The equilibrium geometries, energies, harmonic vibrational frequencies, stability, and aromaticities for the [Formula: see text], E 4 Fe , and [ Fe (η4 - E 4)2]2- ( E = N, P, As, Sb, and Bi ) species are studied using density functional theory (DFT). The ground states of the E 4 Fe and [ Fe (η4 - E 4)2]2- systems are predicted to be Cs and D4d structures, respectively. Orbital analysis indicates that the orbital interactions between the π orbitals of the ligands and the atomic orbitals of the d 6 iron center are the main bonding scheme for these [ Fe (η4 - E 4)2]2- (D4d) complexes. The stability of the [ Fe (η4 - E 4)2]2- complexes exhibits the order P > As > Sb > Bi > N for E. On the basis of comparison with the known ferrocene, the NICS analysis confirms that the [ Fe (η4 - E 4)2]2- (D4d) as well as ferrocene are aromatic. The dissected NICS reveals that the aromaticities of the [ Fe (η4 - E 4)2]2- (D4d) are primarily attributed to the effects of their E–E π bonds and Fe lone pairs.
Concomitant polymorphs of aryl-ether amine via catemer and dimer carboxylic acid supramolecular interactions and their effect on optical properties
