Silver nitrogen ligands

Mononuclear silver(I) complexes with nitrogen ligands can have several coordination numbers, the simplest is dicoordinated and compounds of the type [AgL2]+ occur for a variety of ligands... 

Silver(I) complexes with macrocyclic nitrogen ligands are also very numerous. Mono- or homodi-nuclear silver-containing molecular clefts can be synthesized from the cyclocondensation of functionalized alkanediamines or triamines with 2,6-diacetylpyridine, pyridine-2,6-dicarbalde-hyde, thiophene-2,5-dicarbaldehyde, furan-2,5-dicarbaldehyde, or pyrrole-2,5-dicarbaldehyde in the presence of silver(I).486 97 The clefts are derived from bibracchial tetraimine Schiff base macrocycles and have been used, via transmetallation reactions, to complex other metal centers. The incorporation of a range of functionalized triamines has provided the conformational flexibility to vary the homodinuclear intermetallic separation from ca. 3 A to an excess of 6 A, and also to incorporate anions as intermetallic spacers. Some examples of the silver(I) complexes obtained are shown in Figure 5. 

The coordination of catenated nitrogen ligands to transition metals also dates back to the early work of Griess 89, 90), which included references to copper and silver derivatives of 1,3-diphenyltriazene. Around the turn of the century Meldola and Streatfeild 146-148), Meunier 150-152), Niemen-towski and Roszkowski 159), Cuisa and Pestalozza 55,56), and others reported extensively on triazene complexes of copper, silver, and mercury, and in the late 1930s and early 1940s Dwyer and colleagues 69-74) extended this work to include derivatives of nickel and palladium. However, most work on the coordination chemistry of triazenes and other catenated... 

Subsequently, Schomaker and coworkers have developed the first example of ligand-controlled and tunable silver-catalyzed C(sp )-H amination method (Scheme 9.31) [37]. Simple silver catalysts supported by common nitrogenated ligands were used to tune a nitrene transfer reaction between two different types of C-H bonds while silver catalysts supported by Bubipy appear to prefer amination of the most electron-rich C-H bond, silver supported by a tpa ligand is more sensitive to the steric environment around the C-H bond, as well as the bond dissociation energy. 

Silver(II) Compounds. Sdver(II) is stabilized by coordination with nitrogen heterocychc bases, such as pyridine and dipyridyl. These cationic complexes are prepared by the peroxysulfate oxidation of silver(I) solutions in the presence of an excess of the ligand. An extensive review of the higher oxidation states of silver has beenpubhshed (21). 

Silver(II) complexes in the gas phase have been prepared with several nitrogen- and oxygen-donor ligands including pyridine, tetrahydrofurane, benzene, C02, etc. The complexes are of the type [AgLra]2+, and the compound [Ag(C02)4]2+ is particularly stable.216... 

Three-coordinate silver(I) complexes with nitrogen donor ligands are of the form [AgXL2] (L = 3-ferrocenylpyridine, X = OTf L = 3- or 4-NCPy, 2-, 3-, or 4-NCC6H4NH2, X = N03). 

Thermodynamics of complex formation of silver with several ligands such amines,368 hindered pyridine bases,369 nitrogen donor solvents,370 and azoles371 have been carried out. Other studies include the secondary-ion mass spectra of nonvolatile silver complexes,372 the relationship between Lewis acid-base behavior in the gas phase and the aqueous solution,373 or the rates of hydride abstraction from amines via reactions with ground-state Ag+.374... 

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