Hexacoordinate high-spin Fe(iii) complexes composed of a pentadentate amino-type ligand and pseudohalido coligands

Abstract

A new series of Fe(III) mononuclear complexes of [Fe(Lam)(X)] type {where X = Cl (1), NCSe (2), NCS (3), N3 (4), NCO (5)} have been prepared and characterized in detail....

Investigation of the spin crossover behaviour of a sublimable Fe(ii)-qsal complex: from the bulk to a submonolayer on graphene/SiO2

“…However, the characteristic feature of a decrease of χ M T below 30 K of HS Fe( ii ) species is absent. Therefore, the residual paramagnetic species is assigned to oxidized HS Fe( iii ) (d 5 , s = 5/2, χ M T = 4.38 cm 3 mol −1 K) that are magnetically rather isotropic and where χ M T remains constant down to T = 10 K. 44 Its proportion can be evaluated to be around 11% in the studied sample. The χ M T value above T = 120 K (3.19 cm 3 mol −1 K) allows, then, the realization that there should be some Fe( ii ) in the low spin state at high temperatures that can be evaluated to have a proportion around 6% assuming the χ M T of HS Fe( ii ) to be equal to 3.25 cm 3 mol −1 K §…”

“…However, the characteristic feature of a decrease of χ M T below 30 K of HS Fe(II) species is absent. Therefore, the residual paramagnetic species is assigned to oxidized HS Fe(III) (d 5 , s = 5/2, χ M T = 4.38 cm 3 mol −1 K) that are magnetically rather isotropic and where χ M T remains constant down to T = 10 K. 44 Its proportion can be evaluated to be around 11% in the studied sample. The χ M T value above T = 120 K (3.19 cm 3 mol −1 K) allows, then, the realization that there should be some Fe(II) in the low spin state at high temperatures that can be evaluated to have a proportion around 6% assuming the χ M T of HS Fe(II) to be equal to 3.25 cm 3 mol −1 K. § In summary, the relative proportion of the different species extracted from the magnetic data is found to be (Fe II HS ) 0.83 (Fe II LS ) 0.06 (Fe III HS ) 0.11 at a temperature above 120 K, § while below 80 K when performing a sweep rate lower than 0.4 K min −1 , it is found to be equal to (Fe II LS ) 0.89 (Fe III HS ) 0.11 .…”

Impacts of Alkali Metals on the Structures and Properties of Fe(III) Heterometallic Cyclobutane-1,1-dicarboxylate Complexes

“…The spherical term 6 S of an isolated Fe 3+ ion in an octahedral crystal field splits into the ground state 6 A 1g , which does not degenerate as a result of SOC, and the first excited state 4 T 1g . 12,16,80 Distorting axially, the 4 T 1g level splits into 4 A 2g and 4 E g ; therefore, the location of these sublevels determines the sign of the axial component D. If the excited state 4 E is lower in energy than 4 A 2 , then D < 0 ("easy-axis" type), like that of 1. In contrast, if the energy of the 4 A 2 state is smaller than 4 E, then D > 0 ("easy-plane" type), which is typical of 2 and 3.…”