Potassium dihydrobis borate

Potassium dihydrobis(l-pyrazolyl)borate, m.p. 171-172°C., is a white crystalline solid, highly soluble in water and polar solvents. It may be recrystallized from anisole, but with large solubility losses. The infrared spectrum has a complicated BH2 stretch multiplet in the 2200-2500-cm.-1 range. It is very soluble in water and alcohols, but the ligand undergoes slow solvolysis, and solutions should be made up just before use. 

Potassium dihydrobis(l-pyrazolyl)borate (18.6 g., 0.1 mole) of the solid as prepared in Sec. A is stirred in 300 ml. of distilled water, and any insolubles are removed by filtration. To the resulting clear solution is added, with stirring, 100 ml. of 0.5 M solution of nickel(II) acetate [or any other Ni(II) salt]. A yellowish precipitate forms immediately. The mixture is stirred at room temperature for 10 minutes and is then filtered. The solid is washed with copious amounts of water, then with... 

X-ray crystal structure of the potassium dihydrobis(3-nitro-l,2,4-triazolyl) borate is reported [170], The potassium salt is polymeric and shows several K...N and K...0 interactions. 

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