In this work a new family of binuclear NiII−LnIII complexes of formula [NiLn(L)2(NO3)3]•0.5H2O (Ln = Gd, 1; Tb, 2; Dy, 3; Ho, 4; Er, 5; Yb, 6; Y, 7; has...
The contrasting metal–ion coordination reactivity
behavior
for the multisite ligand H3L ([2,6-bis-{(2-hydroxymethyl-phenylimino)methyl}-4-methylphenol])
with Co(ClO4)2·6H2O in the presence
of ancillary ligands NaPiv (Piv = (CH3)3CCO2
–) and NH4SCN afforded two different
types of mixed-valence tetranuclear cobalt complexes, [CoIII
3CoII(HL)(L)(μ4-O)(μ-OH)((CH3)3CCOO)2]ClO4·H2O (1) and [CoIII
2CoII
2(L)2(NCS)4(CH3CN)2]·CH3CN (2). In
the first case, the presence of bridging pivalate anions triggered
the oxido-hydroxido-bridged dual control for aggregation, whereas
in the second case, terminal thiocyanate coordination forced the dicubane
type of aggregation. The connectivity for different numbers of CoIII and CoII ions are achieved through contrasting
bridges by ancillary water-molecule-derived HO– plus
O2– linkers and ligand-anion-based double phenolato
bridges, where terminal monodentate coordinations finally fulfill
the octahedral geometries around the CoII ions. Alternating
current/direct current (AC/DC) magnetic studies revealed field-induced
slow magnetic relaxation for complex 1 that arises from
the single octahedral CoII ion connected to three other
diamagnetic CoIII ions. Whereas in complex 2, having a tetranuclear CoIII
2CoII
2 structure, the two CoII centers showed an
antiferromagnetic interaction (J = −0.39 cm–1). The structural distortions in these two types of
aggregates lead to different magnitudes of easy-axis
magnetic anisotropy (D = −51.31 cm–1 for 1 and −31.9 cm–1 for 2) and a small but non-negligible transverse component (E/D = 0.263 for 1 and 0.255 for 2). The static and dynamic magnetic data were analyzed using DFT and
CASSCF-based calculations.
A new mononuclear copper(II) complex [Cu(HL)2] (1), has been synthesized from a Schiff base ligand (H2L) and characterized by FTIR spectroscopy, UV-Vis spectroscopy, single crystal X-ray diffraction, and powder X-ray...
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