Synthesis of layered (2-D) V-based bimetallic oxalates from non-aqueous media that cannot be synthesized from aqueous media

Abstract

The reaction of (NBu₄)₃[V^III(ox)₃] (1, ox = oxalate) and M(II) (M = Fe, Co, Ni, Cu) ions in MeCN, leads to the isolation of V-based coordination polymers of [N(n-Bu)₄][Fe^IIV^III(ox)₃]·0.30{[N(n-Bu)₄](BF₄)} (2), [N(n-Bu)₄][Co^IIV^III(ox)₃]·0.75{[N(n-Bu)₄](BF₄)} (3), [N(n-Bu)₄][Ni^IIV^III(ox)₃]·0.20{[N(n-Bu)₄](BF₄)}·0.20MeCN (4), and [N(n-Bu)₄][Cu^IIV^III(ox)₂](BF₄)₂ (5) composition. Due to the lability of [V^III(ox)₃]³⁻ to dissociate ox²⁻, these compounds cannot be prepared from aqueous media. 5 is best described as [N(n-Bu)₄][V^IIICu^II(ox)₂](BF₄)₂, and 2, 3, 4, and 5 are proposed to have a layered (2-D) motif for the M′M(ox)_x (x = 2, 3) extended framework. The [V^IIICu^II(ox)₂] composition of 5 is reported for the first time for a bimetallic oxalate. 2 shows a weak antiferromagnetic interaction between Fe(II), S = 2 and V(III), S = 1 ions (θ = −9.4 K) within the 2-D layers. 3 and 5 do not magnetically order above 2 K. 4 magnetically order as ferromagnets below 2.55 K [taken as the onset of magnetization in χ″(T)], and has a glass transition temperature (χ′_max at 1000 Hz) at 2.26 K.