoride from the anion to form CoF2. 

The most frequently reported mixed C/N-donor ligands are the 2-phenylpyridine anion, ppy (170), orthometalated 2,2 -bipyridine, C3N bpy (171), and derivatives, for example (172). 

The acidification of N—H bonds in amines and stabilization of the amide anion resulting on dissociation can be achieved by a variety of groups, which all have electron-withdrawal properties in common. These anions can then act as N-donors towards Cd or Hg. 

The structure of [H2dmbg] [CuClJ has been reported recently [42]. Not unexpectedly, the [H2dmbg]2+ cation, unlike the [Hdmbg]+ cation, acts as a discrete cation. Like the [Hdmbg]+ cation, however, it is non-planar without an intra-molecular N-H N contact. All seven N-H donor sites are utilised in cation-anion N-H Cl interactions to form a 3-D network structure. 

This book focuses on species of the type (RX)-, that is, on cation- and anion-radicals. These terms were first introduced by Weitz (1928) ( Kationradikale and Anionradikale ). Currently, organic chemists differentiate that the anion-radicals originate from n and o acceptors and the cation-radicals originate from n, a, or n donors. These species are formed during reactions, when an organic molecule either loses one electron from the action of an electron acceptor or acquires one from the action of an electron donor R—X - e —> (R—X)+ or R—X + e —> (R—X). ... 

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