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)

The new one-dimensional (1D) mixed-valence copper­(I/II) coordination polymer [Cu₃(μ-HCOO)₂(HCOO)₃(μ-PTA)₃(PTA)]_<i>n</i>·<i>n</i>H₂O (<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, ¹H, and ³¹P­{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) {Cu₄(μ-HCOO)₄(HCOO)₆}^2– blocks that are multiply assembled by copper­(I) {μ₃-Cu­(PTA)₄}⁺ 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)₂(4²·6). The magnetic susceptibility of <b>1</b> has been studied and described by a model that considers independent contributions of tetracopper­(II) {Cu₄(μ-HCOO)₄(HCOO)₆}^2– blocks, with global antiferromagnetic exchange between the “outer” (<i>J</i> = −23(2) cm^–1) and “inner” (<i>J</i>′ = −112(3) cm^–1) 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