Syntheses and Structures of Uwo New Oxalate-bridged Transition-metal Supramolecular Polymers of [M(2-NH_2py)_2(ox)]

Two new supramolecular polymers [M(2-NH_2py)_2(ox)][M=Co(1),Ni(2);2-NH_2py=2-aminopyridine;ox=oxalate] were hydrothermally synthesized and characterized by elemental analyses,IR and single-crystal X-ray diffraction analyses.The isomorphic compounds 1 and 2 both possess one-dimensional zigzag chain structures,which are composed of [M(2-NH_2py)_2]2 units bridged by tetradentate oxalate ligands to form three-dimensional supramolecular network via the C-H…O hydrogen bonds and π-π stacking interactions.Compound 1 displays antiferromagnetic interaction.     

Synthesis and Crystal Structure of a 1D Coordination Polymer： {[Cu（HSSA）（py）3]·H2O}n （H3SSA = 5-Sulfosalicylic Acid,py = Pyridine）

The title compound [Cu（HSSA）（py）3H2O]n （H3SSA = 5-sulfosalicylic acid, py = pyridine） I has been synthesized and structurally determined by single-crystal X-ray diffraction. I was further characterized by elemental analyses, thermogravimetric analyses, IR and UV-visible spectroscopy. The crystal belongs to the monoclinic system, space group P21/c with a = 9.4564（10）, b = 18.2679（19）, c = 15.7284（12） A,β= 126.045（4）°, V= 2196.9（4）A^3, Z= 4, Dc = 1.618 g/cm^3, Mr = 535.02,μ = 1.141 mm^-1, F（000） = 1100, 2（MoKα） = 0.71073 A, the final R = 0.0429 and wR = 0.1044 for all observed reflections. In the structure, every two Cu（II） atoms are bridged by a bivalent 5-sulfosalicylic anion to form a 1D chain-like coordination polymer. Lattice waters between chains link them to form 2D layers which are further linked by C-H…O hydrogen bonds to form a three-dimensional supramolecular network.     

A Layered Vanadium Oxide with Cobalt（Ⅱ） Coordination Complex： Hydrothermal Synthesis and Crystal Structure of （py）5Co2（H2O）3[V4O12]

A novel layered mixed metal vanadium-cobadt complex, （py）5Co2（H2O）3[V4O12] 1 （py = pyridine）, was hydro（solvo）thermally synthesized and characterized by single-crystal X-ray diffraction. It crystallizes in orthorhombic, space group Pca21 with a = 17.473（4）, b = 11.447（2）, c = 17.509（4）A^°, V = 5005.3（7）A^°3, Z = 4, Mr = 3502.1（12）, Z = 4, Dc = 1.827 g/cm^3,μ（MoKα） = 2.023 mm^-1, F（000） = 1928, S = 1.020, the final R = 0.0400 and wR= 0.1063 for 6035 observed reflections with I 〉 2σ（I） and 460 variables. Complex 1 consists of tetrahedral VO4 groups to form the large layers which are alternately bonded by two cobalt complex species Co（py）2（H2O）2 and Co（py）3（H2O）.     

Syntheses, Crystal Structures, and Properties of Two Mixed-ligand Coordination Polymers： [Zn（bdc）（1,3-bimb）]_n and {[Mn_2（ox）_2（1,3,5-tib）_（4/3）]·4H_2O}_n

Two new coordination polymers,[Zn（bdc）（1,3-bimb）]n（1） and {[Mn2（ox）2（1,3,5tib）4/3]·4H2O}n（2）（H2ox = oxalic acid,H2bdc = terephthalic acid,1,3-bimb = 1,3-bis（imidazol-1ylmethyl）benzene,1,3,5-tib = 1,3,5-tri（imidazol-1-yl）benzene）,were synthesized and characterized by elemental analysis,IR,powder X-ray diffraction（PXRD）,and thermogravimetric（TG） analyses.X-ray diffracation analysis reveals that two kinds of zigzag chains [Zn（bdc）]n and [Zn（1,3-bimb）]n in compound 1 are interweaved to form a 3D 4-fold interpenetrated 66-dia framework.In compound 2,Mn（1） and Mn（2） are linked via 1,3,5-tib ligands to form two different nets of [Mn6（1,3,5-tib）6 ]n along the ab plane with inner-or outer-shape N–Mn–N angles,which are connected by 1D infinite [Mn2（ox）2 ]n chains via Mn–O bonds to result in a（3,3,3,4,4）-connected（4·8·10）3（4·82）3（4·83·102）6（82·104·3）3（83）4 topology.Moreover,the photoluminescence of 1 has been investigated.The crystal of 1 crystallizes in orthorhombic,space group Pna2 with a = 13.2267（6）,b = 9.1717（4）,c = 17.4492（8）,V = 2116.79（16）3,Z = 4,C22 H18N4O4 Zn,Mr = 467.77,Dc = 1.468 g/cm3,F（000） = 960 and μ（MoKα） = 1.197 mm-1.The final R = 0.0280 and wR = 0.0618 for 3695 observed reflections with I 2（I） and R = 0.0389 and wR = 0.0653 for all data.The crystal of 2 crystallizes in rhombohedral,space group R-3 with a = 22.080（8）,c = 31.19（2）,V = 13167（11） 3,Z = 18,C24 H25 Mn2 N8 O13,Mr = 743.40,Dc = 1.688 g/cm3,F（000） = 6822 and μ（MoKα） = 0.945 mm-1.The final R = 0.0429 and wR = 0.1035 for 5160 observed reflections with I 2（I） and R = 0.0824 and wR = 0.1244 for all data.     

Synthesis,Properties and Crystal Structure of a New Bismuth Oxalate： Na（C5NH6） [Bi（H2O）（C2O4）2]2·4H2O

A new bismuth oxalate Na（C5NH6）[Bi（H2O）（C2O4）2]2·4H2O has been obtained under hydrothermal conditions and characterized by X-ray diffraction. It crystallizes in monoclinic, space group C2/m with a = 12.020（5）, b = 11.190（8）, c = 11.067（10）A, β= 121.78（2）°, NaBi2C13NH18O22, Mr= 981.24, V = 1265.4（16） A^3, Z = 2, Dc = 2.575 g/cm^3,μ（MoKcr） = 14.005 mm^-1, F（000） = 912, R = 0.0179 and wR = 0.0394. In the structure, the Bi（III） centers are interconnected by oxalate ligands to produce honeycomb-like layers, which are further pillared by bridging ligand oxalate molecules to form a 3-D open-framework structure. Furthermore, the title compound exhibits blue luminescence with the emission peaks located at 394nm in the solid state at room temperature, and thus it could be useful in the field of photoactive materials.     

Syntheses,Structures, and Properties of Three Coordiantion Polymers： [Cd2（bpp）1.5（Hbpp）（phen）2]n, [Mn3（Htptc）2（phen）2（H2O）2]n,and {[Cu（btc）0.5（1,4-bib）]？2H2O}nSyntheses,Structures, and Properties of Three Coordiantion Polymers： [Cd2（bpp）1.5（Hbpp）（phen）2]n, [Mn3（Htptc）2（phen）2（H2O）2]n,and {[Cu（btc）0.5（1,4-bib）]？2H2O}n

Hydrothermal reactions of three aromatic polycarboxylic acids and the transitional metal cations in the presence of phen and 1,4-bib afford three new coordination polymers： [Cd2（bpp）1.5（Hbpp）（phen）2]n （1）, [Mn3（Htptc）2（phen）2（H2O）2]n （2）, and {[Cu（btc）0.5（1,4- bib）]·2H2O}n（3） （H2bpp = 2,6-bis（4＇-carboxyphenyl）-4-phenylpyridine, H4tptc = terphenyl-2,5,2＇,5＇-tetracar- boxylic acid, H4btc =biphenyl-2,2＇,4,4＇-tetracarboxylic acid, phen =1,10-phenanthroline, and 1,4-bib = 1,4-bis（1H-imidazol-1-yl）benzene）. Their structures have been determined by single- crystal X-ray diffraction analyses, elemental analyses, IR spectra, and powder X-ray diffraction （PXRD） analyses. In compound 1, the CdII cations are linked by bpp2- to form one ladder structure, based on which a 3D network is constructed with the help of non-covalent interactions. The topology of 2 is a 3D （3,4,5）-connected framework with the Point Schl？fli symbol of （42.6）2（43.62.8）（45.64.8）2. Compound 3 shows an unprecedented 3D （4,4）-connected framework with the Point Schl？fli symbol of （64.82）2（65.8）. Moreover, the luminescent property of 1 has been investigated.     

Synthesis, Spectroscopic and Electrochemical Investigations of Two vic-Dioximes and Their Mononuclear Ni（Ⅱ）, Cu（Ⅱ） and Co（Ⅱ） Metal Complexes Containing Morpholine Group

Two vic-dioxime ligands （LxH2） containing morpholine group have been synthesized from 4-[2-（dimethylaminoethyl）] morpholine with anti-phenylchloroglyoxime or anti-monochloroglyoxime in absolute THF at -15 ℃. Reaction of two vic-dioxime ligands with MCl2·nH2O （M： Ni, Cu or Co and n=2 or 6） salts in 1 ： 2 molar ratio afforded metal complexes of type [M（LxH）2] or [M（LxH）2·2H2O]. All of metal complexes are non-electrolytes as shown by their molar conductivities （Am） in DMF （dimethyl formamide） at 10^-3 mol·L^-1. Structures of the ligands and metal complexes have been solved by elemental analyses, FT-IR, UV-Vis, ^1H NMR and ^13C NMR, magnetic susceptibility measurements, molar conductivity measurements. Furthermore, redox properties of the metal complexes were investigated by cyclic voltammetry.     

Solvothermal Synthesis and Structure of the [Co（5-NH2-bdc）（4,4＇-dpdo）（H_2O）]_n Complex （4,4＇-dpdo = 4,4＇-Bipyridrl-N,N＇-dioxide,5-NH_2-bdc = 5-Aminoisophthalic Acid）

The title compound [Co（5-NH2-bdc）（4,4＇-dpdo）（H2O）]n 1 （5-NH2-bdc = 5-aminoiso- phthalic acid,4,4＇-dpdo = 4,4＇-bipyridrl-N,N＇-dioxide） crystallizes in triclinic,space group P1 with a = 4.999（1）,b = 10.072（2）,c = 13.028（3） A,α = 107.72（3）,β = 92.58（3）,γ = 98.11（3）°,V = 615.9（3） A^3,F（000） = 356,Rint = 0.0186,Z = 2,R = 0.0333,wR = 0.0721,S = 1.032 and （Δ/σ）max = 0.001. In the molecule of 1,the Co（II） cation is coordinated by three O-atoms of two 5-NH2-bdc ligands,one N-atom of another 5-NH2-bdc ligand,one O-atom of 4,4＇-dpdo and one terminal O-atom of water molecule. The molecules construct a 2-D network through bridging 5-NH2-bdc and 4,4＇-dpdo ligands,and further form a 3-D network through N–H and O–H hydrogen bonds. The network topology of 1 can be simplified as a rare 2D （3,6）-connected （426381） net.     

Syntheses and Crystal Structures of Two New Metal Phosphonates： [Mn（H2O）2（C12H8N2） （HO3PCH2CH2CO2） ] and [Co（H2O）4（C10H8N2）]-（HOaPCH2CH2CO2）

By the reactions of manganese（if） acetate, 2-sulfoethylphosphonic acid, 1,10-phen （1,10-phen = 1, 10-phenanthroline） or cobalt（Ⅱ） acetate, 4,4＇-bipy and 2-carboxyethylphosphonic acid, two novel compounds of [Mn（H2O）2（C12H8N2） （HO3PCH2CH2CO2） ] （1） and[Co（H2O）4（C10H8N2）]-（HOaPCH2CH2CO2） （2） have been synthesized and characterized by IR spectroscopy, elemental analyses and single-crystal X-ray diffraction. Compound 1 has a 0D structure. Two Mn（ii） ions are linked by two 2-carboxyethylphosphonic acid ligands, forming a centrosymmetric dimer. These dimers are further interlinked into a 2D layer structure by π-π stacking interactions and hydrogen bonds. Compound 2 has a 1D chain structure. The 2-carboxyethylphosphonic acid remains uncoordinated and acts as the organic template. By the bridge of 4,4＇-bipy, the [Co（4,4＇-bipy）]^2＋ chains are formed.     

Direct Synthesis, Crystal Structure and Thermal Kinetics of Supramolecular Complex [Co（H2O）6]·（Hnip）2·（H2nip）2·（DMA）2·（H2O）8 （nip=5-nitroisophthalate, DMA=CH3NHCH3）

The crystal of [Co（H2O）6]·（Hnip）2·（H2nip）2·（OMA）2·（H2O）8 has been cultured using direct method and characterized by X-ray single crystal diffractometry, elemental analysis and FTIR spectroscopy. It crystallizes in triclinic system, P-1 space group with the cell parameters of a=0.7012（1） nm, b=1.1378（2） nm, c=1.6612（3） nm, α= 84.92（3）°, β=85.19（3）°, γ=85.91（3）°, V= 1.3128（5） nm^3, Z=1, Dc= 1.573 g·cm^-3. Final R indices [1〉2σ（I）] are： R1 =0.0279, wR2=0.0765 while R indices for all data are： R1 =0.0327, wR2=0.0806. The Co coordination octahadra are each surrounded by two Hnip, two H2nip, two DMA and eight water molecules that are linked by hydrogen bonds and π-π stacking interactions. Thermal analyses of DSC and TG-DTG have been performed on the complex to predict its thermal decomposition mechanism and determine the most probable kinetic model function using Kissinger, Ozawa, integral and differential methods.     

A thermal spin transition in [Co(bpy)3][LiCr(ox)3] (ox = C2O4(2-); bpy = 2,2'-bipyridine)

In the three-dimensional oxalate network structures [M(II)(bpy)3][M(I)-M(III)(ox)3] (ox= C2O4(2-); bpy = 2,2'-bipyridine) the negatively charged oxalate backbone provides perfect cavities for tris-bipyridyl complex cations. The size of the cavity can be adjusted by variation of the metal ions of the oxalate backbone. In [Co(bpy)3][NaCr(ox)3], the [Co(bpy)3]2 + complex is in its usual 4T1(t2g5e(g)2) high-spin ground state. Substituting Na+ by Li+ reduces the size of the cavity. The resulting chemical pressure destabilises the high-spin state of [Co(bpy)3]2+ to such an extent that the 2E(t2g6e(g)1) low-spin state becomes the actual ground state. As a result. [Co(bpy)3][LiCr(ox)3] becomes a spin-crossover system, as shown by temperature-dependent magnetic susceptibility measurements and single-crystal optical spectroscopy, as well as by an X-ray structure determination at 290 and 10 K.     

Synthesis, Crystal Structure and Property of a Series of Supramolecular Polymers Based on Novel 3,5-Dimethyl- 2,6-bis（3-（pyrid-2-yl）-1,2,4-triazolyl）pyridine Ligand

Solvothermal reactions of 3,5-dimethyl-2,6-bis(3-(pyrid-2-yl)-1,2,4-triazolyl) pyridine (L), 1,4-benzendicarboxylic acid (H2bdc), and transitional metal cations of MII (M = Mn, Co, Cd) in the presence of oxalic acid (H2ox) afford three novel supramolecular polymers (CPs), namely, {[M2(ox)(L)2][bdc][M2(Hox)2(OH)2(H2O)4].3H2O}n (M=Mn for 1, Co for 2, Cd for 3). Single-crystal X-ray diffraction analysis reveals that complexes 1-3 are isostructural and the 3D supramolecular structure was connected through non-covalent interactions. With the help of H2ox, the L ligands cheated with center atoms forming a butterfly [M2(ox)(L)2]2+ building block. The bdc2- ligand linked with the unprecedented [M2(Hox)2(OH)2(H2O)4] units through strong O-H…O hydrogen bonds forming a zigzag chain, which are further connected through π…π interactions between L and bdc2- ligands to form a 3D supramolecular structure. Moreover, elemental analyses, IR, thermogravimetric, PXRD and luminescence have been investigated.     

Structure characterization of several oxalate-bridged transition-metal coordination polymers

Four oxalate-bridged transition-metal supramolecular compounds [Co₂(im)₄(ox)₂] 1, [Co(im)₂(ox)] 2, [Mn(2,2′-bpy)(ox)] 3 and [Fe(H₂O)₂(ox)] 4 (im, imidazole; ox, oxalate; bpy, bipyridine) were obtained from the simple hydrothermal reactions of Mⁿ⁺oxL (M, transition metal; L, aromatic N-donor ligand) system. They all exhibit the 1-D chain structures, consisting of the (or ML²⁺) units linked by oxalate bridges. Interestingly, the 1-D oxalate chains in the title compounds are further self-assembled into the 3-D supramolecular networks through the interchain various secondary bonding interactions. Because the units adopt the different configuration, the oxalate chains show either zigzag type as in compounds 1–3 or linear type as in compound 4. Compounds 1 and 2 are isomeric, and only in packing modes of interchain im molecules there exists the difference.     

{[Eu(ox)(H2O)4]·[CuBr(2‐pzc)2]·4H2O}: Hydrogen Bonding Directed Assembly to Supramolecular Network

A new 3d–4f heterometallic coordination framework, {[Eu(ox)(H₂O)₄] · [CuBr(2‐pzc)₂] · 4H₂O} ( 1 ) [ox = oxalate; 2‐pzc = pyrazine‐2‐carboxylate] was synthesized and characterized by elemental analysis, IR spectroscopy and thermal analysis, as well as single‐crystal X‐ray diffraction. Complex 1 represents one 3D supramolecular heterometallic coordination framework that is assembled from rare lanthanide‐ox anionic chains and CuBr(2‐pzc)₂ cationic units through hydrogen bonds.     

Increasing the ordering temperatures in oxalate-based 3D chiral magnets: the series [Ir(ppy)2(bpy)][M(II)M(III)(ox)3] x 0.5 H2O (M(II)M(III) = MnCr, FeCr, CoCr, NiCr, ZnCr, MnFe, FeFe); bpy = 2,2'-bipyridine; ppy = 2-phenylpyridine; ox = oxalate dianion)

The synthesis, structure, and physical properties of a novel series of oxalate-based bimetallic magnets obtained by using the Ir(ppy)2(bpy)]+ cation as a template of the bimetallic [M(II)M(III)(ox)3]- network are reported. The compounds can be formulated as [Ir(ppy)2(bpy)][M(II)Cr(III)(ox)3] x 0.5 H2O (M(II) = Ni, Mn, Co, Fe, and Zn) and [Ir(ppy)2(bpy)]-[M(II)Fe(III)(ox)3] x 0.5 H2O (M(II) = Fe, Mn) and crystallize in the chiral cubic space group P4(1)32 or P4(3)32. They show the well-known 3D chiral structure formed by M(II) and M(III) ions connected through oxalate anions with [Ir(ppy)2(bpy)]+ cations and water molecules in the holes left by the oxalate network. The M(II)Cr(III) compounds behave as soft ferromagnets with ordering temperatures up to 13 K, while the Mn(II)Fe(III) and Fe(II)Fe(III) compounds behave as a weak ferromagnet and a ferrimagnet, respectively, with ordering temperatures of 31 and 28 K. These values represent the highest ordering temperatures so far reported in the family of 3D chiral magnets based on bimetallic oxalate complexes.     

Cobalt(II)-(dpyo)-dicarboxylate networks: unique H-bonded assembly and rare bridging mode of dpyo in one of them [dpyo = 4,4'-dipyridyl N,N'-dioxide

Polymeric networks, {[Co(dpyo)(ox)]}(n) (1), {[Co(dpyo)(fum)(H(2)O)(2)]}(n) (1) and {[Co(dpyo)(tp)(H(2)O)(2)] x [Co(H(2)O)(6)] x (tp) x (H(2)O)}(n) (3) [ox = oxalate dianion, fum = fumarate dianion, tp = terephthalate dianion and dpyo = 4,4'-dipyridyl N,N'-dioxide] have been synthesized and characterized by single crystal X-ray diffraction analyses. The structural determination reveals 1 and 2 are covalent bonded 2D networks of 4,4 topology and of these, complex 2 undergoes a H-bonding scheme resulting in a 3D supramolecular architecture. Complex 3 is a 1D coordination polymer built up by almost collinear hexacoordinated Co(ii), doubly bridged by a tp carboxylate group and a dpyo oxygen, which in combination with lattice [Co(H(2)O)(6)](2+), tp and water molecules shows an unprecedented 3D supramolecular network through H-bonding. In the polymer the dpyo shows novel mu-4,4 bridging mode towards the cobalt ion. Low temperature magnetic interaction reveals antiferromagnetic coupling in all of the complexes.     

Synthesis of layered (2-D) V-based bimetallic oxalates from non-aqueous media that cannot be synthesized from aqueous media

The reaction of (NBu4)3[V(III)(ox)3] (1, ox = oxalate) and M(II) (M = Fe, Co, Ni, Cu) ions in MeCN, leads to the isolation of V-based coordination polymers of [N(n-Bu)4][Fe(II)V(II)I(ox)3].0.30[[N(n-Bu)4](BF4)] (2), [N(n-Bu)4][Co(II)V(III)(ox)3].0.75[[N(n-Bu)4](BF4)] (3), [N(n-Bu)4][Ni(II)V(III)(ox)3].0.20[[N(n-Bu)4](BF4)].0.20MeCN (4), and [N(n-Bu)4][Cu(II)V(III)(ox)2](BF4)2 (5) composition. Due to the lability of [V(III)(ox)3]3- to dissociate ox2-, these compounds cannot be prepared from aqueous media. 5 is best described as [N(n-Bu)4][V(III)Cu(II)(ox)2](BF4)2, and 2, 3, 4, and 5 are proposed to have a layered (2-D) motif for the MM(ox)x (x = 2, 3) extended framework. The [V(III)Cu(II)(ox)2] composition of 5 is reported for the first time for a bimetallic oxalate. 2 shows a weak antiferromagnetic interaction between Fe(II), S = 2 and V(III), S = 1 ions (theta = -9.4 K) within the 2-D layers. 3 and 5 do not magnetically order above 2 K. 4 magnetically order as ferromagnets below 2.55 K [taken as the onset of magnetization in chi'(T)], and has a glass transition temperature (chi'(max) at 1000 Hz) at 2.26 K.     

Heterotrimetallic oxalato-bridged ReIV2MII complexes (M=Mn, Co, Ni, Cu): synthesis, crystal structure, and magnetic properties

The use of the (NBu4)2[ReIVCl4(ox)] mononuclear species as a ligand toward divalent first row transition metal ions in the presence of imidazole affords the new trinuclear compounds of formula (NBu4)2[{ReIVCl4(mu-ox)}2MII(Him)2] [NBu4+=tetra-n-butylammonium cation, ox=oxalate dianion, Him=imidazole; M=Mn (1), Co (2), Ni (3), Cu (4)] whose preparation, crystal structures, and magnetic properties are reported. 1-4 are isostructural complexes which are made up of discrete trinuclear [{ReIVCl4(mu-ox)}2MII(Him)2]2- anions and bulky NBu4+ cations. The Re and M atoms exhibit somewhat distorted octahedral surroundings which are built by four chloro and two oxalate oxygens (Re) and two imidazole nitrogen and four oxalate oxygen atoms (M), the central M atom being linked to the two peripheral Re atoms through bis-bidentate oxalate. The values of the Re...M separation across bridging oxalate vary in the range 5.646(2) (M=Ni) to 5.794(2) A (M=Mn). Magnetic susceptibility measurements on polycrystalline samples of 1-4 in the temperature range 1.9-300 K show the occurrence of significant intramolecular antiferro- (1) and ferromagnetic (2-4) interactions. The nature and magnitude of the magnetic coupling in 1-4 are qualitatively understood through orbital symmetry considerations.     

Synthesis, structure, and magnetic ordering of layered (2-D) V-based tris(oxalato)metalates

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.     

Oxalate-based soluble 2D magnets: the series [K(18-crown-6)]3[M(II)3(H2O)4{M(III)(ox)3}3] (M(III) = Cr, Fe; M(II) = Mn, Fe, Ni, Co, Cu; ox = C2O4(2-); 18-crown-6 = C12H24O6)

The synthesis and magnetic properties of the oxalate-based molecular soluble magnets with general formula [K(18-crown-6)] 3[M (II) 3(H 2O) 4{M (III)(ox) 3} 3] (M (III) = Cr, Fe; M (II) = Mn, Fe, Ni, Co, Cu; ox = C 2O 4 (2-)) are here described. All the reported compounds are isostructural and built up by 2D bimetallic networks formed by alternating M (III) and M (II) ions connected through oxalate anions. Whereas the Cr (III)M (II) derivatives behave as ferromagnets with critical temperatures up to 8 K, the Fe (III)M (II) present ferri- or weak ferromagnetic ordering up to 26 K.