Multinuclear spin-crossover (SCO) complexes are of fundamental interest in terms of understanding the role of cooperativity in the evolution of spin transitions. Yet, only a few SCO complexes with more than two SCO centers have been reported to date. Our approach to the preparation of such complexes is based on connecting Fe(II) ions capped with tetradentate blocking ligands via nitrogen-terminated linkers, i.e. dicyanometalates [M(CN)2]� (M = Cu, Ag, Au). This building-block approach led to isolation of a series of homo- and heteropolynuclear Fe(II) complexes. Complexes {[Fe(tpma)]4(�-CN)2[�4-Ag2(CN)4]2}X4 (tpma = tris(2-pyridylmethil)amine; X = ClO4�, BF4�, PF6�) and {[Fe(tpma)]2[�2-Au2(CN)4]2} contain d10���d10 bonded bis(dicyanometalate) linkers that connect FeII ions. The latter complex exhibits an onset of spin transition at 300 K. A series of CN-bridged complexes {[Fe(tpma)(�-CN)]4}X4�nH2O was also obtained, all of which exhibit thermal spin crossover, as demonstrated by a combination of magnetic measurements, variable-temperature X-ray crystallography, and M�ssbauer spectroscopy.

Multinuclear Fe(II) complexes with dicyanometalate bridging ligands: Structural variations and spin-crossover behavior

244th National Meeting (2012)

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