Magnetic properties and zero-field splitting in high-spin manganese(III) complexes. 1. Mononuclear and polynuclear Schiff-base chelates

Abstract

Variable-temperature (4.2-300 K) and variable-field (4.2 K, 5-50 kG) susceptibility measurements have been made on a range of manganese(III) Schiff-base complexes. The compounds studied contain either tetradentate salicylaldimines and /3-ketone imines of the types [Mn(salen)X] and [Mn(acen)X], where X is Cl", Br", OAc", SCN", N3", or bidentate salicylaldimines of the type Mn(sal-NR)3. The measurements were generally made on Vaseline mulls of the samples in order to avoid anomalous results due to crystallite alignment. Spin Hamiltonian theory has been used to deduce values of the zero-field splitting parameter, D, and the exchange coupling parameter, J. The D values fall in the range -1 to -4 cm"1, /values of less than -1 cm"1 were detected in some of the "monomers" and up to -5.4 cm"1 in the dimer or linear-chain examples. In linear chains such as [Mn(salen)OAc] and [Mn(salen)N3] a small interchain exchange contribution was required to completely explain the data.

Synthesis, thermal study and some properties of N2O4—donor Schiff base and its Mn(III), Co(II), Ni(II), Cu(II) and Zn(II) complexes

“…5. At room temperature the magnetic moment is 5.94 l B , and it is higher than the expected value for manganese(III) (4.90 l B ), but such height values were observed before [60][61][62]. As the temperature was reduced, the magnetic moment was roughly constant ca.…”

Consequences of Electron-Density Manipulations on the X-ray Photoelectron Spectroscopic Properties of Ferrocenyl-β-diketonato Complexes of Manganese(III). Structure of [Mn(FcCOCHCOCH3)3]

“…39 This induces the formation of multiplet splitting, 40 which in turn causes the peaks of both the Mn 2p and the Fe 2p (of the ligand) to have a broader than expected FWHM.…”

Assembly of Mn(III) Schiff Base Complexes with Heptacyanorhenate (IV)

“…the anisotropy of the Mn III depends greatly on JT distortion. In the case of axial elongation, the SB complexes exhibit a negative ZFS D parameter with finite uniaxial anisotropy [19]. Thus, the Mn III in the square planar {NNOO} coordination environment of the SB ligand (Scheme 2) is an excellent building block for the construction of extended and molecular magnetic assemblies, because it possesses potentially vacant axial positions to bind heterometallic complex by means of ambidentate ligands.…”