Organometallic 1,5-benzodiazepine and 1,5-benzodiaze pinium compounds: Synthesis, characterization, X-ray diffraction structures and theoretical investigation

The organometallic tridentate ketoamine or enaminone compound, (η⁵-Cp)Fe(h⁵-C_JH₄)-C(=0)-CH= C(Me)-NH-C₆H₄-o-NH₂, undergoes an intramolecular cyclocondensation promoted by Cu(C10₄) ₂-6H₂0 (2:1 molar ratio) affording the neutral 2-ferrocenyl-4-methyl-1,5-benzodiazepine, 1. However, when the molar ratio used is 1:1, the ketoamine or enaminone compound transforms into the 2-ferrocenyl-4-methyl-1,5-benzodiazepinium cation, [2]⁺. The X-ray molecular structure of 1 exhibits a seven-membered ring with a boat conformation, and two folding dihedral angles along the N(l)-N(2) and C(11)-C(13) axes. In the case of [2]⁺, the structure shows only one folding dihedral angle along the N(l)-N(2) axis. A rationalization of the properties of 1 and [2]⁺ is provided through DFT calculations.