Ferro- to antiferromagnetic crossover angle in diphenoxido- and carboxylato-bridged trinuclear Ni(II)2-Mn(II) complexes: experimental observations and theoretical rationalization

Abstract

Three new trinuclear heterometallic NiII-MnII complexes have been synthesized using [NiL] metalloligand where H2L = N,N′- bis(salicylidene)-1,3-propanediamine. The complexes [(NiL)4Mn2(OCn)4(CH3OH)4]·2CH3OH (1), [(NiL)4Mn2(OPh)4(CH3OH)2]·H2O (2) and [(NiL)4Mn(OSal)2(CH3OH)2] (3) (where OCn = cinnamate, OPh = phenylacetate, OSal= salicylate) have been structurally characterized. In all three complexes, in addition to the double phenoxido bridge, the two terminal NiII atoms are linked to the central MnII by means of syn-syn bridging carboxylate, giving rise to a linear structure. Complexes 1 and 2 with Ni-O-Mn angle of 97.24 and 96.43° respectively exhibit ferromagnetic interactions ( JNi-Mn = +1.38 and +0.50 cm-1 respectively) whereas 3 is antiferromagnetic (JNi-Mn= -0.24 cm-1) having Ni-O-Mn angle of 98.51°. DFT calculations indicate that there is a clear magneto-structural correlation between Ni-O-Mn angle and JNi-Mn values which is in agreement with the experimental results.