Covalently Linked Dimer of Mn₃ Single-Molecule Magnets and Retention of Its Structure and Quantum Properties in Solution

Abstract

[Mn3O(O2CMe)3(dpd)3/2)]2(I3)2 has been obtained from the reaction of 1,3-di(pyridin-2-yl)propane-1,3-dione dioxime (dpdH2) with triangular [Mn(III)3O(O2CMe)(py)3](ClO4). It comprises two [Mn(III)3O](7+) triangular units linked covalently by three dioximate ligands into a [Mn3]2 dimer. Solid state dc and ac magnetic susceptibility measurements reveal that each Mn3 subunit of the dimer is a separate single-molecule magnet (SMM) with an S = 6 ground state and that the two SMM units are very weakly ferromagnetically exchange coupled. High-frequency EPR spectroscopy on a single crystal displays signal splittings indicative of quantum superposition/entanglement of the two SMMs, and parallel studies on MeCN/toluene (1:1) frozen solutions reveal the same spectral features. The dimer thus retains its structure and inter-Mn3 coupling upon dissolution. This work establishes that covalently linked molecular oligomers of exchange-coupled SMMs can be prepared that retain their oligomeric nature and attendant inter-SMM quantum mechanical coupling in solution, providing a second phase for their study and demonstrating the feasibility of using solution methods for their deposition on surfaces and related substrates for study.

Aminopyridine complexes of Cr(III) basic carboxylates as potential polymer precursors: Synthesis, characterization, and crystal structure of [Cr3O(propionate)6(X-aminopyridine)3]+ (X = 3 or 4)

“…Previously, weak exchange coupling has also been shown for four covalently linked Mn(III) trinuclear oxo-bridged carboxylate assemblies; each trinuclear unit is coupled to two adjacent trinuclear units [6]. The crosslinking of the trinuclear Mn(III) units allowed them to be stable in solution so that they might be deposited on surfaces for application studies [5,6]; however, as Cr(III) undergoes slow exchange reactions, trinuclear oxo-centered Cr(III) carboxylate assemblies are much more stable in solution.…”

“…For example, recently the coupling of two similar trinuclear Mn(III) oxo-centered carboxylate assemblies generates a dimer of trinuclear units that are weakly ferromagnetically coupled, resulting in quantum superposition/entanglement of the two assemblies [5]. Previously, weak exchange coupling has also been shown for four covalently linked Mn(III) trinuclear oxo-bridged carboxylate assemblies; each trinuclear unit is coupled to two adjacent trinuclear units [6].…”

Novel Structures and Magnetic Properties of Two [Mn2] Complexes with 2,4-di-2-pyridyl-2,4-pentanediol as the Ligand

“…2.5853 (7) Mn (2)-Br (2) 2.5710 (7) (2) 98.33 (8) Compound 2 crystallized in a monoclinic C2/c space group. X-ray refinement data for the complex are also listed in Table 1.…”

“…Manganese containing coordination complexes are of great interest due to their unique magnetic properties [1-3] as well as their variety of functions in chemistry [4][5][6]. A very large number of oxygen bridging compounds have been synthesized [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. However, in a survey of the literature, all of the manganese ions in these complexes are connected with neighboring manganese ions through bridging atoms.…”

New mixed-valence MnII4MnIV clusters from an unusual ligand transformation

“…The latter owes much to the propensity of bridging hmpto lead to ferromagnetic (F) coupling [18,21,[31][32][33][34], as indeed do a number of oximate chelates in Mn cluster chemistry [20,35,36]. In addition, some of the Mn 3 SMMs have also proven excellent precursors for making supramolecular aggregates or high nuclearity manganese clusters [37][38][39][40].…”