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 center dot center dot center dot pi interactions

The bis [hydrotris(indazol-1-yl) borato]metal complexes [M{HB(C7H5N2)(3)}(2 )], M(Tp(4Bo))(2), with M = Fe, Co, Ni, Cu, and Zn have been synthesized an d characterized by NMR, IR, UV/Vis, MS, Mossbauer 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 crystalli zation (tetrahydrofuran, chloroform, dioxane) were elucidated by X-ray crys tallography. The metal complexes exhibit the usual pseudo-octahedral D-3d-s ymmetrical geometry for two tripodal ligands with a Jahn-Teller distortion for M = Cu. The crystal packing between the molecular complexes is controll ed mainly by C-H...pi interactions from the indazolyl moieties. This gives rise to large non-covalent framework structures with voids and channels ran ging 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 de pends on the type of solvent.