Determination of electronic ground state properties of a dinuclear iron(II) spin crossover complex

Abstract

The dinuclear complex Me 2 )) 2 (BiBzIm)](ClO 4 ) 2 · 2EtCN (1) has been investigated by Mössbauer spectroscopy carried out in the temperature range from 5 to 150 K with externally applied magnetic fields of up to B = 5 T. By means of a consistent simulation of all experimental data sets within the Spin Hamiltonian formalism, the zerofield splitting D and the rhombicity parameter E/D of the ferrous high-spin (HS) site in this complex was determined to be D = −15.0 ± 1.0 cm −1 and E/D = 0.33 respectively. The sign of the quadrupole splitting of the HS site is positive which indicates that this iron site of the dinuclear complex 1 has an electronic ground state with the d xy orbital being twofold occupied.

Electronic Structure, Vibrational Spectra, and Spin-Crossover Properties of Vacuum-Evaporable Iron(II) Bis(dihydrobis(pyrazolyl)borate) Complexes with Diimine Coligands. Origin of Giant Raman Features

“…The 5 T 2g ground state of the investigated Fe­(II) complexes in their HS configuration is split by a low-symmetry ligand field and spin–orbit coupling. Low-temperature high magnetic field 57 Fe Mössbauer spectroscopy and saturation magnetization measurements provide information about these interactions. ,,− We decided to apply these methods to [Fe­(H 2 B­(pz) 2 ) 2 (Me 2 -phen)] ( 6 ), as this complex is locked in the HS state (see above), which allows investigation of the 5 T 2g state and its magnetic properties at low temperatures without the need of populating a metastable HS state by light irradiation.…”