Synthesis, characterization, and coordination chemistry of the dihydrobis(5-aminotetrazol-1-yl)borate anion

The new anionic dihydrobis(5-aminotetrazol-1-yl)borate ligand was synthesized in high yield and structurally characterized. Electron donating effects of the amino substituent on the tetrazole ring are discussed comparing the basicity and coordination chemistry to the previously reported unsubstituted dihydrobistetrazol-1-ylborate anion. Both mono- and diprotonated ligand species were isolated and structurally characterized. Increased sigma-electron donating strength of the aminotetrazole compound provides more than one tetrazolyl nitrogen position capable of metal coordination. One-dimensional coordination polymers of {H2B(H2NCN4)2}2Cu(NH3)2 and {H2B(H2NCN4)2}Zn(NH3)Cl are structurally characterized demonstrating both a symmetrically bridging and a new unsymmetrically bridging motif involving more than one of the tetrazolyl ring positions of the ligand.