Optimisation of octahedral iron(II) and cobalt(II) spin-crossover metal complex for thermoelectric application

By Ibrahim, N. M. J. N.; Said, S. M.; Hasnan, M. M. I. M.; Sabri, M. F. M.; Abdullah, N.; Mainal, A.; Salleh, M. F. M.; Izam, T. F. T. M. N.
Published in Materials Chemistry and Physics 2019

Abstract

Four spin-crossover (SCO) complexes with general formulae, [M2(CH3COO)4(L)2] and [M(L)3](BF4)2, where M = Fe(II) and Co(II), containing extended ?-conjugated bipyridyl ligand and N3-Schiff bases appended with linear C16 carbon chains at the N atoms were successfully synthesized and characterized. Correlation of its structural properties to thermoelectric behavior is investigated: (1)structure of complexes, (2)choice of metal centre and (3)choice of counter ions. It was found that the structure of the molecule, i.e. molecular versus ionic has the largest impact on the SCO behavior. We found that the molecular complexes with higher percentage of high-spin (73.4% HS for Fe-dinuc and 78% HS for Co-dinuc) have produced the highest Seebeck values in mV K?1 (?0.57

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