Synthesis and characterisation of novel ternary and quaternary transition-metal carbodiimides

• Applicant: Alexander Corkett, Ph.D.
• Subject Area: Solid State and Surface Chemistry, Material Synthesis ; Physical Chemistry of Solids and Surfaces, Material Characterisation
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 441856704

The broad aim of this project is the preparation and characterisation of novel ternary and quaternary transition-metal carbodiimides, motivated by the discovery of a number of promising chemical and physical properties in MNCN and M2(NCN)3 quasi-binary compounds. The realisation of such phases will not only enrich the structural diversity of this family but should also imbue new or enhanced properties. In targeting novel ternary and quaternary carbodiimides, inspiration is well sought from transition-metal oxides and sulphides based on the pseudo-chalcogenide nature of the carbodiimide anion, whilst noting the tendency of the extended linear NCN2− unit to template layered structures. The PI’s recent discovery of the first examples of non-binary transition-metal carbodiimides A2MnSn2(NCN)6 (A = Li and Na), ACr(NCN)2 (A = Li and Na), and NaSc(NCN)2, all of which crystallise in low-symmetry [NiAs]-type modifications, provide the impetus for a first direction. Research theme 1, therefore, seeks to develop novel AaMb(NCN)a+b phases that incorporate alkali-metal (A) and transition-metal (M) cations, before going on to target [NiAs]-type derivatives that combine vacancy and cation-order. Prompted by our preparation of SrZn(NCN)2 and BaZn(NCN)2, a second synthetic direction (Research theme 2) will explore the possibility of accessing novel AeM(NCN)2 (Ae = alkaline-earth metal) carbodiimides, featuring tetrahedrally coordinated transition metals. In-depth structural characterisation will be undertaken through the combined use of X-ray and powder neutron diffraction techniques. The potential for interesting magnetic, electrochemical, catalytic, and luminescence properties will then be examined through a number of established collaborations and complemented by electronic structure calculations. In short, the targeted synthesis and subsequent characterisation of the novel ternary and quaternary transition-metal carbodiimides described in this project will elucidate new structure-property relationships leading to enhanced understanding and application of this emerging family of pseudo-chalcogenides.

• DFG Programme: Research Grants