KHfF₅: a new representative in the M^IM^IVF₅ family

Area of Science:

• Inorganic Chemistry
• Solid-State Chemistry
• Crystallography

Background:

• Complex metal fluorides are crucial in materials science.
• Understanding the structural diversity of hafnium-based fluorides is important for developing new materials.
• Potassium hafnium pentafluoride (KHfF5) is a novel compound within this class.

Purpose of the Study:

• To synthesize and characterize potassium hafnium pentafluoride (KHfF5).
• To determine the crystal structure of KHfF5.
• To compare the structure of KHfF5 with known related compounds.

Main Methods:

• Hydrothermal synthesis technique.
• Single-crystal X-ray diffraction for structure determination.
• Analysis of coordination polyhedra and bonding.

Main Results:

• Potassium hafnium pentafluoride (KHfF5) was successfully synthesized via hydrothermal methods.
• The compound crystallizes in the orthorhombic noncentrosymmetric space group P212121.
• Hf atoms are coordinated by eight F atoms in square antiprismatic polyhedra, forming double chains of interconnected polyhedra.

Conclusions:

• The determined crystal structure of KHfF5 is unique.
• KHfF5 does not possess any isostructural analogues among known M1MIVF5 compounds.
• This finding expands the structural landscape of complex hafnium fluorides.