1,2,4-Triazolato barium complex: The layered polymeric planar structure with an μ2-η2,η1 bridging coordination

► Complex (1) presents an unprecedented μ2-η2,η1 coordination mode. ► Complex 1 with solvated DMSO is first layered polymeric planar azolato alkaline-earth metal complex. ► Compound 1 demonstrates that the 1,2,4-triazolato ligand has a tendency to join the metals in μ2-η1,η2 mode.