Syntheses, Crystal Structure, and Magnetic Properties of Mn12 Single-Molecule Magnets with Naphthalenecarboxylate Bridges, [Mn12O12(O2CC10H7)16(H2O)4] and Their Tetraphenylphosphonium Salts

Abstract

The preparation and physical characterization are reported for three Mn12 single-molecule magnets (SMMs) having naphthalenecarboxylate bridges, [Mn12O12(2-nc)16(H2O)4] (1, 2-ncH = 2-naphthalenecarboxylic acid), its Ph4P+ salt (2) and [Mn12O12(1-nc)16(H2O)4] (3, 1-ncH = 1-naphthalenecarboxylic acid). Complex 1·2CH2Cl2·4.5H2O crystallizes in the monoclinic space group C2/c, with cell dimensions at −160 °C of a = 28.524 Å, b = 17.819 Å, c = 36.058 Å, β = 92.399°, and Z = 4. The X-ray structure analysis of 1·2CH2Cl2·4.5H2O reveals that each [Mn12] molecule is connected to the neighboring molecules through eight π···π interactions to form a two-dimensional structure within the bc-plane. This is the first SMM that self-assembles two-dimensionally via π···π interaction. From Arrhenius plots of the frequency dependence of the temperatures of the χ″M peaks, the effective energy barriers Ueff for the reversal of the magnetization spin were estimated to be 61 K, 53 K, and 61 K for high-temperature phases of 1–3, respectively, and 31 K and 33 K for the low-temperature (LT) phases of 1 and 3, respectively. The analysis of the reduced magnetization data suggests that the LT phase of 1 has an S = 9 ground state with g = 1.998 and D = −0.61 K.

Nanostructures as the Substrate for Single-Molecule Magnet Deposition

“…Gerbier et al utilized this approach by introducing spin-carrying carboxylate groups onto the Mn 12 molecule using 1-[N-t-butyl-N-(oxyl)amino]-4-benzoic acid radicals, which coupled antiferromagnetically to the [Mn 12 O 12 ] core [ 39 ]. Bian et al prepared naphthalene-carboxylate derivatives that assembled two-dimensionally via π-π interactions [ 47 ], and Willemin et al made methacrylate derivatives to produce chemically and thermally stable nanocomposites [ 48 ]. Coronado et al have reported the way for the synthesis of the polycationic form of Mn with an S T = 11 ground state using betaine hexafluorophosphate salt (see Figure 2 b) [ 49 ].…”

Two manganese(II) complexes based on anthracene-9-carboxylate: Syntheses, crystal structures, and magnetic properties

“…So far, this has been at an evolutionary stage with the current focus mainly on understanding the factors that determine the crystal packing as well as exploring relevant properties [3,[7][8][9][10][11]. Among various ligands, the versatile carboxylic acid ligands exhibiting diverse coordination modes, especially benzene-based and naphthalene-based carboxylic acids have been employed and well documented in the preparations of various carboxylato-containing Mn II metalorganic complexes [12][13][14][15][16][17][18][19][20][21][22]. Some of these are benzoic acid [12][13][14][15][16][17][18][19][20][21], naphthalene-2-carboxylic acid [22], and naphthalene-1-carboxylic acid [23].…”