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)

Abstract

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.