Potassium Tris 3,5-dimethylpyrazolyl hydroborate, KTp

The dry solid is then finely ground and loaded into a large sublimation apparatus. The excess dimethylpyrazole is removed by sublimation under high vacuum at 110°C. The sublimation apparatus and its contents are allowed to cool to room temperature before opening to the atmosphere. The white, nonvolatile residue is then dissolved in acetone ( 600-800 mL not all of the solid will dissolve) and filtered to yield a clear solution. The acetone is removed on a rotary evaporator (do not allow the water-bath temperature to exceed 30°C, or decomposition wiU take place), then diethyl ether (100 mL) is added to assist homogenization and filtration of the solid product. The solid is washed with diethyl ether and air dried. The yield is typically 52 g (77%, cf. lit 34%). 

The white, air-stable crystalline solid exhibits the physical and spectroscopic properties reported by Trofimenko. Infrared KBr, i/bh 2438(s) i/cn 1540(s) cm  

In this synthesis, and those to follow, it is possible that local conditions, particularly atmospheric pressure, or changes to the scale of the syntheses may affect the reaction times. The course of the reactions may be conveniently assayed by solution infrared spectroscopy. 

A single-necked, 500-mL round-bottomed flask is charged with W(CO)g (20 g, 57 mmol), KTp (19.11 g, 57 mmol), and a large magnetic stirring bar. Anhydrous A,A-dimethylformamide (200 mL) is added to the mixture and the flask 

Yellow, diamagnetic NEt4[Tp W(CO)3] is air stable and can be stored without precautions. An alternative synthesis of the compound is avaUable it offers improved yields but is longer and more involved. The compound is slightly soluble in acetonitrile but insoluble in water, chlorinated solvents, alcohols and diethyl ether. It is soluble in hot acetonitrile. Infrared MeCN, i/co 1877(s), 1742(s) cm . KBr, i/bh 2528(w) vco 1874(s), 1736(s) i/cn 1540(m) cm .  

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