Chemistry of silver(II): a cornucopia of peculiarities

Abstract

Silver is the heavier congener of copper in the Periodic Table, but the chemistry of these two elements is very different. While Cu(II) is the most common cationic form of copper, Ag(II) is rare and its compounds exhibit a broad range of peculiar physico-chemical properties. These include, but are not limited to: (i) uncommon oxidizing properties, (ii) unprecedented large mixing of metal and ligand valence orbitals, (iii) strong spin-polarization of neighbouring ligands, (iv) record large magnetic superexchange constants, (v) ease of thermal decomposition of its salts with O-, N- or C-ligands, as well as (vi) robust Jahn–Teller effect which is preserved even at high pressure. These intriguing features of the compounds of Ag(II) will be discussed here together with (vii) a possibility of electromerism (electronic tautomerism) for a certain class of Ag(II) salts.

Silverland: the Realm of Compounds of Divalent Silver—and Why They are Interesting

“…Obviously, the ultimate goal is to achieve moderate doping levels to stiff 2D Ag 2+ fluoride lattices, and-while benefiting from both lattice and spin degrees of freedom [2,16,18]-possibly fulfill a dream of the high-T C superconductivity in these materials. AgF 2 here could be considered-in oxocuprate notation-as a (001) material which lacks any other chemical ingredients except those which make up [CuO 2 ]-like sheets.…”

“…Obviously, the Ag 2+ species are more rare than the common Ag 1+ ones; currently, only about 100 compounds of Ag 2+ and as many as over 16,000 of respective Ag 1+ systems have been structurally characterized [2]. However, an effort paid to open the electronic 4d shell, and concomitant exoticism of Ag 2+ species, come with a pleasant (but not unexpected) surprise: the involvement of a more contracted d shell in chemical bonding implies, by necessity, an increased covalence of chemical bonds, and that leads to a number of fascinating consequences for chemistry and physics of such species, as I will outline below.…”

Influence of Xantphos Derivative Ligands on the Coordination in Their Copper(I) and Silver(I) Complexes

“…Compound 2 only shows one irreversible oxidation wave at ca . + 1.30 V, assigned to the Xantphos ligand since silver(II) complexes are not particularly very stable , . In compound 3 only one oxidation wave is observed at 1.33 V, whereas in 4 an absence of peaks is observed.…”

Perfluoro Alkyl Hypofluorites and Peroxides Revisited

“…Owing to the high oxidation potential of Ag II (electron affinity: 21.45 eV), the proposed Ag II alkoxide intermediates are prone to a ligand‐to‐metal electron‐transfer (LMCT) and even to the formation of alkoxyl radical intermediates such as Ag I (O . R F )(OR F ) . A similar radical mechanism has been proposed for the AgF 2 ‐catalyzed low‐temperature reaction of F 2 with SO 3 to yield peroxy disulfuryl difluoride, (FSO 2 O) 2 …”

“…Wechsberg and Cady previously described the reactiono fA gF 2 with F 2 CO and fluorine and assumedt he formation of an Ag II (OR F ) 2 intermediate. [38] Owing to the high oxidationp otentialo fA g II (electron affinity:2 1.45 eV), [39] the proposed Ag II alkoxide intermediates are prone to al igand-to-metal electron-transfer (LMCT) and even to the formation of alkoxyl radical intermediates such as Ag I (OCR F )(OR F ). [39] As imilarr adical mechanism hasb een proposed for the AgF 2 -catalyzed low-temperaturer eaction of F 2 with SO 3 to yield peroxyd isulfuryl difluoride, (FSO 2 O) 2 .…”