Substituting group induced structural transformation from 1D zigzag chain to 2D grid network in cyano-bridged dimetallic complexes derived from Mn ~III(Schiff-base) and [Cr~I(CN)_5NO]~(3-): Synthesis, crystal structure and magnetic properties

摘要

Two cyano-bridged dimetallic complexes derived from Mn ~III(Schiff-base) and [Cr~I(CN)_5NO]~(3-), [Mn(3-CH_3)salen]_3[Cr(CN)_5NO]·2.5H _2O (1) and [Mn(5-CH_3)salen]_6[Cr(CN) _5NO]_2·2CH_3OH·16H_2O (2) [salen = N,N′-ethylenebis (salicylideneiminato)dianion] were synthesized and characterized. The reaction conditions of the two complexes are identical. The substituting group (CH_3-) in the salen-type ligands gives different assembly styles for the two complexes, 1D zigzag chain for 1 while 2D grid network for 2. The magnetic investigation indicates the dominant antiferromagnetic interactions between the Mn(III) and Cr(I) mediated by the CN bridge. Due to the weak interchain antiferromagnetic interactions, no magnetic ordering phase was observed in complex 1. Interestingly, complex 2 showed the long range ferrimagnetic magnetic ordering with T_c = 9 K, in contrast to 1. Furthermore, the hysteresis loop confirms the nature of complex 2 as soft ferrimagnet.