Heterobimetallic One-Dimensional Coordination Polymers MICuII (M = Li and K) Based on Ferromagnetically Coupled Di- and Tetracopper(II) Metallacyclophanes

Abstract

The synthesis, crystal structure and magnetic properties of the coordination polymers of formula [EDAP{Li6(H2O)8[(Cu2(μ-mpba)2)2(H2O)2]}]n (1) and [(EDAP)2{K(H2O)4[Cu2(μ-mpba)2(H2O)2]}Cl·2H2O]n (2), in which mpba = N,N′-1,3-phenylenebis(oxamate) and EDAP2+ = 1,1′-ethylenebis(4-aminopyridinium) are described. Both compounds have in common the presence of the [Cu2(mpba)2]4− tetraanionic unit which is a [3,3] metallacyclophane motif in which the copper(II) ions are five-coordinate in a distorted square pyramidal surrounding. The complex anion in 1 is dimerized through double out-of-plane copper to outer carboxylate-oxygen atoms resulting in the centrosymmetric tetracopper(II) fragment [Cu4(μ-mpba)4(H2O)2]8− which act as a ligand toward six hydrated lithium(I) cations leading to anionic ladder-like double chains whose charge is neutralized by the EDAP2+ cations. In the case of 2, each dicopper(II) entity acts as a ligand towards tetraquapotassium(I) units to afford anionic zig zag single chains of formula {K(H2O)4[Cu2(μ-mpba)2(H2O)2]}n3n− plus EDAP2+ cations and non-coordinate chloride anions. Cryomagnetic measurements on polycrystalline samples 1 and 2 show the occurrence of ferromagnetic interactions between the copper(II) ions across the –Namidate–(C–C–C)phenyl–Namidate– exchange pathway [J = +10.6 (1) and +8.22 cm−1 (2)] and antiferromagnetic ones through the double out-of-plane carboxylate-oxygen atoms [j = −0.68 cm−1 (1), the spin Hamiltonian being defined as H = − J ( S C u 1 · S C u 2 + S C u 2 i · S C u 1 i ) − j ( S C u 2 · S C u 2 i ) ].

Crystal structure, magnetic properties and theoretical study of a bithiazolebis(oxamate)-containing [NiII3] helicate

“…[12][13][14] In so doing, a plethora of tailor-made oligonuclear SCCs like mesocates, grids and cages with interesting magnetic properties were achieved using di-or polytopic oxamates as ligands. [15][16][17][18][19][20][21][22][23][24][25][26] High-nuclearity SCCs, from penta-up to nonanuclear species, were obtained through the metalloligand approach by using oxamato-based di-and trinuclear SCCs as ligands toward coordinatively unsaturated mononuclear metal complexes with different capping ligands. 27,28 In the lack of capping ligands, coordination polymers of varying dimensionalities (nD, n = 1-3) and topologies have been alternatively obtained [29][30][31] and, occasionally, hexa-, deca-and dodecanuclear wheels.…”

Solid-State Self-Assembly of a Linear Hexanuclear Copper(II) Oxamate Complex with Alternating Antiferro- and Ferromagnetic Coupling

“…The great versatility of polychelating oxamate ligands in the coordination of transition metal ions has been described in several reports [12][13][14]. Due to the presence of several sites of coordination and bridging nature [14], they can be used to form discrete mono- [15,16], di- [17], and trinuclear species [18], up to deca-or dodecanuclear nanowheel systems [19,20], as well as extended chains [21], planes [22], and 3D networks [23], so-called metal-organic frameworks [12,13,24]. Supramolecular chemistry plays an important role in this synthetic strategy because it can also drive the dimensionality of the network through coordinative interactions, hydrogen bonds, the interaction between cations and anions, Van der Waals forces, and π-π stacking interactions, to cite some examples [25,26].…”