Magnetic interactions in two heterobridged dinuclear copper(II) complexes: orbital complementarity or countercomplementarity?
The mechanisms of magnetic exchange interactions in two heterobridged mu-hydroxyl-mu-X dicopper complexes A and B (X = azaindole for A and X = pyrazole for B) are investigated by the calculations based on density functional theory combined with the broken-symmetry approach (DFT-BS). It is found that although the coordination circumstances of the copper centers in the two complexes are very similar, the magnetic magnitudes and signs are diametrically opposed. By the theoretical analyses of magnetic orbital interaction and spin distribution, it is indicated that the difference between the magnetic properties of the two complexes is due to the distinction of orbital interaction of two bridge ligands. Namely, the weak ferromagnetic coupling for complex A arises from the orbital countercomplementarity of the hydroxo and azaindole bridges while the strong antiferromagnetic coupling for complex B arises from the orbital complementarity of the hydroxo and pyrazolato bridges.
Wang
Li-Li
LL
Institute of Theoretical Chemistry, Shandong University, Jinan 250100, PR China.
Sun
You-Min
YM
Qi
Zhong-Nan
ZN
Liu
Cheng-Bu
CB
D001372:Aza Compounds / Q000737:chemistry*; D002413:Cations, Divalent / Q000737:chemistry; D003300:Copper / Q000737:chemistry*; D005296:Ferrous Compounds / Q000737:chemistry*; D007211:Indoles / Q000737:chemistry*; D008280:Magnetics; D009942:Organometallic Compounds / Q000737:chemistry*; D011720:Pyrazoles / Q000737:chemistry*; D011789:Quantum Theory; D013816:Thermodynamics
C512290:5-azaindole; C504762:6-azaindole; D001372:Aza Compounds; D002413:Cations, Divalent; D005296:Ferrous Compounds; D007211:Indoles; D009942:Organometallic Compounds; D011720:Pyrazoles; C031280:pyrazole; D003300:Copper