Bite-Angle-Regulated Coordination Geometries: Tetrahedral and Trigonal Bipyramidal in Ni(II) with Biphenyl-Appended (2-Pyridyl)alkylamine ,'-Bidentate Ligands.

Two simple biphenyl-appended (2-pyridyl)alkylamine -bidentate ligands, L and L, having ethylene and methylene spacers between donor groups, with bite angles L ≈ 100° and L ≈ 80°, dictate pseudotetrahedral and trigonal-bipyramidal geometries in six high-spin Ni(II)-halide complexes, [Ni(L)X] and Ni(L)X (where X = Cl, Br, I), respectively. The structures in the solid state, determined using X-ray crystallography, and in solution, determined using spectroscopic methods (UV-vis-NIR and paramagnetic H NMR), which complement each other, are described.