Synthesis, Structure, and Magnetic Ordering of Layered (2-D) V-Based Tris(oxalato)metalates

Abstract

The reaction of K3[M(III)(ox)3].3H2O [M = V (1), Cr; ox = oxalate], Mn(II)/V(II), and [N(n-Bu)4]Br in water leads to the isolation of 2-D V-based coordination polymers, [[N(n-Bu)4][Mn(II)V(III)(ox)3]]n (2), [[N(n-Bu)4][V(II)Cr(III)(ox)3]]n (3), [[N(n-Bu)4][V(II)V(III)(ox)3]]n (4), and an intermediate in the formation of 4, [[N(n-Bu)4][V(II)V(III)(ox)3(H2O)2]]n.2.5H2O (4a), while 1-D [V(II)(ox)(H2O)2]n (5) is obtained by using Na2ox and [V(OH2)6]SO4 in water. The structures of 1-5 have been investigated by single crystal and/or powder X-ray crystallography. In 1, V(III) is coordinated with three oxalate dianions as an approximately D3 symmetric, trigonally distorted octahedron. 1 is paramagnetic [mu(eff) = 2.68 mu(B) at 300 K, D = 3.84 cm(-1) (D/k(B) = 5.53 K), theta = -1.11 K, and g = 1.895], indicating an S = 1 ground state. 2 exhibits intralayer ferromagnetic coupling below 20 K, but does not magnetically order above 2 K, and 3 shows a strong antiferromagnetic interaction between V(II), S = 3/2 and Cr(III), S = 3/2 ions (theta = -116 K) within the 2-D layers. 4 and 4a magnetically order as ferrimagnets at T(c)'s, taken as the onset of magnetization, of 11 and 30 K, respectively. The 2 K remanent magnetizations are 2440 and 2230 emu.Oe mol(-1) and the coercive fields are 1460 and 4060 Oe for 4 and 4a, respectively. Both 4 and 4a clearly show frequency dependence, indicative of spin-glass-like behavior. The glass transition temperatures were at 6.3 and 27 K, respectively, for 4 and 4a. 1-D 5 exhibits antiferromagnetic coupling of -4.94 cm(-1) (H = -2Jsigma(i=1)n.S(i-1) - gmu(B)sigma(i=0)(n)H.S(i)) between the V(II) ions.

Electronic structure of V3+ in NaMgAl(ox)3·9H2O probed by Fourier transform spectroscopy

“…The trisoxalatovanadium (III) anion, [V(ox) 3 ] 3À , has received attention in recent years because of its application as a component in multi-nuclear, mixed-valence molecular magnets [1]. In order to understand the complex magnetic properties of these multi-component systems, the electronic structure of the mononuclear (paramagnetic) components needs thorough investigation, which is lacking for the [V(ox) 3 ] 3À anion.…”

[NH4][(CH3)2NH2]2[Ta(C2O4)4]·2H2O: the first (oxalato)tantalate(V) complex structurally characterized

“…In another series of compounds, [H 2 Cat] 2 [Zr(C 2 O 4 ) 4 ]ÁnH 2 O (H 2 Cat = diprotonated organic cation), the charge-assisted hydrogen bonds (CAHB) serve in connecting the [Zr(C 2 O 4 ) 4 ] 4-ions into the complex assemblies ranging from 1D to 3D interlocked networks [19]. In the chemistry of the 5th group of transition metal elements, the V II and V III are known for their very complex heterometallic oxalates where some of them show magnetic ordering at very low temperatures [20]. There is no structural data on the existence of the mononuclear [V(C 2 [7].…”

Synthesis, Structure, and Magnetic Properties of Hydroxo‐Bridged Vanadium Oxalate V2O2(OH)2(C2O4)(H2O)2

“…[10] Thus, homo-and heterometallic systems involving oxalate ions (ox) as bridging ligands have been studied intensively in the search for new molecular-based magnets. [11][12][13] Because of the variable oxidation states of vanadium (V III , V IV , and V V ) and the coordination geometries of vanadium oxide polyhedra (tetrahedral, square pyramidal, trigonal bipyramidal, and octahedral), [14] many compounds containing both vanadium atoms and oxalate ions have been reported, [10,[15][16][17] with different linkages between the vanadium atoms and the oxalate ions as shown in Figure 1, which result in different magnetic properties.…”

“…[10] Thus, homo-and heterometallic systems involving oxalate ions (ox) as bridging ligands have been studied intensively in the search for new molecular-based magnets. [11][12][13] Because of the variable oxidation states of vanadium (V III , V IV , and V V ) and the coordination geometries of vanadium oxide polyhedra (tetrahedral, square pyramidal, trigonal bipyramidal, and octahedral), [14] many compounds containing both vanadium atoms and oxalate ions have been reported, [10,[15][16][17] with different linkages between the vanadium atoms and the oxalate ions as shown in Figure 1, which result in different magnetic properties. [10,16,[18][19][20][21] Recently, a new bonding mode for vanadium atoms and oxalate ions (Figure 1i) has been found in the compound V 2 O 2 (OH) 2 2 is centrosymmetric in the triclinic system with the space group P1, the center of inversion lies along the C-C bond of the bridging oxalato moiety, or on the common edge of two adjacent VO 6 octahedra.…”

“…As shown in Figure 2, the vanadium(IV) atom binds to two oxygen atoms from one oxalate ligand, one oxygen atom from a water molecule, two oxygen atoms from the µ-OH groups, and one terminal oxo oxygen atom to form a distorted octahedron, a very common geometry in vanadium(IV) compounds. [10,16,[18][19][20][21] The VO 6 octahedra of 1 link together by sharing a common edge consisting of two µ-OH groups to form V 2 O 10 dimers; this type of link is rare in vanadium oxalate compounds. The typical ways to link oxalate ligands with VX 6 (X = O, Cl, F, and/or N) octahedra are shown in Figure 1.…”