Binary [Hydrotris(indazol‐1‐yl)borato]metal Complexes, M(Tp 4Bo ) 2 [1] with M = Fe, Co, Ni, Cu, and Zn: Electronic Properties and Solvent‐Dependent Framework Structures through C−H···π Interactions

The bis[hydrotris(indazol‐1‐yl)borato]metal complexes [M{HB(C 7 H 5 N 2 ) 3 } 2 ], M(Tp 4Bo ) 2 , with M = Fe, Co, Ni, Cu, and Zn have been synthesized and characterized by NMR, IR, UV/Vis, MS, Mössbauer spectrometry (M = Fe) and cyclic voltammetry (M = Fe, Co). The ligand field strength of the Tp 4Bo ligand is slightly higher than that of the normal Tp ligand. The molecular and crystal structure of the compounds with different solvents of crystallization (tetrahydrofuran, chloroform, dioxane) were elucidated by X‐ray crystallography. The metal complexes exhibit the usual pseudo‐octahedral D 3d ‐symmetrical geometry for two tripodal ligands with a Jahn−Teller distortion for M = Cu. The crystal packing between the molecular complexes is controlled mainly by C−H ··· π interactions from the indazolyl moieties. This gives rise to large non‐covalent framework structures with voids and channels ranging in volume from about 19 to 39% of the unit cell volume. The open space is filled by solvent molecules. The crystal packing and the space group depends on the type of solvent.