The Nonanuclear Mo(IV) {(CN)Fe(III)(3-ethoxy-saldptn)}_8Cl_4 Complex Compound Exhibits Multiple Spin Transitions Observed by Moessbauer Spectroscopy

摘要

The pentadentate ligand 3-EO-~5LH_2 = 3-ethoxy-saldptn = N,N′-bis(3-ethoxy-1-hy-droxy-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-~5LH_2 is a sterical extention to ~5LH_2. 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]Cl_4 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 Moessbauer spectra, i.e. multiple electronic transitions.