Abstract

Metal thiocyanates, such as copper(I) thiocyanate (CuSCN) and tin(II) thiocyanate [Sn(SCN)<inf>2</inf>], are emerging as novel semiconductors for electronic applications, and while other thiocyanate coordination polymers are known, their electronic structures and properties have not been investigated. In this work, we employed density functional theory (DFT) and crystal orbital Hamilton population (COHP) to analyze the electronic structures and bonding character of 18 structures of 15 metal thiocyanate compounds as well as a main group thiocyanate, selenium thiocyanate [Se(SCN)<inf>2</inf>]. Interestingly, the ionic thiocyanates (groups 1 and 2) display band dispersions despite their valence and conduction bands (VBs and CBs) being derived mostly from the thiocyanate ligand. Thiocyanates of group 11 show the strongest contributions from the metals with their d electrons strongly dominating the top of the VBs. In contrast, metals from group 12 contribute their s electrons to the bottom CBs. Metals of groups 13 and 14 have lone pair electrons in the s orbitals, which are featured at the top of their VBs, while the metal p states contribute to the CBs. The bonding character and orbital contributions can be explained based on the trend in the electron binding energies of the coordinated atoms. The versatility of adjusting the orbital contribution by changing the metals can be used for tuning the electronic properties of semiconductors based on thiocyanate compounds.