Combined crystal chemistry and DFT studies of ThNCl and Th2N2X (X:Â chalcogen) behaving as pseudo-binaries

Common features and peculiar differentiations characterize binary and ternary thorium nitride Th3N4, thorium nitride chloride ThNCl and the family of thorium nitride chalcogenides Th2N2X (X = O, S, Se, Te) investigated in the framework of the quantum density functional theory DFT. Particularly the dominant effect of the Th-N covalent bond stronger than ionic Th-Cl/Th-X ones as identified from analyses of bonding from overlap integral, electron localization function mapping, electronic density of states and charge transfer, is found at the origin of the layered-like structural arrangements in Th-N monolayers within ThNCl (Cl / [ThN]/ Cl) and Th-N double layers in Th2N2X (X / [Th2N2] / X) with the result of pseudo binary compounds: [ThN]+Cl− and [Th2N2] 2+X2−. All compounds are found semi-conducting with ∼2 eV band gap. It is claimed that such insights into Solid State Chemistry can help rationalizing complex compounds more comprehensively (two examples given).