Difluorochloronium(III) Fluoridometallates – from Molecular Building Blocks to (Helical) Chains

Difluorochloronium(III) compounds were synthesized from the reaction of metal powders (Ru, Os, Ir, Au), metal fluorides (NbF 5 , SbF 3 , BiF 5 ) or a metal chloride (TaCl 5 ) with excess liquid chlorine trifluoride. The compounds ClF 2 [AuF 4 ], ClF 2 [ M F 6 ] ( M = Nb, Ta, Ru, Os, Ir, Sb, Bi) and ClF 2 [Ta 2 F 11 ] were obtained in crystalline form and their crystal structures were determined by single‐crystal X‐ray diffraction. The ClF 2 + cations in the investigated compounds are bent, containing two strong, short, mainly covalent Cl–F bonds and two sterically active, free valence electron pairs in a pseudo‐tetrahedral arrangement. The coordination around the Cl atom is extended by two highly ionic, long fluorine bridges to neighboring fluoridometallate anions, resulting in a total coordination number of six. The crystal structures vary among the ClF 2 + compounds and range from molecular building blocks, such as dimeric (ClF 2 [AuF 4 ]) 2 and (ClF 2 [Ta 2 F 11 ]) 2 , to chains, some of which being helical, as in ClF 2 [ M F 6 ], ( M = Nb, Ta, Ru, Os, Ir, Sb, Bi). Quantum‐chemical solid‐state and gas‐phase calculations were carried out to elucidate the bonding within the ClF 2 + cations and their interactions with the bridging F atoms.