Tl5NO33CB11H122: A Novel Carbadodecaborate Double Salt with an Unprecedented Crystal Structure

The novel compound Tl 5 NO 3 3 CB 11 H 12 2 was prepared by the aqueous reaction of (HNEt 3 )CB 11 H 12 with Tl 2 CO 3 after the treatment of the resulting product with diluted nitric acid. Tl 5 NO 3 3 CB 11 H 12 2 crystallizes as colorless platelets in the hexagonal space group P 6 3 / m with the lattice parameters a = 767.52(4) pm and c = 3026.75(17) pm ( c / a = 3.944) for Z = 6. Unlike other double salts of closo -(carba)borates, Tl 5 NO 3 3 CB 11 H 12 2 does not crystallize in a well-known structure type, but with a completely new structure, which contains electroneutral layers held together only by van-der-Waals interactions. These layers consist of NO 3 − -centered (Tl + ) 6 octahedra, which are linked to their four neighbors via faces. The connecting faces and the non-connecting faces occur opposite to each other, creating a layer with a hexagonal recess, in which the closo -carbaborate anions find their place attached via Tl + ‧‧‧H δ− bonds. In the Raman spectrum of Tl 5 NO 3 3 CB 11 H 12 2 , the most prominent vibration bands are the respiratory vibration of the closo -carbaborate skeleton at 762 cm −1 and the valence vibrations of the B−H bonds in the range between 2470 and 2620 cm −1 . • Synthesis and crystal structure of Tl 5 NO 3 3 CB 11 H 12 2 • Kagome net formed by the nitrate anions • Electroneutral layers held together only by van-der-Waals interactions