Syntheses, structures and magnetic properties of three Co(II) coordination architectures based on a flexible multidentate carboxylate ligand and different N-donor ligands

Three new cobalt complexes, {[Co₅(tci)₂(bimb)₃(µ₃-O)₂(H₂O)₂]·3DMF·4H₂O} _n (1), {[Co₃(tci)₂(bib)]·2DMF·2H₂O} _n (2) and {[Co(Htci)(bpea)_0.5]·H₂O} _n (3) (H₃tci = tris(2-carboxyethyl)isocyanurate, bimb = 4,4′-bis(imidazol-1-yl)biphenyl, bib = 1,4-bis(imidazol-1-yl)benzene, bpea = 1,2-bis(4-pyridyl)ethane, DMF = N,N′-dimethylformamide), have been successfully synthesized through the assembly of Co(II) ions, H₃tci and different N-donor ligands, respectively. All complexes were structurally characterized by single crystal X-ray diffraction, elemental analyses, IR spectra, thermogravimetric (TG) analyses and X-ray powder diffraction (XRPD). Complex 1 exhibits a 3D three-fold parallel interpenetrated 3D → 3D structure with (6⁵·8) CdSO₄ topology. Complex 2 is built from [Co₃(µ₂-O_carboxyl)₂(CO₂)₄] clusters and linear bib ligands, displaying a two-fold parallel interpenetrated (3,8)-connected (4³)₂(4⁶·6¹⁸·8⁴) topology, while complex 3 is a 3D pillar-layered structure involving an infinite -Co-(µ₂-Ocarboxyl)(CO₂)-Co-chain. The diverse structures of the three complexes indicate that the skeletons of different N-donor ligands play an important role in the assembly of such different frameworks. In addition, magnetic investigation indicates that besides spin-orbit coupling of Co(II) ions, there exist antiferromagnetic exchange interactions in Co₅ and Co₃ clusters of 1 and 2, respectively.     

A cyano-bridged hetero-tetranuclear [Sm2(o-phen)2(DMF)6(H2O)2(μ-CN)4Fe2(CN)8] · 5H2O · CH3OH: synthesis,structure, Mössbauer spectrum,and magnetism

Two new hetero-tetranuclear complexes, [Sm₂(o-phen)₂(DMF)₆(H₂O)₂(µ-CN)₄Fe₂(CN)₈]·;5H₂O·;CH₃OH (1) and [Sm₂(o-phen)₂(DMF)₆(H₂O)₂(µ-CN)₄Co₂(CN)₈]·;5H₂O (2), have been prepared from reaction of SmCl₃·;6H₂O, K₃[Fe(CN)₆]·;3H₂O or K₃[Co(CN)₆], and o-phen in methanol/DMF, and characterized. The structure of 1 consists of a cyano-bridged discrete cyclic tetranuclear complex in which the Sm(III) and Fe(III) centers are linked by four CN groups. Mössbauer spectrum of ⁵⁷Fe indicates that both Fe(III) atoms in 1 have the same low-spin (S?=?1/2) electronic ground state. From comparison of the magnetic data of 1 and 2, at low temperature for 1 indicates weak ferromagnetic coupling between Sm(III) and Fe(III).     

Phase equilibria in a ternary fullerenol-d(C<Subscript>60</Subscript>(OH)<Subscript>22–24</Subscript>)–SmCl<Subscript>3</Subscript>–H<Subscript>2</Subscript>O system at 25°C

The solubility in a ternary fullerenol-d (C₆₀(OH)_22–24)–SmCl₃–H₂O system at 25°C is studied via isothermal saturation in ampules. The solubility diagram is shown to be a simple eutonic one that consists of two branches corresponding to the crystallization of fullerenol-d (C₆₀(OH)_22–24 · 30H₂O) and samarium(III) chloride SmCl₃ · 6H₂O crystallohydrates and contains one nonvariant eutonic point corresponding to saturation with both crystallohydrates. The long branch of C₆₀(OH)_22–24 · 30H₂O crystallization shows the effect of fullerenol-d salting out of saturated solutions; in contrast, the short branch of SmCl₃ · 6H₂O crystallization shows the pronounced salting-in effect of samarium(III) chloride.     

A quarter of a century after its synthesis and with >200 papers based on its use, `Co(CO3)0.5(OH)·0.11H2O′ proves to be Co6(CO3)2(OH)8·H2O from synchrotron powder diffraction data

The successful attempt to solve the crystal structure of Co(CO₃)_0.5(OH)·0.11H₂O (denoted CCH ), based on synchrotron powder diffraction data, leads to a drastic revision of the chemical formula to Co₆(CO₃)₂(OH)₈·H₂O [hexacobalt(II) bis(carbonate) octahydroxide monohydrate] and to a hexagonal cell instead of the orthorhombic cell suggested previously [Porta et al. (1992). J. Chem. Soc. Faraday Trans. 88 , 311–319]. This results in a new structure‐type related to malachite involving infinite chains of [CoO₆] octahedra sharing edges along a short c axis, delimiting tunnels having a three‐branched star section. All reports discussing cobalt hydroxycarbonates ( CCH ) without any structural knowledge and especially its topotactic decomposition into Co₃O₄ have, as a result, to be reconsidered.     

1，1'-二羟基-5，5'-联四唑的镧系金属配合物的合成、表征及热行为

以1,1′-二羟基-5,5′-联四唑(H_2BTO)为配体,镧系金属离子作为金属中心,采用溶剂热法制备了5种金属配合物:[La_2(BTO)_3(H_2O)_8]·2H_2O (1)、[Ce_2(BTO)_3(H_2O)_8]·2H_2O (2)、[Pr_2(BTO)_3(H_2O)_8]·2H_2O (3)、[Sm_2(BTO)_3(H_2O)_8]·2H_2O (4)和[Nd_2(BTO)_3(DMF)_4]·6H_2O (5)。通过单晶X射线衍射和元素分析对5种配合物的结构进行了表征。结果表明,5种配合物均属于单斜晶系,P2_1/n空间群。利用差示扫描量热法研究了配合物1～4的热稳定性,采用Kissinger法和Ozawa法分别计算了其热分解动力学参数。     

[Sm(NO3)3(TPTZ)(H2O)]·2H2O [TPTZ is 2,4,6‐tris(2‐pyridyl)‐1,3,5‐triazine]

The title compound, aqua­tris­(nitrato)[2,4,6‐tris(2‐pyridyl)‐1,3,5‐triazine]samarium dihydrate, [Sm(NO₃)₃­(C₁₈H₁₂N₆)­(H₂O)]·­2H₂O, was prepared from Sm(NO₃)₃·6H₂O and 2,4,6‐tris(2‐pyridyl)‐1,3,5‐triazine. The metal atom is ten‐coordinate being bonded to the terdentate TPTZ ligand, three bidentate nitrates and a water mol­ecule.     

Syntheses and structural determination of binuclear nine-coordinate (NH4)4[SmIII2(Httha)2]·16H2O and 2-D ladder-like binuclear nine-coordinate (NH4)4[SmIII2(dtpa)2]·10H2O

Two rare-earth metal coordination compounds, (NH₄)₄[Sm^III₂(Httha)₂]·16H₂O (1) (H₆ttha?=?triethylenetetramine-N,N,N′,N′′,N′′′,N′′′-hexaacetic acid) and (NH₄)₄[Sm^III₂(dtpa)₂]·10H₂O (2) (H₅dtpa?=?diethylenetriamine-N,N,N′,N′′,N′′-pentaacetic acid), have been synthesized through reflux and characterized by FT-IR spectroscopy, thermal analysis, and single-crystal X-ray diffraction techniques. Sm^III of (NH₄)₄[Sm^III₂(Httha)₂]·16H₂O (1) is nine-coordinate, forming tricapped trigonal prismatic coordination with three amine nitrogens and six oxygens, in which four oxygens are from one ttha and two from the other ttha. (NH₄)₄[Sm^III₂(Httha)₂]·16H₂O (1) crystallizes in the monoclinic crystal system with P2(1)/c space group. The crystal data are: a?=?13.9340(13) Å, b?=?22.890(3) Å, c?=?20.708(2) (14) Å, β?=?99.521(2)°, and V?=?6513.7(13) ų. There are two –NH⁺– groups in the [Sm^III₂(Httha)₂]^4?. The polymeric (NH₄)₄[Sm^III₂(dtpa)₂]·10H₂O (2) also is nine-coordinate with tricapped trigonal prismatic conformation and crystallizes in the triclinic crystal system with P–1 space group. The cell dimensions are: a?=?9.8240(8) Å, b?=?10.0329(9) Å, c?=?13.0941(11) Å, β?=?77.1640(10)°, and V?=?1227.30(18) ų. In (NH₄)₄[Sm^III₂(dtpa)₂]·10H₂O, there are two types of ammonium cations, which connect [Sm^III₂(dtpa)₂]^4? and lattice water through hydrogen bonds, leading to a 2-D ladder-like layer structure.     

Syntheses,Crystal Structures,and Magnetic Properties of Two Cobalt Coordination Polymers Constructed From 1,3‐Bis(2,4‐dicarboxyphenyl) Benzene and Bis(imidazole) Linkers

Abstract. The 3D cobalt(II) coordination polymers [Co_1.5(HDDB)(1,4‐bib)_1.5(H₂O)]_n ( 1 ), and {[Co₂(DDB)(1,3‐bib)₂(μ₂‐H₂O)] · H₂O}_n ( 2 ) were assembled by mixed‐ligand synthetic strategy [H₄DDB = 1,3‐bis(2,4‐dicarboxyphenyl) benzene, 1,3‐bib = 1,3‐bis(1H‐imidazol‐4‐yl)benzene, and 1,4‐bib = 1,4‐bis(1H‐imidazol‐4‐yl)benzene]. Their structures were determined by single‐crystal X‐ray diffraction analyses and further characterized by elemental analyses (EA), IR spectroscopy, powder X‐ray diffraction (PXRD), and thermogravimetric (TG) analyses. Single X‐ray diffraction analysis reveals that complex 1 is an interestingly 3D (3,3.6)‐connected (6³)₄(6⁵ · 8⁸ · 10²) net, and complex 2 is an unprecedented dinuclear [Co₂(COO)(μ₂‐H₂O)] SBUs based 3D (3,6)‐connected (3 · 6 · 7)(3² · 4³ · 5⁴ · 6³ · 7 · 8²) net. Additionally, the magnetic properties of 2 were investigated.     

Die ersten Hydrogencarbonate mit einer trimeren [H2(CO3)3]4−-Baugruppe: Zur Darstellung und Kristallstruktur von Rb4H2(CO3)3 · H2O und K4H2(CO3)3 · 1,5 H2O

The First Hydrogencarbonates with a Trimeric [H₂(CO₃)₃]^4? Group: Preparation and Crystal Structure of Rb₄H₂(CO₃)₃ · H₂O and K₄H₂(CO₃)₃ · 1.5 H₂O Rb₄H₂(CO₃)₃ · H₂O and K₄H₂(CO₃)₃ · 1,5 H₂O were prepared by means of the reaction of (CH₃)₂CO₃ with RbOH resp. KOH in aqueous methanole. Trimer [H₂(CO₃)₃]^4?-anions were found in the crystal structure of Rb₄H₂(CO₃)₃ · H₂O (orthorhombic, Pnma (no. 62), a = 1 218.0(1) pm, b = 1 572.3(6) pm, c = 615.9(1) pm, V_EZ = 1 179.5(5) · 10⁶ pm³, Z = 4, R1(I ≥ 2σ(I)) = 0.027, wR2(I ≥ 2σ(I)) = 0.055). K₄H₂(CO₃)₃ · 1,5 H₂O crystallizes in an OD-structure. The determined superposition structure (orthorhombic, Pbam (no. 55), a = 1 161.8(1) pm, b = 597.0(1) pm, c = 383.85(3) pm, V_EZ = 266.3(1) · 10⁶ pm³, Z = 1, R1(I ≥ 2σ(I)) = 0.035, wR2(I ≥ 2σ(I)) = 0.074) can be derived from the structure of the rubidium compound. The thermal decomposition of the substances is discussed.     

Synthesis and characterization of CuII and CoII complexes derived from 2,4,6-tri-(2-pyridyl)-1,3,5-triazine (TPT) by chemical and tribochemical reactions

Four Cu^II and Co^II complexes–[Cu(L₁)Cl₂(H₂O)]3/2H₂O · 1/2EtOH, [Cu(L₁)₂Cl₂]6H₂O, [Co(L₁)Cl₂]3H₂O · EtOH, and [Co₂(L₁)(H₂O)Cl₄]1.5H₂O · EtOH (L₁ = 2,4,6-tri(2-pyridyl)-1,3,5-triazine; TPT)–were synthesized by conventional chemical method and used to synthesize another four metal complexes–[Cu(L₁)I₂(H₂O)]6H₂O, [Cu(L₁)₂I₂]6H₂O, [Co(L₁)I(H₂O)₂]I · 2H₂O, and [Co₂(L₁)I₄(H₂O)₃]–using tribochemical reaction, by grinding it with KI. Substitution of chloride by iodide occurred, but no reduction for Cu^II or oxidation of Co^II. Oxidation of Co^II to Co^III complexes was only observed on the dissolution of Co^II complexes in d₆-DMSO in air while warming. The isolated solid complexes (Cu^II and Co^II) have been characterized by elemental analyses, conductivities, spectral (IR, UV-Vis, ¹H-NMR), thermal measurements (TGA), and magnetic measurements. The values of molar conductivities suggest non-electrolytes in DMF. The metal complexes are paramagnetic. IR spectra indicate that TPT is tridentate coordinating via the two pyridyl nitrogens and one triazine nitrogen forming two five-membered rings around the metal in M : L complexes and bidentate via one triazine nitrogen and one pyridyl nitrogen in ML₂ complexes. In binuclear complexes, L is tridentate toward one Co^II and bidentate toward the second Co^II in [Co₂(L₁)Cl₄]2.5H₂O · EtOH and [Co₂(L₁)I₄(H₂O)₃]. Electronic spectra and magnetic measurements suggest a distorted-octahedral around Cu^II and high-spin octahedral and square-pyramidal geometry around Co^II.     

Synthesis, Spectral and Thermal Analyses of Novel Bi- and Polyhomonuclear Complexes of Pyrimidine Bisazo-dianil Derivatives

Seven new bi‐ and polyhomonuclear transition metal complexes with three polyhydroxlated bisazodianil ligands were synthesized and characterized. The ligands were derived from condensation of 6‐(5‐formyl‐2‐hydroxyphenylazo)‐2,4‐dihydroxypyrimidine with aliphatic diamines (H₈L¹, H₈L² and H₆L³). The data of elemental and thermal analyses, molar conductance measurement, IR, electronic and ESR spectra as well as magnetic moment measurements support the formation of [L¹Co₇Cl₆(H₂O)₁₀]·22H₂O ( 1 ), [H₂L²Mn₆Cl₆(H₂O)₈]·3H₂O·2EtOH ( 3 ), [L²Co₈Cl₈(H₂O)₁₂]·24H₂O ( 4 ), [H₄L³Co₂Cl₂(H₂O)₂]·8H₂O·2EtOH ( 6 ) with a tetrahedral geometry and [H₂L¹Ni₅Cl₄(H₂O)₁₆]·19H₂O·EtOH ( 2 ), [L²Ni₈Cl₈(H₂O)₂₈]·8H₂O·EtOH ( 5 ) with an octahedral geometry while [H₆L³Cu₃(H₂O)₇]Cl₃·10H₂O ( 7 ) has a distorted tetrahedral arrangement. The mode of bonding between the metal ions and the ligand molecules is determined and the metal‐metal interaction was studied. The activation thermo‐kinetic parameters for the thermal decomposition steps of the complexes E*, ΔH*, ΔS*, and ΔG* were calculated.     

Thermal Decomposition Studies of Mixed Rare Earth Hydrogen Selenite Crystals

Mixed rare earth hydrogen selenite crystals, neodymium praseodymium hydrogen selenite (Nd_xPr_1−x(HSeO₃)(SeO₃)⋅2H₂O), Neodymium samarium hydrogen selenite (Nd_xSm_1−x(HSeO₃)(SeO₃)⋅2H₂O) and praseodymium samarium hydrogen selenite (Pr_xSm_1−x(HSeO₃)(SeO₃)⋅2H₂O) were prepared by gel diffusion technique. Simultaneous thermogravimetric and differential thermal analysis were carried out on the grown crystals. Decomposition is observed to occurs in six steps, which gives the evidence of successive losses of H₂O and SeO₂. The final product due to decomposition is a mixed rare earth oxides. FT-IR spectrum of the crystal samples heated at different temperatures complemented to the TG-DTA results. This revised version was published online in July 2006 with corrections to the Cover Date.     

Infrarotspektroskopische und thermoanalytische Untersuchung von Trikobalt(II)-dihydroxidsulfat-dihydrat,Co3(OH)2(SO4)2 · 2H2O

The infrared spectra between 600 and 4000 cm^?1 of Co₃(OH)₂(SO₄)₂ · 2H₂O, Co₃(OH)₂(SO₄)₂, and Co₃(OD)₂(SO₄)₂ · 2D₂O are reported and discussed. The spectra are mainly examined in relation to the binding state of the water molecules. The results are in good agreement with the previously described crystal structure studies. Thermogravimetry, differential thermal analysis and X-ray diffraction methods were used to investigate the unusual thermal decomposition behaviour of Co₃(OH)₂(SO₄)₂ · 2H₂O. The kinetics of the dehydration reaction are discussed.     

One Novel 3D Supramolecular Network Based on Dicobalt-Carboxylate Secondary Building Units with Polycarboxylate Ligands 1, 2, 3, 4-Butanetetracarboxylic Acid

A novel cobalt–carboxylate framework constructed from secondary building units (SBUs), {[Co₁₆(btca)₈(H₂O)₄₀]·16H₂O}_n (1) (H₄btca = 1,2,3,4-butanetetracarboxylic acid) has been hydrothermally synthesized and characterized by techniques of single-crystal X-ray diffraction analyses, elemental analyses, infrared spectra, powder X-ray diffraction and thermogravimetric analyses. The complex exhibits 2D 4-connected sql net with (4⁴ × 6²) topology symbol built from [Co₂(COO)₄(H₂O)₅] SBUs and is further extended into a 3D supramolecular architecture via strong O–H···O hydrogen bonds. Moreover, the magnetic measurements indicate complex 1 exhibit antiferromagnetic behavior.     

Mixed-ligand CoII and CdII complexes with 4-aminoantipyrine

Self-assembly of 4-aminoantipyrine (AAP) and 5-nitroisophthalic acid (H₂NIP) with Co(CH₃COO)₂ or Cd(NO₃)₂ in CH₃OH–H₂O at room temperature generated {[Co₂(AAP)(NIP)(H₂O)₈][Co(AAP)(NIP)₂(H₂O)₂](H₂O)_4.5} (1) and {[Cd(AAP)(NIP)(H₂O)](H₂O)} _n (2), which were further characterized by X-ray diffraction, IR spectra, elemental analysis and solid-state fluorescence spectra. The structure analysis indicates that 1 contains two individual fragments, one NIP-bridged six-coordinate binuclear Co^II cation and a mononuclear Co^II dianion. The binuclear units are connected into 1-D chains via O–H?···?O hydrogen bond interactions, which were further assembled into a 2-D supramolecular layer bridged by the mononuclear Co^II unit. Complex 2 is a linear NIP bridged seven-coordinate Cd^II polymeric chain with the terminal AAP ligands as decorations, and are further extended into 2-D network by classic hydrogen bonds and π?···?π stacking interactions. Both solid complexes exhibit emission spectra from intraligand electron transfer at room temperature.     

Ten complexes constructed by two reduced Schiff base tetraazamacrocycle ligands: syntheses,structures, magnetic and luminescent properties

Ten new complexes, [Cu₂(L¹)(NO₃)₂]·2H₂O (1), [Cu₄(L¹)₂]·4ClO₄·H₂O (2), [Cu₂(L¹)(H₂O)₂]·(adipate) (3), [Cu₆(L¹)₂(m-bdc)₄]·2DMF·5H₂O (4), [Cu₂(L¹)(Hbtc)]·5H₂O (5), [Cu₂(L¹)(H₂O)₂]·(ntc)·3H₂O (6), [Co₂(L²)]·[Co(MeOH)₄(H₂O)₂] (7), [Co₃(L²)(EtOH)(H₂O)] (8), [Ni₆(L²)₂(H₂O)₄]·H₂O (9) and [Zn₄(L²)(OAc)₂]·0.5H₂O (10), have been synthesized. 1 displays a [Cu₂(L¹)(NO₃)₂] monomolecular structure. 2 shows a supramolecular chain including [Cu₂L¹]²⁺. In 3, two Cu(II) ions are connected by L¹ to form a [Cu₂(L¹)(H₂O)₂]²⁺ cation. In 4, the m-bdc anions bridge Cu(II) ions and L¹ anions to form a layer. Both 5 and 6 display 3-D supramolecular structures. 7 consists of both [Co₂L²]^2? and [Co(MeOH)₄(H₂O)₂]²⁺ units. 8 and 9 show infinite chain structures. In 10, Zn(II) dimers are linked by L² to generate a 3-D framework. The magnetic properties for 4 and 8 and the luminescent property for 10 have been studied.     

Synthesis,spectroscopic, and thermal analyses of trinuclear Mn(II), Co(II), Ni(II), and Zn(II) complexes with some sulfa derivatives

New bi- and trihomonuclear Mn(II), Co(II), Ni(II), and Zn(II) complexes with sulfa-guanidine Schiff bases have been synthesized for potential chemotherapeutic use. The complexes are characterized using elemental and thermal (TGA) analyses, mass spectra (MS), molar conductance, IR, ¹H-NMR, UV-Vis, and electron spin resonance (ESR) spectra as well as magnetic moment measurements. The low molar conductance values denote non-electrolytes. The thermal behavior of these chelates shows that the hydrated complexes lose water of hydration in the first step followed by loss of coordinated water followed immediately by decomposition of the anions and ligands in subsequent steps. IR and ¹H-NMR data reveal that ligands are coordinated to the metal ions by two or three bidentate centers via the enol form of the carbonyl C=O group, enolic sulfonamide S(O)OH, and the nitrogen of azomethine. The UV-Vis and ESR spectra as well as magnetic moment data reveal that formation of octahedral [Mn₂L¹(AcO)₂(H₂O)₆] (1), [Co₂(L¹)₂(H₂O)₈] (2), [Ni₂L¹(AcO)₂(H₂O)₆] (3), [Mn₃L²(AcO)₃(H₂O)₉] (5), [Co₃L²(AcO)₃(H₂O)₉] · 4H₂O (6), [Ni₃L²(AcO)₃(H₂O)₉] · 7H₂O (7), [Mn₃L³(AcO)₃(H₂O)₆] (9), [Co₂(HL³)₂(H₂O)₈] · 4H₂O (10), [Ni₃L³(AcO)₃(H₂O)₉] (11), [Mn₃L⁴(AcO)₃(H₂O)₉] · H₂O (13), [Co₂(HL⁴)₂(H₂O)₈] · 5H₂O (14), and [Ni₃L⁴(AcO)₃(H₂O)₉] (15) while [Zn₂L¹(AcO)₂(H₂O)₂] (4), [Zn₃L²(AcO)₃(H₂O)₃] · 2H₂O (8), [Zn₃L³(AcO)₃(H₂O)₃] · 3H₂O (12), and [Zn₃L⁴(AcO)₃(H₂O)₃] · 2H₂O (16) are tetrahedral. The electron spray ionization (ESI) MS of the complexes showed isotope ion peaks of [M]⁺ and fragments supporting the formulation.     

Hydroxo-Lanthanide Cluster Organic Framework Built by Hexanuclear Cluster Units

A novel hydroxo-lanthanide cluster organic framework, Sm₃L₈(μ ₃-OH)(H₂O)·H₂O (1), derived from the 4-pyridin-4-ylbenzoic acid (HL) has been hydrothermally made and structurally characterized by single crystal X-ray diffraction. Structure analysis shows the hexanuclear Sm₆ cluster unit is composed of inorganic tetranuclear hydroxo [Sm₄(OH)₂]¹⁰⁺ (Sm₄) cluster and dimeric [Sm₂(COO)₄]²⁺ (Sm₂) core. The Sm₆ cluster units are connected by L ligands to form a 2D Ln-based cluster organic framework. From the topological point of view, the layer architecture can be described as 4-connected sql net. Furthermore, the elemental analysis, PXRD, IR and TGA are also studied.     

Dodecanuclear water cluster in bowl: microwave-assisted synthesis of a heptanuclear cobalt(II) cluster

A heptanuclear double-bowl-like cluster [Co₇(mmp)₆(OH)₆]₂·(ClO₄)₂·12H₂O (1·12H₂O, Hmmp is 2-methoxy-6-methyliminomethyl-phenol) has been synthesized through the microwave-assisted reaction of Co(ClO₄)₂·6H₂O with 2-hydroxy-3-methoxy-benzaldehyde (Hhmb) and methylamine in mixed solvent (acetonitrile : distilled water = 9 : 1) for 29 min. 1·12H₂O was heated until 180 °C and it formed a non-water complex [Co₇(mmp)₆(OH)₆]₂·(ClO₄)₂ (1). The core of 1·12H₂O can be described as a double bowl, while the dodecanuclear water cluster stands on the bowl. Magnetic investigations show that 1·12H₂O and 1 display ferromagnetic interaction between cobalt ions. Moreover, 1 shows single molecular magnet behavior under 2 K. Magnetic studies indicate that hydrogen bond plays a vital role in transferring magnetic exchange effects.     

Influence of secondary ligand on structures and topologies of lanthanide coordination polymers with 1,3,5-triazine-2,4,6-triamine hexaacetic acid

A series of new lanthanide coordination polymers has been synthesized and structurally characterized; [Ln₄(TTHA)₂(pzac)(H₃O)₂(H₂O)]·5H₂O (Ln = Pr (1a) and Nd (1b)), [Sm₈(TTHA)₄(pzac)_0.5(H₃O)(H₂O)_7.5]·4H₂O (2), [Ln₄(HTTHA)₂(SO₄)(H₂O)₄]·5H₂O (Ln = Pr (3a) and Nd (3b)), where H₆TTHA = 1,3,5-triazine-2,4,6-triamine hexaacetic acid, and H₂pzac = 2,5-dioxo-piperazine-1,4-diacetic acid. The compounds feature 3-D frameworks comprising the deprotonated H₆TTHA as the primary ligand and either the in situ generated pzac^2? or sulfate as the secondary ligands. The influence of the deprotonated H₆TTHA in directing the framework structures through preferential coordination modes and molecular conformation is described. The effect of the secondary ligands in increasing the compactness of the frameworks and in the alternation of the framework topologies based on the four-connected pts type is described.