1D and 2D end-to-end azide-bridged cobalt(II) complexes: syntheses, crystal structures, and magnetic properties

Two new polynuclear azido-bridged Co(II) compounds with formulas catena-[Co(mu1,3-N3)(N3)(py)2(H2O)]n (1) and [Co(mu1,3-N3)2(4-acpy)2]n (2) (py=pyridine, 4-acpy=4-acetylpyridine) have been structurally and magnetically characterized. Compound 1 crystallizes in the orthorhombic system Fddd space group and consists of a single end-to-end azido-bridged chain with the Co(II) atoms in a CoN5O slightly distorted octahedron. Compound 2 crystallizes in the monoclinic system P21/a space group and shows 2D sheets built up through end-to-end azido bridges with the Co(II) atoms in a CoN6 environment. The magnetic properties of 1 and 2 are reported. In the high-temperature region, the plots of chiM or chiMT vs T for 1 and 2 compounds can be fitted by using the Curie-Weiss law, and the best-fit values are -69.1 and -22.6 K, respectively. For 2 magnetic ordering and spontaneous magnetization is achieved below Tc=25 K.     

Coordination chemistry of conformation-flexible 1,2,3,4,5,6-cyclohexanehexacarboxylate: trapping various conformations in metal-organic frameworks

To study the conformations of 1,2,3,4,5,6-cyclohexanehexacarboxylic acid (H(6)L), eleven new coordination polymers have been isolated from hydrothermal reactions of different metal salts with 1e,2a,3e,4a,5e,6a-cyclohexanehexacarboxylic acid (3e+3a, H(6)L(I)) and characterized. They are [Cd(12)(mu(6)-L(II))(mu(10)-L(II))(3)(mu-H(2)O)(6)(H(2)O)(6)]16.5 H(2)O (1), Na(12)[Cd(6)(mu(6)-L(II))(mu(6)-L(III))(3)]27 H(2)O (2), [Cd(3)(mu(13)-L(II))(mu-H(2)O)] (3), [Cd(3)(mu(6)-L(III))(2,2'-bpy)(3)(H(2)O)(3)]2 H(2)O (4), [Cd(4)(mu(4)-L(VI))(2)(4,4'-Hbpy)(4)(4,4'-bpy)(2)(H(2)O)(4)]9.5 H(2)O (5), [Cd(2)(mu(6)-L(II))(4,4'-Hbpy)(2)(H(2)O)(10)]5 H(2)O (6), [Cd(3)(mu(11)-L(VI))(H(2)O)(3)] (7), [M(3)(mu(9)-L(II))(H(2)O)(6)] (M=Mn (8), Fe (9), and Ni (10)), and [Ni(4)(OH)(2)(mu(10)-L(II))(4,4'-bpy)(H(2)O)(4)]6 H(2)O (11). Three new conformations of 1,2,3,4,5,6-cyclohexanehexacarboxylate, 6e (L(II)), 4e+2a (L(III)) and 5e+1a (L(VI)), have been derived from the conformational conversions of L(I) and trapped in these complexes by controlling the conditions of the hydrothermal systems. Complexes 1 and 2 have three-dimensional (3D) coordination frameworks with nanoscale cages and are obtained at relatively low temperatures. A quarter of the L(I) ligands undergo a conformational transformation into L(II) while the others are transformed into L(III) in the presence of NaOH in 2, while all of the L(I) are transformed into L(II) in the absence of NaOH in 1. Complex 3 has a 3D condensed coordination framework, which was obtained under similar reaction conditions as 1, but at a higher temperature. The addition of 2,2'-bipyridine (2,2'-bpy) or 4,4'-bipyridine (4,4'-bpy) to the hydrothermal system as an auxiliary ligand also induces the conformational transformation of H(6)L(I). A new L(VI) conformation has been trapped in complexes 4-7 under different conditions. Complex 4 has a 3D microporous supramolecular network constructed from a 2D L(III)-bridged coordination layer structure by pi-pi interactions between the chelating 2,2'-bpy ligands. Complexes 5-7 have different frameworks with L(II)/L(VI) conformations, which were prepared by using different amounts of 4,4'-bpy under similar synthetic conditions. Both 5 and 7 are 3D coordination frameworks involving the L(VI) ligands, while 6 has a 3D microporous supramolecular network constructed from a 2D L(II)-bridged coordination layer structure by interlayer N(4,4'-Hbpy)--HO(L(II)) hydrogen bonds. 3D coordination frameworks 8-11 have been obtained from the H(6)L(I) ligand and the paramagnetic metal ions Mn(II), Fe(II), and Ni(II), and their magnetic properties have been studied. Of particular interest to us is that two copper coordination polymers of the formulae [{Cu(II) (2)(mu(4)-L(II))(H(2)O)(4)}{Cu(I) (2)(4,4'-bpy)(2)}] (12 alpha) and [Cu(II)(Hbtc)(4,4'-bpy)(H(2)O)]3 H(2)O (H(3)btc=1,3,5-benzenetricarboxylic acid) (12 beta) resulted from the same one-pot hydrothermal reaction of Cu(NO(3))(2), H(6)L(I), 4,4'-bpy, and NaOH. The Hbtc(2-) ligand in 12 beta was formed by the in situ decarboxylation of H(6)L(I). The observed decarboxylation of the H(6)L(I) ligand to H(3)btc may serve as a helpful indicator in studying the conformational transformation mechanism between H(6)L(I) and L(II-VI). Trapping various conformations in metal-organic structures may be helpful for the stabilization and separation of various conformations of the H(6)L ligand.     

A novel three-dimensional network constructed from tetramolybdate clusters linked via two types of copper complex fragments: synthesis, characterization, and magnetic behavior of [[CuII(2,2'-bpy)][CuII(IN)2][Mo4O12(OH)2]

A novel three-dimensional copper molybdate with mixed ligands, [[Cu(II)(2,2'-bpy)][Cu(II)(IN)(2)][Mo(4)O(12)(OH)(2)]] (IN(-) = isonicotinate ion, 2,2'-bpy = 2,2'-bipyridine), 1, has been hydrothermally synthesized and structurally characterized, and this compound is built from an unprecedented tetranuclear molybdenum oxide cluster covalently bonded to two types of copper complex fragments, [Cu(II)(2,2'-bpy)](2+) and [Cu(II)(IN)(2)], via terminal oxygen atoms of [MoO(6)] octahedra. Crystal data for compound 1: monoclinic, space group C2/c, a = 16.4755 A, b = 10.3714 A, c = 17.4382 A, alpha = 90.0000 degrees, beta = 94.8098 degrees, gamma = 90.0000 degrees; V = 2969.24 A(3); Z = 2. Variable temperature magnetic susceptibility indicates that both ferromagnetic and antiferromagnetic interactions exist in 1.     

Synthesis, Structure and Characterization of [Cu(2,2''-bpy)2][{Cu(2,2''-bpy)2}2W12O40(H2)]·4H2O

An organic-inorganic compound [Cu(2,2'-bpy)2][{Cu(2,2'-bpy)2}2W12O4o(H2)]·4H2O (Mr = 4048.00) was prepared from the hydrothermal reaction of Na2WO4·2H2O, CuCl2·2H2O,2,2'-bipyridine (2,2'-bpy) and H2O at 160 ℃ for 4 days. The compound crystallizes in the monoclinic system, space group P21/n with a = 18.9196(8), b = 20.4212(8), c = 21.8129(9)(A), β=96.992(3)°, V= 8365.0(6) (A)3, Dc= 3.214 g/cm3, Z = 4,μ(MoKα) = 17.269 mm-1 and F(000) = 7324.Of the 119837 total reflections, 17315 were unique (Rint = 0.0489). The final R = 0.0385 and wR =0.0770 for 11142 observed reflections with I ＞ 2σ(I). Single-crystal X-ray diffraction reveals that the structure is composed of [{Cu(2,2'-bpy)2}2W12O40(H2)]2- anions, discrete [Cu(2,2'-bpy)2]2 cations and lattice water molecules, and the anion is made up of a {W12O40(H2)}6- α-Keggin core decorated with two {Cu(2,2'-bpy)2}2 groups through bridging oxygen atoms.     

Variation in the coordination mode of arenedisulfonates: syntheses and structural characterization of mononuclear and dinuclear cadmium(II) arenedisulfonate complexes with two- to zero-dimensional architectures

Seven cadmium(II) arenedisulfonate compounds, namely [Cd(2,2'-bpy)(2)(H(2)O)(peds)].4H(2)O (1), [Cd(2)(2,2'-bpy)(4)(H(2)O)(2)(1,5nds)](1,5nds).4H(2)O (2), [Cd(cyclam)(1,5nds)](2) (3), ([Cd(inia)(2)(H(2)O)(2)(2,6nds)].4H(2)O)(n)(4), ([Cd(inia)(2)(H(2)O)(2)(bpds)].4H(2)O)(n)(5), ([Cd(2)(inia)(4)(H(2)O)(3)(peds)(2)].2H(2)O)(n)(6), and [Cd(1,5nds)(H(2)O)(2)](n) (7), where 2,2'-bpy = 2,2'-bipyridyl, cyclam = 1,4,8,11-tetraazacyclotetradecane, inia = isonicotinamide, nds = naphthalenedisulfonate, bpds = 4,4'-biphenyldisulfonate, and peds = 4,4'-phenyletherdisulfonate, have been obtained from aqueous solution by using similar procedures and structurally characterized by X-ray single-crystal diffraction, IR spectroscopy, and thermal gravimetric analysis. In 1, the peds anion coordinates as a monodentate ligand, leading to a mononuclear unit. In 2 and 3, the 1,5nds anions coordinate as mu(2)-bridging ligands in different modes, producing charged or neutral dinuclear clusters. In 4 and 5, 2,6nds and bpds behave as mu(2)-spacers, resulting in 1-dimensional polymers. While in 6, the peds acts both as terminal and bridging ligands with the SO(3)(-) groups being either monodentate or mu(2)-bridging, creating a knotted 1-dimensional polymer with dinuclear clusters as the repeating units. In 7, 1,5nds acts as a bridging ligand with each SO(3)(-) coordinated as a mu(2)-bridging group to adjacent Cd(II) centers, leading to a 2-dimensional polymer. Together with the reported ([Cu(en)(2)(1,5nds)].2H(2)O)(n) (8), all of the six possible coordination modes adopted by organodisulfonate anions, on the assumption that each SO(3)(-) group could be monodentate or mu(2)-bridging, are realized by introducing nitrogen-containing organic ligands as auxiliaries.     

New polynuclear manganese clusters from the use of the hydrophobic carboxylate ligand 2,2-dimethylbutyrate

The syntheses, structures, and magnetic properties are reported of [Mn12O12(O2CPe(t))16(MeOH)4] (4), [Mn6O2(O2CH2)(O2CPe(t))11(HO2CPe(t))2(O2CMe)] (5), [Mn9O6(OH)(CO3)(O2CPe(t))12(H2O)2] (6), and [Mn4O2(O2CPe(t))6(bpy)2] (7, bpy = 2,2'-bipyridine), where Pe(t) = tert-pentyl (Pe(t)CO2H = 2,2-dimethylbutyric acid). These complexes were all prepared from reactions of [Mn12O12(O2CPe(t))16(H2O)4] (3) in CH2Cl2. Complex 4 x 2MeCN crystallizes in the triclinic space group P1 and contains a central [Mn(IV)4O4] cubane core that is surrounded by a nonplanar ring of eight alternating Mn(III) and eight mu3-O(2-) ions. This is only the third Mn12 complex in which the four bound water molecules have been replaced by other ligands, in this case MeOH. Complex 5 x (1/2)CH2Cl2 crystallizes in the monoclinic space group P2(1)/c and contains two [Mn3(mu3-O)]7+ units linked at two of their apexes by two Pe(t)CO2(-) ligands and one mu4-CH2O2(2-) bridge. The complex is a new structural type in Mn chemistry, and also contains only the third example of a gem-diolate unit bridging four metal ions. Complex 6 x H2O x Pe(t)CO2H crystallizes in the orthorhombic space group Cmc2(1) and possesses a [Mn(III)9(mu3-O)6(mu-OH)(mu3-CO3)]12+ core. The molecule contains a mu3-CO3(2-) ion, the first example in a discrete Mn complex. Complex 7 x 2H2O crystallizes in the monoclinic space group P2(1)/c and contains a known [Mn(III)2Mn(II)2(mu3-O)2]6+ core that can be considered as two edge-sharing, triangular [Mn3O] units. Additionally, the synthesis and magnetic properties of a new enneanuclear cluster of formula [Mn9O7(O2CCH2Bu(t))13(THF)2] (8, THF = tetrahydrofuran) are reported. The molecule was obtained by the reaction of [Mn12O12(O2CCH2Bu(t))16(H2O)4] (2) with THF. Complexes 2 and 4 display quasireversible redox couples when examined by cyclic voltammetry in CH2Cl2; oxidations are observed at -0.07 V (2) and -0.21 V (4) vs ferrocene. The magnetic properties of complexes 4-8 have been studied by direct current (DC) and alternating current (AC) magnetic susceptibility techniques. The ground-state spin of 4 was established by magnetization measurements in the 1.80-4.00 K and 0.5-7 T ranges. Fitting of the reduced magnetization data by full matrix diagonalization, incorporating a full powder average and including only axial anisotropy, gave S = 10, g = 2.0(1), and D = -0.39(10) cm(-1). The complex exhibits two frequency-dependent out-of-phase AC susceptibility signals (chi(M)') indicative of slow magnetization relaxation. An Arrhenius plot obtained from chi(M)' vs T data gave an effective energy barrier to relaxation (U(eff)) of 62 and 35 K for the slower and faster relaxing species, respectively. These studies suggest that complex 4 is a single-molecule magnet (SMM). DC susceptibility studies on complexes 5-8 display overall antiferromagnetic behavior and indicate ground-state spin values of S < or = 2. AC susceptibility studies at < 10 K confirm these small values and indicate the population of low-lying excited states even at these low temperatures. This supports the small ground-state spin values to be due to spin frustration effects.     

2D copper(II) complex built from N-methyl-1,3-diamino-2-propanolate and azide ligands: structure, magnetic, and DFT studies

The synthesis, structural characterization, and magnetic behavior of a new 2D copper(II) compound with formula {[Cu2(mu-O2CMe)(mu-MedapO)(mu1,1-N3)2]n (CH3OH)n} 1, in which MedapOH is N-methyl-1,3-diamino-2-propanol is reported herein. 1 crystallizes in the triclinic system, space group P1, with unit cell parameters a = 6.688(5) A, b = 10.591(6) A, c = 12.100(7) A, alpha = 113.01(3) degrees, beta = 105.08(4) degrees, gamma = 93.93(3) degrees, Z = 2. The structure of 1 consists of neutral alternate 1D chains formed by the sequence of [Cu(1)-(mu1,1-N3)2-Cu(1)-(MedapO/acetate)-Cu(2)-(mu1,1-N3)2-Cu2)]. Each dinuclear [Cu(1)-Cu(2)] unit interacts with similar dinuclear units of neighbor chains in basis to large Cu-N(azido) distances to give a 2D arrangement. The magnetic behavior of 1 has been checked giving a net ferromagnetic coupling. The fit of the chiM versus T data as dinuclear compound affords a J value of 53.0 cm(-1) as a consequence of the orbital countercomplementarity phenomenon. The exchange pathways have been justified by density functional calculations.     

Two Metal-organic Frameworks（MOFs） Assembled from One Asymmetric Semirigid Multicarboxylate Ligand：Syntheses and Crystal Structural Characterizations

Hydrothermal reactions between a new flexible multicarboxylate ligand of 3-(2-carboxy-phenoxy)-benzoic acid(H2L) and transitional metal cations of M2+(M = Cu2+,Ni2+) in the presence of the secondary ligands of 1,10-phenanthroline(phen),2,2'-bipyridine(2,2?-bpy),and 4,4'-bipyridine(4,4'-bpy) afford two novel coordination polymers Ni2(H2O)2L2(phen)(μ-4,4'-bpy)(1) and CuIIL(2,2'-bpy)(2).Both compounds were characterized by X-ray crystallography.Crystal data of 1:C31H24N3NiO7,Mr = 609.24,monoclinic,space group P21/c,a = 17.560(8),b = 10.528(5),c = 30.613(15) ,V = 5659(5) 3,Z = 4,Dc = 1.430 g/cm3,F(000) = 502,μ = 0.739 mm-1,R = 0.0902,wR = 0.1346(I > 2σ(I)),S = 1.002.Crystal data of 2:C24H16CuN2O5,Mr = 475.93,monoclinic,space group P21/n,a = 9.8904(13),b = 11.0782(16),c = 18.321(3) ,β = 11.0782(16)°,V = 1993.8(5) 3,Z = 4,Dc = 1.585 g/cm3,F(000) = 972,μ = 1.137 mm-1,R = 0.0433,wR = 0.0723(I > 2σ(I)) and S = 1.004.Compound 1 displays a one-dimensional(1D) zigzag chain structure constructed from phen ligands and the deprotonated ligands of L2-,which further forms a ladder-shaped supramolecular architecture via the bridge of 4,4'-bpy ligand.Complex 2 also possesses a ladder-shaped architecture based on the dinuclear CuII units.     

Hydrogencyanamide-bridged one-dimensional polymers built on Mn(III)-Schiff base fragments: synthesis, structure, and magnetism

The ability of NCNH(-) to construct transition metal coordination polymers and to transmit magnetic coupling was investigated. By introduction of various tetradentate Schiff base ligands (L) and different solvents (S), nine NCNH(-)-bridged manganese(III) coordination complexes were obtained. Their structures can be divided into three types: I) NCNH-bridged chains built on mononuclear [Mn(III)(L)] units, [Mn(III)(L)(mu(1,3)-NCNH)](n) (L=5-Brsalen (1), 5-Clsalen (2)); II) NCNH-bridged chains built on dinuclear [Mn(III) (2)(L)(2)] units, complexes 3-8, [Mn(III) (2)(L)(2)(mu(1,3)-NCNH)]ClO(4)S (L=salen, 5-Fsalen, 5-Clsalen, 5-OCH(3)salen; S=CH(3)OH or C(2)H(5)OH); III) NCNH-bridged Mn(III) dimers linked by hydrogen bonds into a 1D polymer, {[Mn(III)(3-OCH(3)salen)(H(2)O)](2)(mu(1,3)-NCNH)}ClO(4) x 0.5 H(2)O (9, salen=N,N'-bis(salicylidene)-1,2-diaminoethane). In these complexes, the N[triple chemical bond]C--NH(-) resonance structure dominates the bonding mode of the NCNH(-) ligand adopting the mu(1,3)-bridging mode. Magnetic characterization shows that the asymmetric NCNH(-) bridge transmits antiferromagnetic interaction between Mn(III) ions and often favors the weak ferromagnetism caused by spin canting in these one-dimensional chains. However, these complexes exhibit different magnetic behaviors at low temperatures.     

Structural analysis, spectroscopic, and magnetic properties of the 1D triple-bridged compounds [M(dca)2(bpa)] (M = Mn, Fe, Co, Zn; dca = dicyanamide; bpa = 1,2-bis(4-pyridyl)ethane) and the 3D [Ni(dca)(bpa)2]dca·6H2O

The family of compounds [Mn(dca)(2)(bpa)] (1), [Fe(dca)(2)(bpa)] (2), [Co(dca)(2)(bpa)] (3), [Zn(dca)(2)(bpa)] (4), and [Ni(dca)(bpa)(2)]dca·6H(2)O (5), with dca = dicyanamide and bpa = 1,2-bis(4-pyridyl)ethane, has been synthesized. These compounds have been characterized by single crystal (1, 2, 4, and 5) and powder X-ray diffraction (3), by Fourier transform infrared (FTIR), UV-vis, and electron paramagnetic resonance (EPR) spectroscopies, and by magnetic measurements. Compound 1 crystallizes in the monoclinic C2/c space group, Z = 4, with a = 16.757(6), b = 9.692(3), and c = 13.073(4) ?, and β = 123.02(2)°; Compound 2 crystallizes in the monoclinic C2/c space group, Z = 4, with a = 16.588(5), b = 9.661(3), c = 12.970(5) ?, and β = 123.16(3)°; Compound 4 crystallizes in the monoclinic C2/c space group, Z = 4, with a = 16.519(2), b = 9.643(2), c = 12.943(2) ?, and β = 123.15(1)°; Compound 5 crystallizes in the monoclinic C2/c space group, Z = 4, with a = 18.504(4), b = 19.802(3), and c = 8.6570(18) ?, and β = 99.74(2)°. The compounds 1-4 are isostructural and show a one dimensional (1D) disposition, with the metal(II) ions bridged by double μ(1,5) dca ligands and unusually by a third bridge consisting of the bpa ligand, which adopts a very low torsion angle to accommodate in the structure. This kind of structure is unusual, even considering the voluminous bpa bridge. The compound 5 shows a 3D structure with layers of Ni-bpa joined by single dca bridges. Magnetic susceptibility measurements show antiferromagnetic couplings, increasing for 1-3. Compound 5 shows very slight antiferromagnetic interactions.     

Five new manganese-mu-azido 2D compounds synthesized in aqueous hydrazoic acid from pyrazine derivatives

The syntheses, structural characterization, and magnetic behavior of five new 2D manganese(II) complexes with empirical formulas [Mn(N(3))(2)(2,6-DiMepyz)(H(2)O)](n)() (1), [Mn(N(3))(2)(Etpyz)(H(2)O)](n)() (2), [Mn(N(3))(2)(H(2)O)(2)](n)()(2,3-DiMepyz)(n)() (3), [Mn(N(3))(2)(Clpyz)(2)](n)() (4), and [Mn(N(3))(2)(Ipyz)(2)](n)() (5) (pyz = pyrazine (1,4-diazine)) are reported. 1 crystallizes in the monoclinic system, space group P2(1)/c, with unit cell parameters a = 7.513(4) A, b = 17.438(7) A, c = 8.404(4) A, beta = 94.53(4) degrees , and Z = 4. 2 crystallizes in the triclinic system, space group P, with unit cell parameters a = 7.386(2) A, b = 8.434(2) A, c = 9.442(3) A, alpha = 71.82(2) degrees , beta = 72.08(2) degrees , gamma = 88.54(2) degrees , and Z = 2. 3 crystallizes in the monoclinic system, space group C2/c, with unit cell parameters a = 20.438(7) A, b = 7.711(2) A, c = 7.457(2) A, beta = 93.76(3) degrees , and Z = 4. 4 crystallizes in the orthorhombic system, space group Pbca, with unit cell parameters a = 8.600(2) A, b = 13.440(4) A, c = 24.083(7) A, and Z = 8. 5 crystallizes in the orthorhombic system, space group Pbca, with unit cell parameters a = 8.521(2) A, b = 13.787(3) A, c = 26.237(5) A, and Z = 8. The compounds 1-5 have only azido bridging ligands. In 1-3 each manganese atom is linked to the four nearest neighbors by only end-to-end azido bridges, forming square layers. 4 and 5 show alternating end-to-end and end-on azido bridges between manganese atoms. The magnetic properties of 1-5 are reported. At high temperatures the plots of chi(M) or chi(M)T vs T for the 1-3 compounds can be fitted as homogeneous 2D systems with J = -4.9, -4.4, and -3.9 cm(-)(1) for 1-3, respectively. For 1, 3, and 5 magnetic ordering and spontaneous magnetizations is achieved below T(c) = 35, 29, and 22 K, respectively, whereas 2 and 4 do not show spontaneous magnetization up to 2 K.     

Two new one-dimensional compounds with end-to-end dicyanamide as a bridging ligand: syntheses and structural characterization of trans-[Mn(4-bzpy)2(N(CN)2)2]n and cis-[Mn(Bpy)(N(CN)2)2]n, (4-bzpy = 4-benzoylpyridine; bpy = 2,2'-bipyridyl)

Two new one-dimensional compounds, trans-[Mn(4-bzpy)2(N(CN)2)2]n (1) and cis-[Mn(bpy)(N(CN)2)2]n (2), have been synthesized and studied from a magnetic point of view (4-bzpy = 4-benzoylpyridine; bpy = 2,2'-bipyridyl). The crystal structures of 1 and 2 have been solved. Compound 1 crystallizes in the monoclinic system, P2(1)/n group, a = 6.374(2) A, b = 7.584(2) A, c = 26.766(5) A, beta = 91.87 degrees, and Z = 2, whereas compound 2 crystallizes in the monoclinic system, C2/c group, a = 6.707(2) A, b = 17.188(5) A, c = 13.096(5) A, beta = 90.54 degrees, and Z = 4. The two compounds consist of chains with double mu 1,5-dicyanamide bridges between neighboring manganese(II) atoms. The weak antiferromagnetic coupling found for the two compounds (J = -0.3 cm-1 for 1 and -0.4 cm-1 for 2) has been studied by MO analysis, and the superexchange pathway through the mu 1,5-(NCNCN-) bridge has been compared with the shorter mu 1,3-(NNN-).     

Complementarity and countercomplementarity in polynuclear copper(II) complexes with R2NCH2CH(OH)CH2NR2 (R = H, CH3): crystal structures and magnetic study

The syntheses, structural characterization and magnetic behavior of five new copper(II) polynuclear compounds with formulae [Cu4(mu2-CH3COO)2(mu-bdmap)2(micro(1,5)-dca)2(dca)2(H2O)2] 1, [Cu2(mu2-CH3COO)(mu-bdap)(mu(1,1,5)-dca)(mu(1,3)-dca)]n 2, [Cu4(mu2-CH3COO)2(mu-bdmap)2(mu(1,1)-NCS)2(NCS)2] 3, [Cu2(mu2-CH3COO)(mu-bdap)(NCS)2] 4 and [Cu2(mu(1,3)-N3)(mu-bdmap)(N3)2]n 5 in which bdmapH is 1,3-bis(dimethylamino)-2-propanol, bdapH is 1,3-bis(amino)-2-propanol and dca is the anionic dicyanamide ligand, are reported herein. Tetranuclear complex 1 crystallizes in the monoclinic system, space group P2(1)/n, with unit cell parameters a = 8.284(8), b = 21.52(1), c = 11.432(3) A, beta = 105.19(2) degrees , Z = 2. Bi-dimensional complex 2 crystallizes in the triclinic system, space group P1, with unit cell parameters a = 8.184(5), b = 8.792(2), c = 10.887(2) A, alpha = 75.65(2), beta = 76.55(3), gamma = 74.36(3) degrees , Z = 2. Tetranuclear complex 3 crystallizes in the triclinic system, space group P1, with unit cell parameters a = 8.455(4), b = 9.114(9), c = 12.744(8) A, alpha = 104.62(8), beta = 99.86(6), gamma = 106.10(8) degrees, Z = 1. Dinuclear complex 4 crystallizes in the triclinic system, space group P1, with unit cell parameters a = 8.15(1), b = 8.18(2), c = 11.44(1) A, alpha = 69.39(2), beta = 80.36(2), gamma = 80.37(2) degrees , Z = 2. One-dimensional complex 5 crystallizes in the orthorhombic system, space group P2(1)2(1)2(1), with unit cell parameters a = 20.45(4), b = 11.36(3), c = 6.43(1) A, Z = 4. The magnetic behavior of all the complexes has been checked giving a bulk antiferromagnetic coupling in all the cases with |J| values in the range 109-144 cm(-1) for 1-4. Compound 5 is diamagnetic in the 2-300 K range of temperatures. The found J values 1-5 for can be justified from the structural data taking into account the orbital countercomplementarity for 1-4 and the orbital complementarity for 5.     

Two New Dinuclear MnII Cluster-based Metal-organic Frameworks: Syntheses,Crystal Structures,and Magnetic Properties

Two new dinuclear Mn^II cluster-based metal-organic frameworks, namely [Mn₂(L)(DMPU)₃]_n ( 1 ) and [Mn(L)_0.5(4,4'-bipy)_0.5(H₂O)]_n ( 2 ) (H₄L = biphenyl-3,3',5,5'-tetracarboxylic acid, DMPU = 1,3-dimethyltetrahydropyrimidin-2(1H)-one, 4,4'-bipy = 4,4'-bipyridine), were solvothermally synthesized and characterized by single-crystal X-ray diffraction, powder X-ray diffraction, and magnetic studies. Compound 1 crystallizes in the monoclinic P2₁/n space group and displays a 3D framework with 4-connected crb/BCT -type topology, and compound 2 crystallizes in the monoclinic C2/c space group and displays a 3D framework with (4,6)-connected sqc422 -type topology. The magnetic studies of compounds 1 and 2 show the presence of weak antiferromagnetic interactions within the dinuclear Mn^II units.     

Hydrothermal Synthesis and Crystal Structure of a Novel Dinuclear Co(Ⅱ) Complex:[Co2(2,2'-bpy)_2(μ-L)_2(L)_2(μ-H_2O)](HL=4-Chlorobenzoic Acid)

A new 4-chlorobenzoic acid bridge Co(Ⅱ) complex [Co2(2,2'-bpy)2(μ-L)2(L)2(μ-H2O)] (HL=4-chlorobenzoic acid) has been obtained by hydrothermal synthesis,and X-ray single-crystal diffraction analysis shows that it crystallizes in the monoclinic system,space group C2/c with a=22.537(5),b=16.212(3),c=15.306(3) ,β=124.37(3)°,V=4616.1(16) 3,Mr=1070.45,Dc=1.540 g/cm3,Z=4,μ=1.012 mm-1,F(000)=2176,the final R=0.0338 and wR=0.0810. The title complex is composed of dinuclear [Co2(2,2'-bpy)2(μ-L)2(L)2(μ-H2O)] molecules. Each Co(Ⅱ) atom is coordinated by two nitrogen atoms from one 2,2'-bipyridine ligand,three oxygen atoms from three 4-chlorobenzoic ions and another oxygen atom from one water molecule. The two Co(Ⅱ) atoms are connected by two 4-chlorobenzoic ions and one bridged water molecule. The dinuclear molecules are interlinked by hydrogen bond and π-π stacking interactions into a three-dimensional supramolecular network.     

含2,3-吡嗪二羧酸的镉配位聚合物的合成、晶体结构和荧光性质

在水溶液中合成了含2,3-吡嗪二羧酸配体的3个镉配位聚合物,{[Cd(pzdc)(2,2′-bpy)]·H₂O}_n(1),{[Cd(pzdc)(2,2′-bpy)]2H₂O}_n (2)和{[Cd(pzdc)(H₂O)₂]·2H₂O}_n (3)。配合物1属单斜晶系,P2₁/c空间群;配合物2为单斜晶系,P2₁/n空间群;配合物3为单斜晶系,P2₁/c空间群。每个pzdc配体通过4个配位原子与3个金属Cd配位,在配合物1和2中形成了具有(4,8²)网格状的二维平面构型,而在配合物3中得到了一维链状和氢键3D网络结构。尽管配合物1和2的分子只是结晶水分子数目存在差异,且具有相同的(4,8²)网格状二维平面构型,但是他们的分子结构趋向存在很大差别。配合物1和3的荧光光谱均在415 nm处出现较强的发射峰。     

Syntheses and Characterizations of Two New Coordination Polymers Based on Dicarboxylate and Nitrogen-contained Mixed Ligands

Two new carboxylate coordination polymers [Ni(2,3'-oba)(bib)]n] and [Mn(2,4'-oba)(bib)0.5]n(2,3'-oba = 2-(3-carboxyphenoxy)benzoic acid,2,4'-oba = 2-(4-carboxyphenoxy) ben-zoic acid and bib = 1,4-bis(2-methyl-imidazol-yl)butane) have been synthesized and characterized by elemental analysis,IR and X-ray single-crystal diffraction studies.Compound 1 crystallizes in monoclinic,space group P21/c,while compound 2 in the triclinic space group P.Compound 1 displays a one-dimensional ladder-like chain.The dinuclear paddle-wheel secondary building units(SBUs) constructed by four 2,4'-oba2-ligands in compound 2 are linked by bib into a 2D(4,4) layer structure.     

Assembly of heterometallic clusters and coordination polymers by combining Mo-S-based clusters with Mn2+

Addition of [Mo(V)2O2S2(edt)2]2- (edt =1,2-ethanedithiolate) to acetonitrile and/or methanol solutions of MnII containing bipyridines [4,4'-trimethylenedipyridine (TDP), 4,4'-bipyridine (4,4'-bpy), 2,2'-bipyridine (2,2'-bpy)] or 15-crown-5 produces three new heterometallic cluster coordination polymers, [Mn2[Mo2O2S2(edt)2]2(TDP)3(CH3OH)2(NCMe)2].3CH3OH.0.25MeCN (1), [Mn(TDP)2(H2O)2]2+[Mn[Mo2O2S2(edt)2)2(TDP)2]]2-.6CH3OH (2), [Mn[Mo2O2S2(edt)2](TDP)2(CH3OH)(H2O)].CH3OH (3), and three new multinuclear clusters, [Mn[Mo2O2S2(edt)2](4,4'-bpy)(CH3OH)4].0.5(4,4'-bpy) (4), [Mn[Mo2O2S2(edt)2](2,2'-bpy)2].2CH3OH (5), and (NEt4)2[Mn(15-crown-5)[Mo2O2S2(edt)2]2] (6). All compounds were characterized by X-ray crystallography. The coordination mode of Mn in these compounds depends on the ligands and the crystallization conditions. Compound 2 readily converts to 1 or 3 depending on the reaction and solvent conditions. Compounds 1 and 2 were analyzed using thermogravimetric analysis combined with mass spectroscopy (TG-MS) in the temperature range 25-500 degrees C. The room-temperature magnetic moments for compounds 1-6 were determined.     

Polymeric networks of copper(II) phenylmalonate with heteroaromatic n-donor ligands: synthesis, crystal structure, and magnetic properties

Two new phenylmalonate-bridged copper(II) complexes with the formulas [Cu(4,4'-bpy)(Phmal)](n).2nH(2)O (1) and [Cu(2,4'-bpy)(Phmal)(H(2)O)](n)() (2) (Phmal = phenylmalonate dianion, 4,4'-bpy = 4,4'-bipyridine, 2,4'-bpy = 2,4'-bipyridine) have been synthesized and characterized by X-ray diffraction. Complex 1 crystallizes in monoclinic space group P2(1), Z = 4, with unit cell parameters of a = 9.0837(6) Angstroms, b = 9.3514(4) Angstroms, c = 11.0831(8) Angstroms, and beta = 107.807(6) degrees , whereas complex 2 crystallizes in orthorhombic space group C2cb, Z = 8, with unit cell parameters of a = 10.1579(7) Angstroms, b = 10.3640(8) Angstroms, and c = 33.313(4) Angstroms. The structures of 1 and 2 consist of layers of copper(II) ions with bridging bis-monodentate phenylmalonate (1 and 2) and 4,4'-bpy (1) ligands and terminal monodentate 2,4'-bpy (2) groups. Each layer in 1 contains rectangles with dimensions of 11.08 x 4.99 Angstroms(2), the edges being defined by the Phmal and 4,4'-bpy ligands. The intralayer copper-copper separations in 1 through the anti-syn equatorial-apical carboxylate-bridge and the 4,4'-bpy molecule are 4.9922(4) and 11.083(1) Angstroms, respectively. The anti-syn equatorial-equatorial carboxylate bridge links the copper(II) atoms in complex 2 within each layer with a mean copper-copper separation of 5.3709(8) Angstroms. The presence of 2,4'-bpy as a terminal ligand accounts for the large interlayer separation of 15.22 Angstroms. The copper(II) environment presents a static pseudo-Jahn-Teller disorder which has been studied by EPR and low-temperature X-ray diffraction. Magnetic susceptibility measurements of both compounds in the temperature range 2-290 K show the occurrence of weak antiferromagnetic [J = -0.59(1) cm(-1) (1)] and ferromagnetic [J = +0.77(1) cm(-1) (2)] interactions between the copper(II) ions. The conformation of the phenylmalonate-carboxylate bridge and other structural factors, such as the planarity of the exchange pathway in 1, account for the different nature of the magnetic interaction.     

1,3-dialkyl- and 1,3-diaryl-3,4,5,6-tetrahydropyrimidin-2-ylidene rhodium(i) and palladium(II) complexes: synthesis, structure, and reactivity

The synthesis of novel 1,3-diaryl- and 1,3-dialkylpyrimidin-2-ylidene-based N-heterocyclic carbenes (NHCs) and their rhodium(i) and palladium(II) complexes is described. The rhodium compounds bromo(cod)[1,3-bis(2-propyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene]rhodium (7), bromo(cod)(1,3-dimesityl-3,4,5,6-tetrahydropyrimidin-2-ylidene)rhodium (8) (cod=eta(4)-1,5-cyclooctadiene, mesityl=2,4,6-trimethylphenyl), chloro(cod)(1,3-dimesityl-3,4,5,6-tetrahydropyrimidin-2-ylidene)rhodium (9), and chloro(cod)[1,3-bis(2-propyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene]rhodium (10) were prepared by reaction of [[Rh(cod)Cl](2)] with lithium tert-butoxide followed by addition of 1,3-dimesityl-3,4,5,6-tetrahydropyrimidinium bromide (3), 1,3-dimesityl-3,4,5,6-tetrahydropyrimidinium tetrafluoroborate (4), 1,3-di-2-propyl-3,4,5,6-tetrahydropyrimidinium bromide (6), and 1,3-di-2-propyl-3,4,5,6-tetrahydropyrimidinium tetrafluoroborate, respectively. Complex 7 crystallizes in the monoclinic space group P2(1)/n, and 8 in the monoclinic space group P2(1). Complexes 9 and 10 were used for the synthesis of the corresponding dicarbonyl complexes dicarbonylchloro(1,3-dimesityl-3,4,5,6-tetrahydropyrimidin-2-ylidene)rhodium (11), and dicarbonylchloro[1,3-bis(2-propyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene]rhodium (12). The wavenumbers nu(CO I)/nu(CO II) for 11 and 12 were used as a quantitative measure for the basicity of the NHC ligand. The values of 2062/1976 and 2063/1982 cm(-1), respectively, indicate that the new NHCs are among the most basic cyclic ligands reported so far. Compounds 3 and 6 were additionally converted to the corresponding cationic silver(i) bis-NHC complexes [Ag(1,3-dimesityl-3,4,5,6-tetrahydropyrimidin-2-ylidene)(2)]AgBr(2) (13) and [Ag[1,3-bis(2-propyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene](2)]AgBr(2) (14), which were subsequently used in transmetalation reactions for the synthesis of the corresponding palladium(II) complexes Pd(1,3-dimesityl-3,4,5,6-tetrahydropyrimidin-2-ylidene)(2) (2+)(Ag(2)Br(2)Cl(4) (4-))(1/2) (15) and Pd[1,3-bis(2-propyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene)(2)]Cl(2) (16). Complex 15 crystallizes in the monoclinic space group P2(1)/c, and 16 in the monoclinic space group C(2)/c. The catalytic activity of 15 and 16 in Heck-type reactions was studied in detail. Both compounds are highly active in the coupling of aliphatic and aromatic vinyl compounds with aryl bromides and chlorides with turnover numbers (TONs) up to 2000000. Stabilities of 15 and 16 under Heck-couplings conditions were correlated with their molecular structure. Finally, selected kinetic data for these couplings are presented.