Thermolysis of one or two equivalents of tert-butyltetrazole with KBH4, followed by the addition of 18-crown-6 afforded the crystalline solids [K(18-crown-6)][BH3(tBuCN4)] and [K(18-crown-6)][BH2(tBuCN4)2] in good yields. [K(18-crown-6)][BH2(CF3CN4)2] was obtained by similar treatment of two equivalents of trifluoromethyltetrazole with KBH4. Formation of a hydrotris(tetrazolyl)borate complex, [K(18-crown-6)(THF)][BH(NiPr2CN4)3],  was obtained by monitoring the reaction of KBH4 with three equivalents of diisopropylaminotetrazole in molten 18-crown-6. The new complexes were confirmed by spectroscopic and analytical methods, and X-ray crystallography. All complexes contain coordination of the boron atom to N(2) of the tetrazolyl ring and exhibit coordination modes that were previously unknown for poly(tetrazolyl)borate complexes. [K(18-crown-6)(THF)][BH(NiPr2CN4)3] has ?2-coordination to the potassium center through N(3) of one of the tetrazolyl units and the hydride of the ligand. This is the first example of a hydrotris(tetrazolyl)borate ligand and it is analogous to hydrotris(pyrazolyl)borate ligands due to its ability to act as a tridentate, mono-anionic donor to metal centers.

Synthesis of poly(tetrazolyl)borate ligands and their coordination to the [K(18-crown-6)]<sup>+</sup> fragment: Formation of a tris(tetrazolyl)borate complex

243rd National Meeting (2012)

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Synthesis of poly(tetrazolyl)borate ligands and their coordination to the [K(18-crown-6)]+ fragment: Formation of a tris(tetrazolyl)borate complex

Synthesis of poly(tetrazolyl)borate ligands and their coordination to the [K(18-crown-6)]⁺ fragment: Formation of a tris(tetrazolyl)borate complex