A binuclear thorium complex with a Th-O-Th unit.

Complex 1, [(TrapenTMS)ThCl, TrapenTMS = N(CH2Ph(o-NSiMe3)3)], reacts with sodium azide to afford the dimeric complex 2, [(TrapenTMSN3Th)2]. Treatment of 2 with KC8 yields a binuclear oxo-bridged thorium complex 3, [(TrapenTMSTh)2(µ-O)]. The crystal structure of 3 reveals a highly symmetrical configuration with a Th-O-Th unit, and the Th-O bond length is 2.271(2) Å. Density functional theory calculations indicate significant covalent character in the Th-O-Th interaction, surpassing that in related Th-N-Th systems and the Th-O bonding in complex 3 displays stronger covalent interactions.