The Origin of Magnetic Anisotropy and Single-Molecule Magnet Behavior in Chromium(II)-Based Extended Metal Atom Chains

Abstract

S2 1. Synthesis General. Unless otherwise noted, reagents and solvents were of commercial origin and used without further purification. Naphthalene was resublimed and NaSCN was recrystallized from acetone before use. Dichloromethane and diethyl ether for the synthesis of 1a•Et2O were purified using an Inert Technologies solvent purification system. For the synthesis of 2a4CHCl32Et2O and 2b anhydrous dichloromethane (Sigma-Aldrich) was directly used, while chloroform was washed with water, stirred over CaCl2 overnight and distilled under N2; diethyl ether was pre-dried over CaCl2 overnight and distilled from its sodium benzophenone ketyl solution under N2; n-hexane was dried over 4A molecular sieves; all these solvents were degassed by three freeze-pump-thaw cycles. 1 The H2tpda ligand was prepared as described elsewhere, 2,3 recrystallized from boiling methanol or 2-propanol and checked by 1 H NMR spectroscopy and melting point measurement. All reactions involving chromium(II) complexes were carried out under Ar or N2 atmosphere using Schlenk techniques or glovebox methods. Elemental analysis was carried out by Microlab Kolbe (Oberhausen, Germany, 1a•Et2O) or on a Carlo Erba EA1110 CHNS-O automatic analyzer (2a4CHCl32Et2O and 2b). The IR spectra were measured on a Nicolet 6700 FT-IR spectrometer using a Smart iTR accessory between 600 and 4000 cm-1 with 4 cm-1 resolution (1a•Et2O) or on a JASCO 4700 FT-IR spectrometer between 400 and 4000 cm-1 with 2 cm −1 resolution (2a4CHCl32Et2O and 2b). Electrospray Ionization Mass Spectrometry (ESI-MS) was performed on an Agilent Technologies 6310A Ion Trap LC-MS(n) spectrometer. Synthesis of [Cr3(dpa)4Cl2]•Et2O (1a•Et2O). Complex 1a was prepared following a literature procedure 4,5 and isolated as the monodiethylether solvate 6,7 by layering a dichloromethane solution with diethyl ether, yielding a crop of dark green crystals in 60% yield after a week of diffusion. Anal. Calcd for

Theoretical Studies on the Structures of Metal String Complexes Crn(L)4Cl2 (n = 3, 5, 7; L = Oligo-α-Pyridylamide) under the Effect of an Electric Field

“…Meanwhile, the Cr even –Cr odd bonds are notably elongated by 0.194–0.318 Å, which is about 65–106 times larger than the above average reduction (0.003 Å), and their Wiberg bond indexes decreased from 0.606–0.706 to 0.185–0.305 (Figures S1 and S2). The bond lengths (2.519–2.542 Å in Table S4) are in agreement with the conclusion reported by Cornia et al that there can only be a very weak interaction ( d CrCr > 2.5 Å) . It was also observed that the configuration (Table S4) in 2.057 V nm –1 was similar to asymmetric Cr 7 (μ 7 -pzpz) 4 Cl 2 with pyrazine-modified oligo-α-pyridylamido ligands, as reported by Peng et al These significant changes suggest that the Cr even –Cr odd bonds experience weaker interactions and the Cr odd –Cr even multiple bonds are formed, which results in the switching from an on state to an off state .…”

“…Since the first report on the synthesis and structural characterization of [Cu 3 (dpa) 4 Cl 2 ] was published in 1990, a series of studies have been reported by Peng’s group, − Berry’s group, , and Cornia’s group , to develop the structurally similar compounds and to study their molecular structures and physicochemical properties such as magnetic properties, electrical conductivity, and electrochemical properties. Cotton et al found that [Cr 3 (dpa) 4 Cl 2 ] exhibits an asymmetric configuration in benzene and toluene solvents, but in a more polar tetrahydrofuran solvent, it has a symmetric configuration with equal Cr–Cr bonds.…”

Single molecule magnets of cobalt and zinc homo- and heterometallic coordination polymers prepared by a one-step synthetic procedure

“…This indicates that the linker effectively separates the magnetic subunits and no SCM behavior would be expected, only SMM. [73][74][75][76] The observed behavior and anisotropic values are similar to other published mononuclear Co(II) complexes in pseudo-octahedral geometry and also in other Co(II) CPs. [77][78][79][80][81][82] Dynamic susceptibility measurements were performed to study the possibility of slow relaxation of the magnetization.…”

Synthesis and Characterisation of Luminescent [CrIII2L(μ‐carboxylato)]3+ Complexes with High‐Spin S=3 Ground States (L=N6S2 donor ligand)

“…[ 29 , 30 , 31 ] The magnetic exchange interactions in the majority of these dimers is antiferromagnetic in nature. [ 32 , 33 ] Only few ferromagnetically coupled chromium(III) complexes have been reported. [ 34 , 35 , 36 ] Recently, a method for the targeted construction of ferromagnetically coupled chromium(III) complexes was reported.…”