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(BH(2)(RCN(4))(2))(18-crown-6) (R = H, Me, NMe(2), and NiPr(2)) are described. Complexes where R = H and Me have B-N bonds to N(1) of the tetrazolyl groups and form one-dimensional polymers, whereas those with R = NMe(2) and NiPr(2) possess isomeric B-N bonds to N(2) of the tetrazolyl moieties and adopt chelating kappa(3)-N,N',H-coordination modes to the potassium ion.