Four di-Cu(II)-substituted sandwich-type germanomolybdates obtained under different reaction conditions: from zero-dimensional to two-dimensional structure

Four di-Cu(II)-substituted sandwich-type germanomolybdates, (H(2)en)(2)H(7){[Na(0.5)(H(2)O)(3.5)](2)[Cu(2)(β-Y-GeMo(9)O(33))(2)]}·6H(2)O (1), (H(2)en)(2)H{[Na(2.5)(H(2)O)(12)](2)[Cu(en)(2)][Cu(2)(β-Y-GeMo(9)O(33))(2)]}·8H(2)O (2), [Na(4)(H(2)O)(12)](2)H(4)[Cu(2)(β-Y-GeMo(9)O(33))(2)]}·11H(2)O (3) and [Cu(en)(2)](2)[Cu(en)(2)(H(2)O)](2){[Cu(en)(2)](2)[Cu(2)(β-Y-GeMo(9)O(33))(2)]}·8H(2)O (4) (en = ethylenediamine), have been prepared. It is interesting that 1-3 were obtained in the same aqueous solution reaction system but exhibited different structures: 1 displays a 0D structure, 2 shows an organic-inorganic 1D chain structure, while 3 displays a 2D network. 4 was synthesized under hydrothermal condition by the same reagents, which represents the first transition metal-sandwiched organic-inorganic 2D heteropolymolybdate.     

Syntheses, structures, and magnetic properties of unusual nonlinear polynuclear copper(II) complexes containing derivatives of 1,2,4-triazole and pivalate ligands

Novel polynuclear Cu(II) complexes containing derivatives of 1,2,4-trizaole and pivalate ligands, [Cu(3)(mu(3)-OH)(mu-adetrz)(2)(piv)(5)(H(2)O)].6.5H(2)O (1) (adetrz = 4-amino-3,5-diethyl-1,2,4-triazole, piv = pivalate), [Cu(4)(mu(3)-OH)(2)(mu-atrz)(2)(mu-piv)(4)(piv)(2)].2MeOH.H(2)O (2) (atrz = 4-amino-1,2,4-triazole), [Cu(4)(mu(3)-OH)(2)(mu-tbtrz)(2)(mu-piv)(2)(piv)(4)].4H(2)O (3) (tbtrz = 4-tert-butyl-1,2,4-trizaole), and [Cu(4)(mu(3)-O)(2)(mu-admtrz)(4)(admtrz)(2)(mu-piv)(2)(piv)(2)].2[Cu(2)(mu-H(2)O)(mu-admtrz)(piv)(4)].13H(2)O [4 = 4a.2(4b).13H(2)O; admtrz = 4-amino-3,5-dimethyl-1,2,4-triazole], have been prepared and structurally characterized. 1 is an asymmetrical triangular complex containing a [Cu(3)(mu(3)-OH)] core with two Cu---Cu edges spanned by bridging adetrz ligands. 2, 3, and 4a are novel tetranuclear compounds containing a [Cu(4)(mu(3)-O)(2)] or [Cu(4)(mu(3)-OH)(2)] core with Cu---Cu edges spanned by bridging 1,2,4-triazole or pivalate ligands. 4b is a dinuclear compound with one admtrz and one water bridge, and it is the first dinuclear Cu(II) triazole complex with one bridging water molecule. 1 is one of few reported triangular Cu(II) complexes with derivatives of 1,2,4-triazole, while 2, 3, and 4a are the first group of the nonlinear tetranuclear Cu(II) compounds with derivatives of 1,2,4-triazole. Variable-temperature magnetic susceptibility studies on the powder samples of 1-3 reveal the overall antiferromagnetic coupling between Cu(II) ions with J values of -55.6 to -12.8 cm(-1) (1), -216.4 to 0 cm(-1) (2), and -259.8 to 4.8 cm(-1) (3).     

Synthesis and some first-row transition-metal complexes of the 1,2,4-triazole-based Bis(terdentate) ligands TsPMAT and PMAT

The employment of a strategy based on nucleophilic substitution, rather than Schiff base condensation, for the preparation of 1,2,4-triazole-based ligands has been investigated and has led to the synthesis of two new ligands, 4-amino-3,5-bis{[N-(2-pyridylmethyl)-N-(4-toluenesulfonyl)amino]methyl}-4H-1,2,4-triazole (TsPMAT, 14) and 4-amino-3,5-bis{[(2-pyridylmethyl)amino]methyl}-4H-1,2,4-triazole (PMAT, 15). These are the first examples of bis(terdentate) ligands incorporating the 1,2,4-triazole unit. TsPMAT (14) forms a dinuclear 2:2 complex with Co(BF4)2.6 H2O even when reacted in a metal-to-ligand molar ratio of 2:1. Similarly, the reaction of PMAT (15) with Mn(ClO4)2.6H2O or M(BF4)2.6 H2O (M=Fe, Co, Ni, Zn) in a ligand-to-metal molar ratio of 1:1 has afforded a series of complexes with the general formula [M(II) (2)(PMAT)2]X4. The metal centres in these complexes of TsPMAT (14) and PMAT (15) are encapsulated by two ligand molecules and doubly bridged by the N2 units of the 1,2,4-triazole moieties, which gives rise to N6 coordination spheres that are strongly distorted from octahedral, as evidenced by the X-ray crystal structure analyses of [Co(II) (2)(TsPMAT)(2)](BF(4))(4)6 MeCN (246 MeCN) and [Fe(II) 2(PMAT)2](BF4)4DMF (27DMF). Studies of the magnetic properties of [Co(II) 2(TsPMAT)2](BF4)4.4 H2O (244 H2O), [Mn(II) 2(PMAT)2](ClO4)4 (26), and [Co(II) 2(PMAT)2](BF4)4 (28) have revealed weak antiferromagnetic coupling (J=-3.3, -0.16, and -2.4 cm(-1), respectively) between the two metal centres in these complexes.     

Di- and tetra-nuclear copper(II), nickel(II), and cobalt(II) complexes of four bis-tetradentate triazole-based ligands: synthesis, structure, and magnetic properties

Four bis-tetradentate N(4)-substituted-3,5-{bis[bis-N-(2-pyridinemethyl)]aminomethyl}-4H-1,2,4-triazole ligands, L(Tz1)-L(Tz4), differing only in the triazole N(4) substituent R (where R is amino, pyrrolyl, phenyl, or 4-tertbutylphenyl, respectively) have been synthesized, characterized, and reacted with M(II)(BF(4))(2)·6H(2)O (M(II) = Cu, Ni or Co) and Co(SCN)(2). Experiments using all 16 possible combinations of metal salt and L(TzR) were carried out: 14 pure complexes were obtained, 11 of which are dinuclear, while the other three are tetranuclear. The dinuclear complexes include two copper(II) complexes, [Cu(II)(2)(L(Tz2))(H(2)O)(4)](BF(4))(4) (2), [Cu(II)(2)(L(Tz4))(BF(4))(2)](BF(4))(2) (4); two nickel(II) complexes, [Ni(II)(2)(L(Tz1))(H(2)O)(3)(CH(3)CN)](BF(4))(4)·0.5(CH(3)CN) (5) and [Ni(II)(2)(L(Tz4))(H(2)O)(4)](BF(4))(4)·H(2)O (8); and seven cobalt(II) complexes, [Co(II)(2)(L(Tz1))(μ-BF(4))](BF(4))(3)·H(2)O (9), [Co(II)(2)(L(Tz2))(μ-BF(4))](BF(4))(3)·2H(2)O (10), [Co(II)(2)(L(Tz3))(H(2)O)(2)](BF(4))(4) (11), [Co(II)(2)(L(Tz4))(μ-BF(4))](BF(4))(3)·3H(2)O (12), [Co(II)(2)(L(Tz1))(SCN)(4)]·3H(2)O (13), [Co(II)(2)(L(Tz2))(SCN)(4)]·2H(2)O (14), and [Co(II)(2)(L(Tz3))(SCN)(4)]·H(2)O (15). The tetranuclear complexes are [Cu(II)(4)(L(Tz1))(2)(H(2)O)(2)(BF(4))(2)](BF(4))(6) (1), [Cu(II)(4)(L(Tz3))(2)(H(2)O)(2)(μ-F)(2)](BF(4))(6)·0.5H(2)O (3), and [Ni(II)(4)(L(Tz3))(2)(H(2)O)(4)(μ-F(2))](BF(4))(6)·6.5H(2)O (7). Single crystal X-ray structure determinations revealed different solvent content from that found by microanalysis of the bulk sample after drying under a vacuum and confirmed that 5', 8', 9', 11', 12', and 15' are dinuclear while 1' and 7' are tetranuclear. As expected, magnetic measurements showed that weak antiferromagnetic intracomplex interactions are present in 1, 2, 4, 7, and 8, stabilizing a singlet spin ground state. All seven of the dinuclear cobalt(II) complexes, 9-15, have similar magnetic behavior and remain in the [HS-HS] state between 300 and 1.8 K.     

Copper perchlorate and tetrafluoridoborate compounds with the ligand 1,4,5-triazanaphthalene. Gradual transformation of mononuclear Cu(II) compounds via polynuclear mixed-valence Cu(II)/Cu(I) species to dinuclear Cu(I); syntheses, characterizations and X-ray structures

When the ligand 1,4,5-triazanaphthalene (abbreviated as tan) is reacted with Cu(II) BF(4)(-) and ClO(4)(-) salts, a variety of mononuclear compounds has been found, all with the [Cu(tan)(4)] unit and varying amounts of weakly coordinating axial ligands and lattice solvents. Reproducible compounds formed include two purple compounds, analyzing as [Cu(tan)(4)](ClO(4))(2)(CH(3)OH)(2)(H(2)O) (1) and [Cu(tan)(4)](BF(4))(2)(CH(3)OH)(1.5)(H(2)O) (3), and two blue compounds, analyzing as [Cu(tan)(4)](ClO(4))(2)(H(2)O)(2) (2) and [Cu(tan)(4)](2)(BF(4))(2)(H(2)O)(2) (4). Upon standing at room temperature, red-coloured, mixed-valence dinuclear-based 3D coordination polymers are formed by conversion of the purple/blue products, of which [Cu(2)(tan)(4)](n)(BF(4))(3n) (5) and the isomorphic methanol-water adduct [Cu(tan)(4)](n)(BF(4))(3n)(CH(3)OH)(n)(H(2)O)(5n) (5A) are presented in this paper. In addition a fully reduced dinuclear Cu(I) compound of formula [Cu(2)(tan)(3)(ClO(4))(2)] (7) has been observed, and structurally characterized, as a rare three-blade propeller structure, with a Cu-Cu distance of 2.504 ?.     

1,2,4-Triazole functionalized adamantanes: a new library of polydentate tectons for designing structures of coordination polymers

A series of functionalized adamantanes: 1,3-bis(1,2,4-triazol-4-yl)(tr(2)ad); 1,3,5-tris(1,2,4-triazol-4-yl)-(tr(3)ad); 1,3,5,7-tetrakis(1,2,4-triazol-4-yl)adamantanes (tr(4)ad) and 3,5,7-tris(1,2,4-triazol-4-yl)-1-azaadamantane (tr(3)ada) were developed as a new family of geometrically rigid polydentate tectons for supramolecular synthesis of framework solids. The coordination compounds were prepared under hydrothermal conditions; their structures reveal a special potential of the triazolyl adamantanes for the generation of highly-connected and open frameworks as well as structures based upon polynuclear metal clusters assembled with short-distance N(1),N(2)-triazole bridges. Complexes [Cd{L}(2)]A·nH(2)O [L = tr(3)ad, A = 2NO(3)(-) (4), CdCl(4)(2-) (5); L = tr(3)ada, A = CdI(4)(2-) (7)] are isomorphous and adopt a layered 3,6-connected structure of CdI(2) type. [{Cu(3)(OH)}(2)(SO(4))(5)(H(2)O)(2){tr(3)ad}(3)]·26H(2)O (6) is a layered polymer based upon Cu(3)(μ(3)-OH) nodes and trigonal tr(3)ad links. In [Cu(3)(OH)(2){tr(3)ada}(2)(H(2)O)(4)](ClO(4))(4) (8), [Cu(2){tr(3)ada}(2)(H(2)O)(3)](SO(4))(2)·7H(2)O (9) and [Cd(2){tr(3)ada}(3)]Cl(4)·28H(2)O (10) (UCl(3)-type net) the organic tripodal ligands bridge polynuclear metal clusters. Complexes [Ag{tr(4)ad}]NO(3)·3.5H(2)O (11) and [Cu{tr(4)ad}(H(2)O)](ClO(4))(2)·3H(2)O (12) have 3D SrAl(2)-type frameworks with the metal ions and adamantane tectons as topologically equivalent tetrahedral nodes, while in [Cd(3)Cl(6){tr(4)ad}(2)]·9H(2)O (13) the ligands bridge trinuclear six-connected Cd(3)Cl(6)(μ-tr)(4)(tr)(2) clusters. In the compounds [Cd(2){tr(2)ad}(4)(H(2)O)(4)](CdBr(4))(2)·2H(2)O (2) and [Cd{tr(2)ad}(4){CdI(3)}(2)]·4H(2)O (3) the bitopic ligands provide simple links between the metal ions, while in [Ag(2){tr(2)ad}(2)](NO(3))(2)·2H(2)O (1) the ligand is tetradentate and generates a 3D framework.     

Guanine-containing copper(II) complexes: synthesis, X-ray structures and magnetic properties

Three new compounds of formula {[Cu(gua)(H(2)O)(3)](BF(4))(SiF(6))(1/2)}(n) (1), {[Cu(gua)(H(2)O)(3)](CF(3)SO(3))(2).H(2)O}(n) (2) and [Cu(gua)(2)(H(2)O)(HCOO)]ClO(4).H(2)O.1/2HCOOH] (3) [gua = 2-amino-1H-purin-6(9H)-one] showing the unprecedented coordination of neutral guanine, have been synthesised and structurally characterized. The structures of the compounds 1 and 2 contain uniform copper(II) chains of formula [Cu(gua)(H(2)O)(3)](n)(2n+), where the copper atoms are bridged by guanine ligands coordinated via N(3) and N(7). The electroneutrality is achieved by uncoordinated tetrafluoroborate and hexafluorosilicate (1) and triflate (2). Each copper atom in 1 and 2 is five-coordinated in a distorted square pyramidal environment: two water molecules in trans positions and the N(3) and N(7a) nitrogen atoms of two guanine ligands build the basal plane whereas a water molecule fills the axial position. The values of the copper-copper separation across the bridging guanine ligand are 7.183(1) (1) and 7.123(1) A (2). is an ionic salt whose structure is made up of mononuclear [Cu(gua)(2)(H(2)O)(HCOO)](+) cations and perchlorate anions plus water and formic acid as crystallization molecules. The two guanine ligands in the cation are coordinated to the copper centre through the N(9) atom. The copper atom in 3 is four-coordinated with two monodentate guanine molecules in the trans position, a water molecule and a monodenate formate ligand building a quasi square planar surrounding. Magnetic susceptibility measurements for 1 and 2 in the temperature range 1.9-300 K show the occurrence of significant intrachain antiferromagnetic interactions between the copper(ii) ions across the guanine bridge [J = -9.6(1) (1) and -10.3(1) cm(-1) (2) with H = -J summation operator(i)S(i).S(i+1)].     

Polymeric networks of copper(II) using succinate and aromatic N-N donor ligands: synthesis, crystal structure, magnetic behaviour and the effect of weak interactions on their crystal packing

Four succinato-bridged complexes of copper(II) have been synthesized. Complex 1, [Cu(2)(mu-OH(2))(2)L(bpy)(2)(NO(3))(2)](n) and 2, [Cu(2)(mu-OH(2))(2)L(phen)(2)(NO(3))(2)](n)(bpy = 2,2[prime or minute]-bipyridine; phen = 1,10-phenanthroline and LH(2)= succinic acid) exhibit 1D coordination polymer structures where both the nitrate ions are directly linked to the copper(ii) producing synthons in a 2D sheet. A novel 2D grid-like network, ([Cu(4)L(2)(bpy)(4)(H(2)O)(2)](ClO(4))(4)(H(2)O))n3, is obtained upon changing the nitrate by perchlorate anion in complex 1, where the channels are occupied by the anions. On changing the nitrate by tetrafluoroborate anion in complex 2, a novel octanuclear complex, [Cu(8)L(4)(phen)(12)](BF(4))(8).8H(2)O 4, is isolated. The coligand bpy and phen in these complexes show face-to-face (in 1,2,3,4) or edge-to-face (in 4 )pi-pi interactions forming the multidimensional supramolecular architectures. Interestingly, the appearance of edge-to-face pi-pi interactions in complex facilitates the formation of discrete octanuclear entities. Variable-temperature (300-2 K) magnetic measurements of complexes have been done. Complexes 1 and 2 show very weak antiferromagnetic (OOC-CH(2)-CH(2)-COO) and ferromagnetic coupling (mu-H(2)O). Complex 3 also shows antiferromagnetic (syn-syn mu-OCO), and ferromagnetic coupling (mu-O of the -COO group). Complex 4 with two types (syn-syn and syn-anti) of binding modes of the carboxylate group shows strong antiferromagnetic interaction.     

Two novel 3-D coordination polymers with 5-methoxyisophthalate and flexible N-donor co-ligands showing pentanuclear or alternate mono/binuclear Cu(II) units

Two novel 3-D coordination polymers with different Cu(II) subunits as nodes and mixed bridging ligands as linkers, namely [Cu(5)(μ(3)-OH)(2)(1,3-bip)(2)(CH(3)O-ip)(4)](n) (1) and {[Cu(4)(1,3-btp)(2)(CH(3)O-p)(4)(H(2)O)(2)]·2H(2)O}(n) (2) (CH(3)O-H(2)ip = 5-methoxyisophthalate, 1,3-bip = 1,3-bis(imidazol)propane, 1,3-btp = 1,3-bis(1,2,4-triazol-1-yl)propane), were prepared under hydrothermal conditions. Complex 1 exhibits a CsCl-type network with [Cu(5)(μ(3)-OH)(2)](8+) clusters acting as nodes, which represents the first 3-D network based on pentanuclear Cu(II) clusters. Complex 2 features a 3-D pillared-layer network with (4,6)-connected (4(4).6(2))(4(4).6(8).8(3))-fsc topology, which is a rare example of homometallic coordination polymers constructed by alternate binuclear metal clusters and single metal centres. Variable-temperature magnetic susceptibility measurements show dominant ferromagnetic interactions in the pentanuclear clusters of 1 and strong antiferromagnetic interactions in the dinuclear paddle-wheel units of 2.     

Self-assembly and anion-exchange properties of a discrete cage and 3D coordination networks based on cage structures

By using tridentate ligand 4-(3-pyridinyl)-1,2,4-triazole (pytrz), cage-like complexes of {[Cu(mu2-pytrz)2](ClO4)(SO4)0.5C2H5OH.0.25 H2O}6 (1), {[Cu3(mu3-pytrz)4(mu2-Cl)2(H2O)2](ClO4)2Cl(2).2 H2O}n (2), and {[Cu3(mu3-pytrz)3(mu3-O)(H2O)3](ClO4)2.5(BF4)(1.5)5.25 H2O}n (3) have been synthesized with different copper(II) salts. Complex 1 represents the second example of a M6L12 metal-organic octahedron with an overall Th symmetry. Complex 2 is constructed from a 3(8) cage-building unit (CBU) and each CBU connects six neighboring cages to give the first 3D metal-organic framework (MOF) based on octahedral M6L12. Complex 3 is built from Cu24(pytrz)12 CBUs with the trinuclear copper clusters serving as second building units (SBUs) and decorating each corner of the M24L12 polyhedron. The Cu24(pytrz)12 building unit is linked by extra ligands to give an extended 3D framework that has the formula Cu24(pytrz)24 and possesses a CaB6 topology. The mixed anions ClO4- and BF4- in 3 are both included in the inner cavity of the cage and can be completely exchanged by ClO4- through the open windows of the cage, as evidenced by the crystal structure of the 3D MOF {[Cu3(mu3-pytrz)3(mu3-O)(H2O)3](ClO4)(4)4.5 H2O}n (4). Complex 4 can also be synthesized when employing 1 as a precursor in an extensive study of the anion-exchange reaction. This represents the first successful conversion of a discrete cage into a 3D coordination network based on a cage structure. Complex 2 remains invariable during anion-exchange reactions because uncoordinated Cl- ions are located in the comparatively small inner cavity.     

Antisymmetric exchange in triangular tricopper(II) complexes: correlation among structural, magnetic, and electron paramagnetic resonance parameters

Two new trinuclear copper(II) complexes, [Cu(3)(μ(3)-OH)(daat)(Hdat)(2)(ClO(4))(2)(H(2)O)(3)](ClO(4))(2)·2H(2)O (1) and [Cu(3)(μ(3)-OH)(aaat)(3)(H(2)O)(3)](ClO(4))(2)·3H(2)O (2) (daat = 3,5-diacetylamino-1,2,4-triazolate, Hdat = 3,5-diamino-1,2,4-triazole, and aaat = 3-acetylamino-5-amino-1,2,4-triazolate), have been prepared from 1,2,4-triazole derivatives and structurally characterized by X-ray crystallography. The structures of 1 and 2 consist of cationic trinuclear copper(II) complexes with a Cu(3)OH core held by three N,N-triazole bridges between each pair of copper(II) atoms. The copper atoms are five-coordinate with distorted square-pyramidal geometries. The magnetic properties of 1 and 2 and those of five other related 1,2,4-triazolato tricopper(II) complexes with the same triangular structure (3-7) (whose crystal structures were already reported) have been investigated in the temperature range of 1.9-300 K. The formulas of 3-7 are [Cu(3)(μ(3)-OH)(aaat)(3)(H(2)O)(3)](NO(3))(2)·H(2)O (3), {[Cu(3)(μ(3)-OH)(aat)(3)(μ(3)-SO(4))]·6H(2)O}(n) (4), and [Cu(3)(μ(3)-OH)(aat)(3)A(H(2)O)(2)]A·xH(2)O [A = NO(3)(-) (5), CF(3)SO(3)(-) (6), or ClO(4)(-) (7); x = 0 or 2] (aat =3-acetylamino-1,2,4-triazolate). The magnetic and electron paramagnetic resonance (EPR) data have been analyzed by using the following isotropic and antisymmetric exchange Hamiltonian: H = -J[S(1)S(2) + S(2)S(3)] - j[S(1)S(3)] + G[S(1) × S(2) + S(2) × S(3) + S(1) × S(3)]. 1-7 exhibit strong antiferromagnetic coupling (values for both -J and -j in the range of 210-142 cm(-1)) and antisymmetric exchange (G varying from to 27 to 36 cm(-1)). At low temperatures, their EPR spectra display high-field (g < 2.0) signals indicating that the triangles present symmetry lower than equilateral and that the antisymmetric exchange is operative. A magneto-structural study showing a lineal correlation between the Cu-O-Cu angle of the Cu(3)OH core and the isotropic exchange parameters (J and j) has been conducted. Moreover, a model based on Moriya's theory that allows the prediction of the occurrence of antisymmetric exchange in the tricopper(II) triangles, via analysis of the overlap between the ground and excited states of the local Cu(II) ions, has been proposed. In addition, analytical expressions for evaluating both the isotropic and antisymmetric exchange parameters from the experimental magnetic susceptibility data of triangular complexes with local spins (S) of (1)/(2), (3)/(2), or (5)/(2) have been purposely derived. Finally, the magnetic and EPR results of this work are discussed and compared with those of other tricopper(II) triangles reported in the literature.     

Pyrophosphate-mediated magnetic interactions in Cu(II) coordination complexes

The reaction in water of Cu(NO(3))(2)·2.5H(2)O with 2,2'-bipyridine (bipy), 1,10-phenanthroline (phen), or 1,10-phenanthroline-5-amine (phenam), and sodium pyrophosphate (Na(4)P(2)O(7)), at various pHs, afforded three new copper(II)-pyrophosphate complexes, namely, {[Cu(bipy)(cis-H(2)P(2)O(7))](2)}·3H(2)O (1a), {[Cu(phen)(H(2)O)](4)(HP(2)O(7))(2)}(ClO(4))(2)·4H(2)O (2), and {[Cu(2)(phenam)(2)(P(2)O(7))](2)·25H(2)O}(n) (3). A solvent free crystalline phase of 1a was also isolated with formula {[Cu(bipy)(trans-H(2)P(2)O(7))](2)} (1b), which can be regarded as a pseudo-polymorph of 1a. Single crystal X-ray analyses revealed these compounds to have uncommon molecular architectures, with 3 being an unprecedented pyrophosphate-containing two-dimensional (2D) polymer. Compounds 1a/1b and 2 are discrete di- and tetra-nuclear complexes, respectively. The cationic {[Cu(phen)(H(2)O)](4)(HP(2)O(7))(2)}(2+) unit in 2 presents a unique quasi-flat structure, held together by solely in-plane pyrophosphate bridging modes (short O(eq)-P-O(eq) and long O(eq)-P-O-P-O(eq) pathways), a coordination arrangement also not previously reported. A different tetranuclear copper(II)-pyrophosphate arrangement is found in 3, with two classically bridged dimers (O(eq)-P-O(eq) pathway) joined together by auxiliary equatorial-axial μ-O pyrophosphate bridges. Here, the bidimensionality is reached through bridging phenam ligands, which provide further inter-"tetramer" metal-metal connections [(N,N')(eq)-(N')(ax) pathway], leading to the formation of an expanded covalent network based on the [Cu(2)(phenam)(2)(P(2)O(7))](2) moiety. Variable-temperature magnetic susceptibility measurements on polycrystalline samples of 2 and 3 revealed net antiferromagnetic coupling between metal centers with J(2a) = -7.9(2) cm(-1), J(2b) = -46.9(3) cm(-1), J(2c) = 0 cm(-1) in 2 (H = -J(2a)[S(Cu(1))·S(Cu(2)) + S(Cu(1a))·S(Cu(2a))] - J(2b)[S(Cu(1))·S(Cu(2a)) + S(Cu(1a))·S(Cu(2))] - J(2c)S(Cu(2))·S(Cu(2a))), and J(3a) = -87.9(2) cm(-1), J(3b) = -5(1) cm(-1) and J(3c) = +5(3) cm(-1) in 3 (H = -J(3a)[S(Cu(1))·S(Cu(2)) + S(Cu(1a))·S(Cu(2a))] - J(3b)[S(Cu(1))·S(Cu(2a)) + S(Cu(1a))·S(Cu(2))] - J(3c)S(Cu(2))·S(Cu(2a))). For 1a, a net ferromagnetic coupling is observed with J(1a) = +0.86(1) cm(-1) (H = -J S(A)·S(B) + S(A)·D· S(B) + βH (g(A)S(A) + g(B)S(B)). This is the first example of ferromagnetic coupling in pyrophosphate-complexes reported to date. A structure-function correlation study focusing on magnetic exchange across the observed diverse pyrophosphate-bridges is described with density functional theory (DFT) calculations included to support the stated observations.     

Platinum(II) hydrazido complexes

Reaction of 1,2-dimethylhydrazine with the platinum hydroxo complex [(dppp)Pt(mu-OH)](2)(BF(4))(2) gives the bridging 1,2-dimethylhydrazido(-2) product [(dppp)(2)Pt(2)(mu-eta(2):eta(2)-MeNNMe)](BF(4))(2) 1. Crystals of 1.CH(2)Cl(2) from CH(2)Cl(2)/Et(2)O are monoclinic (C/2) with a = 19.690(1), b = 18.886(1), c = 17.170 (1) A, and beta = 92.111(1) degrees. Treatment of [(dppp)Pt(mu-OH)](2)(OTf)(2) with 1,1-dimethylhydrazine gives [(dppp)(2)Pt(2)(mu-OH)(mu-NHNMe(2))](OTf)(2) 2. Crystals of 2.CH(2)Cl(2) from CH(2)Cl(2)/Et(2)O are triclinic (P-1) with a = 12.910 (3), b = 13.927(3), c = 17.5872 (3) A, alpha = 87.121(3), beta = 89.997(4), and gamma = 84.728(3) degrees. Reaction of [(dppp)Pt(mu-OH)](2)(OTf)(2) with 1 equiv of phenylhydrazine in CH(2)Cl(2) gives [(dppp)(2)Pt(2)(mu-OH)(mu-NHNHPh)](OTf)(2) 3. Two equivalents of phenylhydrazine with [(dppp)Pt(mu-OH)](2)(X)(2) gives [(dppp)Pt(mu-NHNHPh)](2)(X)(2) 4 (X = BF(4), OTf). Crystals of 3.ClCH(2)CH(2)Cl from ClCH(2)CH(2)Cl/(i)()Pr(2)O are monoclinic (P2(1)/n) with a = 20.990(2), b = 13.098(1), c = 25.773 (2) A, and beta = 112.944(2) degrees. Crystals of 4(X = BF(4)).ClCH(2)CH(2)Cl(.)()2((t)()BuOMe) from ClCH(2)CH(2)Cl/(t)()BuOMe are monoclinic (C2/m) with a = 30.508(1), b = 15.203(1), c = 19.049 (1) A, and beta = 118.505(2) degrees.     

Dinuclear silver(I) complexes for the design of metal-ligand networks based on triazolopyrimidines

Silver(I) coordination complexes with the versatile and biomimetic ligands 1,2,4-triazolo[1,5-a]pyrimidine (tp), 5,7-dimethyl-1,2,4-triazolo[1,5-a]pyrimidine (dmtp) and 7-amine-1,2,4-triazolo[1,5-a]pyrimidine (7atp) all feature dinuclear [Ag(2)(μ-tp)(2)](2+) building units (where tp is a triazolopyrimidine derivative), which are the preferred motif, independently of the counter-anion used. According to AIM (atoms in molecules) and ELF (electron localization function) analyses, this fact is due to the great stability of these dinuclear species. The complexes structures range from the dinuclear entities [Ag(2)(μ-tp)(2)(CH(3)CN)(4)](BF(4))(2) (1), [Ag(2)(μ-tp)(2)(CH(3)CN)(4)](ClO(4))(2) (2), [Ag(2)(μ-7atp)(2)](ClO(4))(2) (3) and [Ag(2)(μ-dmtp)(2)(CH(3)CN)](PF(6))(ClO(4)) (4) over the 1D polymer chain [Ag(2)(μ-CF(3)SO(3))(2)(μ-dmtp)(2)](n) (5) to the 3D net {[Ag(2)(μ(3)-tp)(2)](PF(6))(2)·～6H(2)O}(n) (6) with NbO topology.     

A reversible SCSC transformation from a blue metamagnetic framework to a pink antiferromagnetic ordering layer exhibiting concomitant solvatochromic and solvatomagnetic effects

A [Co(6)(μ(3)-OH)(4)(datrz)(2)](6+) ribbon-based blue framework with a metamagnetic transition from an antiferromagnetic ordering to a weak spontaneous magnetization state, {[Co(3)(CH(3)OH)(μ(3)-OH)(2)(datrz)(sip)]·2.25H(2)O}(n) (1, Hdatrz = 3,5-diamino-1,2,4-triazole, sip(3-) = 3,5-dicarboxybenzenesulfonate), was solvothermally synthesized. 1 exhibits a reversible single-crystal-to-single-crystal transformation by solvent exchange to generate a pink antiferromagnetic ordering coordination layer with a similar [Co(6)(μ(3)-OH)(4)(datrz)(2)](6+) ribbon to 1, {[Co(3)(H(2)O)(3)(μ(3)-OH)(2)(datrz)(sip)]·2.125H(2)O}(n) (2). Such concomitant solvatochromic and solvatomagnetic effects are scarcely observed and are significantly due to the coexistence of differently distorted metal coordination spheres and the cleavage/generation of the weak coordination bond.     

Synthesis of a series of 4-pyridyl-1,2,4-triazole-containing cadmium(II) luminescent complexes

Using two 4-substitued triazole ligands, 4-(pyrid-2-yl)-1,2,4-triazole (L(1)) and 4-(pyrid-3-yl)-1,2,4-triazole (L(2)), a series of novel triazole-cadmium(II) complexes varying from zero- to three-dimensional have been prepared and their crystal structures determined via single-crystal X-ray diffraction. [Cd(2)(micro(2)-L(1))(3)(L(1))(2)(NO(3))(mu(2)-NO(3))(H(2)O)(2)](NO(3))(2).1.75H(2)O (1) is a binuclear complex containing bidendate, monodedate and free nitrate anions. When the bridging anions SCN(-) and dca (dca = N(CN)(2)(-)) were added to the reaction system of 1, one-dimensional (1D) [Cd(L(1))(2)(NCS)(2)](n) (2) and two-dimensional (2D) [Cd(L(1))(2)(dca)(2)](n) (3) were isolated, respectively. When L(2) instead of L(1) was used, [Cd(L(2))(2)(NCS)(2)(H(2)O)(2)] (4) and 1D [Cd(L(2))(2)(dca)(2)](n) (5) were obtained. When the ratio of Cd to L(2) was changed from 1:2 to 1:1 in the reaction system of 5, three-dimensional (3D) {[Cd(3)(micro(2)-L(2))(3)(dca)(6)].0.75H(2)O}(n) (6) with 1D microporous channels along the a direction was isolated. Further investigations on other Cd(ii) salts and the L(2) ligand in a Cd to L(2) ratio of 1:1, an unexpected complex [Cd(mu(2)-L(2))(mu(3)-SO(4))(H(2)O)](n) (7) with a 3D open framework was obtained. All of the complexes exhibit strong blue fluorescence emission bands in the solid state at ambient temperature, of which the excitation and emission maxima are red-shifted to longer wavelength as compared to those in water. Powder X-ray diffraction and thermal studies were used to investigate the bulk nature of the 3D coordination polymers 6 and 7.     

3d-Metal derivatives of the [Cu(I)(SO3)4]7- ion: structure and magnetism

The Cu(SO(3))(4)(7-) anion, which consists of a tetrahedrally coordinated Cu(I) centre coordinated to four sulfur atoms, is able to act as a multidentate ligand in discrete and infinite supramolecular species. The slow oxidation of an aqueous solution of Na(7)Cu(SO(3))(4) yields a mixed oxidation state, 2D network of composition Na(5){[Cu(II)(H(2)O)][Cu(I)(SO(3))(4)]}·6H(2)O. The addition of Cu(II) and 2,2'-bipyridine to an aqueous Na(7)Cu(SO(3))(4) solution leads to the formation of a pentanuclear complex of composition {[Cu(II)(H(2)O)(bipy)](4)[Cu(I)(SO(3))(4)]}(+); a combination of hydrogen bonding and π-π stacking interactions leads to the generation of infinite parallel channels that are occupied by disordered nitrate anions and water molecules. A pair of Cu(SO(3))(4)(7-) anions each act as a tridentate ligand towards a single Mn(II) centre when Mn(II) ions are combined with an excess of Cu(SO(3))(4)(7-). An anionic pentanuclear complex of composition {[Cu(I)(SO(3))(4)](2)[Fe(III)(H(2)O)](3)(O)} is formed when Fe(II) is added to a Cu(+)/SO(3)(2-) solution. Hydrated ferrous [Fe(H(2)O)(6)(2+)] and sodium ions act as counterions for the complexes and are responsible for the formation of an extensive hydrogen bond network within the crystal. Magnetic susceptibility studies over the temperature range 2-300 K show that weak ferromagnetic coupling occurs within the Cu(II) containing chains of Na(5){[Cu(II)(H(2)O)][Cu(I)(SO(3))(4)]}·6H(2)O, while zero coupling exists in the pentanuclear cluster {[Cu(II)(H(2)O)(bipy)](4)[Cu(I)(SO(3))(4)]}(NO(3))·H(2)O. Weak Mn(II)-O-S-O-Mn(II) antiferromagnetic coupling occurs in Na(H(2)O)(6){[Cu(I)(SO(3))(4)][Mn(II)(H(2)O)(2)](3)}, the latter formed when Mn was in excess during synthesis. The compound, Na(3)(H(2)O)(6)[Fe(II)(H(2)O)(6)](2){[Cu(I)(SO(3))(4)](2)[Fe(III)(H(2)O)](3)(O)}·H(2)O, contained trace magnetic impurities that affected the expected magnetic behaviour.     

Ag(I)/V(V) Heterobimetallic Frameworks Generated from Novel-Type {Ag(2)(VO(2)F(2))(2)(triazole)(4)} Secondary Building Blocks: A New Aspect in the Design of SVOF Hybrids

A series of new silver(I)-containing MOFs [Ag(2)(tr(2)ad)(2)](ClO(4))(2) (1), [Ag(2)(VO(2)F(2))(2)(tr(2)ad)(2)]·H(2)O (2), [Ag(2)(VO(2)F(2))(2)(tr(2)eth)(2)(H(2)O)(2)] (3), and [Ag(2)(VO(2)F(2))(2)(tr(2)cy)(2)]·4H(2)O (4) supported by 4-substituted bifunctional 1,2,4-triazole ligands (tr(2)ad = 1,3-bis(1,2,4-triazol-4-yl)adamantane, tr(2)eth = 1,2-bis(1,2,4-triazol-4-yl)ethane, tr(2)cy = trans-1,4-bis(1,2,4-triazol-4-yl)cyclohexane) were hydrothermally synthesized and structurally characterized. In these complexes, the triazole heterocycle as an N(1),N(2)-bridge links either two adjacent Ag-Ag or Ag-V centers at short distances forming polynuclear clusters. The crystal structure of compound 1 is based on cationic {Ag(2)(tr)(4)}(2+) fragments connected in a 2D rhombohedral grid network with (4,4) topology. The neighboring layers are tightly packed into a 3D array by means of argentophilic interactions (Ag···Ag 3.28 ?). Bridging between different metal atoms through the triazole groups assists formation of heterobimetallic Ag(I)/V(V) secondary building blocks in a linear V-Ag-Ag-V sequence that is observed in complexes 2-4. These unprecedented tetranuclear {Ag(2)(VO(2)F(2))(2)(tr)(4)} units (the intermetal Ag-Ag and Ag-V distances are 4.24-4.36 and 3.74-3.81 ?, respectively), in which vanadium(V) oxofluoride units possess distorted trigonal bipyramidal environment {VO(2)F(2)N}ˉ, are incorporated into 1D ribbon (2) or 2D square nets (3, 4) using bitopic μ(4)-triazole ligands. The valence bond calculation for vanadium atoms shows +V oxidation state in the corresponding compounds. Thermal stability and photoluminescence properties were studied for all reported coordination polymers.     

Inorganic-organic hybrid compounds based on octamolybdates and multidentate N-donor ligand: syntheses, structures, photoluminescence and photocatalysis

Six inorganic-organic hybrid compounds, namely, [Cu(2)(2,4'-tmbpt)(2)(β-Mo(8)O(26))(H(2)O)(2)]·7H(2)O (), [Cu(2,4'-tmbpt)(γ-Mo(8)O(26))(0.5)(H(2)O)]·H(2)O (), [Co(2,4'-Htmbpt)(2)(γ-Mo(8)O(26))(H(2)O)(2)] (), [Zn(2,4'-Htmbpt)(2)(γ-Mo(8)O(26))(H(2)O)(2)] (), [Ni(2,4'-tmbpt)(α-Mo(8)O(26))(0.5)(H(2)O)]·2.5H(2)O () and [Ag(2,4'-Htmbpt)(β-Mo(8)O(26))(0.5)] (), have been synthesized under hydrothermal conditions (2,4'-tmbpt = 1-((1H-1,2,4-triazol-1-yl)methyl)-3-(2-pyridyl)-5-(4-pyridyl)-1,2,4-triazole). The structures of compounds have been determined by single-crystal X-ray diffraction analyses and characterized by infrared spectra (IR), elemental analyses, powder X-ray diffraction (PXRD) analyses and thermogravimetric analyses (TGA). Compound shows a 3D (3,4)-connected framework constructed by the 2D Cu(ii)-organic fragments and [β-Mo(8)O(26)](4-) anions. Compound exhibits a 2D layer structure based on Cu(ii)-organic chains and [γ-Mo(8)O(26)] chains. The layers are extended into a 3D supramolecular framework by hydrogen-bonding interactions. Compounds and are isostructural, and display 1D chain structures. The chains are further interlinked by hydrogen-bonding interactions to form 3D supramolecular architectures. Compound shows a 3D framework based on the 2D Ni(ii)-organic fragments and [α-Mo(8)O(26)](4-) anions. In compound , the 1D chains constructed by the Ag(i) ions, 2,4'-Htmbpt ligands and [β-Mo(8)O(26)](4-) anions are extended by hydrogen-bonding interactions into a 2D supramolecular layer. Each layer threads into the adjacent layers, yielding a 2D → 3D interdigitated structure. Moreover, the photoluminescent properties of and , the optical band gaps of , and the photocatalytic properties of have also been investigated.     

Syntheses and magneto-structural study of several polynuclear copper(II) complexes derived from 1,3-Bis(dimethylamino)-2-propanolato

The syntheses, structural characterization, and magnetic behavior of the three new polynuclear copper(II) complexes with formulas [Cu(4)(eta(2):mu-CH(3)COO)(2)(mu-OH)(2)(mu-OH(2))(mu-bdmap)(2)](ClO(4))(2).H(2)O (1), [Cu(8)(NCO)(2)(eta(1):mu-NCO)(4)(mu-OH)(2)(mu(3)-OH)(2)(mu-OH(2))(3)(mu-bdmap)(4)](ClO(4))(2)x2H(2)O (2), and [Cu(9)(eta(1):mu-NCO)(8)(mu(3)-OH)(4)(OH(2))(2)(mu-bdmap)(4)](ClO(4))(2).4H(2)O (3), in which bdmapH is 1,3-bis(dimethylamino)-2-propanol, are reported. Tetranuclear complex 1 crystallizes in the triclinic system, space group P, with unit cell parameters a = 12.160(1) A, b = 13.051(1) A, c = 13.235(1) A, alpha = 110.745(1) degrees , beta = 109.683(1) degrees , gamma = 97.014(1), and Z = 2. Octanuclear complex 2 crystallizes in the monoclinic system, space group C2/c, with unit cell parameters a = 26.609(1) A, b = 14.496(1) A, c = 16.652(1) A, beta = 97.814(1) degrees , and Z = 4, and nonanuclear complex 3 crystallizes in the monoclinic system, space group C2/c, with unit cell parameters a = 24.104(1) A, b = 13.542(1) A, c = 24.355(1) A, beta = 109.98(1) degrees , and Z = 4. The magnetic behavior of the three complexes has been checked showing strong antiferromagnetic coupling in all the cases.