In this talk I will discuss peculiar chemistry and physics of the compounds containing higher oxidation states of silver, notably Ag(II) and Ag(III) [1]. First, methods of their synthesis and their uncommon oxidizing properties will be described; selected reactions of the best currently known oxidizer, AgF₂ ⁺, will be presented.

Then I will briefly analyze crystal structures of selected compounds and point out the plasticity of the coordination sphere of the Jahn–Teller active Ag(II) cations [2]. Next I will focus on chemical bonding between silver cations and ligands with emphasis on remarkably strong Ag(4d)/L(2p) mixing (covalence) as well as unprecedented inversion of binding energies of the metal and fluorine states for KAgF₄ [3]. Then I will turn to the electronic and magnetic properties of diverse fluoride- and various oxo- derivatives of Ag(II). Of particular interest will be their semiconducting properties as well as unusually strong magnetic superexchange constants, J, [4,5] seen even for systems containing organic ligands where up to 5-atom superexchange pathway exists between paramagnetic Ag(II) centres [6,7,8]. The record large value of J, antiferromagnetic in sign and exceeding –120 meV, thus comparable to those seen for undoped oxocuprates(II), is predicted for two-dimensional high-pressure form of AgF₂ [4]. Obvious consequences for a possible generation of a novel family of high-TC superconductors will be discussed [9,10]. Finally, thermal stability and unusual decomposition pathway of the compounds of Ag(II) and Ag(III) [11] will be described and linked to their electronic and magnetic properties. The lecture will conclude with description of the first high-pressure experiments for Ag(II) compounds. Unexpected robustness of the crystal structure as well as persistence of the Jahn–Teller effect will be demonstrated for Ag(II)SO₄ at pressures up to 30 GPa, or 300 000 atm [12]. I will also discuss interesting experiments on AgF₂/AgF mixture and on K₂AgF₄ up to 40 GPa.

References

[1] W. Grochala, R. Hoffmann, Angew. Chem. Int. Ed. Engl. 40 (15): 2743-2781 2001.

[2] W. Grochala, Phys. Stat. Sol. B 243(11): R81-R83 2006.

[3] W. Grochala et al., ChemPhysChem 4(9): 997-1001 2003.

[4] T. Jaroń, W. Grochala, Phys. Stat. Sol. RRL 2(2): 71-73 2008.

[5] P. Malinowski et al., Angew. Chem. Int. Ed. Engl. 49(9): 1683-1686 2010.

[6] P. J. Leszczynski et al., Dalton Trans. 41(2): 396-402 2012.

[7] J. L. Manson et al., Inorg. Chem. 51(4): 1989-1991 2012.

[8] J. L. Manson et al., J. Am. Chem. Soc. 131(13): 4590-4591 2009.

[9] W. Grochala, Nature Mater. 5(7): 513-514 2006.

[10] W. Grochala, J. Mater. Chem. 19(38): 6949-6968 2009.

[11] P. Malinowski et al., Chem. Eur. J. 17(38): 10524-10527 2011.

[12] M. Derzsi et al., CrystEngComm, submitted 2012.

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