Non-coordinated Water Molecules Research Articles

Super-Ionic Conductive Magnet Based on a Cyano-Bridged Mn–Nb Bimetal Assembly

A two-dimensional manganese-octacyanoniobate based magnet, MnII3[NbIV(CN)8]2(4-aminopyridine)10(4-aminopyridinium)2·12H2O, was prepared. This compound shows a spin-flip transition with a critical magnetic field value of ca. 200 Oe, which originates from metamagnetism. In addition, an impedance measurement indicates that this compound is a super-ionic conductor with 4.6 × 10–4 S cm–1. The observed super-ionic conductivity is explained by the proton conduction (so-called the Grotthuss mechanism) through the hydrogen-bonding network, i.e., Lewis acidity of the Mn ion accelerates the deprotonation of the ligand water molecules, and then the released proton propagates via ligand water molecules, noncoordinated water molecules, and 4-aminopyridinium cations.

Zigzag polymer chains incatena-poly[[[triaqua(isobutyrato-κO)magnesium(II)]-μ-isobutyrato-κ2O:O′] monohydrate

The structure of the title compound, {[Mg(C4H7O2)2(H2O)3]·H2O}n, features one-dimensional ···(μ2-ib)Mg(μ2-ib)Mg··· zigzag chains (ib is isobutyrate) parallel to the c axis. The octahedral Mg environment is completed by three fac-oriented terminal water ligands, as well as one further monodentate end-on coordinated ib ligand. In the crystal structure, the hydrophobic ib groups are all oriented within one half of the coordination perimeter of each chain, whereas the water ligands, together with hydrogen-bonded noncoordinated solvent water molecules, define the other half. Along the a axis, neighbouring strands are oriented so that both the hydrophilic and hydrophobic sides are adjacent to each other. This results in an extensive hydrogen-bonding network within the hydrophilic areas, also involving an additional solvent water molecule per formula unit. There are van der Waals contacts between the aliphatic isopropyl groups of the hydrophobic areas.

On the (non-)existence of Tutton salts with formula types [M(H2O)6](ClO4)2(H2O)2and Na2M(SO4)2(H2O)6(Mis a first-row transition metal)

Two structures of the Tutton salt family, originally reported with composition [Cu(H2O)6](ClO4)2(H2O)2 and Na2Cu(SO4)2(H2O)6, have been redetermined based on the original intensity data. With respect to the original [Cu(H2O)6](ClO4)2(H2O)2 model, the perchlorate anion and the noncoordinating water molecule are replaced by a sulfate anion and an ammonium cation. With respect to the original Na2Cu(SO4)2(H2O)6 model, the sodium site is replaced by a mixed-occupancy potassium/ammonium site. The resulting revised formulae are (NH4)2Cu(SO4)2(H2O)6 [diammonium hexaaquacopper(II) disulfate] and [(NH4)1.176K0.824]Cu(SO4)2(H2O)6, respectively. In both cases, the redetermination led to chemically more sensible structure models, accompanied by lower reliability factors. Three other reported structures with formula types [M(H2O)6](ClO4)2(H2O)2 or Na2M(SO4)2(H2O)6 (M is a first row transition metal) have also been re-examined. From crystal-chemical considerations, their existence is likewise questioned. It is shown that the deposition of structure factors is beneficial for detailed re-examinations of problematic structure models.

A recurrent Motive in the Supramolecular Assembly of Coordination Compounds with 2,6-bis(Benzimidazol-2-yl)piridine (Bzimpy) and Two Identical H-bond Acceptor Co-ligands: [Cd(Ac)2(Bzimpy)], [Zn(Ac)2(Bzimpy)]·H2O (Ac:acetato) and Related Compounds

We report the crystal structures of two novel coordination compounds with similar complex composition: [Cd(Ac)2(Bzimpy)] (I) and [Zn(Ac)2(Bzimpy)]·H2O (II). Both compounds are monomeric. Compound I consists of a Cd(II) center heptacoordinated with three N atoms from a Bzimpy molecule and four O atoms from two bidentate acetato molecules. Compound II consists of a Zn(II) center pentacoordinated with three N atoms from a Bzimpy molecule and two O atoms from two monodentate acetato molecules. A non-coordinated water molecule completes the formula. In addition, we highlight some common features in the supramolecular assembly of both compounds and with similar structures deposited in the version 5.33 of the CSD. This assembly occur through H-bridges and π–π offset stacked interactions, giving rise to the formation of what we call “directed ring” of two types: two molecular components 2Rd and three molecular components 3Rd. Structures are viewed as composed of well defined substructures in order to analyze them. The crystal structures of the title compounds are reported, highlighting similarities in the form of the 3-D construction of the crystal in a set of coordination compounds of transition metals containing one molecule of neutral, non-substituted Bzimpy ligand and two identical molecules of an H-bridge acceptor, non-strong H-bridge donor co-ligand.

The effect of conformational changes on non‐coordinated water occupancy associated with R and T allosteric states of Carp Hemoglobin

The chemistry of non‐coordinated water molecules in the apolar internal environment of proteins is poorly understood. Our recent discovery of a spectral marker for the entry of noncoordinated water into the distal heme pocket of myoglobin has helped clarify this molecule's functional importance in ligand binding. We will apply our novel spectrokinetic assay to test the hypothesis that conformational changes can affect ligand binding indirectly by changing the occupancy of non‐coordinated water in apolar cavities. A comparison of the spectrokinetics between the visible and Soret spectral regions distinguishes protein relaxations from those associated with changes in internal water occupancy. Hemoglobin from Carp, Cyprinus carpio, shows differences in the putative water occupancy signal between the R and T allosteric states, which correspond to changes in ligand binding dynamics. These results suggest that conformational induced changes in water occupancy may play a role in allosteric induced changes in ligand binding dynamics. This knowledge will increase the understanding of the role these water molecules play in allosteric regulation.

Hydrothermal synthesis, crystal structure and heterogeneous catalytic activity of a novel inorganic–organic hybrid complex, possessing infinite La–O–La linkages

In this paper, a novel lanthanum coordination polymer formulated as {[La2(Hpdc)3(H2O)4]·2H2O}n (1, H3pdc=3,5-pyrazoledicarboxylic acid) has been synthesized by the reaction of H3pdc with chloride salt of La(III) under hydrothermal conditions and characterized by elemental analysis, FT-IR, TGA and single-crystal X-ray diffraction. The complex crystallized in the monoclinic system Cc space group. The single-crystal X-ray structural analysis revealed that central metal La atoms are nine-coordinate and linked by bridging μ2-OCOO- groups to form [La(1)-(μ2-OCOO−)2-La(2)]n inorganic–organic chains that produce a supramolecular polymeric framework structure. The three-dimensional structure of 1 is accompanied by non-coordinating water molecules. Thermal behavior and catalytic performance of 1 have also been studied. The complex 1 showed 100% selectivity and a conversion rate of 24% on the oxidation of thymol (T) to thymoquinone (TQ).

Dynamics of the Distal Cavity in Myoglobin Variants

The non-coordinated water molecule in the distal pocket of a myoglobin (Mb) can be a dominant factor in controlling the binding of CO to the active site. Experimental data showed that the mutations of the distal-pocket residues (V68F, V68L, L29F and L29W) modified myglobion's reaction rates with nitrite and water occupancy after photodissociation of CO. In this work molecular dynamics (MD) simulations revealed pronounced changes in the distal cavity volume for all variants and wild-type (WT), particularly when water leaves or enters the cavity. A 10% reduction in mean cavity volume was observed for WT when water exits the cavity (60.8 A3 and 55.4 A3 occupied vs. unoccupied respectively). In contrast, the L29F substitution resulted in 75% contraction in unoccupied volume making it less accessible, correlating with lower experimental water occupancy reported for L29F as compared to WT. The main dynamical pathway for water migration in and out of the distal cavity for all five systems was via H64. The imidazole ring of H64 acted as a gate to the cavity and was stabilized by the cavity bound waters. The exit of water molecules from the WT and V68F distal cavities increased the dynamics of H64 leading to significant population in the solvent exposed conformation. This conformational flexibility of H64 should ease the entrance of water molecules back into the distal cavity. In L29F and L29W variants which have lower experimental water occupancy in comparison to WT and V68F, the H64 showed reduced motions with the elevated population in the conformation precluding the entrance of water. This work demonstrated that the dynamics of residues lining the cavity play an important role in governing the water access to the distal pocket and the binding affinity for gaseous ligands to Mb.

Aqua{2-(pyridin-2-yl)-N-[(pyridin-2-yl)methylidene]ethanamine-κ3N,N′,N′′}(sulfato-κ2O,O′)copper(II) tetrahydrate

The title complex, [Cu(SO4)(C13H13N3)(H2O)]·4H2O, was obtained by mixing copper sulfate penta­hydrate and 2-(pyridin-2-yl)-N-(pyridin-2-yl­methyl­idene)ethanamine in eth­anol under reflux conditions. The CuII ion shows a Jahn–Teller-distorted octa­hedral geometry, with equatorial positions occupied by three N atoms from the tridentate ligand (average Cu—N = 2.004 Å) and one O atom from a bidentate sulfate anion [Cu—O = 1.963 (2) Å]. The axial positions are occupied by one O atom from a coordinating water mol­ecule [Cu—O = 2.230 (3) Å] and one weakly bonded O atom [Cu—O = 2.750 (2) Å] from the bidentate sulfate ion. The complex mol­ecules are connected through O—H⋯O hydrogen bonds between the coordinating water mol­ecules and sulfate ions from neighboring complexes, forming a double chain parallel to the c axis. The chains are stabilized through additional hydrogen bonds by one of the non-coordinating water mol­ecules bridging between neighboring strands of the double chains. The remaining three water mol­ecules fill the inter­stitial space between the double chains and are involved in an intricate hydrogen-bonding network that consolidates the structure.

Catena-Poly[[[dichlorido(pyridin-1-ium-3-yl)arsenic(III)]-μ-chlorido] monohydrate

The crystal structure of the title compound, {[AsCl3(C5H5N)]·H2O}n, is characterized by polymeric chains consisting of alternating arsenic and chlorine atoms running parallel to the a axis. O—H⋯Cl and N—H⋯O hydrogen bonds mediated by non-coordinating water mol­ecules assemble these chains into a three-dimensional framework. The AsIII atom, the atoms of the pyridinium ring and the water O atom have m site symmetry and the bridging Cl atom has site symmetry 2. This is the first reported organotrichloro­arsenate(III) in which arsenic adopts a ψ-octa­hedral fivefold coordination.

Tetraaqua{5-[(pyridin-2-ylmethylidene)amino]benzene-1,3-dicarboxylato-κ2N,N′}nickel(II) tetrahydrate

The title structure, [Ni(C14H8N2O4)(H2O)4]·4H2O, contains a mononuclear NiII complex formed by a chelating bidentate Schiff base and by four Ni-bonded water mol­ecules. The NiII atom is in a distorted octa­hedral coordination by two N atoms in a cis disposition [Ni—N = 2.0753 (16) and 2.1048 (16) Å] and by four water O atoms [Ni—O = 2.0500 (15)–2.0822 (15) Å]. The crystal structure is completed by four further non-coordinating water mol­ecules and all constituents are linked in a three-dimensional manner by an extensive system of 16 O—H⋯O hydrogen bonds.

Synthesis and Physical Properties of K4[Fe(C5O5)2(H2O)2](HC5O5)2·4H2O (C5O52–= Croconate): A Rare Example of Ferromagnetic Coupling via H-bonds

The reaction of the croconate dianion (C(5)O(5))(2-) with a Fe(III) salt has led, unexpectedly, to the formation of the first example of a discrete Fe(II)-croconate complex without additional coligands, K(4)[Fe(C(5)O(5))(2)(H(2)O)(2)](HC(5)O(5))(2)·4H(2)O (1). 1 crystallizes in the monoclinic P2(1)/c space group and presents discrete octahedral Fe(II) complexes coordinated by two chelating C(5)O(5)(2-) anions in the equatorial plane and two trans axial water molecules. The structure can be viewed as formed by alternating layers of trans-diaquabis(croconato)ferrate(II) complexes and layers containing the monoprotonated croconate anions, HC(5)O(5)(-), and noncoordinated water molecules. Both kinds of layers are directly connected through a hydrogen bond between an oxygen atom of the coordinated dianion and the protonated oxygen atom of the noncoordinated croconate monoanion. A H-bond network is also formed between the coordinated water molecule and one oxygen atom of the coordinated croconate. This H-bond can be classified as strong-moderate being the O···O bond distance (2.771(2) Å) typical of moderate H-bonds and the O-H···O bond angle (174(3)°) typical of strong ones. This H-bond interaction leads to a quadratic regular layer where each [Fe(C(5)O(5))(2)(H(2)O)(2)](2-) anion is connected to its four neighbors in the plane through four equivalent H-bonds. From the magnetic point of view, these connections lead to an S = 2 quadratic layer. The magnetic properties of 1 have been reproduced with a 2D square lattice model for S = 2 ions with g = 2.027(2) and J = 4.59(3) cm(-1). This model reproduces quite satisfactorily its magnetic properties but only above the maximum. A better fit is obtained by considering an additional antiferromagnetic weak interlayer coupling constant (j) through a molecular field approximation with g = 2.071(7), J = 2.94(7) cm(-1), and j = -0.045(2) cm(-1) (the Hamiltonian is written as H = -JS(i)S(j)). Although this second model might still be improved since there is also an extra contribution due to the presence of ZFS in the Fe(II) ions, it confirms the presence of weak ferromagnetic Fe-Fe interactions through H-bonds in compound 1 which represents one of the rare examples of ferromagnetic coupling via H-bonds.

FeIII(dmbpy)(CN)4]−: a new building block for designing single-chain magnets

We herein present the synthesis and magneto-structural study of a new family of heterobimetallic chains of general formula {[Fe(III)(dmbpy)(CN)(4)](2)M(II)(H(2)O)(2)}(n)·pnH(2)O [dmbpy = 4,4'-dimethyl-2,2'-bipyridine; M = Mn (2), Cu (3), Ni (4) and Co (5) with p = 4 (2), 3 (3), 9 (4) and 3.5 (5)] which were prepared by using the mononuclear PPh(4)[Fe(III)(dmbpy)(CN)(4)]·3H(2)O (1) building block (PPh(4)(+) = tetraphenylphosphonium) as a ligand toward fully solvated M(II) ions. The structure of 1 consists of discrete [Fe(III)(dmbpy)(CN)(4)](-) anions, tetraphenylphosphonium cations and noncoordinated water molecules. Complexes 2-5 are isostructural compounds whose structure consists of neutral 4,2-wave like heterobimetallic chains of formula {[Fe(III)(dmbpy)(CN)(4)](2)M(II)(H(2)O)(2)}(n) where the [Fe(III)(dmbpy)(CN)(4)](-) entity adopts a bis-monodentate coordination mode toward trans-[M(II)(H(2)O)(2)] units through two of its four cyanide groups in cis positions. 1 exhibits the magnetic behaviour of magnetically isolated six-coordinate low-spin Fe(III) complexes with an important orbital contribution. 2 behaves as ferrimagnetic Fe(III)(2)Mn(II) chains, whereas 3-5 exhibit intrachain ferromagnetic couplings between the low-spin Fe(III) and either Cu(II) (3), Ni (4) or Co(II) (5) as well as frequency-dependence of the out-of-phase ac susceptibility signals below 3.0 (3), 5.5 (4) and 5.0 K (5). The relaxation time and the energy to reverse the magnetization of 3-5 are related to the anisotropy of the M(II) center and to the intra- and interchain magnetic interactions. Unprecedentedly in the world of cyanide-bearing complexes, 5 exhibits a double slow relaxation of the magnetization.

Reversible structural switch in the nano-cavity of crystalline metallo-macrocycles with smooth ligand exchange by non-coordinating guest stimuli

A tetranuclear Ni(II)-macrocycle consisting of β-dipeptides demonstrates effects of water vapor on the structural switching of the nano-cavity by ligand exchange in the single-crystal state. The content of non-coordinating water molecules regulates the opening and closing of the cavity through cooperation of smooth ligand exchange and internal hydrogen-bond switching.

Diffusion of water in molecular magnet Cu0.75Mn0.75[Fe(CN)6]⋅7H2O

Here we report the dynamical behaviour of water in Prussian blue analogue (PBA) Cu0.75Mn0.75[Fe(CN)6]⋅7H2O molecular magnet in the temperature range 260–360 K as studied using the quasielastic neutron scattering technique. While significant quasielastic broadening is observed in the hydrated sample, no broadening was observed in the dehydrated one. Data analysis showed that the observed quasielastic broadening in Cu0.75Mn0.75[Fe(CN)6]⋅7H2O corresponds to the dynamics of the non-coordinated water molecules at the 32f site and the coordinated water molecules at the 24e site, existing in the cavities created by the absence of Fe(CN)6 units. The non-coordinated water molecules at 8c interstitial sites do not contribute to the broadening, suggesting that they are immobile at least within the time window of the spectrometer used. Behaviour of the elastic incoherent structure factor is consistent with the model where the water molecules undergo translational diffusion localized within the cavity of 5.1 Å. While all the non-coordinated water molecules at the 32f site are dynamic over the entire range of temperatures, the coordinated ones at the 24e site become progressively dynamic with temperature. The water molecules were found to undergo hindered ( ∼ 1.16 × 10−5 cm2 s−1 at 300 K) diffusion compared to bulk water and the diffusivity followed Arrhenius behaviour within the measured temperature range with an activation energy of 1.26 kcal mol−1.

The Coordination Behaviour of the Peroxodisulfate Anion with Group XII Metal Ions: [Zn(H2O)(C12H8N2)2(S2O8)]·H2O and Related Compounds

The title compound is monomeric with a Zn(II) hexacoordinated center. The coordination sphere is formed by four nitrogens from two phenanthroline molecules, one oxygen from a monodentate peroxodisulfate ion, and one oxygen from a water molecule. A non-coordinated water molecule completes the formula with an important role in the stabilization of the structure through the formation of two OHW–H···Opds bridges (acting as a donor) and one OCW–H···OHW bridge where it is an acceptor group (HW: hydration water; pds: peroxodisulfato; CW: coordinated water). The compound is triclinic, space group P-1 with a = 8.763 (3) A, b = 9.068 (3) A, c = 17.531 (6) A, α = 96.48 (2)°, β = 103.94 (3)°, γ = 104.57 (3)°, V = 1286.0 (7) A3 and Z = 2. The structure was solved by direct methods with a conventional R (on F) = 0.050 for 4534 reflections with Fo > 4σ(Fo). The compound is isomorphous with the Cd analogue (in Harvey et al. Aust J Chem 54:307, 2001). An eventual dependence of conformation and coordination mode of the peroxodisulfate anion on the ancillary organic ligand taking part in the coordination compounds analyzed is discussed. The crystal structure of [Zn(H2O)(C12H8N2)2(S2O8)]·H2O is reported. In addition, similarities in conformation and coordination mode of the peroxodisulfato anion in hybrid (organic–inorganic) complexes of group XII metal ions containing similar organic ligands are discussed.

Direct assembly of new cobalt(iii)-lanthanide(iii) heterometallic frameworks with NaCl-like topology

Through hydrothermal treatment, a series of new 3D noninterpenetrating cobalt(III)-lanthanide(III) heterometallic coordination assemblies bearing 2,2′-bipyridine-4,4′-dicarboxylate (H2bpdc) ligands, CoLn2(bpdc)3(NO3)3(H2O)6·3.5H2O (Ln = Gd (2), Eu (3), Sm (4), La (5)), have been obtained which may be regarded as being derived from Co2(Hbpdc)2(bpdc)2(H2O)2·2H2O (1) with one-dimensional (1D) zigzag chains. The results of single-crystal X-ray analysis and the X-ray photoelectron spectroscopy study show that each Co center in all of the compounds is located in six-coordinate octahedral surroundings, and exhibits the trivalent oxidation state. Compounds 2–5 possess isostructural 3D NaCl-type frameworks containing Ln2O16 building blocks, exhibiting square pores with dimensions of ca. 8 × 8 A2 along the [010] direction, which are occupied by nitrate anions and non-coordinated water molecules. The frameworks of 2–5 are stable up to ca. 300 °C followed by removal of the coordinated and uncoordinated water molecules, as is evident from the associated weight loss. The magnetic and gas adsorption properties for the Co(III)-Gd(III) system have been investigated.

Coordination polymers constructed from alkali metal ions and (HO)10cucurbit[5]uril

Three novel coordination polymers {[K(H2O)](NO3⊂C30H28N20O20)[K(η2-NO3)]}Cl(H3O)22+·7H2O (1), {[Rb3(μ2-H2O)(μ3-H2O)(H2O)5SO4]+(H2O⊂C30H29N20O20)}Cl(H3O)+·2H2O (2), [Cs2(H2O⊂C30H26N20O20)]SO42−(H3O)44+ (3), were obtained by reactions of the corresponding alkali metal salts with an organic macrocyclic ligand perhydroxycucurbit[5]uril, (HO)10Q[5], and their structures were determined by single-crystal X-ray diffraction studies. The results revealed that, in complexes 1 and 3, the (HO)10Q[5] ligands are interlinked into two-dimensional networks through coordination of their carbonyl groups and hydroxy groups to the alkali metal ions (K+ and Cs+) in between, while in complex 2, the carbonyl groups and hydroxy groups of the (HO)10Q[5] ligands are coordinated by the Rb+ ions to form an acclivitous ‘ladder’ structure. Furthermore, solid-state packing of the complexes 1 and 3 shows the formation of open channels occupied by counterions and non-coordinating water molecules. The thermogravimetric analysis (TGA) of complex 1 was characterized.

Synthesis, crystal structure and spectroscopic studies of copper(II) complex of C-meso-1,5,8,12-tetramethyl-1,4,8,11-tetraazacyclotetradecane

Copper(II) complex coordinated with cyclam-type macrocyclic tetramine, C-meso-1,5,8,12-tetramethyl-1,4,8,11-tetraazacyclotetradecane (2Cdmc) has been synthesized and characterized by single crystal X-ray crystallographic analysis and UV–Vis absorption spectra. Solved molecular structure of [Cu(2Cdmc)(H2O)]Cl2·2H2O (1) revealed that macrocyclic ligand 2Cdmc was in the most stable trans-III structure, but the C-methyl groups of 2Cdmc adopted energetically unfavorable axial configuration (C-axial). This complex 1 is the second example of complex of cyclam-type tetramine with only axially oriented C-methyl groups. This complex adopted five-coordinated square-pyramidal geometry with one water molecule occupying one of the two apical sites. Network of hydrogen bonds involving counter anions (Cl−), coordinating and non-coordinating water molecules, and N–H of 2Cdmc was present. UV–Vis spectra in various solutions also indicated the formation of five-, or six-coordinated complex in methanol and DMSO, but four-coordinated complex in water.

Magnetic Properties of Segregated Layers Containing MII3(μ3−OH)2 (M = Co or Ni) Diamond Chains Bridged by cis,cis,cis-1,2,4,5-Cyclohexanetetracarboxylate

We report the hydrothermal synthesis, X-ray crystal structures, and thermal, optical, and magnetic properties of two isostructural layered coordination polymers, [M(II)(5)(OH)(2)(chtc)(2)(H(2)O)(10)]·2H(2)O where M = Co (1Co) or Ni (2Ni) and chtc = cis,cis,cis-1,2,4,5-cyclohexanetetracarboxylate. The structures consist of segregated layers where each layer is formed of M(3)(OH)(2) diamond chains, involving edge- and corner-sharing octahedra, bridged by M(chtc)(2). In the space created by the chains and the bridges exists channels, which house the coordinated and noncoordinated water molecules, all hydrogen bonded to form a dodecamer, with a central cyclohexane chair shape ring. Interestingly, the water molecules of 2Ni are more difficult to remove than those of 1Co, but pyrolysis of the latter takes place at higher temperature. The magnetic properties are characterized by Néel transition to fully compensated antiferromagnets at 5.8 K (1Co) and 3.0 K (2Ni). The moments are easily reversed in an applied field of 150 Oe (1Co) and 300 Oe (2Ni) to a ferrimagnet with one uncompensated moment followed by a nonlinear increase to a saturation corresponding to a ferrimagnet with three uncompensated moments. Further, point charge calculations to estimate the weak bonding energies between the various types of interaction are reported.

Exploiting the linking propensity of a water encapsulated POV cluster anion [As 6V 15O 42(H 2O)] 6− towards lanthanide cations: Syntheses, crystal structures and thermal properties of [{M(H 2O) 7} 2(As 6V 15O 42(H 2O)]· xH 2O (M = La 3+, Sm 3+ and Ce 3+; x = 12, 13 and 11, respectively)

The polyoxovanadate cluster anion [As 6V 15O 42(H 2O)] 6−, an well known magnetic object, has been reacted with lanthanide ions (namely La 3+, Sm 3+ and Ce 3+ ions) in a controlled synthesis resulting in the formation of a new series of coordination polymers [{La(H 2O) 7} 2As 6V 15O 42(H 2O)]·12H 2O ( 2), [{Sm(H 2O) 7} 2As 6V 15O 42(H 2O)]·13H 2O ( 3) and [{Ce(H 2O) 7} 2 As 6V 15O 42(H 2O)]·11H 2O ( 4). In compounds 2, 3 and 4, the high nuclearity spin cluster [As 6V 15O 42(H 2O)] 6− acts as a tetradentate ligand with terminal oxo groups (V O) as donor centers. Compounds 2–4 are characterized by elemental and routine spectroscopic analyses and finally by single crystal X-ray structure determination. Compounds 2–4 are isomorphous in which each {V15} cluster anion is coordinated to four Ln 3+ ion through its terminal oxygen atoms and each Ln 3+ ion is coordinated to two cluster anions and seven water molecules satisfying the coordination number of nine around a lanthanide cation. In the crystal structure, the non-coordinated (lattice) water molecules, lanthanum-coordinated water molecules and V O t oxygen atoms (O t = terminal oxygen) are involved in O–H···O hydrogen bonding interactions. The hydrogen bonding distances are measured as O···O separations, since hydrogen atoms could not be located in the crystal structures. The hydrogen bonding distances are varied in the range of 2.640–3.000 Å. The title compounds are additionally characterized by thermogravimetric analysis.