| Abstract
| - Four mononuclear MnII complexes with pentadentate amino-pyridine ligands are described, the sixth position being occupied by a chloride anion or a water molecule. The X-ray structures evidence two different wrappings for the same [N5] ligand. DFT calculations reproduce well the experimental ZFS values as determined by HF-EPR studies. In addition, in contrast with chloro systems, the spin−spin and spin−orbit coupling parts are shown to be comparable for mixed N,O-coordination sphere complexes.
- The two pentadentate amino-pyridine ligands L52 and L53 (L52 and L53 stand for the N-methyl-N,N′,N′-tris(2-pyridylmethyl)ethane-1,2-diamine and the N-methyl-N,N′,N′-tris(2-pyridylmethyl)propane-1,3-diamine, respectively) were used to synthesize four mononuclear MnII complexes, namely [(L52)MnCl](PF6) (1(PF6)), [(L53)MnCl](PF6) (2(PF6)), [(L52)Mn(OH2)](BPh4)2 (3(BPh4)2), and [(L53)Mn(OH2)](BPh4)2 (4(BPh4)2). The X-ray diffraction studies revealed different configurations for the ligand L5n (n = 2, 3) depending on the sixth exogenous ligand and/or the counterion. Solid state high-field electron paramagnetic resonance spectra were recorded on complexes 1−4 as on previously described mononuclear MnII systems with tetra- or hexadentate amino-pyridine ligands. Positive and negative axial zero-field splitting (ZFS) parameters D were determined whose absolute values ranged from 0.090 to 0.180 cm−1. Density-functional theory calculations were performed unraveling that, in contrast with chloro systems, the spin−spin and spin−orbit coupling contributions to the D-parameter are comparable for mixed N,O-coordination sphere complexes.
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