0000000000347170
AUTHOR
P. Kerep
Unprecedented multiple electronic spin transition in hepta- and nonanuclear complex compounds observed by Mössbauer spectroscopy
Abstract The precursor [Fe(III)(5L)Cl](5LH2 = N,N′-bis(1-hydroxy-2- benzyliden)-1,7-diamino-4-azaheptane) is a high-spin (S = 5/2) complex. This precursor combined with the bridging units [Fe(II)(CN)6]4−, [Co(III)(CN)6]3−, and [Mo(CN)8]4− yields starshaped hepta- and nonanuclear clusters, [Fe(II){(CN)Fe(III)(5L)}6]Cl2, [Co(III){(CN)Fe(III)(5L)}6]Cl3 and [Mo(IV){(CN)Fe(III)(5L)}8]Cl4. The starshaped compounds are high-spin systems at room temperature. On cooling to 20 K some of the iron(III) centers in the Co(III)- and Mo(IV)-star switch to the low-spin state as proven by Mossbauer spectroscopy, i.e., multiple electronic transitions, while the Fe(II)-star remains in the high-spin state.
Effect of N-substitution in multinuclear complexes allows interplay between magnetic states and multistability investigated by Mössbauer spectroscopy
A series of pentadentate ligands N-X-5LH2 (X=H, Methyl, Benzyl)=N-X-saldptn (4-X-N,N′-bis(l-hydroxy-2-benzylidene)-1,7-diamino-4-azaheptane) has been prepared by a Schiff base condensation between 1,7-diamino-4-X-azaheptane and salicylaldehyde. Complexation with Fe(III) yields a series of high-spin (S=5/2) complexes of [FeIII(N-X-5L)Cl]. Such precursors were combined with [Mo(CN)8]4− and a series of blue nonanuclear cluster compounds [MoIV(CN)FeIII(N-X-5L)8]Cl4 resulted. Such star-shaped nonanuclear compounds are high-spin systems at room temperature. On cooling to 10K some of the iron(III) centers switched to the low-spin state as proven by Mossbauer spectra, i.e. multiple electronic trans…
The Nonanuclear [Mo(IV) {(CN)Fe(III)(3-ethoxy-saldptn)}8]Cl4 Complex Compound Exhibits Multiple Spin Transitions Observed by Mössbauer Spectroscopy
The pentadentate ligand 3-EO-5LH2 = 3-ethoxy-saldptn = N,N′-bis(3-ethoxy-1-hydroxy-2-benzyliden)-1,7-diamino-4-azaheptane has been prepared by a Schiff base condensation between 1,7-diamino-4-azaheptane and the corresponding 3-ethoxy-salicyaldehyde. 3-EO-5LH2 is a sterical extention to 5LH2. Its complexation with Fe(III) gave the high-spin (S = 5/2) complex of [Fe(III)(3-EO-5L)Cl]. This precursor was combined with [Mo(CN)8]4− and a blue nonanuclear cluster [Mo(IV){(CN)Fe(III)(3-EO-5L)}8]Cl4 resulted. This starshaped nonanuclear compound is a high-spin system at room temperature. On cooling to 10 K some of the eight iron(III) centers switched to the low-spin state as proven by Mossbauer spec…