Formation and Characterization of Homoleptic Thorium Isocyanide Complexes.

Homoleptic thorium isocyanide complexes have been prepared via the reactions of laser-ablated thorium atoms and (CN)2 in a cryogenic matrix, and the structures of the products were characterized by infrared spectroscopy and theoretical calculations. Thorium atoms reacted with (CN)2 under UV irradiation to form the oxidative addition product Th(NC)2, which was calculated to have closed-shell singlet ground state with a bent geometry. Further reaction of Th(NC)2 and (CN)2 resulted in the formation of Th(NC)4, a molecule with a tetrahedral geometry. Minor products such as ThNC and Th(NC)3 were produced upon association reactions of CN with Th and Th(NC)2. Homoleptic thorium cyanide isomers Th(CN)x (x = 1-4) are predicted to be less stable than the corresponding isocyanides. The C-N stretches of thorium cyanides were calculated to be between 2170 and 2230 cm-1 at the B3LYP level, more than 120 cm-1 higher than the N-C stretches of isocyanides and with much weaker intensities. No experimental absorptions appeared where Th(CN)x should be observed.