Anion-Tunable Configuration Isomerism and Magnetic Coupling in a Tetranuclear Discrete, One-Dimensional (1D) Chiral Chain and 1D-Decker Copper(II) Complexes of a Carbohydrazine Derivative
journal contribution
posted on 2014-01-06, 00:00 authored by Wei Huang, Yuchao Jin, Dayu Wu, Genhua WuThe reactions of ligand <i>N</i>′-[(pyridin-2-yl)methylene]pyrazine-2-carbohydrazide (ppcd)
with different copper salts (<b>1</b>, acetate; <b>2</b>, perchlorate; <b>3</b>, sulfate) in MeOH could afford one
acetate-bridge tetranuclear discrete [Cu<sub>2</sub>(ppcd)(ac)<sub>2</sub>(H<sub>2</sub>O)(OH)]<sub>2</sub>·H<sub>2</sub>O (<b>1</b>), one-dimensional (1D) chiral chain [Cu(ppcd)]ClO<sub>4</sub> (<b>2</b>), and a 1D-decker complex of a trinuclear copper(II)
subunit, Cu<sub>3</sub>(ppcd)<sub>2</sub>(H<sub>2</sub>O)<sub>4</sub>(SO<sub>4</sub>)<sub>2</sub> (<b>3</b>). Single-crystal X-ray
analysis revealed that conformation isomerism of the ppcd ligand was
associated with the configuration of −N–N– (trans
or cis) and could induce the versatile coordination mode in the presence
of different anions. The 1D chiral chain was interestingly obtained
from the achiral rigid ligand in complex <b>2</b>. Magnetic
studies indicated that the magnitude of the antiferromagnetic coupling
can be tuned because of the configuration isomerism [compound <b>1</b> is practically diamagnetic at room temperature (<i>J</i> ≈ −1000 cm<sup>–1</sup>), with a
strong antiferromagnetic one (<i>J</i> = −255.4 cm<sup>–1</sup>) for <b>2</b> in the 1D uniform chain and an
antiferromagnetic one (<i>J</i> = −123.6 cm<sup>–1</sup>) for <b>3</b> within the trinuclear copper subunit].
