The First Series of Heterometallic Ln^III‐V^IV Complexes Based on Substituted Malonic Acid Anions: Synthesis, Structure and Magnetic Properties

Abstract

The reaction of VOSO 4 with K 2 cbdc (cbdc 2is cyclobutane-1,1-dicarboxylate anion) and Ln(NO 3 ) 3 (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, Tm, Yb, Lu) yielded 17 novel heterometallic Ln III -V IV compounds comprising stable bischelate units {V IV O(cbdc) 2 (H 2 O)}. Three structural types of compounds are formed depending on the nature of the rare-earth metal: 1D polymers {[Ln(VO)(cbdc) 2 (H 2 O) 7 ]·0.5[VO(cbdc) 2 ]} n (structural type I) [Ln = La (1), Ce (2)], 3D polymers {[KLn(VO) 2 (cbdc) 4 (H 2 O) 9 ]·3.5H 2 O} n (structural type II) [Ln = La 5075 [Ln = Y (13), Er (14), Tm (15), Yb (16), Lu (17)] containing dinuclear units {LnV}. Magnetic properties were investigated for all isolated compounds. The Gd III -V IV compound has ferromagnetic and antiferromagnetic exchange interactions between isotropic V IV and Gd III ions. Calculations using the DFT method at the UB3LYP/6-31G(d,p)/SDD level of theory were performed in order to explain the different nature of exchange interactions in two Gd III -V IV pairs. The Yb III -V IV complex displays single-molecule magnet properties; the effective energy barrier was estimated at ΔE eff /k B = 26 K. The magnetic properties of Ln III -V IV compounds with heavy lanthanide ions (Ln III = Er, Tm, Yb) were rationalized in terms of crystal-field calculations for Ln III ions. and clear magnetic hysteresis of purely molecular origin, which are characteristic of single-molecule magnets (SMM). [3] Complexes of 3d-4f metals are considered as good candidates for SMMs due to high anisotropy of some lanthanide ions (Tb III , Dy Meanwhile 3d-4f compounds containing a vanadyl ion V IV O 2+ as the 3d center with a single 3d electron (S = 1 / 2 ) are quite rare, although they may provide insight into the mechanism of spin-spin exchange interactions. Despite quite a large number of V IV -4f complexes were described in recent literature, [11] only a few of them were magnetically characterized. [11a,11b,11d,11e,11g,11j,11l] For example, some V IV -Ln III complexes with ferromagnetically coupled V IV and Ln III ions have been reported. [11d,11e] Ishida et al. [11j] performed AC magnetic susceptibility measurements for five isostructural V IV -Ln III complexes, but these compounds did not exhibit SMM behavior. Besides, 3d-4f complexes are of interest as precursors of complex oxides. [12] One synthetic approach to prepare 3d-4f compounds is based on the use of stable 3d-metal complexes with free functional groups capable of acting as metal-containing ligands, Eur. J. Inorg. Chem. 2018, 5075-5090 www.eurjic.org

Mapping Magnetic Properties and Relaxation in Vanadium(IV) Complexes with Lanthanides by Electron Paramagnetic Resonance

“…The temperature dependence of magnetic susceptibility for compounds I and II was reported and discussed previously [19] (see Figure S2). The vanadium units are well magnetically isolated from each other in I, II, and magnetic susceptibility is essentially temperature-independent within 2-300 K. The compounds III and IV feature very similar vanadium-based building blocks, allowing us to assume that all general trends should be the same for compounds I-IV.…”

“…The structures of compounds I and II were described in detail previously [19]. Compounds I and II are isostructural octanuclear molecular complexes formed by two binuclear cationic fragments [Ln(VO)(cbdc) 2 (H 2 O) 7 ] + , two anionic moieties [VO(cbdc) 2 (H 2 O)] 2− , and two K + cations, which connect them.…”

“…Below we describe the developed approaches, the obtained results, and compare them with those of other previously studied vanadium-based molecular spin qubits. (II) have been synthesized by the reaction of aqueous vanadyl nitrate [prepared via metathesis between VOSO 4 •3H 2 O and Ba(NO 3 ) 2 in water] with a freshly prepared aqueous solution of K 2 cbdc (cbdc 2is cyclobutane-1,1-dicarboxylate anion) and Ln(NO 3 ) 3 (I: Ln = Y, II: Ln = Lu) [19]. The replacement of K 2 cbdc by Na 2 cbdc in similar reactions led to the formation of compounds [NaY(VO) 2 (cbdc) 4 (H 2 O) 10 ] n (III) and [NaLu(VO) 2 (cbdc) 4 (H 2 O) 10 ] n (IV).…”

Effect of the Alkaline Metal Ion on the Crystal Structure and Magnetic Properties of Heterometallic GdIII-VIV Complexes Based on Cyclobutane-1,1-Dicarboxylate Anions

“…In 2, the {GdV 2 } − units were linked into a 3D-polymeric structure by Rb atoms bonding the O3, O7 carboxylate atoms of the {(V(1)O)(cbdc) 2 (H 2 O)} moieties and the O10, O12, O13 carboxylate atoms of the {(V(2)O)(cbdc) 2 (H 2 O)} moieties, as well as the water molecules coordinated to the V2 (O3W) and Gd (O8W, O13W) atoms (Figure 5, Tables 1 and S2). Unlike the {[KGd(VO) 2 (cbdc) 4 (H 2 O) 9 ]•3.5H 2 O} n structure obtained previously, in which the K atom additionally coordinated only one water molecule [45], the Rb atom in the structure of 2 bound two water molecules (O12W, O13W). The crystal structure of 2 was additionally stabilized by a network of hydrogen bonds formed by carboxylate O atoms (O10 and O17), water molecules coordinated to the V (O3W and O4W) and Gd (O9W, O10W, O13W) atoms, as well as solvate water molecules (O1W, O2W, O5W) (Table S6).…”

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

“…By varying the substituents in the methylene group of malonic acid, it is possible to change the structure and properties of the resulting compounds, which was previously demonstrated for homometallic complexes of manganese­(II), − cobalt­(II), − nickel­(II), , copper­(II), − etc. Moreover, the structure of malonate complexes of transition metals, and hence their properties, can be changed by introducing atoms of s-, d-, or f-elements into a compound. − To date, vast data on the synthesis, structural features, and properties of transition metal complexes (with the exception of iron) with anions of substituted malonic acids and atoms of s-elements have been collected.…”