[Re₆(μ₃-Se)₈]²⁺ Core-Containing Cluster Complexes with Isonicotinic Acid: Synthesis, Structural Characterization, and Hydrogen-Bonded Assemblies

Three new complexes of the [Re₆(μ₃-Se)₈]²⁺ core-containing cluster with isonicotinic acid (INA) were synthesized and characterized by multinuclear NMR (¹H and ³¹P) and high-resolution mass spectrometry. Their molecular and crystal structures were determined by single-crystal X-ray diffraction studies. Unusual degrees of deprotonation of the INA ligand(s) are observed in the crystal structure, possibly due to the activation by the Lewis acidic cluster core. Extensive hydrogen bonding interactions occurring between carboxylate groups of neighboring cluster units as revealed by crystallographic studies lead to the assembly of both linear and zigzag multi-cluster chains in the solid state.