Scientists of TIPC successfully synthesized a novel fluorinated polyoxomolybdate, K₅Mo₄O₁₄F, in which the unusual polyanion [Mo₄O₁₄F]^5– consists of face-sharing [Mo₂O₈F] bioctahedra linked with [MoO₄] tetrahedra. This unique structural feature provides the very rare case that simultaneously violates Pauling’s electrostatic valence (II) and atomic coordination (IV) rules, as well as the stable tendency governed by the polyhedral sharing (III) rule. The structural stability of K₅Mo₄O₁₄F was confirmed from thermal experiments over a wide temperature range and further elucidated by first-principles calculations. 

Inorg. Chem., 2015, 54 (13), pp 6066–6068