Correlating Structural Features and 207Pb NMR Parameters with the Stereochemical Activity of PbII Lone Pairs in Birefringent Pb[2,6-bis(benzimidazol-2-yl)pyridine] Complexes

摘要: A series of PbII materials containing the highly anisotropic tridentate ligand 2,6-bis(benzimidazol-2-yl)pyridine (bbp) and [Au(CN)2]–, Hg(CN)2 or halide bridging units, [Pb(bbp)Br2]·2H2O, Pb(bbp)I2, [Pb(bbp)I]2(µ-I)[Au(CN)2], [Pb(bbp)Br]2(µ-Br)[Au(CN)2], [Pb(bbp)Br2][Hg(CN)2], Pb(bbp)Cl[Au(CN)2]·0.25H2O Pb(H2O)(bbp)2[Au(CN)2]2, have been prepared, structurally characterised investigated spectroscopically by 207Pb solid-state NMR spectroscopy. Of these, five possess similar coordination geometries, providing an ideal to investigate structural parameters as indicators for stereochemical activity correlation with chemical shift span parameter (Ω). The bond length substituent opposite stereochemically active lone pair angle between axial ligands were found correlate weakly Ω these compounds (R2 = 0.85 0.66, respectively) expanded set varying components structures 0.60 0.67, respectively), which indicates that (or similar) can be used estimate degree lone-pair activity. Compounds also birefringent values ranging from 0.31(5) Pb(H2O)(bbp)2[Au(CN)2]2 0.660(4) latter being amongst most reported.