Ag3(SO3F)4: A Rare Example of a Mixed‐Valent AgII/AgI Compound Showing 1D Antiferromagnetism

摘要: Dark brown AgI2AgII(SO3F)4, known for over 30 years, is the first example of four well-characterized mixed-valent (1+/2+) compounds silver. It crystallizes in monoclinic space group, P21/c, with a = 5.33670(19) A, b 12.9486(4) c 19.5976(7) β 100.6407(13)°, V 1330.95(8) A3, Z 4 and dcalcd. 3.59 g cm–3. Its chemical formula best written as [AgI2(SO3F)]+[AgII(SO3F)3]–. AgII centres form 1D chains linked through OSO bridges that result pronounced antiferromagnetic coupling TN 225 K superexchange constant (J) –7.5 meV per pair coupled cations. Ligand environments around AgI differ substantially, which suggests genuine mixed- (i.e., localized) not intermediate-valent delocalized) character title compound. Indeed, electronic absorption observed up to 7500 cm–1, so intervalence charge-transfer transition across band gap must fall above 0.8 eV. The compound stable mere 75 °C, marks onset its thermal decomposition AgISO3F SO3F· radical. AgI2AgII(SO3F)4 is, after AgSO4, second-known semiconducting oxa derivative AgII.