Binuclear copper(II) complexes of some sexadentate phthalazine-hydrazone ligands with strong antiferromagnetic exchange
Sexadentate phthalazine-hydrazone ligands (N 6), involving pyridine and N-methylimidazole as peripheral donor groups, form binuclear hydroxo-bridged copper(II) complexes which exhibit very strong antiferromagnetic exchange (−2 J=885−1211 cm −1), which is propagated via a superexchange mechanism thro...
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Published in | Inorganica Chimica Acta Vol. 178; no. 2; pp. 169 - 178 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
Lausanne
Elsevier B.V
15.12.1990
Elsevier Science |
Subjects | |
Online Access | Get full text |
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Summary: | Sexadentate phthalazine-hydrazone ligands (N
6), involving pyridine and
N-methylimidazole as peripheral donor groups, form binuclear hydroxo-bridged copper(II) complexes which exhibit very strong antiferromagnetic exchange (−2
J=885−1211 cm
−1), which is propagated via a superexchange mechanism through the bridging diazine (NN) and hydroxide groups. When the hydroxide bridge in [Cu
2(APHPH)(OH)(H
2O)
2](ClO
4)
2·H
2O (APHP=1,4-dihydrazinophalazine-bis(2-pyridine) acetaldimine) (−2
J=988 cm
−1) is replaced by a pyrazolide bridge, a dramatic decrease in exchange is observed (−2
J=521 cm
−1) indicating the importance of hydroxide as a dominant superexchange bridge. The complexes are highly colored, exhibiting very intense visible absorptions (16 400–16 700 cm
−1) associated with charge transfer transitions. The crystal and molecular structure of [Cu
2(APHPH)(OH)(H
2O)
2](ClO
4)
2·H
2O (
VI) is reported.
VI crystallized in the monoclinic system, space group
P2
1/
n, with
a=8.0110(20),
b=24.100(5),
c=15.6750(20) Å, β=100.240(20)° and four formula units per unit cell. Refinement by full-matrix least-squares gave final residuals of
R=0.076 and
R
w=0.038. This complex has a hydroxo-bridged suare-pyramidal structure with a CuCu separation of 3.296(2) Å and a CuO(H)Cu angle of 117.8(3)°. |
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ISSN: | 0020-1693 1873-3255 |
DOI: | 10.1016/S0020-1693(00)86778-X |