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)]n·nH2O (1) 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 1 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 1 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” (J = −23(2)
cm–1) and “inner” (J′ = −112(3) cm–1) pairs of copper
atoms. Compound 1 widens the still limited family of
PTA-driven coordination polymers, also representing the first homometallic
mixed-valence derivative bearing this cagelike aminophosphine building
block.