Bpe Ligands Research Articles

Influence of the Synthetic Conditions on the Structural Diversity of Extended Manganese−Oxalato−1,2-bis(4-pyridyl)ethylene Systems

We report herein the synthesis and physicochemical characterization of eight new manganese-oxalato compounds with 1,2-bis(4-pyridyl)ethylene (bpe): {(Hbpe)(2)[Mn(2)(μ-ox)(3)]·∼0.8(C(2)H(5)OH)·∼0.4(H(2)O)}(n) (1), {[Mn(μ-ox)(μ-bpe)]·xH(2)O}(n) (2), [Mn(2)(μ-ox)(2)(μ-bpe)(bpe)(2)](n) (3), [Mn(μ-ox)(μ-bpe)](n) (4a and 4b), and {[Mn(4)(μ-ox)(3)(μ-bpe)(4)(H(2)O)(4)]·(X)(2)·mY}(n) with X = NO(3)(-) (5a), Br(-) (5b), and ClO(4)(-) (5c) and Y = solvation molecules. The appropriate selection of the synthetic conditions allowed us to control the crystal structure and to design extended 2D and 3D frameworks. Compound 1 is obtained at acid pH values and its crystal structure consists of stacked [Mn(2)(μ-ox)(3)](2-) layers with cationic Hbpe(+) molecules intercalated among them. Compound 2 was obtained at basic pH values with a manganese/bpe ratio of 1:1, and the resulting 3D structure consists of an interpenetrating framework in which metal-oxalato chains are bridged by bpe ligands, leading to a microporous network that hosts a variable number of water molecules (between 0 and 1) depending on the synthetic conditions. Compound 3, synthesized with a manganese/bpe ratio of 1:3, shows a 2D framework in which linear metal-oxalato chains are joined by bis-monodentate 1,2-bis(4-pyridyl)ethylene ligands. The thermal treatment of compound 3 permits the release of one of the bpe molecules, giving rise to two new 2D crystalline phases of formula [Mn(μ-ox)(μ-bpe)](n) (4a and 4b) depending on the heating rate. The open structures of 5a-5c were synthesized in a medium with a high concentration of nitrate, perchlorate, or bromide salts (potassium or sodium as cations). These anions behave as templating agents directing the crystal growing toward a cationic porous network, in which the anions placed in the voids and channels of the structure present high mobility, as inferred from the ionic exchange experiments. Variable-temperature magnetic susceptibility measurements show an overall antiferromagnetic behavior for all compounds, which are discussed in detail.

A New Metal–Organic ZnII Supramolecular Assembled via Hydrogen Bonds and N···N Interactions as a New Precursor for Preparation Zinc(II) Oxide Nanoparticles, Thermal, Spectroscopic and Structural Studies

A new 1D supramolecular involving two different ligands, {[Zn(GB)2]·(μ-bpe)3} n (ClO4)2n ·nH2O (GB = 2-guanidinobenzimidazole and bpe = 1,2-bis(4-pyridyl)ethylene, has been synthesised, characterized by elemental analysis, IR-, 1H NMR-, 13C NMR spectroscopy. The thermal stability of compound {[Zn(GB)2]·(μ-bpe)3} n (ClO4)2n ·nH2O was studied by thermal gravimetric and differential thermal analyses. The single crystal X-ray analysis shows that the complex is a one-dimensional polymer involving macrocycle rings as a result of non-covalent bridging bpe ligands via N–H···N and N···N interactions, N–H···bpe···bpe···H–N, with the basic repeating {[Zn(GB)2](μ-bpe)3}(ClO4)2·H2O units and by connecting [Zn(GB)2]2+ nodes. ZnO nanoparticles were obtained by calcination of compound {[Zn(GB)2]·(μ-bpe)3} n (ClO4)2n ·nH2O at 500 °C in air. The nanoparticles were characterized by X-ray diffraction and scanning electron microscopy.

Structural, Spectroscopic, and Magnetic Characterization of the Coordination Polymers [MII(NCS)2(bpe)2]·3H2O·2C2H6SO [M = Co, Ni; bpe = 1,2-Bis(4-pyridyl)ethylene]. Two Interpenetrated Porous Networks

Two novel coordination polymers are obtained by the reaction of M(NO3)2·6H2O (M = CoII, NiII) with KNCS and bpe (bpe = 1,2-bis(4-pyridyl)ethylene). Both compounds, [CoII(NCS)2(bpe)2]·3H2O·2C2H6SO (1) and [NiII(NCS)2(bpe)2]·3H2O·2C2H6SO (2), exhibit the same structure, consisting of two mutually interpenetrated networks made of parallel sheets. The effect of perpendicular concatenation results in fully interlocked networks, which makes the structure define large channels of square geometry. These channels spread along the z-axis, where solvent molecules are located and stack in columns. A compressed octahedral environment, with four bridging bpe ligands occupying the equatorial sites and two terminal N-bonded thiocyanate groups occupying the axial ones, is observed for each metal ion. The magnetic susceptibility measurements show an antiferromagnetic behavior with interactions of low order as a consequence of such a long distance between the metal ions bridged through the bpe ligand. This type of porous co...

μ-1,2-Bis(4-pyridyl)ethane-κ2N:N′]bis[(4′-phenyl-2,2′:6′,2′′-terpyridine-κ3N,N′,N′′)silver(I)] bis(trifluoromethanesulfonate)

In the title compound, [Ag2(C12H12N2)(C21H15N3)2](CF3SO3)2, the AgI atom is coordinated by three N atoms of one 4′-phenyl-2,2′:6′,2′′-terpyridine (phtpy) ligand and one pyridyl N atom of the 1,2-bis­(4-pyrid­yl)ethane (bpe) ligand, displaying a distorted square-planar geometry. Two AgI atoms are bridged by one trans-bpe ligand, generating a dinuclear cation. The dinuclear cation is located on a centre of inversion, which is in the middle of the ethyl­ene fragment of the bpe ligand. In the crystal, the pyridyl rings of neighboring dinuclear units are stacked by π–π inter­actions with centroid–centroid distances of 3.667 (2) and 3.835 (2) Å. The F and O atoms of the CF3SO3 − anions are involved in inter­molecular C—H⋯F and C—H⋯O hydrogen-bonding inter­actions, respectively, with –CH groups from the phtpy ligands.

2+2] Photodimerization in the Solid State Aided by Molecular Templates of Rectangular Macrocycles Bearing Oxamidato Ligands

A series of binuclear half-sandwich iridium and rhodium complexes bearing oxamidato ligands [Cp*2M2(μ-N,N′-bis(aryl)oxamidato)Cl2] (1a, M = Ir, aryl = Ph; 1b, M = Ir, aryl = C6H4-p-Me; 2a, M = Rh, aryl = Ph; 2b, M = Rh, aryl = C6H4-p-Me) functioned as potential ‘‘organometallic clip’’ linear templates were synthesized by the reactions of the lithium salts of oxamide with [Cp*MCl2]2 (M = Ir or Rh), respectively. Treatment of the binuclear complexes (1a−2b) with trans-1,2-bis(4-pyridyl)ethylene (4,4′-bpe) in the presence of AgOTf (OTf = CF3SO3) gave the corresponding tetranuclear complexes of general formula [Cp*4M4(μ-N,N′-bis(aryl)oxamidato)2(μ-4,4′-bpe)2](OTf)4 (3a, M = Ir, aryl = Ph; 3b, M = Ir, aryl = C6H4-p-Me; 4a, M = Rh, aryl = Ph; 4b, M = Rh, aryl = C6H4-p-Me) in high yields. Confirmed by the single-crystal X-ray analysis, the molecular structures of tetranuclear complexes 3a and 4a showed that two binuclear fragments as building blocks were connected by μ-4,4′-bpe to construct a rectangular cavity with the dimensions 5.58 × 13.59 Å (3a) and 5.55 × 13.65 Å (4a). The two μ-4,4′-bpe ligands in 3a and 4a are close to each other within 4.2 Å to allow the [2+2] photoreaction in the solid state, which was proved by 1H NMR of the resulting products (5a−6b′) and single-crystal X-ray analysis.

An unusual polycatenating network self-assembled by the 2D → 2D parallel → 3D parallel interpenetration of coordinative and hydrogen-bonded (6,3) motifs

In the title coordination compound, catena-poly[[[bis[diaquacadmium(II)]-mu(2)-trans-1,2-bis(4-pyridyl)ethene]bis{mu(2)-2,2'-[(5-carboxymethoxy-m-phenylene)dioxy]diacetato}] trans-1,2-bis(4-pyridyl)ethene solvate dihydrate], {[Cd(2)(C(12)H(10)O(9))(2)(C(12)H(10)N(2))(H(2)O)(4)].C(12)H(10)N(2).2H(2)O}(n), (I), each Cd(II) centre adopts a pentagonal-bipyramidal coordination geometry. The incompletely deprotonated 2,2'-[(5-carboxymethoxy-m-phenylene)dioxy]diacetate (TCMB) ligands and trans-1,2-bis(4-pyridyl)ethene (bpe) ligands both act as bidentate bridges, linking the Cd(II) centres into one-dimensional ladders, which are connected into an undulating two-dimensional (6,3) layer through O-H...N hydrogen bonds between the carboxylate groups of the TCMB ligands and the N atoms of the uncoordinated bpe ligands. Each undulating layer polycatenates two other identical layers, exhibiting the unusual combination of both 2D --> 2D parallel and 2D --> 3D parallel interpenetration (2D and 3D are two- and three-dimensional, respectively).

A series of three-dimensional lanthanide metal–organic frameworks with biphenylethene-4,4′-dicarboxylic acid: Hydrothermal syntheses and structures

Biphenylethene-4,4′-dicarboxylic acid (H2bpea) reacts with lanthanide(III) oxide (Ln = Sm, Eu, Gd, Tb, Er) or nitrate salts of lanthanide(III) (Ln = Eu, La, Tb) under hydrothermal conditions to form a series of lanthanide complexes 1–8, which were characterized by elemental analysis, IR, PL TG and single-crystal X-ray diffraction. These eight complexes exhibit four different kinds of 3-D frameworks. The complexes [Ln(bpea)(formate)]n (Ln = Sm (1), Eu (2), Gd (3), Tb (4), Er (5)) were isomorphous and exhibited 3-D pillared layered frameworks. The eight-coordinated lanthanide ions in complexes 1–5 are bridged by the formate anions into 2-D covalent nets, which are further interconnected by the bpea ligands to produce the 3-D framework. While the formate anions are neglected, the new generated 3-D framework shows a four-connected SrAl2 net. The nine-coordinated europium ions in complex [Eu(bpea)(formate)]n (6) are also bridged by the formate anions into similar 2-D covalent nets, which are further interconnected by the bpea ligands to produce a different 3-D framework. Interestingly, complex 6 displays a 2-fold interpenetrating 3-D structure with Pts topology while neglecting the formate anions. The main reason is due primarily to the coordination geometry of the europium ion and the novel μ4:η6-bridging coordination mode of the bpea ligands. Complexes 7 and 8 have the same composition of [Ln(bpea)1.5(H2O)2]n (Ln = La (7) and Tb (8)), but crystallize in the P21/n and P space groups, respectively. In complex 7, the lanthanum centers are bridged by the bpea ligands in a common μ4:η4-bridging coordination mode into 2-D double layer motifs, which are further connected by the other μ4:η4-bridging bpea ligands to produce a 3-D hybrid framework with sixty-membered macro rings. By contrast, the terbium centers in complex 8 are bridged by the bpea ligands in an unprecedented μ4:η5-bridging coordination mode into 2-D layer architectures, which are further connected by the other μ2:η2-bridging bpea ligands to produce a 3-D hybrid framework.

Supramolecular assembly under the control of the chelating ligand for the MnII/bridging ligands/3-sulfobenzoate system and catalytic properties for the disproportionation of hydrogen peroxide

Six MnII 3-sulfobenzoate complexes with neutral ligands, [Mn(4,4′-bipy)2(H2O)4](3-sb)·3H2O (1), {[Mn(3-sb)(bpe)1.5(H2O)2](bpe)0.5·H2O}n (2), [Mn(3-sb)(phen)(H2O)3](4,4′-bipy)·H2O (3), [Mn2(3-sb)2(phen)2 (4,4′-bipy)(H2O)4] (4), [Mn(3-sb)(phen)2(H2O)] (bpe)0.5·4H2O (5), and [Mn(3-sb)(phen)2(H2O)](bpe)0.5·H2O (6) [where 3-sb is 3-sulfobenzoate, 4,4′-bipy is 4,4′-bipyridine, bpe is 1,2-bis(4-pyridine)ethylene, and phen is 1,10-phenanthroline], were synthesized and characterized by several modern analytic methods. The molecular structures for the six complexes are monomers for complexes 3, 5, and 6, cation–anion species for complex 1, dimer for complex 4, and 1-D polymer for complex 2. The phen ligands in complexes 3 and 4 generate some effects on the hydrogen-bonding network, π–π interactions, and supramolecular assembly. TG analysis showed that desolvated complexes containing 4,4′-bipy are less stable than those of complexes containing bpe ligands. The emission strength order is 1 > 5 > 6 > 3 > 2 > 4, while the UV-vis absorption strengths are 4 > 3 > 1 for complexes containing 4,4′-bipy, and 5 > 6 > 2 for bpe metal complexes. The catalytic experiments showed that these six complexes are catalytically active for the disproportionation of H2O2 in the presence of imidazole and complex 3 has the best catalytic activity.

Poly[aqua[μ2-cis-1,2-bis(4-pyridyl)ethylene-κ2N:N′](μ2-5-nitroisophthalato-κ3O:O′,O′′)nickel(II)

In the title compound, [Ni(C8H3NO6)(C12H10N2)(H2O)]n, the NiII atom is octa­hedrally coordinated by two cis N atoms from two different 1,2-bis­(4-pyrid­yl)ethyl­ene (bpe) ligands, two O atoms from one chelating carboxyl group of the 5-nitro­isophthalic acid (nip) ligand, one O atom from another monodentate nip ligand and one O atom from a water mol­ecule, forming a three-dimensional network structure. Inter­molecular O—H⋯O hydrogen bonding stabilizes this arrangement. The asymmetric unit of the structure contains one NiII atom, one water mol­ecule, one nip ligand and two half-mol­ecules of the bpe ligand with an inversion centre at the mid-point of the central C=C bond.

Crystal structure of tetraaqua-bis(dipyrido[3,2-a:2',3'-c]phenazine)- (biphenylethene-4,4'-dicarboxylato)dicobalt(II) biphenylethene-4,4'- dicarboxylate —water (1:6), [Co2(H2O)4(C18H10N4)2(C16H10O4)][C16H10O4] · 6H2O

C68H60Co2N8O18, triclinic, P1 (no. 2), a = 7.299(5) A, b = 13.865(5) A, c = 15.840(5) A, α = 83.889(5)°, * = 83.626(5)°, γ = 78.785(5)°, V = 1556.7 A, Z = 1, Rgt(F) = 0.045, wRref(F) = 0.096, T = 293 K. Source of material A mixture of biphenylethene-4,4'-dicarboxylatic acid (H2bpea, 1.mmol), dipyrido[3,2-a:2',3'-c]phenazine (dppz, 0.5 mmol), and CoCl2.·.6H2O (1 mmol) was suspended in a mixed solution of deionized water (12 ml) and sealed in a 20 ml Teflon-lined autoclave. Upon heating at 140 °C for three days, the autoclave was slowly cooled to room temperature. Red crystals were collected, washed with deionized water and dried. Experimental details H atoms on C atoms were generated geometrically and refined as riding atoms with d(C—H) = 0.93 A and Uiso(H) = 1.2 Ueq(C). TheH atoms of thewatermolecules (O1W,O2WandO3W)were found in a difference Fourier map and refined, but the H atoms of water molecules (O4W and O5W) were not located. Discussion The coordination polymers based on a N-donor chelating ligand, such as 1,10-phenanthroline (phen), have been widely studied. However, far less attention has been payed to the derivatives of phen. Dipyrido[3,2-a:2',3'-c]phenazine (dppz) as an important phen derivative possesses fruitful aromatic systems and may be a good candidate for the construction of metal-organic supramolecular architectures [1]. Here, we selected biphenylethene-4,4'dicarboxylatic acid (H2bpea) as a organic linker and dppz as a Ndonor chelating ligand, forming a new coordination polymer, [Co2(H2O)4(bpea)(dppz)2]2.·.bpea.·.6H2O. In the title crystal structure eachCo(II) is six-coordinated in a distorted octahedral environment and is surrounded by two carboxylate oxygen atoms from one bpea anion, two water molecules and two nitrogen atoms from one dppz ligand. The average Co—O and Co—N distances are comparable to the literature data. Two neighbouringCo(II) atoms are linked by the same bpea ligand to form a dimer. Slipped --stack arrangements between dppz and bpea ligands were observed (centroid-to-centroid distance of 3.69(4) A, vertical face-to-face distance of 3.52(3) A, and dihedral angle of 1.07(4)°), which extends the dimers into a supramolecular structure. 528 Z. Kristallogr. NCS 224 (2009) 528-530 / DOI 10.1524/ncrs.2009.0231 © by Oldenbourg Wissenschaftsverlag, Munchen Crystal: red block, size 0.19 × 0.28 × 0.33 mm Wavelength: Mo K+ radiation (0.71073 A) .: 6.15 cm−1 Diffractometer, scan mode: Bruker APEX CCD, #/% 2,max: 52.82° N(hkl)measured, N(hkl)unique: 12364, 6303 Criterion for Iobs, N(hkl)gt: Iobs > 2 )(Iobs), 3566 N(param)refined: 455 Programs: SHELXS-97 [2], SHELXL-97 [3], SHELXTL [4] Table 1. Data collection and handling.

Synthesis, Structures, and Properties of Two Novel Supramolecular Architectures Constructed from [2,3‐f]Pyrazino[1,10]phenanthroline‐2,3‐dicarboxylic Acid

AbstractTwo new compounds, [Ag(Hppdb)]n (1) and {[Ag2(Hppdb)2(bpe)]·5.5H2O}n(2) [H2ppdb = [2,3‐f]pyrazino[1,10]phenanthroline‐2,3‐dicarboxylic acid, bpe = trans‐1,2‐bis(4‐pyridyl)ethylene], were synthesized and characterized. In 1, Hppdb– ions link AgI cations to form an infinite 1D [–Ag–(Hppdb)–Ag–]n chain, furthermore, the dimensionality is extended to 2D layers through synergistic π–π stacking, hydrogen‐bonding and weak Ag···O interactions. Correspondingly, the dimeric [(Ag)(Hppdb)]2 subunits in 2 are connected by bpe ligands to generate a loop‐link‐shaped 1D chain motif, which is further joined through a R22(18)C–H···O hydrogen‐bonding ring to afford interesting diagonal/diagonal inclined catenation 2D + 2D → 3D supramolecular architectures. In addition, solid‐state properties such as photoluminescence and thermal stability of the two compounds were studied.

A 3D Metal-Organic Framework with CdSO4-type Topology Through Assembly of Mixed Ligands

Rational self-assembly of a long 3,3′,4,4′-benzophenonetetracarboxylate (bptc) ligand and metal salt in the presence of linear bidentate ligand yields a novel polymer with CdSO4-type topology. An interesting feature of the complex is that the bridged water molecule weakly coordinates to the Ni cation, forming an infinite metal–aqua chain as the fundamental unit. Furthermore, the metal–aqua chains are pillared by 1,2-bis(4-pyridy)ethene (bpe) ligands to extend a 3D rhombic framework.

Catena-Poly[[bis(2-hydroxy-2-phenylacetato-κ2O1,O2)zinc(II)]-μ-1,2-di-4-pyridylethane-κ2N:N′

The title compound, [Zn(C8H6O3)2(C12H12N2)]n, consists of [Zn(Hopa)2] (H2opa = 2-hydr­oxy-2-phenyl­acetic acid or mandelic acid) units bridged by 1,2-di-4-pyridylethane (bpe) ligands, forming a polymeric chain developing parallel to the b axis. The bridging bpe ligand is arranged around a twofold axis passing through the middle of the ethane C—C bond. The geometry around the ZnII ion is distorted octa­hedral, constructed by four O atoms from two Hopa− ligands and two N atoms from two bridging bpe ligands. O—H⋯O hydrogen bonds link the chains, forming a three-dimensional network.

Five novel transition metal coordination polymers with 2D/3D framework structure based on flexible H 2tzda and ancillary ligand bpe

Five new transition metal coordination polymers based on H 2tzda and co-ligand bpe, {[ M(tzda)(bpe)]·H 2O} n [ M=Zn( 1), Cd( 2), Mn( 3), Co( 4)] and [Ni 2(tzda) 2(bpe) 2(H 2O)] n ( 5) [H 2tzda=(1,3,4-thiadiazole-2,5-diyldithio)diacetic acid, bpe=1,2-bis(4-pyridyl)ethane], have been hydrothermally synthesized and structurally characterized. Compounds 1–4 feature a 2D-layered architecture generated from [ M(tzda)] n moiety with double-chain structure cross-linking bpe spacers. However, the conformations bpe adopts in 3 and 4 are different from those in 1 and 2 due to the rotation of C–C single bond in bpe. Polymer 5 exhibits an interesting 3D porous framework with 2-fold interpenetration, in which intriguing 1D double helix chains are observed. The photoluminescence properties of 1 and 2 in the solid-state at room temperature are investigated. In addition, variable-temperature magnetic data show weak antiferromagnetic behavior in 3–5.

Mixed-ligand complexes with trans-1-(2-pyridyl)-2-(4-pyridyl)ethylene terminal and different aromatic polycarboxyl linkers: Synergistic modulation of metallosupramolecular architectures via coordinative and secondary interactions

A series of Co II, Ni II, and Cu II complexes with trans-1-(2-pyridyl)-2-(4-pyridyl)ethylene (bpe) and various polycarboxyl co-ligands have been prepared under general condition and characterized by IR, elemental analysis, and TG-DTA techniques. Single-crystal X-ray diffraction indicates that these complexes display multifarious binuclear, 1-D, and 2-D coordination motifs in virtue of the bridging polycarboxyl building blocks, in which the bpe ligand uniformly adopts the unidentate coordination by using its 4-pyridyl group. Remarkably, higher-dimensional extended networks are further formed with the aid of additional secondary interactions based on bpe (such as H-bonding and π– π stacking). These results demonstrate that bpe is a reliable bifunctional tecton to construct diverse supramolecular architectures via synergistic effect of multiple intermolecular interactions.

Photochemical [2+2] cycloaddition of the olefinic double bonds in the supramolecular rectangle [Ru4(η6-p-cymene)4(μ-oxalato)2(μ-4,4′-bipyridylethylene)2]4+

Abstract Self-assembly of 4,4′-bipyridylethylene (bpe) bidentate connector with the dinuclear arene ruthenium clip [Ru2(η6-p-cymene)2(μ-oxalato)Cl2] in the presence of silver triflate affords the cationic organometallic rectangle [Ru4(η6-p-cymene)4(μ-oxalato)2(μ-bpe)2]4+ ([1][CF3SO3]4). Upon UV irradiation of a methanol solution of [1]4+, dimerisation of the olefinic double bonds of the two parallel bpe ligands occurs, thus giving rise to the [2+2] cycloaddition derivative [Ru4(η6-p-cymene)4(μ-oxalato)2(μ-tpcb)]4+ ([2][CF3SO3]4) (tpcb = tetrakis(4-pyridyl)cyclobutane). The [2+2] photodimerisation reaction was followed by 1H NMR spectroscopy. Moreover, the molecular structure of these two systems was deduced by one-dimensional and two-dimensional NMR experiments (1H, 13C, ROESY, COSY, HSQC). These data suggest the formation of only the rctt-tetrakis(4-pyridyl)cyclobutane isomer.

New copper(II) 1D polymer containing dimethyl(phenylsulfonyl)amidophosphate: Synthesis, crystal structure and magnetic properties

The reaction of sodium dimethyl(phenylsulfonyl)amidophosphate Na L (H L = C 6H 5SO 2NHP(O)(OCH 3) 2) with Cu(NO 3) 2 · 6H 2O and o-bpe (1,2-bis(pyridine-2-yl)ethane) in appropriate ratios, afford the formation of 1D coordination polymer [Cu( L) 2 · o-bpe] n in good yield. The crystal structures of H L ( 1) and [Cu( L) 2 · o-bpe] n ( 2) are reported. In the crystal package the molecules of 1 are linked by intermolecular hydrogen bonds formed by the phosphoryl oxygen atoms which serve as acceptors and nitrogen atoms of amide groups as donors. The crystal structure of 2 indicates the presence of unsaturated Cu( L) 2 unit bridged by o- bpe ligand in the one-dimensional polymeric chain. The Cu(II) atoms have distorted 4 + 2 octahedral CuO 4N 2 environment formed by the oxygen atoms belonging to the sulfonyl and phosphoryl groups of two deprotonated chelate ligands and nitrogen atoms of the bridging o-bpe ligands. The magnetic study of 2 has revealed the presence of a weak intrachain antiferromagnetic exchange interaction between copper ions.

Controlling self-assembly of zinc(II)-benzoate coordination complexes with 1,4-bis(4-pyridyl)ethane by varying solvent and ligand-to-metal ratio: Their catalytic activities

Four new coordination polymers formed by zinc-benzoate with the 1,2-bis(4-pyridyl)ethane (bpe) bridging ligand have been prepared and characterized. Zinc-benzoates can be rationally tuned to form four different structures with a bridging bpe ligand by controlling ligand-to-zinc-benzoate molar ratios and by using different solvent systems, and reveal three coordination polymers having similar one-dimensional characteristics but having different mono-, di-, trinuclear nodes ( 1– 3), and a dinuclear ring type molecule ( 4). This work reveals that the ligand-to-metal ratio and solvent play very important roles in the formation of different coordination structures. We have also shown that the compounds 1– 4 catalyzed efficiently the transesterification of a variety of esters. The complex 3 showed the most efficient reactivity and is the best among the catalytic efficiencies reported previously with zinc-containing coordination and polymeric compounds. The substrates with the electron-withdrawing substituents have undergone faster transesterification than those with the electron-donating ones. In addition, the scope of the application of 1– 4 as transesterification catalysts has been expanded to now include ethanol and propanol, suggesting that this catalytic system can be potentially useful for preparing various esters by transesterification. Moreover, the transesterification reaction mechanism was discussed by 1H NMR study.

Self‐Assembly of Cluster‐Based Nanoscopic Supramolecules into One‐Dimensional Coordination Polymers

Octahedral metal clusters , (Mn(Salen)) + (or (Mn(7‐MeSalen)) +) (Salen = N, N′‐ethylene‐bis‐(salicylidene)iminate) and ditopic organic linkers (4, 4′‐bpe (trans‐1, 2‐bis(4‐pyridyl)‐ethylene) or 4, 4′‐dpyo (4, 4′‐dipyridyl N, N′‐dioxide)) self‐assemble to form three cluster‐based 1D coordination polymers: {(4, 4′‐dpyo) [(Mn(Salen))2(Nb6Cl12(CN)6)] } · 2MeOH (1), 1.5MeCN · 8H2O (2), and [(Mn(Salen))2(Nb6Cl12(CN)6)]} · 16H2O (3). Single crystal X‐ray diffraction analyses show that the frameworks of the three coordination polymers are built of heterotrimeric and/or heteropentameric supramolecular species linked by ditopic organic ligands. The framework of 1 consists of anionic chains built of heterotrimeric dianions (T) linked by 4, 4′‐dpyo. The chains run along two directions ([0 2 −2] and [0 3 3]) leading to the formation of channels along the crystallographic (a) direction where the cations [Mn(Salen)(S)2]+ and solvent molecules are located. Also, 2 was reported earlier, it possesses a neutral 1D chain built of neutral heterpentameric supramolecules: [(Mn(7‐MeSalen))2(Mn(7‐MeSalen)(S))2(Nb6Cl12(CN)6)] (P) linked by 4, 4′‐bpe ligands. Hydrogen bonds between non‐bridging cyanide ligands and coordinated solvent molecules connect the chains into 2D hydrogen‐bonded frameworks. Finally, 3 features an anionic chain, built of alternating heterotrimers and heteropentamers [(Mn(Salen)(S))2(Mn(Salen))2(Nb6Cl12(CN)6)] linked by the organic spacer 4, 4′‐bpe. The anionic charge is compensated by the in situe‐assembled dimers. Magnetic measurements reveal that the Mn(III) ions are well isolated and only weak magnetic interactions are observed. The thermal stability of the three compounds was investigated.

Synthesis and Structure of Novel RuII - N≡C - Me Complexes and their Activity Towards Nitrile Hydrolysis: An Examination of Ligand Effects

The synthesis and isolation of new RuII–acetonitrile complexes, of general formula trans,fac-[Ru(bpea)(B)(MeCN)](BF4)2 (bpea = N,N-bis(2-pyridylmethyl)ethylamine; B = bpy, 2,2′-bipyridine, 4; B = dppe, 1,2-bis(diphenylphosphino)ethane, 5), together with a synthetic intermediate trans,fac-[Ru(NO3)(bpea)(dppe)](BF4), 6, are described. Ru(bpea)Cl3, 1, is used as the starting material for the synthesis of all complexes 2–6 presented in this paper, which are characterized by analytical, spectroscopic (IR, UV/Vis, 1D and 2D NMR), and electrochemical techniques (cyclic voltammetry). Furthermore, complexes 4, 5, and 6 have also been characterized in the solid state by single crystal X-ray diffraction analysis. Their structures show a distorted octahedral geometry where the bpea ligand binds in a facial mode, the bidentate ligands bpy and dppe bind in a chelate manner, and finally the MeCN or the NO3 – ligand occupy the sixth position of the octahedral Ru metal centre. The kinetics of the basic hydrolysis of the coordinated MeCN ligand for complexes 4 and 5 and for the related complex [Ru(phen)(MeCN)([9]aneS3)](BF4)2, 7, which contains the 1,4,7-trithiacyclonane ligand ([9]aneS3) and 1,10-phenanthroline (phen) is also described. Second-order rate constants for acetonitrile hydrolysis measured at 25°C of k = 1.01 × 10–3 M–1 s–1 for 4, 1.08 × 10–4 M–1 s–1 for 5, and 6.8 × 10–3 M–1 s–1 for 7, have been obtained through UV-vis spectroscopy. Activation parameters have also been determined over the temperature range 25.0–45.0°C and agree with a mechanism that involves an associative rate-determining step. Finally the electronic and steric influence of the auxiliary ligands on this reaction for the above and related complexes is discussed.