Mössbauer and magnetic studies on solid mixed-ligand iron(III) dithiocarbamates

Iron(III) Spin Crossover Compounds

“…Unlike the normal situation in iron(II) and also in many other iron(III) systems, 57 Fe Mössbauer spectroscopy generally fails to give clear evidence of the simultaneous existence of the two electronic states. The 57 Fe Mössbauer spectra of the dithiocarbamate systems exhibit only a single quadrupole doublet with broad line widths within the temperature range of the spin crossover [35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50]. The rapid inter-conversion of spin states-faster or comparable to the lifetime of the 57 Fe nucleus (t=1.410 7 s)-in those materials prevents the observation of separate lines for high spin and low spin molecules.…”

Spin crossover studies in mixed ligand complexes of tris(N-ethyl, N′-n-butyldithiocarbamato)iron(III) with NN, NO and OO containing bidentate ligands and their thermal decomposition

“…Thus, on the basis of RT measurements, μ eff values of all the six complexes, Fe(ebtc) 2 L and Fe(ebtc)L 2 can be divided into two groups: high spin ( 6 A 1g ) for 'phen' and 'oxine' substituted complexes whereas an intermediate spin ( 4 T 2g ) state for 'acac' substituted complexes. Wajda et al [4] also investigated spin crossover behaviour in [Fe(dtc) 2 (dtc )] type complexes by magnetic and Mössbauer spectra and suggested shift in spin equilibrium with change in ligand. Thus, the mixed ligand complexes do not exhibit simply the slowing down of the spin state interconversion rate, but a change of the thermal equilibrium.…”

“…Variable temperature Mössbauer spectral studies have been extensively used for investigating the spin crossover in a variety of mixed ligand iron(III) complexes [4,5]. These complexes show an unusual temperature dependence of their Mössbauer spectral behaviour.…”

“…These complexes show an unusual temperature dependence of their Mössbauer spectral behaviour. Wajda et al [4] reported asymmetric doublets for the complex [Fe(Et 2 dtc)(morphdtc)] at 300 and 80 K and attributed this due to shift in spin equilibrium compared to that for [Fe(morphdtc) 3 ]. Later Lanjewar and Garg [5] reported RT Mössbauer spectral studies for [Fe(edc) 2 L] and [Fe(edc) L 2 ] type complexes.…”

“…Many solution and solid-state studies have been reported in literature [1][2][3][4]. Takemoto and Hutchinson [2] investigated spin crossover in [Fe(bipy) 2 (NCS) 2 ], [Fe(phen) 2 (NCS) 2 ] and [Fe(phen) 2 (NCSe) 2 ].…”