New Mononuclear Mn(III) Complexes with Hydroxyl-Substituted Hexadentate Schiff Base Ligands

Abstract

This paper reports the syntheses, crystal structures and magnetic properties of Mn(III) hexadentate Schiff base complexes [Mn(4-OH-sal-N-1,5,8,12)]NO3(1) and [Mn(4-OH-sal-N-1,5,8,12)]ClO4(2), where (4-OH-sal-N-1,5,8,12)2− (4,4′-((1E,13E)-2,6,9,13-tetraazatetradeca-1,13-diene-1,14-diyl)bis(3-methoxyphenol) is a new hydroxyl-substituted hexadentate Schiff base ligand. The introduction of the (4-OH-sal-N-1,5,8,12)2− ligand induces more hydrogen bonding interactions, in addition to promoting the formation of intermolecular interactions among the cations. However, the close-packing structures of both complexes lead to their stabilization in the high-spin state in the temperature range of 2−300 K.

Spin-state switching: chemical modulation and the impact of intermolecular interactions in manganese(iii) complexes

“…73 Our detailed studies on [Mn(X-sal 2 -323)](ReO 4 ) (X = 5 Cl, 1 ; X = 5 Br, 2 ; X = 3,5 Cl, 3 ; X = 3,5 Br, 4 ; and X = 5 NO 2 , 5 ) confirm the significant impact of the ligand substituent on the spin-state switching behavior of the manganese( iii ) center in a MnN 4 O 2 coordination environment, where the cooperative effect coming from the solid-state structural features plays a very important role. In addition, our comprehensive findings along with the similar manganese( iii ) complexes having an isostructural [Mn(X-sal 2 -323)] + unit with various counter anions (BPh 4 − , ClO 4 − , NO 3 − , PF 6 − , TCNQ 1.5 − , OTf − , NTf 2 − , and ReCl 6 − ) 57–87 (Tables S12–S17†) allow us to conclude the immense effect of the ReO 4 − counter anion on the spin-state switching feature of manganese( iii ) complexes in a MnN 4 O 2 coordination environment.…”

“…54–56 Since then, many research groups including us have been exploring spin-state switching of the manganese( iii ) system in MnN 4 O 2 based on N 4 O 2 hexadentate Schiff base ligands. 57–87…”

Synthesis, Characterization and Breast Anti-cancer Activity of Iron(II), Cobalt(II), Nickel(II) and Copper(II) Complexes with a Hexadentate Schiff Base Ligand Derived from 2,5-Dihydroxy-1,4-benzoquinone with 5-Amino-2-methylphenol

“…This stability is due to the presence of the basic donor nitrogen atom of the azomethine group. Furthermore, Schiff bases are designed and synthesized widely because of the attachment with metal ions in different manners, their stability, and their biological effects [15][16].…”