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The enthalpy of seven polymorphs of AgF 2 has been scrutinized up to 50 GPa using density functional theory (DFT) calculations. We show that α-Ag II F 2 (Pbca, with its puckered-sheet structure and an elongated octahedral 4 + 2 coordination of Ag) transforms above 15 GPa into a layered polymorph δ (Abma). The Jahn-Teller effect persists and the coordination of Ag(II) is of the 4 + 4 type; the Ag-F-Ag bridges are bent. Cubic γ structure of the CaF 2 type (Fm3m), and its Pa3 variant (η), rutile (ζ ), and tetragonal 'infinite chain' P4mm structure related to AgFBF 4 (ε) are not preferred in the entire pressure window that was investigated. Electronic structure of high-pressure δ-Ag II F 2 form shows features that are characteristic for two-dimensional (2D) materials, a prerequisite for high-T C superconductivity.Our calculations also suggest that experimentally observed hightemperature β-AgF 2 (I mcm, disproportionated, i.e. a charge-density-wave form, Ag I Ag III F 4 ) is indeed metastable; it is slightly endothermic compared to α-Ag II F 2 .This contribution is dedicated to Professor Andrzej Sadlej, eminent Polish quantum chemist, on the occassion of his 65th birthday 0953-8984/07/116206+13$30.00

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