Pentanuclear Cluster Research Articles

3D Ln-MOFs containing pentanuclear clusters exhibiting magnetic refrigeration and slow magnetic relaxation

Two isostructural lanthanide-based 3D metal–organic frameworks (Ln-MOFs), [Ln5(μ3-OH)6(TZI)3(DMA)1.5(H2O)9.5]·DMA [Ln = Gd (1) and Dy (2), H3TZI = 5-(1H-tetrazol-5-yl)isophthalic acid], have been synthesized and structurally and magnetically characterized. In 1 and 2, the pentanuclear clusters with mixed (μ3-OH)(μ2-carboxylate) bridges are connected into 1D chains by μ2-H2O bridges, and then these chains are linked into 3D structures by the TZI ligands. The magnetic study suggests that 1 shows significant cryogenic magnetocaloric effects (−ΔSm = 41.3 J kg−1 K−1, ΔH = 70 kOe, 2.5 K), whereas 2 exhibits slow relaxation of magnetization.

Co–Co and Co–Fe cyano-bridged pentanuclear clusters based on a methylpyrazinyl-diamine tetradentate ligand: spin crossover and metal substitution effects

A pentanuclear [CoII3CoIII2] cluster complex has been developed by a solvothermal synthesis. Its highly stable metal-mixed Fe–Co derivatives display robust spin crossover (T1/2 = 268 K) controlled by the degree of substitution.

N-donor auxiliary ligand-directed assembly of CoIIcompounds with a 2,2′-dinitro-biphenyl-4,4′-dicarboxylate ligand: structures and magnetic properties

To explore the influence of different N-donor auxiliary ligands on the self-assembly and structures of CoII-based coordination polymers (CPs), six coordination compounds, formulated as {Co(dnpdc)(bipy)}n (1), {[Co3(dnpdc)3(bipy)3(H2O)2]·2H2O}n (1s), {[Co5(OH)2(dnpdc)4(bpp)2(H2O)2]·2H2O}n (2), {[Co5(OH)2(dnpdc)4(bpp)2(H2O)2]·2H2O}n (3), {Co(dnpdc)(bcim)·(H2O)0.5}n (4) and {Co2(dnpdc)2(bpee)(bpim)}n (5) where bipy = 4,4′-bipyridine, bpee = bis(4-pyridyl)ethene, bpp = 1,3-bis(4-pyridyl)propane, bimb = 1,4-bis(imidazolyl)benzene, bcim = 4-bis(imidazol-1-ylmethyl)benzene and bpim = 4,4′-bis(imidazolyl)biphenyl, have been rationally designed and generated through the hydrothermal reaction of the dicarboxylate derivative ligand (H2dnpdc), Co(NO3)2, and a series of different N-donor co-ligands. These N-donor ligands were employed in the crystal preparation of these CPs as structure-directing ligands owing to their structural specialties and size-matching fashions. X-ray analyses revealed that these compounds exhibit two- or three-dimensional architectures. Compounds 1 and 5 are iso-structural, and both exhibit 3D “pillared” frameworks based on 1D [Co(OCO)2]n chains. Compound 1s, prepared at higher temperature, displays unusual (4,6)-connected and three-fold interpenetrated frameworks based on mononuclear and dinuclear nodes. Compound 2 features a new 10-connected 3D topology net based on a novel Co5(μ-OH)2(μ-OCO)6 pentanuclear cluster linked by mixed bpp and dnpdc ligands. Compound 3 exhibits a 6-fold interpenetrated diamond net. Compound 4 shows 2D sheets constructed from flexible bcim and dnpdc ligands. The magnetic properties of compounds 1, 2 and 5 have also been investigated to help us tentatively understand their structure–property relationships.

Assembly of a Highly Stable Luminescent Zn5 Cluster and Application to Bio‐Imaging

AbstractThe assembly sequence of the coordination cluster [Zn5(H2Ln)6](NO3)4]⋅8 H2O⋅2 CH3OH (Zn5, H3Ln=(1,2‐bis(benzo[d]imidazol‐2‐yl)‐ethenol) involves in situ dehydration of 1,2‐bis(benzo[d]imidazol‐2‐yl)‐1,2‐ethanediol (H4L) through the formation of the [Zn(H3L)2]+ monomer, dimerization to [Zn2(H3L)2]+, dehydration of the ligand to [Zn2(H2Ln)2]+, and the final formation of the pentanuclear cluster. The cluster has the following special characteristics: 1) high stability in both refluxing 37 % HCl and 27 % NH3, 2) low cytotoxicity, and 3) pH‐sensitive fluorescence in the visible‐to‐near‐infrared (Vis/NIR) region in the solid state and in solution. We have applied it as a fluorescent probe both in vivo and in vitro. Its H‐bonding ability is the key to its affinity and selectivity for imaging lysosomes in HeLa cells and tumors in male BALB/C mice. It provides a new type of sensitive and biocompatible fluorescent probe for detecting small tumors (13.5 mm3).

Three-dimensional metal-organic framework based on pentanuclear manganese clusters as building blocks

A rare 3-D Mn–organic framework, [(CH3)2NH2]3[Mn5(btc)4(Ac)(H2O)4]·5H2O (1), based on pentanuclear manganese clusters as building blocks has been prepared and structurally characterized by EA, IR, TGA, PXRD, and single-crystal X-ray diffraction. Structural analysis indicates the pentanuclear manganese cluster in 1 has a bow-like configuration, which is the first found to act as secondary building unit in the field of metal–organic framework. Gas adsorption measurements reveal that 1 can absorb a considerable amount of N2 and CO2.

Synthesis, properties and surface self-assembly of a pentanuclear cluster based on the new π-conjugated TTF-triazole ligand

The new π-extended redox-active ligand with both TTF and triazole units, 6-(4,5-bis(propylthio)-1,3-dithiol-2-ylidene)-1H-[1,3]dithiolo[4′,5′:4,5]benzo [1,2-d] [1–3]triazole, has been successfully prepared. Based on the versatile ligand and Cu(tta)2 precursors (tta− = 4,4,4-trifluoro-1-(thiophen-2-yl)butane-1,3-dione), a TTF-based pentanuclear CuII cluster (Cu5(tta)4(TTFN3)6) is synthesized and structurally characterized. Their absorption and electrochemical properties are investigated. Antiferromagnetic couplings are operative between metal ion centers bridged by triazoles in the complex. The self-assembled structure of the cluster complex on a highly oriented pyrolytic graphite (HOPG) surface was observed using scanning tunneling microscopy and density functional theory (DFT) calculations have been performed to provide insight into the formation mechanism. The introduction of the redox-active TTF unit into the cluster complexes with interesting magnetic properties renders them promising candidates for new multifunctional materials.

Assembly of Two Novel Cd3/(Cd3 + Cd5)-Cluster-Based Metal–Organic Frameworks: Structures, Luminescence, and Photocatalytic Degradation of Organic Dyes

Two new three-dimensional (3D) multinodal Cd(II)–organic frameworks, [Cd3(dccpa)(bipy)0.5(H2O)4]·5H2O (1) and [(CH3)2NH2]2[Cd11(dccpa)4(DMF)4(H2O)8]·4H2O (2) (H6dccpa = 3,4-di(3,5-dicarboxyl phenyl) phthalic acid, bipy = 4,4′-bipyridine), have been prepared and fully characterized. Compound 1 possesses a 3D neutral framework with a new (6,6,7)-connected topology based on a single trinuclear cluster, while 2 features a 3D anionic framework with a new (5,6,6,10)-connected topology containing mixed trinuclear and pentanuclear clusters. Remarkably, 1 and 2 show promising photocatalytic activities toward the degradation of rhodamine B and methyl blue, which suggests that different kinds of cluster units may exert different impacts on the decomposition of organic dyes.

Sequential Synthesis of 3d-3d'-4f Heterometallic Heptanuclear Clusters in between Lacunary Polyoxometalates.

In this work, we have successfully created several unprecedented discrete 3d-3d'-4f heterotrimetallic clusters in between lacunary polyoxometalates (POMs). By the three-step sequential introduction of metal cations into a trivacant lacunary POM TBA4H6[A-α-SiW9O34] (TBA = tetra-n-butylammonium) in organic media, five kinds of sandwich-type POMs with double-diamond-shaped 3d-3d'-4f heptanuclear clusters (IIIFeM4Ln2, TBAnHm[FeM4{Ln(L)2}2O2(A-α-SiW9O34)2], M = Mn(3+), Cu(2+); Ln = Gd(3+), Dy(3+), Lu(3+); L = acac (acetylacetonate), hfac (hexafluoroacetylacetonate)) were successfully synthesized for the first time. By introduction of two [Ln(L)2](+) units on the ends of pentanuclear clusters [FeMn4O18(OH)2](23-) and [FeCu4O18(OH)2](27-), the magnetic interactions between Mn(3+)-Mn(3+) and Cu(2+)-Cu(2+) could be modulated. Among a series of the heterometallic heptanuclear compounds, IIIFeMn4Lu2 exhibited the slow magnetic relaxation characteristic for a single-molecule magnet under the zero applied magnetic fields.

Synthesis and Crystal Structure of Binuclear and Pentanuclear Nickel(II) Complexes Containing 4-(salicylaldiminato)antipyrine Schiff base

The new title binuclear Ni (II) compound  (1) and the novel pentanuclear Ni (II) cluster {[  } (2) are formed from the reaction of an asymmetric Schiff base ligand L (L = 4-(salicylaldiminato)antipyrine) with Ni .4  in the former or Ni(ClO4)2.6H2O in presence of malonate in the later.  Complex (1) consists of ( ]+ cation) and one uncoordinated tetraphenylborate anion.  The cation adopts a distorted octahedral arrangement around each metal center.  In the binuclear unit both Ni(II) ions are linked through two phenolate (µ2-O) oxygen atoms of L, and two oxygen atoms of a bridging carboxylate group. Each Ni (II) coordinates to four oxygen atoms at the basal plane, two oxygen atoms from two bridging phenolate groups, one from pyrazolone ring and the last of an aqua molecule, and at the axial positions to a bridging carboxylate-O atom and an azomethine nitrogen atom.  In the pentanuclear cluster (2) consisting of [ ]+2 cation and two tetraphenylborate anions, the core of the cation is assembled by four [Ni( )] units, linked to the central Ni-ion by two bridging water molecules. The resulting coordination sphere for the external symmetry related nickel ions is a pseudo octahedron.  The central Ni-atom unusually adopts dodecahedron geometry through its coordination to eight bridging water molecules. In complex (1) each Ni-atom is coordinated to one tridentate L ligand and in complex (2) each [Ni ( )] unit is coordinated to two bidentate L ligands.  Inter-and intramolecular hydrogen bonds are present in both crystal structures.

A novel 3D energetic coordination polymer containing Co(II) atoms in a pentanuclear cluster

A novel coordination polymer [Co5(OH)2(dnbpdc)4(H2O)6]·16H2O (1) (dnbpdc = 6,6′-dinitro-4,4′-biphenyldicarboxylic acid) is obtained from a hydrothermal reaction. The structure of complex 1 is characterized by elemental analysis, IR spectroscopy, and single crystal X-ray diffraction analysis. The title compound (C56H70Co5N8O56, Mr = 2045.85) crystallizes in the triclinic space group P-1 with a = 11.9349(2) A, b = 12.1895(2) A, c = 15.420(2) A, α = 109.390(7)°, β = 94.786(1)°, γ = 108.027(9)°, V = 1968.4(4) A3, Z = 1, Dc = 1.726 g/cm3, F(000) = 1045, μ(MoKα) = 1.154 mm–1, T = 133(2) K, the final R = 0.0316 and wR = 0.0692 for 7032 observed reflections with I > 2σ(I). The coordination polymer is built of a pentanuclear Co(II) cluster, four dnbpdc ligands, two hydroxyl groups, six coordination water and sixteen crystal water molecules. Ligand oxygen atoms exhibit three types of coordination modes (monodentate, syn-syn bridging bidentate and bridging tridentate). Moreover, the infinite three-dimensional supramolecular network is generated by coordination and hydrogen bonds. The thermal stability of complex 1 is evaluated by differential scanning calorimetry and thermogravimetric analysis.

A tetrakis(amido)phosphonium cation containing 2-pyridyl (2Py) substituents,[P(NH2Py)4]+ and its reactivity studies with Ag(I) salts

Poly-imido analogues of various phosphorus oxo anions have gained recent attention in inorganic chemistry. Current methods to obtain these anions require strong organometallic deprotonating agents in reaction with phosphonium salt like [(NHPh)4P]Cl or phosphoramides such as [(RNH)3P=E] (E = NSiMe3, O, S or Se) in non-polar solvents. Recently, employing salts of soft and reactive transition metal ions, we have developed methods to obtain these anions in polar and protic solvents. Herein, we have described a facile anion exchange route that stabilizes the highly labile tetrakis(2-pyridylamino)phosphonium cation as its nitrate salt, [P(NH2Py)4]NO3. This molecule exhibits a double chain structure mediated by H-bonding interactions of the pyridylamino segments (N-H...N). The phosphonium salt upon reaction with excess silver triflate results in a pentanuclear Ag(I) complex, {Ag5[P(N 2Py)2(NH 2Py)2]} ⋅(F3 CSO 3)3, stabilized by two imido-phosphinate [P(N2Py)2(NH 2Py)2]− ligands. Formation of a similar penta-nuclear cluster has been observed before when AgClO4 was used as a base. Our previous results with the related phosphate precursor, [PO(NH2Py)3], in reaction with various Ag(I) salts have shown to yield complexes of the corresponding neutral, mono- and dianionic ligands. However, the stability of the Ag5-cluster within the mono-anionic casing of the [P(N2Py)2(NH2Py)2]− ligand have seemingly overwhelmed the subtle reactivity changes offered by various Ag(I) salts. Employing an anion exchange route, synthesis of a stable tetrakis(2-pyridylamino)phosphonium cation as its nitrate salt, [P(NH2Py)4]NO3 has been described. The precursor phosphonium salt upon reaction with excess silver triflate results in a pentanuclear Ag(I) complex, {Ag5[P(N2Py)2(NH2Py)2]}•(F3CSO3)3, stabilized by two imido-phosphinate [P(N2Py)2(NH2Py)2]− ligands.

Influence of N-donor sites in 5-(x-pyridyl)-1H-tetrazole ligands (x = 2, 4) on assembly of polyoxometalate-based compounds modified by multinuclear metal clusters and infinite chains

Through tuning the N-donor site of the pyridyl group in 5-(x-pyridyl)-1H-tetrazole ligands (x = 2, 4), four new Keggin-based compounds, [Cu7(2-ptz)8(OH)2(H2O)2(HPMoVI10MoV2O40)]·4H2O (1), [Cu5(2-ptz)6(HPMoVI10MoV2O40)(H2O)4]·4H2O (2), [Ag6(4-ptz)4(H2SiMo12O40)] (3) and [Ag5(4-ptz)4(H2PMo12O40)]·5H2O (4) (2-ptzH = 5-(2-pyridyl)-1H-tetrazole, 4-ptzH = 5-(4-pyridyl)-1H-tetrazole), were successfully synthesized under hydrothermal conditions and structurally characterized. Compound 1 possesses two kinds of CuII subunits: penta-nuclear clusters and mono-nuclear subunits, which connect with each other to form a one dimensional (1D) stair-like metal–organic chain. The adjacent 1D stair-like chains are further linked by tetradentate Keggin anions to construct a 2D layer. In compound 2, the tetra-nuclear CuII clusters and mono-nuclear CuII subunits construct a 2D metal–organic layer, which is further linked by bidentate Keggin anions to build a 3D framework. In compound 3, the 4-ptz ligand links AgI ions with tetrazole groups to form 1D infinite Ag–ptz chains, which are extended by the pyridyl group of 4-ptz and the tetrazole groups of other 4-ptz molecules to construct a 2D layer. The adjacent 2D layers are further linked by 6-connected Keggin anions to build a 3D framework. In compound 4, the 4-ptz ligands are linked by AgI ions to form 1D infinite Ag–ptz belts. The Keggin anions are linked by AgI ions to construct another infinite inorganic chain, in which each Keggin anion provides six oxygen atoms to coordinate with the AgI ions from adjacent Ag–ptz belts to construct a 2D layer. The roles of the ptz ligands with different N-donor sites in the construction of multinuclear clusters and 1D chains are discussed. The electrochemical and photocatalytic properties of the title compounds were investigated as well.

Mn(II)2Gd(III)3 Phosphonate as a Molecular Refrigerant

3d-Gd phosphonate clusters are attractive for their potential applications as magnetic coolers. A new pentanuclear cluster [Mn(II)2Gd(III)3(OH)(dtbmfPO3)2(tBuCO2)8(HO2CtBu)(H2O)2]·HO2CtBu·CH3CN (1) (dtbmfPO3H2 = (2,7-di-tert-butyl-9-methyl-9H-fluoren-9-yl)phosphonic acid) has been synthesised and characterised. The cluster has a planar structure in which the trinuclear {MnGd2(OH)} and dinuclear {MnGdO2} units are joined together by two phosphonate groups. The magnetic studies reveal that 1 shows antiferromagnetic interactions and a large magnetocaloric effect (ΔS = 20.9 J kg–1 K–1 at ΔH = 7 T).

An azide-bridged copper(II) complex: poly[piperazine-1,4-dium [tetra-μ₃-azido-κ¹²N¹:N¹:N¹-hexa-μ₂-azido-κ¹²N¹:N¹-di-μ₂-azido-κ⁴N¹:N³-pentacopper(II)] tetrahydrate

A new Cu(II)-azide complex, {(C4H12N2)[Cu5(N3)12]·4H2O}n, has been synthesized by the reaction of piperazine, Cu(OAc)2·2H2O (OAc is acetate) and NaN3. In the structure, μ2-1,1- and μ3-1,1,1-azide anions bridge five Cu(II) cations to form a linear pentanuclear cluster unit, which is further linked by μ2-1,1- and μ2-1,3-azide anions to form a two-dimensional condensed [Cu5(N3)12]n layer. The diprotonated piperazine and the solvent water molecules are hydrogen bonded to the coordination layers to form a three-dimensional supramolecular network.

Five copper(ii) metal–organic coordination complexes with micro-channels based on flexible bis(imidazole) and carboxybenzaldehyde ligands; structural influence of experimental conditions on their frameworks

Five new copper(II) metal–organic coordination complexes, [Cu2(1,2-bix)2(L)4] (1), [Cu(1,3-bix)(L)2]n·nCH3OH·3H2O (2), [Cu(1,3-bix)(L)2]n·nH2O (3), [Cu5(1,3-bix)2(L)6(NO3)2(H2O)2(OH)2]·2H2O (4) and [Cu(1,4-bix)(L)2]n (5), have been synthesized using 4-carboxybenzaldehyde (HL) and 1,n-bis(imidazol-l-ylmethyl)benzene (1,n-bix; n = 2, 3, 4) as ligands. These complexes were structurally characterized by single-crystal X-ray crystallography and further characterized by FT-IR spectroscopy and thermogravimetric analysis (TGA). Complex 1 is a symmetrical binuclear structure, and in compound 2 the 1D ladders are entangled through π–π stacking interactions to generate a 3D network with one-dimensional micro channel. A 3D coordination framework 2 converted to network 3 by just increasing the reaction temperature. Metal–organic polymer 3 is comprised of 1D corrugated double chains structure. Complex 4 has a pentanuclear (Cu5) cluster structure and compound 5 shows a 1D zigzag chain. The magnetic properties of the complexes 1 and 3 are reported briefly.

An eight-connected porous metal–organic framework based on hetero pentanuclear clusters

A new MOF based on hetero pentanuclear clusters, [(CH3)2NH2]1.66[Cd1.84Na0.66(BDC)3]·DMF·0.5EtOH (1), has been prepared. Iodine adsorption studies reveal that 1 can reversibly adsorb iodine. Furthermore, electrochemical impedance spectroscopy (EIS) of 1⊃I2 shows that it has a relatively high conductivity at room temperature.

Diverse Self-Assembly from Predesigned Conformationally Flexible Pentanuclear Clusters Observed in a Ternary Copper(II)–Triazolate–Sulfoisophthalate System: Synthesis, Structure, and Magnetism

Self-assembly from the predesigned Cu(II)5 secondary building unit (SBU) in the ternary Cu(II)-triazolate-sulfoisophthalate system generates three interesting magnetic samples: an open pillared-layer framework with nanosized Cu(II)30 metallamacrocycle-based sublayer (1), a (3,6)-connected 2-fold interpenetrating network consisting of alternating Cu(II)5 and Cu(II)1 cores (2), and a (4,8)-connected architecture constructed from centrosymmetric Cu(II)7 clusters and four-branched 5-sulfoisophthalate (sip(3-)) connectors (3). These various structures significantly result from the variable connectivity and the slight expansion of the predetermined conformationally flexible Cu(II)5 SBUs. Furthermore, these intriguing structural motifs in 1-3 essentially induce different magnetic phenomena. A field-dependent metamagnetic transition from antiferromagnetic ordering to weak ferromagnetism is observed in the frustrated Cu(II)30-based sublayer of 1. The paramagnetic Cu(II)1 core in 2 virtually contributes to an S = (1)/2 spin ground state due to the completely compensated magnetic moment in the 1,2,3-triazolate (ta(-))-bridged Cu(II)5 cluster containing ribbon. In contrast, strong antiferromagnetic interactions in the locally centrosymmetric Cu(II)7 cluster lead to an overall S = (1)/2 spin ground state of 3. Thus, the SBU-derived self-assembly strategy provides important hints for polymetallic cluster based high-dimensional magnetic materials, which also brings a new vision for the design and construction of novel functional materials.

Activation of Linear Alkanes by a Hydrido Triruthenium Cluster and Associated Skeletal Rearrangements

Abstract We explored polyhydrido cluster reaction chemistry for over two decades, developing rational syntheses of di-, tri-, tetra-, and pentanuclear clusters of ruthenium. In our study of cluster chemistry, we found that triruthenium pentahydrido complex [{Cp*Ru(µ-H)}3(µ3-H)2] (1) (Cp*: η5-C5Me5) reacts with linear alkanes to exclusively afford a closo-ruthenacyclopentadiene complex 2. The reaction mechanism has been elucidated by the isolation and alternative preparation of several important intermediates by the reaction of 1 with other hydrocarbons, such as alkynes, dienes, and alkenes. The mechanism is shown to consist of two reversible and four irreversible steps involving dihydrogen elimination, where the cooperative interaction of neighboring metal centers with hydrocarbons on the cluster is clearly seen. Facile migration of a hydride from a metal center to the carbon atom is also observed during the reaction, which emphasizes the crucial role of hydrido ligands in the skeletal rearrangement of hydrocarbyl ligands on a polyhydrido cluster. In addition, coupling reaction between two hydrocarbyl ligands placed on each face of the triruthenium core with concomitant partial cleavage of the cluster skeleton has also been observed. Such a flexible cluster skeleton enables unusual transformation of hydrocarbons on the cluster.

Synthesis, structure and properties of zinc(II) coordination polymers with 9H-carbazole-2,7-dicarboxylic acid

From a new dicarboxylate ligand, 9 H -carbazole-2,7-dicarboxylic acid (2,7-H 2 CDC), three Zn(II) metal-organic frameworks were synthesized in the absence or presence of ditopic N-donor ligands. They are formulated as [Zn 5 ( μ 3 -OH) 2 (2,7-CDC) 4 (DEF) 2 ] ( 1 ) (DEF= N , N -diethylformamide), [Zn 2 (2,7-CDC) 2 (DABCO)(H 2 O)]·5DMF·H 2 O ( 2 ) (DABCO=1-diaza-bicyclo[2.2.2]octane, DMF= N , N -dimethylformamide), and [Zn 2 (2,7-CDC) 2 (bpea)]·3DMA·2 H 2 O ( 3 ) (bpea=1,2- bis (4-pyridyl)ethylane, DMA= N , N -dimethylacetamide). Compounds 1 and 3 display the 3D pcu frameworks. In 1 the unusual pentanuclear [Zn 5 ( μ 3 -OH) 2 (COO) 8 ] secondary building units (SBUs) are linked by dicarboxylate ligands. Differently, in 3 the well-known paddle–wheel [Zn 2 (COO) 4 ] SBUs are linked by dicarboxylate and dipyridyl ligands. Compound 2 shows the rare self-catenated 3D alb -3,6-C2/c net topology based on the dinuclear paddle–wheel SBU and a mononuclear unit. The stability and fluorescent properties of the compounds have been studied. A new dicarboxylate ligand, 9 H -carbazole-2,7-dicarboxylic acid, was used to construct Zn(II) metal-organic frameworks, including a novel self-catenated network with the rare 3D alb -3,6-C2/c net and two pcu -type networks based on an unprecedented pentanuclear clusters and the common paddle–wheel units. The compounds show blue fluorescent properties. • MOFs with a new carbazole-based dicarboxylate ligand. • New pentanuclear [Zn 5 ( μ 3 -OH) 2 (COO) 8 ] secondary building unit. • The rare self-catenated 3D alb -3,6-C2/c net.

Tri- and pentanuclear NCS-bridged [MoIII–CuII] cluster compounds: Crystal structures and magnetic properties

Two heteronuclear NCS-bridged compounds, namely [{Cu(3,3,3-tet)(CH3CN)}2{Mo(NCS)6}][Mo(NCS)6][PPh4]2·6CH3CN (1) and [{Cu(3,3,3-tet)(CH3CN)}4{Mo(NCS)6}][Mo(NCS)6]3[Cu(3,3,3-tet)(CH3CN)]2 (2) (with 3,3,3-tet=N,N-bis(3-aminopropyl)-1,3-propanediamine) have been synthesized and their crystal structures were characterized by single crystal X-ray diffraction studies. For the cationic trinuclear cluster of 1 one hexaisothiocynato Mo(III) unit, [Mo(NCS)6]3−, is linked to two Cu units through two NCS bridging ligands, and the anionic pentanuclear cluster of 2 results from the linkage of the Mo unit to four Cu moieties. In 1 and 2, the coordination of a solvent molecule (i.e. acetonitrile) in one apical position of Cu prevents the extension of the system, while charge neutrality is achieved by co-crystallization of non-bonded Cu and/or Mo complexes. Magnetic studies of 1 and 2 reveal the weak antiferromagnetic interaction between the two spin carriers CuII and MoIII, through the NSC ligand. For 1, modeling the experimental data yields a value of JMoCu=−5.9cm−1 (H=−J(S1S2+S2S3)) for the exchange interaction.