Self-assembly of high-nuclearity metal clusters: programmed expansion of a metallasiloxane cage to an octacopper(II) cluster

The novel octanuclear copper(II) cluster [Cu6[(PhSiO2)6]2[NCCu(Me6tren)]2(MeOH)4]2+ (1) has been isolated as a perchlorate salt by reacting the hexacopper(II) metallasiloxane cage [Cu6[(PhSiO2)6]2(nBuOH)x] (x = 4, 6) with [Cu(Me6tren)CN]ClO4 in a methanol/chloroform mixture (Me6tren = tris(2-(dimethylamino)ethyl) amine). Crystal data for 1(ClO4)2 x MeOH: monoclinic, space group P2(1)/n (no. 14), a = 16.8490(3) angstroms, b = 22.2966(4) angstroms, c = 17.2508(3) angstroms, beta = 94.7658(5) degrees, V = 6458.3(2) angstroms3, Z = 2. The structure comprises a highly distorted hexagonal Cu6 array linked to two [Cu(Me6tren)] units via cyanide bridges. Magnetic measurements reveal that the addition of the copper cyanide complexes dramatically affects the magnetism of the Cu6 unit, whose ground spin state changes from S = 3 to S = 0.     

Influence of steric hindrance of organic ligand on the structure of Keggin-based coordination polymer

Five Keggin-based 3D coordination polymers, namely, [Cu3(pz)3(PW12O40)] (pz = pyrazine) (1), [Cu3(2,3-Me2pz)3(PW12O40)] (2,3-Me2pz = 2,3-dimethylpyrazine) (2), [Cu2(2,5-Me2pz)(1.5)(2,5-HMe2pz)(PW12O40)] (2,5-Me2pz = 2,5-dimethylpyrazine) (3), [Cu3(2,3-Me2pz)3(PMo12O40)] (4), and [Ag3(pz)3(PW12O40)].0.5H2O (5), were synthesized and structurally characterized. Crystal data are as follows: trigonal, space group R3c, a = 18.4070(14) angstroms, c = 22.544(3) angstroms, gamma = 120 degrees, and Z = 6 for 1; orthorhombic, space group Pccn, a = 16.599(2) angstroms, b = 20.470(3) angstroms, c = 14.3757(18) angstroms, and Z = 4 for 2; triclinic, space group P1, a = 10.667(2) angstroms, b = 11.147(2) angstroms, c = 20.207(4) angstroms, alpha = 90.983(4) degrees, beta = 108.128(3) degrees, gamma = 92.150(4) degrees, and Z = 2 for 3; orthorhombic, space group Pccn, a = 16.450(3) angstroms, b = 20.170(4) angstroms, c = 14.244(3) angstroms, and Z = 4 for 4; and rhombohedral, space group R32, a = 18.2047(13) angstroms, c = 23.637(3) angstroms, gamma = 120 degrees, and Z = 6 for 5. Their structural differences were investigated using crystal structure analysis, revealing that the influence of steric hindrance of organic ligand on the structures of Keggin-based coordination polymers is realized through changing the number of metal-organic units surrounding the POM anion.     

Ferromagnetism and chirality in two-dimensional cyanide-bridged bimetallic compounds

The combination of hexacyanoferrate(III) anions, [Fe(CN)(6)](3)(-), with nickel(II) complexes derived from the chiral ligand trans-cyclohexane-1,2-diamine (trans-chxn) affords the enantiopure layered compounds [Ni(trans-(1S,2S)-chxn)(2)](3)[Fe(CN)(6)](2).2H(2)O (1) and [Ni(trans-(1R,2R)-chxn)(2)](3)[Fe(CN)(6)](2).2H(2)O (2). These chiral systems behave as ferromagnets (T(c) = 13.8 K) with a relatively high coercive field (H(c) = 0.17 T) at 2 K. They also exhibit an unusual magnetic behavior at low temperatures that has been attributed to the dynamics of the magnetic domains in the ordered phase.     

Extremely long axial Cu-N bonds in chiral one-dimensional zigzag cyanide-bridged Cu(II)(-)Ni(II) and Cu(II)(-)Pt(II) bimetallic assemblies

Preparations, crystal structures, and spectral and magnetic properties of two new chiral one-dimensional cyano-bridged coordination polymers, [Cu(II)L2]M(II)(CN)].2H2O (M(II) = Ni(II) (1) and Pt(II) (2), L = trans-cyclohexane-(1R,2R)-diamine) have been presented. Complex 1 crystallizes in the monoclinic P2(1) space group with a = 9.864(4) A, b = 15.393(8) A, c = 7.995(4) A, beta = 110.32(3) degrees , V = 1138.4(10) A3, and Z = 2, while 2 crystallizes in the monoclinic P2(1) space group with a = 9.899(3) A, b = 15.541(4) A, c = 8.102(2) A, beta = 111.02(2) degrees , V = 1163.6(5) A3, and Z = 2. The unique zigzag cyano-bridged chains along the crystallographic b axis consist of alternate chiral [CuL(2)]2+ cations and square-planar [M(CN)4]2- anions. One side of the axial Cu-N(triple bond C) bond distances are 2.324(6) and 2.34(1) A with Cu-N[triple bond]C angles of 137.8(6) degrees and 138.2(9) degrees for 1 and 2, respectively. On the other hand, the opposite side of the axial Cu-N(triple bond C) bond distances are 3.120(8) and 3.09(1) A with significantly large bent Cu-N[triple bond]C angles of 97.9(5) degrees and 96.8(7) degrees for 1 and 2, respectively. The novel axial bonding features of extremely long semi-coordination Cu-N bonds are attributed to coexistence of pseudo-Jahn-Teller elongation and electrostatic interaction in the unique zigzag cyano-bridged chains. The characteristic bonding features with overlap between small 3d (Ni(II)) or large 5d (Pt(II)) and 3d (Cu(II)) orbitals results in larger shifts in XPS peaks of not only Cu2p(1/2) and Cu2p(3/2) but also Ni2p(1/2) and Ni2p(3/2) for 1 than those of 2, which is also consistent with weak antiferromagnetic interactions with Weiss constants of -5.31 and -5.94 K for 1 and 2, respectively. The d-d, pi-pi*, and CT bands in the electronic, CD, and MCD spectra for 1 and 2 in the solid state at room temperature are discussed from the viewpoint of magneto-optical properties.     

From one-dimensional chains to three-dimensional networks: solvothermal synthesis of thiogallates in ethylenediamine

Five new thiogallates have been prepared solvothermally in the presence of ethylenediamine and characterized by single-crystal X-ray diffraction, thermogravimetry, and elemental analysis. [enH2][Ga4S7(en)2] (1), which crystallizes in the monoclinic space group P2(1)/c with lattice parameters a = 12.8698(12) angstroms, b = 10.4812(9) angstroms, c = 16.5473(14) angstroms and beta = 102.457(4) degrees (Z = 4), exhibits a layered structure in which both covalently and hydrogen-bonded template molecules coexist. The structures of [M(en)3](0.5)[GaS2] (M = Mn (2) (orthorhombic, Cmcm, a = 9.5555(6) angstroms, b = 15.0696(10) angstroms, c = 12.2893(7) angstroms, Z = 8) M = Co (3) (orthorhombic, Cmcm, a = 9.4660(7) angstroms, b = 15.0990(11) angstroms, c = 12.2540(8) angstroms, Z = 8), M = Ni (4) (orthorhombic, Cmcm, a = 9.4510(10) angstroms, b = 15.1416(15) angstroms, c = 12.2387(11) angstroms, Z = 8)) and Mn(en)2Ga2S4 (5) (monoclinic, C2/c, a = 14.3002(11) angstroms, b = 7.9509(5) angstroms, c = 12.1184(6) angstroms, beta = 100.191(4) degrees , Z = 4) are closely related and contain one-dimensional [GaS2]- chains, which are separated by [M(en)3]2+ counterions in 2, 3, and 4, and linked into a three-dimensional structure by [Mn(en)2]2+ units in 5.     

Cu(tn)]3[Cr(CN)6](2).3H2O: a unique two-dimensional Cu-Cr cyano-bridged ferromagnet (tn = 1,3-diaminopropane)

Reaction of the two-coordinate 'assembling complex-ligand' [Cu(tn)]2+ with the building block [Cr(CN)6]3- leads to a unique two-dimensional Cu-Cr cyano-bridged ferromagnet with unusual mu 3- and mu 4-bridging [Cu(tn)]2+ units.     

Crystal structures and magnetic properties of new cyano-bridged two-dimensional grid-like bimetallic assemblies [Ni(tn)2]2[Cr(CN)5((NO)]OH*H2O and [NI(tn)2]2[Co(CN)6]NO3*2H2O (tn=1,3-propanediamine)

Two bimetallic assemblies, [Ni(tn)(2)](2)[Cr(CN)(5)(NO)]OH.H(2)O (1) and [Ni(tn)(2)](2)[Co(CN)(6)]NO(3).2H(2)O (2) (tn = 1,3-diaminopropane), have been prepared and structurally and magnetically characterized. Crystal data for 1 (2): space group P1 (P1), a = 8.698(3) (8.937(2)) A, b = 10.001(2) (9.863(1)) A, c = 10.158(2) (10.064(1)) A, alpha = 87.40(2) (86.064(10)) degrees, beta = 65.10(2) (65.489(10)) degrees, gamma = 81.63(2) (81.572(12)) degrees and Z = 1 (1). Both structures consist of two-dimensional grid-like polycations containing Ni-N triple bond C-M linkages (M = Cr or Co) and counteranions (OH, NO(3)). Magnetic studies of 1 showed that the complex displays a metamagnetic behavior originating from intralayer ferromagnetic and interlayer antiferromagnetic interactions. Long-range antiferromagnetic ordering was observed at T(N) = 3.3 K. Complex 2 exhibits intramolecular ferromagnetic interactions through the diamagnetic N triple bond C-Co-N triple bond C bridges, owing to superexchange involving the empty d(sigma) orbital of the diamagnetic Co(III) ion.     

Synthesis and reactivity of the Tl1 salts of

Synthons Tl1[TCNE]*- (1) and Tl12[TCNE]2- (2), for [TCNE]*- and [TCNE]2-, respectively, in metathesis reactions have been quantitatively prepared and characterized. The structure of 1 was solved and refined in a monoclinic unit cell at 27 degrees C [C2/c, a = 12.6966 (12) angstroms, b=7.7599 (7) angstroms, c=15.5041 (15) angstroms, beta = 96.610 (5) degrees , V= 1517.4 (2) angstroms3, Dcalcd = 2.911 gcm-3, Z=8, R1 = 0.0575, omegaR2=0.0701] and exhibits nuCN absorptions at 2,191 (s) and 2,162 (s) cm-1 consistent with metal-bound [TCNE]*-. The structure of 1 consists of a distorted square antiprismatic octacoordinate Tl1 bound to six monodentate [TCNE]*-s with TlN separations ranging from 2.901 to 3.171 angstroms averaging 3.020 angstroms, and one bidentate [TCNE]*- with TlN separations averaging 3.279 angstroms. The TlN bonding is attributed to electrostatic bonding. The [TCNE]*-s form dimerized zigzag chains with intra- and interdimer separations of 2.87 and 3.29 angstroms, respectively. The tight pi-[TCNE](2)2- dimer is diamagnetic and has the shortest intradimer [TCNE]*- distance reported. These synthons for [TCNE]*- and [TCNE]2- in metathesis reactions lead to the precipitation of, for example, TlIX (X = Cl, Br, OAc). Reaction of 1 with MnIII(porphyrin)X (X = Cl, OAc) forms the molecule-based magnets of [MnIII(porphyrin)][TCNE] composition, while the reaction of [CrI(C6H6)2]Br and (Me2N)2CC(NMe2)2Cl2, [TDAE]Cl2, with 1 forms [CrI(C6H6)2] [TCNE] and [TDAE][TCNE]2, respectively. The structure of [TDAE][TCNE]2.MeCN was solved and refined in an orthorhombic unit cell at 21 degrees C [I222, a = 10.2332(15), b = 13.341(6), c = 19.907(8) angstroms, V= 2717.7 angstroms3, Z = 4; Dcalcd = 1.216 gcm-3, R=0.083, Romega = 0.104] and exhibits upsilonCN absorptions at 2,193 (m), 2,174 (s), and 2,163 (s) cm-1 consistent with isolated [TCNE](2)2- , in contrast to the aforementioned TlI bound [TCNE](2)2-. The reaction of 2 with [TDAE]Cl2 forms [TDAE]2+[TCNE]2-.     

Trimerization of alkali dicyanamides M[N(CN)2] and formation of tricyanomelaminates M3[C6N9] (M = K, Rb) in the melt: crystal structure determination of three polymorphs of K[N(CN)2], two of Rb[N(CN)2], and one of K3[C6N9] and Rb3[C6N9] from X-ray powder diffractometry

The alkali dicyanamides M[N(CN)2] (M=K, Rb) were synthesized through ion exchange, and the corresponding tricyanomelaminates M3[C6N9] were obtained by heating the respective dicyanamides. The thermal behavior of the dicyanamides and their reaction to form the tricyanomelaminates were investigated by temperature-dependent X-ray powder diffractometry and thermoanalytical measurements. Potassium dicyanamide K[N(CN)2] was found to undergo four phase transitions: At 136 degrees C the low-temperature modification alpha-K[N(CN)2] transforms to beta-K[N(CN)2], and at 187degrees C the latter transforms to the high-temperature modification gamma-K[N(CN)2], which melts at 232 degrees C. Above 310 degrees C the dicyanamide ions [N(CN)2]- trimerize and the resulting tricyanomelaminate K3[C6N9] solidifies. Two modifications of rubidium dicyanamide have been identified: Even at -25 degrees C, the a form slowly transforms to beta-Rb[N(CN)2] within weeks. Rb[N(CN)2] has a melting point of 190 degrees C. Above 260 degrees C the dicyanamide ions [N(CN)2]- of the rubidium salt trimerize in the melt and the tricyanomelaminate Rb3[C6N9] solidifies. The crystal structures of all phases were determined by powder diffraction methods and were refined by the Rietveld method. alpha-K[N(CN)2] (Pbcm, a = 836.52(1), b = 46.90(1), c =7 21.27(1) pm, Z = 4), gamma-K[N(CN)2] (Pnma, a = 855.40(3), b = 387.80(1), 1252.73(4) pm, Z = 4), and Rb[N(CN)2] (C2/c, a = 1381.56(2), b = 1000.02(1), c = 1443.28(2) pm, 116.8963(6) degrees, Z = 16) represent new structure types. The crystal structure of beta-K[N(CN)2] (P2(1/n), a = -726.92(1), b 1596.34(2), c = 387.037(5) pm, 111.8782(6) degrees, Z = 4) is similar but not isotypic to the structure of alpha Na[N(CN)2]. alpha-Rb[N(CN)2] (Pbcm, a = 856.09(1), b = 661.711(7), c = 765.067(9) pm, Z = 4) is isotypic with alpha-K[N(CN)2]. The alkali dicyanamides contain the bent planar anion [N(CN)2]- of approximate symmetry C2, (average bond lengths: C-N(bridge) 133, C-N(term) 113 pm; average angles N-C-N 170 degrees, C-N-C 120 degrees). K3[C6N9] (P2(1/c), a = 373.82(1), b = 1192.48(5), c = 2500.4(1) pm, beta = 101.406(3) degrees, Z = 4) and Rb,[C6N9] (P2(1/c), a = 389.93(2), b = 1226.06(6), c = 2547.5(1) pm, 98.741(5) degrees, Z=4) are isotypic and they contain the planar cyclic anion [C6N9]3-. Although structurally related, Na3[C6N9] is not isotypic with the tricyanomelaminates M3[C6N9] (M = K, Rb).     

Architectural isomerism in the three-dimensional polymeric spin crossover system [Fe(pmd)2[Ag(CN)2]2]: synthesis, structure, magnetic properties, and calorimetric studies

Two coordination polymers formulated [Fe(pmd)2[Ag(CN)2]2] (pmd = pyrimidine) have been synthesized and characterized. Both polymers, considered to be architectural isomers, display different crystal structures and magnetic properties. Isomer 1 crystallizes in the monoclinic C2/c space group with a = 6.9750(8) angstroms, b = 16.1700(9) angstroms, c = 14.2020(8) angstroms, beta = 97.954(2) degrees, V = 1586.37(14) angstroms3, and Z = 4. The crystal structure of isomer 2 has been studied at 250 and 150 K. At both temperatures, 2 displays the orthorhombic Pccn space group with a = 15.7700(2) [14.8950(2)] angstroms, b = 8.2980(4) [8.1580(4)] angstroms, c = 13.4180(6) [13.3480(5)] angstroms, V = 1755.87(14) [1621.96(10)] angstroms3, and Z = 4 for 250 [150] K. The iron(II) ions define distorted octahedral [FeN6] chromophores in both isomers. The equatorial positions are occupied by four [Ag(CN)2]- bridging ligands, which connect the defining layers of two iron(II) ions. Isomer 1 has two crystallographically distinct [Ag(CN)2]- groups; one is essentially linear, while the other is severely distorted [C(5)-Ag(2)-C(5i)] = 138.8(5) degrees. This fact facilitates the parallel interpenetration of two layers, which in addition show short Ag(1)....Ag(2) interactions (distance Ag(1)....Ag(2) = 2.9972(10) angstroms). Isomer 2 shows only one type of Ag atom, which is slightly bent [C-Ag-C = 161.54(12) degrees], and as a consequence, the layers defined are not interpenetrated. In both cases, the axial positions are occupied by the pmd ligands which interact with the Ag atoms of adjacent layers defining a 3D coordination polymer. Compound 1 is high spin in the whole range of temperatures, while 2 undergoes a cooperative high-spin <--> low-spin effect centered at ca. 184 K with a hysteresis loop ca. 5 K wide. The experimental enthalpy and entropy variations were 11.5 +/- 0.4 kJ mol(-1) and 64 +/- 3 J K(-1) mol(-1). Consistency between the experimental thermodynamic data and the magnetic data was checked in the frame of regular solution theory.     

Synthesis and Crystal Structure of a Cyano- bridged Bimetallic Complex[La(DMSO)_3(H_2O)_3- Cr(CN)_6]·H_2O (DMSO = Dimethylsulfoxide) with One-dimensional Chain Molecular Structure

1 INTRODUCTION Over the last decade, there has been continuous interest in cyanide-bridged lanthanide-transition me- tal complexes due to their extensive applications in preparing rare earth orthoferrites[1], chemical sensor materials[2], fluorescent ma…     

Novel examples of high-dimensional mixed-valence copper cyanide complexes

The first examples of high-dimensional mixed-valence homometallic cyano-bridged copper complexes were synthesized and characterized: net-structured [Cu(CN)(4){Cu(cyclam)}(1.5)](2)(n)()(H(2)O)(5)(n) (1), ladder-type double-chain-structured [Cu(CN)(2){Cu(CN)(2)Cu(cyclam)}](n)()(H(2)O)(n) (2), layer-structured [{Cu(CN)(2)}(2)Cu(cycalm)](n) (3), and hydrogen-bond-based 2-D [Cu(CN)(3)Cu(cyclam)](n)()(CH(3)OH)(n) (4) (cyclam = 1,4,8,11-tetraazacyclotetradecane). (1) Crystallizes in triclinic space group P with a = 8.3589(11) A, b = 13.478(2) A, c = 14.828(2) A, alpha = 66.895(2) degrees , beta = 77.916(3) degrees , gamma = 85.939(3) degrees , and Z = 1; (2) crystallizes in triclinic space group P with a = 8.2305(12) A, b = 9.8861(15) A, c = 13.219(2) A, alpha = 84.863(3) degrees , beta = 75.744(3) degrees , gamma = 89.818(3) degrees , and Z = 2; 3 crystallizes in monoclinic space group P2(1)/c with a = 6.830(2) A, b = 8.482(2) A, c = 17.306(4) A, beta = 98.144(4) degrees , and Z = 2; 4 crystallizes in triclinic space group P with a = 9.470(1) A, b = 10.034(1) A, c = 12.064(1) A, alpha = 67.325(2), beta = 75.593(2), gamma = 70.672(2), and Z = 2. The coordination sphere of Cu(I) sites in the complexes shows diverse structures: tetrahedral [CuC(4)] for (1), tetrahedral [CuC(3)N] and triangular [CuC(2)N] for (2), triangular [CuC(2)N] for (3), and triangular [CuC(3)] for 4. In particular, (1) constitutes the first example of a structurally characterized system containing a bridging tetrahedral [Cu(CN)(4)](3)(-) unit. The diverse structural nature of these complexes is governed by the capping amines and the content of water in the reaction media. The magnetic interactions are negligible in these mixed-valence complexes.     

Synthesis and Crystal Structure of a Cyano-bridged Bimetallic Complex[La(DMSO)3(H2O)3Cr(CN)6]·H2O (DMSO = Dimethylsulfoxide) with One-dimensional Chain Molecular Structure

The title complex [La(DMSO)3(H2O)3Cr(CN)6](H2O was obtained by the reaction of LaCl3(7H2O, DMSO and K3[Cr(CN)6] in aqueous solution on a hot water bath. The crystal crystallizes in orthorhombic, space group P212121 with a = 9.827(3), b = 15.037(4), c = 17.633(5)A, C12H26CrLaN6O7S3, Mr = 653.48, Z = 4, V = 2605.7(13) A3, Dc = 1.666 g/m3, μ (MoKα) = 2.314 mm-1, F(000) = 1300, R = 0.0205 and wR = 0.0481 for 5038 observed reflections (I > 2σ(I)). La3+ ion is eight-coordinated by three DMSO molecules, three H2O molecules and two [Cr(CN)6]3- units. The structure of the title complex possesses a cyano-bridged onedimensional zigzag chain structure with alternating La(DMSO)3(H2O)3 and Cr(CN)6 moieties, which are linked by some hydrogen bonds to form a 3D network structure.     

Syntheses; 77Se, 203Tl, and 205Tl NMR; and theoretical studies of the Tl2Se6(6-), Tl3Se6(5-), and Tl3Se7(5-) anions and the X-ray crystal structures of [2,2,2-crypt-Na]4[Tl4Se8].en and [2,2,2-crypt-Na]2[Tl2Se4](infinity)1.en

The 2,2,2-crypt salts of the Tl4Se8(4-) and [Tl2Se4(2-)]infinity1 anions have been obtained by extraction of the ternary alloy NaTl0.5Se in ethylenediamine (en) in the presence of 2,2,2-crypt and 18-crown-6 followed by vapor-phase diffusion of THF into the en extract. The [2,2,2-crypt-Na]4[Tl4Se8].en crystallizes in the monoclinic space group P2(1)/n, with Z = 2 and a = 14.768(3) angstroms, b = 16.635(3) angstroms, c = 21.254(4) angstroms, beta = 94.17(3) degrees at -123 degrees C, and the [2,2,2-crypt-Na]2[Tl2Se4]infinity1.en crystallizes in the monoclinic space group P2(1)/c, with Z = 4 and a = 14.246(2) angstroms, b = 14.360(3) angstroms, c = 26.673(8) angstroms, beta = 99.87(3) degrees at -123 degrees C. The TlIII anions, Tl2Se6(6-) and Tl3Se7(5-), and the mixed oxidation state TlI/TlIII anion, Tl3Se6(5-), have been obtained by extraction of NaTl0.5Se and NaTlSe in en, in the presence of 2,2,2-crypt and/or in liquid NH3, and have been characterized in solution by low-temperature 77Se, 203Tl, and 205Tl NMR spectroscopy. The 1J(203,205Tl-77Se) and 2J(203,205Tl-203,205Tl) couplings of the three anions have been used to arrive at their solution structures by detailed analyses and simulations of all spin multiplets that comprise the 205,203Tl NMR subspectra arising from natural abundance 205,203Tl and 77Se isotopomer distributions. The structure of Tl2Se6(6-) is based on a Tl2Se2 ring in which each thallium is bonded to two exo-selenium atoms so that these thalliums are four-coordinate and possess a formal oxidation state of +3. The Tl4Se8(4-) anion is formally derived from the Tl2Se6(6-) anion by coordination of each pair of terminal Se atoms to the TlIII atom of a TlSe+ cation. The structure of the [Tl2Se4(2-)]infinity1 anion is comprised of edge-sharing distorted TlSe4 tetrahedra that form infinite, one-dimensional [Tl2Se42-]infinity1 chains. The structures of Tl3Se6(5-) and Tl3Se7(5-) are derived from Tl4Se4-cubes in which one thallium atom has been removed and two and three exo-selenium atoms are bonded to thallium atoms, respectively, so that each is four-coordinate and possesses a formal oxidation state of +3 with the remaining three-coordinate thallium atom in the +1 oxidation state. Quantum mechanical calculations at the MP2 level of theory show that the Tl2Se6(6-), Tl3Se6(5-), Tl3Se7(5-), and Tl4Se8(4-) anions exhibit true minima and display geometries that are in agreement with their experimental structures. Natural bond orbital and electron localization function analyses were utilized in describing the bonding in the present and previously published Tl/Se anions, and showed that the Tl2Se6(6-), Tl3Se6(5-), Tl3Se7(5-), and Tl4Se8(4-) anions are electron-precise rings and cages.     

New magnetic copper(II) coordination polymers with the polynitrile ligand (C[C(CN)2]3)2- and N-donor co-ligands

Reactions between CuCl2 and K2tcpd (tcpd2- = [C10N6]2- = (C[C(CN)2]3)2-) in the presence of neutral co-ligands (bpym = 2,2'-bipyrimidine, and tn = 1,3-diaminopropane) in aqueous solution yield the new compounds [Cu2(bpym)(tcpd)2(H2O)4] x 2H2O (1), [Cu(tn)(tcpd)] (2), and [Cu(tn)2(tcpd)] x H2O (3), which are characterized by X-ray crystallography and magnetic measurements. Compound 1 displays a one-dimensional structure in which the bpym ligand, acting with a bis-chelating coordination mode, leads to [Cu2(bpym)]4+ dinuclear units which are connected by two mu2-tcpd2- bridging ligands. Compound 2 consists of a three-dimensional structure generated by [Cu(tn)]2+ units connected by a mu4-tcpd2- ligand. The structure of 3 is made up of centrosymmetric planar [Cu(tn)]2+ units connected by a mu2-tcpd2- ligand leading to infinite zigzag chains. In compounds 1 and 3, the bridging coordination mode of the tcpd2- unit involves only two nitrogen atoms of one C(CN)2 wing, while in 2, this ligand acts via four nitrogen atoms of two C(CN)2 wings. Despite this difference, the structural features of the tcpd2- units in 1-3 are essentially similar. Magnetic measurements for compound 1 exhibit a maximum in the chi(m) vs T plot (at approximately 150 K) which is characteristic of strong antiferromagnetic exchange interactions between the Cu(II) metal ions dominated by the magnetic exchange through the bis-chelating bpym. The fit of the magnetic data to a dimer model gives J and g values of -90.0 cm(-1) and 2.12, respectively. For compounds 2 and 3 the thermal variations of the magnetic susceptibility show weak antiferromagnetic interactions between the Cu(II) metal ions that can be well reproduced with an antiferromagnetic regular S = 1/2 chain model that gives J values of -0.07(2) and -0.18(1) cm(-1) with g values of 2.12(1) and 2.13(1) for compounds 2 and 3, respectively (the Hamiltonian is written in all the cases as H = -2JS(a)S(b)).     

An unusual 3D coordination polymer based on bridging interactions of the nucleobase adenine

The first 3D coordination polymer containing a nucleobase as a bridging ligand, [[Cu2(mu-ade)4(H2O)2][Cu(ox)(H2O)]2 x approximately 14H2O]n (1), has been synthesized by reaction of adenine (Hade) with a basic solution of K2[Cu(ox)2] x 2H2O (ox = oxalato dianion). Compound 1 crystallizes in the trigonal space group R3 with a = b = 31.350(1) angstroms, c = 14.285(1) angstroms, V = 12158.7(10) angstroms3, and Z = 9. X-ray analysis shows a covalent 3D network in which the copper(II) centers are bridged by tridentate mu-N3,N7,N9 adeninate ligands. The compound has relatively large, nanometer-sized tubes associated with the self-assembly process directed solely by metal-ligand interactions. The covalent 3D framework remains intact upon removal of the guest water molecules trapped in the nanotubes. Magnetic measurements indicate an overall antiferromagnetic behavior of the compound.     

Template Synthesis of a Tetraaza Macrocycle Which Involves Benzaldehyde Rather Than Formaldehyde as a Building Block. Isolation and Structure Determination of the Open-Chain Schiff Base Intermediate Complex

The classical formaldehyde building block has been replaced by the bulkier benzaldehyde in the Cu(II) template synthesis of the cyclam-like tetraaza macrocycle of type 1, in which nitroethane operated as locking fragment. The synthetic pathway involves three distinct steps: (i) Schiff base condensation of the metal-free open-chain tetramine; (ii) Cu(II) coordination and preorientation of the Schiff base; (iii) nucleophilic attack by the deprotonated nitroethane fragment and formation of the macrocyclic complex. Both the Schiff base Cu(II) complex and the Cu(II) macrocyclic complex were isolated in a crystalline form and their molecular structures were determined: {N-[2-((E)-benzylideneamino)ethyl]-N'-[2-((Z)-benzylideneamino)ethyl]propane-1,3-diamine}copper(II) nitrate: triclinic, space group P&onemacr;, with a = 12.296(5) ?, b = 10.787(6) ?, c = 10.547(7) ?, V = 1161(1) ?(3), and Z = 2 (R = 0.055, R(w) = 0.061); [(5R,6S,7S)-6-methyl-6-nitro-5,7-diphenyl-1,4,8,11-tetraazacyclotetradecane]copper(II) perchlorate: monoclinic, space group P2(1)/n, with a = 15.246(5) ?, b = 23240(7) ?, c = 8.540(4) ?, V = 2980(2) ?(3), and Z = 4 (R = 0.095, R(w) = 0.095). This allowed us to define mechanistic details of the macrocyclization process. It is suggested that the same three-step pathway takes place in the much easier and faster one-pot template syntheses of cyclam-like macrocyles, which involve formaldehyde as a building block.     

Synthesis and Crystal Structure of Dinuclear Copper Cluster Compound ［Cu（dtp）PPh_3］_2

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The encapsulation of ferrocyanide by copper(II) complexes of tripodal tetradentate ligands. Novel H-bonding networks incorporating heptanuclear and pentanuclear heterometallic assemblies

Substitution of the weakly binding aqua ligand in [Cu(tren)OH2](2+) and [Cu(tpa)OH2](2+) (tren = tris(2-aminoethyl)amine; tpa = tris(2-pyridylmethyl)amine) by a cyano ligand on ferricyanide results in the assembly of heteropolynuclear cations around the cyanometalate core. In water, the reduction of the Fe(III) core to Fe(II) generates complexes that feature heteropolycations in which ferrocyanide is encapsulated by the Cu(II) moieties: [(Cu(tpa)CN)6Fe][ClO4]8-3H2O 1, [(Cu(tren)CN)6Fe][ClO4]8-10H2O 2, [(Cu(tren)CN)6Fe][Fe(CN)6]2[ClO4]2-15.8H2O 3, and [(Cu(tren)CN)6Fe][(Cu(tren)CN)4Fe(CN)2][Fe(CN)6)]4-6DMSO-21H2O 4. The formation of discrete molecules, in preference to extended networks or polymeric structures, has been encouraged through the use of branched tetradentate ligands in conjunction with copper(II), a metal center with the propensity to form five-coordinate complexes. Complex 3 crystallizes in the monoclinic space group P2(1)/c (#14) with a = 14.8674(10), b = 25.9587(10), c = 27.5617(10) A, beta = 100.8300(10) degrees, and Z = 4, and it is comprised of almost spherical heptanuclear cations, [(Cu(tren)CN)6Fe](8+), whose charge is balanced by two ferricyanide and two perchlorate counteranions. Complex 4 crystallizes in the triclinic space group P1 (# 1) with a = 14.8094(8), b = 17.3901(7), c = 21.1565(11) A, alpha = 110.750(3), beta = 90.206(2), gamma = 112.754(3) degrees, and Z = 1, and it is comprised of the heptanuclear [(Cu(tren)CN)6Fe](8+) cation and pentanuclear [(Cu(tren)CN)4Fe(CN)2](4+) cation, whose terminal cyano ligands are oriented trans to each other. The charge is balanced exclusively by ferricyanide counteranions. In both complexes, H-bonding interactions between hydrogens on primary amines of the tren ligand, terminal cyano groups of the ferricyanide counterions, and the solvent of crystallization generate intricate 3D H-bonding networks.     

Inter-string arrays of bimetallic assemblies with alternative Cu2+-Cl-Cu2+ and Cu-NC-M (M = Co3+, Fe+3, Cr+3) bridges: syntheses, crystal structure, and magnetic properties

Three bimetallic assemblies with alternate homometallic bridges through chloride ligands and heterometallic bridges through cyanide ligands of formula [(323)(2)Cu(2)(Cl)M(CN)(6)](n).2n(H(2)O), where 323 = N,N'-bis(3-aminopropyl)ethylenediamine and M = Co(3+) for 1, Fe(3+) for 2, and Cr(3+) for 3, were synthesized. They have been characterized structurally, analytically, spectroscopically, and magnetically. All three assemblies crystallize in the monoclinic system in the same space group P2(1)/n, with a = 11.642(2) A, b = 10.285(3) A, c = 13.622(2) A, beta = 95.69(3) degrees, V = 1623.1(6) A(3), and Z = 4 for 1; a = 11.681(4) A, b = 10.315(3) A, c = 13.567(5) A, beta = 95.62(3) degrees, V = 1626.8(9) A(3), Z = 4 for 2, and a = 11.782(4) A, b = 10.386(2) A, c = 13.755(4) A, beta = 95.51(3) degrees, V = 1657.4(8) A(3), Z = 4 for 3. Crystal structure analyses reveal that one-dimensional zigzag chains propagate in two different crystallographic directions (a and b) which are held together during the course of their propagation. All three assemblies have a homometallic Cu-Cl-Cu core in common. Assembly 1 exhibits metamagnetic behavior and shows weak antiferromagnetic interactions between Cu(2+) paramagnetic centers, through the chloride bridges. The Neel temperature, T(N), is 3.5 K, and the critical field is 4 T. In the presence of a magnetic field larger than 4 T, the local spin doublets of Cu(2+) in the assembly 1 remain in parallel arrangements. Assemblies 2 and 3 may be described as an alternative repetition of the antiferromagnetically coupled Cu-Cl-Cu fragment and ferromagnetically coupled Cu-CN-Fe(3+)/Cr(3+)fragment. The overall magnetic character of the strings in assemblies 2 and 3 are antiferromagnetic. Ferromagnetic interaction evidenced by the (Cu-CN-Fe(3+)/Cr(3+)) fragment was masked by the antiferromagnetic interaction between the Cu(2+) centers through the chloride bridge. The magnetic properties agree well with those expected for two [323 Cu(2+)] and a [Fe(CN)](3+) unit with spin-orbit coupling effect of the low-spin iron(III) ions for 2 and for two [323 Cu(2+)] and a [Cr(CN)](3+) unit for 3. In aqueous solution, trinuclear [(323)(2)Cu(2)M(CN)(6)](+) and dinuclear [(323)CuM(CN)(6)](-) species were observed.