Synthesis, Structure, and Properties of Al(Rbpy)3 Complexes (R = t‐Bu, Me): Homoleptic Main-Group Tris-bipyridyl Compounds

The article of record as published may be found at http://dx.doi.org/10.1021/acs.inorgchem.6b00034The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.inorg- chem.6b00034. Crystallographic data for 1 (CIF) Crystallographic data for 2 (CIF) Characterizationdata(PDF)The neutral homoleptic tris-bpy aluminum complexes Al(Rbpy)3, where R = tBu (1) or Me (2), have been synthesized from reactions between AlX precursors (X = Cl, Br) and neutral Rbpy ligands through an aluminum disproportion process. The crystalline compounds have been characterized by single-crystal X-ray diffraction, electrochemical experiments, EPR, magnetic susceptibility, and density functional theory (DFT) studies. The collective data show that 1 and 2 contain Al3+ metal centers coordinated by three bipyridine (bpy•)1− monoanion radicals. Electrochemical studies show that six redox states are accessible from the neutral complexes, three oxidative and three reductive, that involve oxidation or reduction of the coordinated bpy ligands to give neutral Rbpy or Rbpy2− dianions, respectively. Magnetic susceptibility measurements (4− 300 K) coupled with DFT studies show strong antiferromagnetic coupling of the three unpaired electrons located on the Rbpy ligands to give S = 1/2 ground states with low lying S = 3/2 excited states that are populated above 110 K (1) and 80 K (2) in the solid-state. Complex 2 shows weak 3D magnetic interactions at 19 K, which is not observed in 1 or the related [Al(bpy)3] complex.DTRA (HDTRA-1-12-1-007