Synthesis of the first nickel borate nitrate K${}_7$Ni[B${}_{18}$O${}_{24}$(OH)${}_9$](NO${}_3$)${}_6$ · (H${}_3$BO${}_3$)

The novel potassium nickel borate nitrate K${}_7$Ni[B${}_{18}$O${}_{24}$(OH)${}_9$](NO${}_3$)${}_6$ · (H${}_3$BO${}_3$) was obtained from a simple hydrothermal synthesis in a stainless-steel autoclave at T = 513 K starting with nickel dichloride hexahydrate, and boric and nitric acid with the pH adjusted to 8 by KOH. Single-crystal X-ray diffraction data provided the basis for the structure analysis and refinement. The compound crystallizes in the trigonal space group R$\overline{3}$ (no. 148) with the lattice parameters a = 1222.29(8) and c = 5478.4(4) pm. Generally, K${}_7$Ni[B${}_{18}$O${}_{24}$(OH)${}_9$](NO${}_3$)${}_6$ · (H${}_3$BO${}_3$) is comprised of nitrate layers and complex nickel borate layers surrounded by boric acid, nitrate anions, and potassium cations.