Complexes of the [K(18-Crown-6)]⁺ Fragment with Bis(tetrazolyl)borate Ligands: Unexpected Boron−Nitrogen Bond Isomerism and Associated Enforcement of κ³-N,N′,H-Ligand Chelation

The syntheses and solid-state structures of K(BH₂(RCN₄)₂)(18-crown-6) (R = H, Me, NMe₂, and NiPr₂) are described. Complexes where R = H and Me have B−N bonds to N¹ of the tetrazolyl groups and form one-dimensional polymers, whereas those with R = NMe₂ and NiPr₂ possess isomeric B−N bonds to N² of the tetrazolyl moieties and adopt chelating κ³-N,N′,H-coordination modes to the potassium ion.