Synthesis,crystal structure and spectroscopic properties of trans‐dibromidobis(2,2‐dimethylpropane‐1,3‐diamine‐κ2N,N′)chromium(III) perchlorate

The title complex salt, trans‐anti‐[CrBr₂(Me₂tn)₂]ClO₄ (where Me₂tn = 2,2‐dimethylpropane‐1,3‐diamine, C₅H₁₄N₂), was prepared and its structure determined by single‐crystal X‐ray diffraction at 100 K. The asymmetric unit contains three conformationally similar complex cations and three perchlorate anions. In each complex cation, the Cr^III centre is coordinated by four N atoms of two chelating Me₂tn ligands in the equatorial plane and by two Br atoms in a trans‐axial arrangement, to give a distorted octahedral geometry. Interionic contacts are dominated by extensive hydrogen bonding, involving the NH groups of the Me₂tn ligand as donors and the anion O atoms or coordinated Br atoms as acceptors, resulting in two‐dimensional layers in the bc plane. Ligand field analysis based on the angular overlap model, and IR and electronic spectroscopic properties, are also discussed.