Unique Mixed-Valence Cu(I)/Cu(II) Coordination Polymer
with New Topology of Bitubular 1D Chains Driven by 1,3,5-Triaza-7-phosphaadamantane
(PTA)
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Abstract
The new one-dimensional (1D) mixed-valence copper(I/II)
coordination
polymer [Cu<sub>3</sub>(μ-HCOO)<sub>2</sub>(HCOO)<sub>3</sub>(μ-PTA)<sub>3</sub>(PTA)]<sub><i>n</i></sub>·<i>n</i>H<sub>2</sub>O (<b>1</b>) has been obtained from
copper(II) formate, copper(0) powder, and 1,3,5-triaza-7-phosphaadamantane
(PTA) in MeCN medium. It has been characterized by IR, <sup>1</sup>H, and <sup>31</sup>P{H} NMR and EPR spectroscopy, and elemental,
differential thermal, powder, and single-crystal X-ray diffraction
analysis. The latter features the intricate bitubular 1D chains composed
of the novel tetracopper(II) {Cu<sub>4</sub>(μ-HCOO)<sub>4</sub>(HCOO)<sub>6</sub>}<sup>2–</sup> blocks that are multiply
assembled by copper(I) {μ<sub>3</sub>-Cu(PTA)<sub>4</sub>}<sup>+</sup> units. The topological analysis of <b>1</b> discloses
a binodal 3,3-connected network with the unprecedented topology described
by the point symbol of (4·6·8)<sub>2</sub>(4<sup>2</sup>·6). The magnetic susceptibility of <b>1</b> has been
studied and described by a model that considers independent contributions
of tetracopper(II) {Cu<sub>4</sub>(μ-HCOO)<sub>4</sub>(HCOO)<sub>6</sub>}<sup>2–</sup> blocks, with global antiferromagnetic
exchange between the “outer” (<i>J</i> = −23(2)
cm<sup>–1</sup>) and “inner” (<i>J</i>′ = −112(3) cm<sup>–1</sup>) pairs of copper
atoms. Compound <b>1</b> widens the still limited family of
PTA-driven coordination polymers, also representing the first homometallic
mixed-valence derivative bearing this cagelike aminophosphine building
block
