Topochemical Reaction Involving Double-to-Single Layer Conversion: Mo₃Ta₂O₁₀N with a Kagomé Lattice.

Area of Science:

• Materials Science
• Solid-State Chemistry
• Inorganic Chemistry

Background:

• Topochemical reactions in transition metal oxides typically preserve the metal framework, modifying valence and coordination.
• Conventional reactions like SrFeO3 → SrFeO2 maintain a 1:1 structural correspondence.
• Metastable phases with diverse functionalities are accessible via topochemical transformations.

Purpose of the Study:

• To report an unprecedented topochemical transformation in Mo2Ta2O11.
• To investigate the structural and electronic consequences of collapsing MoO4 tetrahedral bilayers.
• To explore the synthesis of novel materials with unique structural motifs and electronic properties.

Main Methods:

• Ammonolysis of Mo2Ta2O11 at 500 °C in the presence of Mo(CO)6.
• Structural characterization using X-ray diffraction (implied by space group determination).
• Electronic and magnetic property measurements (magnetic susceptibility, NMR).

Main Results:

• Successful collapse of MoO4 tetrahedral bilayers into MoO6 octahedral layers, breaking the 1:1 structural correspondence.
• Formation of a new compound, Mo3Ta2O10N, with an 18% contraction along the c-axis.
• Discovery of an Mo-based kagomé lattice with finite d-electrons (Mo4.33+), unlike the d0 precursor.

Conclusions:

• Topochemical reactions can induce extensive structural reorganizations beyond conventional framework preservation.
• The synthesized Mo3Ta2O10N exhibits itinerant kagomé system characteristics.
• This work expands the scope of low-temperature synthesis routes for complex metastable materials.