S-Functionalized Tripods with Monomethylene Spacers: Routes to Tetrairon(III) Single-Molecule Magnets with Ultrashort Tethering Groups

Abstract

The organization of single-molecule magnets (SMMs) on surfaces is a mainstream research path in molecular magnetism. Of special importance is the control of grafting geometry in chemisorbed monolayers on metal surfaces. We herein present the synthesis, solid-state structure, and magnetic characterization of propeller-like tetrairon(III) SMMs containing the shortest-reported tethering groups for gold surfaces. Functionalization of molecular structure is attained using 2-R-2-(hydroxymethyl)propane-1,3-diol tripodal proligands (H3LR). The R substituents comprise a monomethylene spacer and three different terminations known to act as stable precursors of S-Au bonds (R = CH2SCN, CH2SAc and CH2SSnBu). These chemical groups are shown to be chemically compatible with the tetrairon(III) core and to afford fully-functional SMMs in crystalline form and in fair to excellent yields.

Engineering Chemisorption of Fe4 Single‐Molecule Magnets on Gold

“…[45] Such an approach remains in principle feasible for any spacer's length, as long as n ≥ 2. [51] Tollens condensation [52,53] of the appropriate terminally unsaturated aldehyde with formaldehyde and CaO in ethanol is the key step that affords the metal-chelating trimethylol unit in a one-pot reaction (Figure 1a). The yield of Tollens condensation is limited by the concomitant formation of partially-hydroxylated species along with hemiformals and dehydration byproducts whose separation can be rather difficult.…”

Impacts of Alkali Metals on the Structures and Properties of Fe(III) Heterometallic Cyclobutane-1,1-dicarboxylate Complexes

“…Coordination compounds of iron­(III) are being actively studied due to a spin-crossover phenomenon − or molecular magnet properties, − allowing them to be used in spintronics and quantum engineering. , Complexes of iron­(III) are known to be capable of exhibiting the properties of molecular magnets, i.e., molecules with a directionally bistable magnetic moment, both in the case of polynuclear systems ,, and in the case of mononuclear compounds exhibiting the properties of a magnet at the level of one ion. , The Fe 3+ ions in the complexes show various coordination numbers, from 3 to 7; ,,− however, the magnetic properties of quasioctahedral iron­(III) complexes have insufficiently been studied. Complexes in which Fe 3+ ions are in a distorted octahedral environment are characterized by negative or positive D values. ,− One of the major factors affecting the magnetic properties of coordination compounds of 3d-metals is the coordination environment of the central ion. − Therefore, the choice of an appropriate ligand plays a key role in the design of coordination compounds and, in some cases, enables us to synthesize compounds with the required properties. ,− …”

“…Coordination compounds of iron(III) are being actively studied due to a spin-crossover phenomenon 1−3 or molecular magnet properties, 4−6 allowing them to be used in spintronics and quantum engineering. 7,8 Complexes of iron(III) are known to be capable of exhibiting the properties of molecular magnets, i.e., molecules with a directionally bistable magnetic moment, both in the case of polynuclear systems 6,9,10 and in the case of mononuclear compounds exhibiting the properties of a magnet at the level of one ion. 3,4 The Fe 3+ ions in the complexes show various coordination numbers, from 3 to 7; 2,3,11−13 however, the magnetic properties of quasioctahedral iron(III) complexes have insufficiently been studied.…”