In:
ChemPhysChem, Wiley, Vol. 11, No. 9 ( 2010-06-21), p. 1961-1970
Kurzfassung:
The ability of bridging thiophenolate groups (RS − ) to transmit magnetic exchange interactions between paramagnetic Ni II ions is examined. Specific attention is paid to complexes with large NiSRNi angles. For this purpose, dinuclear [Ni 2 L 1 (μ‐OAc)⋅I 2 ][I 5 ] ( 2 ) and trinuclear [Ni 3 L 2 (OAc) 2 ][BPh 4 ] 2 ( 3 ), where H 2 L 1 and H 2 L 2 represent 24‐membered macrocyclic amino‐thiophenol ligands, are prepared and fully characterized by IR‐ and UV/Vis spectroscopy, X‐ray crystallography, static magnetization M measurements and high‐field electron spin resonance (HF‐ESR). The dinuclear complex 2 has a central N 3 Ni 2 (μ‐S) 2 (μ‐OAc)Ni 2 N 3 core with a mean NiSNi angle of 92°. The macrocycle L 2 supports a trinuclear complex 3 , with distorted octahedral N 2 O 2 S 2 and N 2 O 3 S coordination environments for one central and two terminal Ni II ions, respectively. The NiSNi angles are at 132.8° and 133.5°. We find that the variation of the bond angles has a very strong impact on the magnetic properties of the Ni complexes. In the case of the Ni 2 ‐complex, temperature T and magnetic field B dependencies of M reveal a ferromagnetic coupling J =−29 cm −1 between two Ni II ions (H= J S 1 S 2 ). HF‐ESR measurements yield a negative axial magnetic anisotropy ( D 〈 0) which implies a bistable (easy axis) magnetic ground state. In contrast, for the Ni 3 ‐complex we find an appreciable antiferromagnetic coupling J ′=97 cm −1 between the Ni II ions and a positive axial magnetic anisotropy ( D 〉 0) which implies an easy plane situation.
Materialart:
Online-Ressource
ISSN:
1439-4235
,
1439-7641
DOI:
10.1002/cphc.200900935
Sprache:
Englisch
Verlag:
Wiley
Publikationsdatum:
2010
ZDB Id:
2025223-7
