Synthesis, characterization, crystal structure and preliminary reactivity behaviour of new heteropolytopic ligands based on the 1,3,5-triazine spacer and pyrazolyl, tris-pyrazolylmethyl and tris-pyrazolylethoxy bonding fragments

Four new potentially polytopic nitrogen donor ligands based on the 1,3,5-triazine fragment, L(1)-L(4) (L(1) = 2-chloro-4,6-di(1H-pyrazol-1-yl)-1,3,5-triazine, L(2) = N,N'-bis(4,6-di(1H-pyrazol-1-yl)-1,3,5-triazin-2-yl)ethane-1,2-diamine, L(3) = 2,4,6-tris(tri(1H-pyrazol-1-yl)methyl)-1,3,5-triazine, and L(4) = 2,4,6-tris(2,2,2-tri(1H-pyrazol-1-yl)ethoxy)-1,3,5-triazine) have been synthesized and characterized. The X-ray crystal structure of L(3) confirms that its molecular nature consists of a 1,3,5-triazine ring bearing three tripodal tris(pyrazolyl) arms. L(1), L(2), and L(4) react with Cu(I), Cu(II), Pd(II) and Ag(I) salts yielding mono-, di-, and oligonuclear derivatives: [Cu(L(1))(Cy(3)P)]ClO(4), [{Ag(2)(L(2))}(CF(3)SO(3))(2)]·H(2)O, [Cu(2)(L(2))(NO(3))(2)](NO(3))(2)·H(2)O, [Cu(2)(L(2))(CH(3)COO)(2)](CH(3)COO)(2)·3H(2)O, [Pd(2)(L(2))(Cl)(4)]·2H(2)O, [Ru(L(2))(Cl)(OH)]·CH(3)OH, [Ag(3)(L(4))(2)](CF(3)SO(3))(3) and [Ag(3)(L(4))(2)](BF(4))(3). The interaction of L(3) with Ag(I), Cu(II), Zn(II) and Ru(II) complexes unexpectedly produced the hydrolysis of the ligand with formation, in all cases, of tris(pyrazolyl)methane (TPM) derivatives. In detail, the already known [Ag(TPM)(2)](CF(3)SO(3)) and [Cu(TPM)(2)](NO(3))(2), as well as the new [Zn(TPM)(2)](CF(3)SO(3))(2) and [Ru(TMP)(p-cymene)]Cl(OH)·2H(2)O complexes have been isolated. Single-crystal XRD determinations on the latter derivatives confirm their formulation, evidencing, for the Ru(II) complex, an interesting supramolecular arrangement of the anions and crystallization water molecules.     

Transformations of the natural cytokinin N6-isopentenyladenine in aqueous acidic media: structural aspects

N6-Isopentenyladenine (L1) was subjected to variously acidic media in 0.1 M, 1 M and 2 M HCl. In dependence on the acidity of the medium, the formation of three main acid hydrolysis products, involving the N6-isopentenyladeninium (HL1) (1), 7,8,9,10-tetrahydro-7,7-dimethyl-3H-pyrimido[2,1-i]purin-6-ium (HL2) (2) or 5-amino-4-(4,4-dimethyl-3,4,5,6-tetrahydropyrimidin-2-yl)-imidazolium (H(2)L3) (3-5) cations, were determined and characterized by multinuclear solution-state NMR spectroscopy and in the solid state by single crystal X-ray analysis. The coordination abilities of these transformation products have been also investigated. The compounds of the compositions [Zn(HL1)Cl(3)]·H(2)O (1), [Zn(3)(HL2)(2)Cl(8)] (2), (H(2)L3)[CuCl(4)] (4) and (H(2)L3)[ZnCl(4)] (5) have been prepared in dependence on the acidity of the medium used by the reactions of L1 with ZnCl(2)·1.5H(2)O or CuCl(2)·2H(2)O. Based on the NMR spectroscopic and X-ray crystallographic results, the mechanism of transformation of L1 in the acidic medium, involving the protonation, cyclization and ring fission, has been suggested.     

The halogen bond made visible: experimental charge density of a very short intermolecular Cl···Cl donor-acceptor contact

[ZnCl(2)(3,4,5-trichloropyridine)(2)] features short intermolecular Cl···Cl contacts between halogen atoms of different nature, and a charge density study provides experimental evidence for the accepted model of the halogen bonds: an arene-bonded Cl atom acts as a donor of electron density towards the "sigma hole" of a chlorido ligand attached to a neighbouring Zn(II) cation.     

Zinc paddlewheel dimers containing a strong π···π stacking supramolecular synthon: designed single-crystal to single-crystal phase changes and gas/solid guest exchange

The ligand 4-(1,8-naphthalimido)benzoate, L(C4)(-), containing a linear link between the strong π···π stacking 1,8-naphthalimide supramolecular synthon and the carboxylate donor group, reacts with Zn(O(2)CCH(3))(2)(H(2)O)(2) in the presence of dimethylsulfoxide (DMSO) to yield [Zn(2)(L(C4))(4)(DMSO)(2)]·2(CH(2)Cl(2)). This compound contains the "paddlewheel" Zn(2)(O(2)CR)(4) secondary building unit (SBU) that organizes the rigid phenylene and naphthalimide rings of the carboxylate ligands in a square arrangement. The supramolecular architecture is dominated by π···π stacking interactions between naphthalimide rings of one dimer with four adjacent dimers, essentially at right angles, forming an open three-dimensional network structure. Two symmetry equivalent networks of this type interpenetrate generating overall a densely packed three-dimensional, 2-fold interpenetrated architecture in which the CH(2)Cl(2) solvate molecules are trapped in isolated pockets. Upon cooling, single crystals of [Zn(2)(L(C4))(4)(DMSO)(2)]·2(CH(2)Cl(2)) undergo two distinct crystallographic phase transitions, as characterized by X-ray diffraction at different temperatures, without loss of crystallinity. These two new phases have supramolecular structures very similar to the room temperature structure, but changes in the ordering of the CH(2)Cl(2) solvate cause shifting of the naphthalimide rings and a lowering of the symmetry. Crystals of [Zn(2)(L(C4))(4)(DMSO)(2)]·2(CH(2)Cl(2)) undergo a single-crystal to single-crystal gas/solid guest exchange upon exposure to atmospheric moisture, or faster if placed under vacuum or heated under dry gas to 100 °C, followed by atmospheric moisture, to yield [Zn(2)(L(C4))(4)(DMSO)(2)]·3.9(H(2)O). The molecular and supramolecular structures of this new compound are very similar to the dichloromethane adduct, with now the water molecules encapsulated into the framework. The remarkable feature of both the phase changes and exchange of solvates is that this robust network is not porous; local distortions (ring slippage and tilting changes) of the π···π stacking interactions of the naphthalimide rings that organize these structures allow these changes to take place without the loss of crystallinity. The complexes [Zn(2)(L(C4))(4)(DMSO)(2)]·2(CH(2)Cl(2)) and [Zn(2)(L(C4))(4)(DMSO)(2)]·3.9(H(2)O) show green emission in the solid state.     

TTF salts of optically pure cobalt pyridine amidates; detection of soluble assemblies with stoichiometry corresponding to the solid state

Optically pure anionic complexes of pyridinecarboxamide ligands, N(2),N(6)-bis((R)-α-methylbenzyl)pyridine-2, 6-dicarboxamide H(2)(R,R-L(1)) and N(2),N(6)-bis((S)-1-methoxypropan-2-yl)pyridine-2, 6-dicarboxamide H(2)(S,S-L(2)) have been synthesised and fully characterised. The complexes: (18-crown-6)K[Co(III)(R,R-L(1))(2)], (18-crown-6)K[Fe(III)(R,R-L(1))(2)] and K[Co(III)(S,S-L(2))(2)]·3H(2)O show interesting extended structures from 0D discrete units through 1D zigzag chains to 2D honeycomb layers. The complex anions were used in the synthesis of radical cation salts with tetrathiafulvalene (TTF). The salts (TTF)[Co(III)(R,R-L(1))(2)] and (TTF)[Co(III)(S,S-L(2))(2)]·EtOAc were characterised by single crystal X-ray diffraction and conductivity measurements. Both compounds comprise mono-oxidised TTF molecules and exhibit similar layered structures with no direct TTF stacking but in which phenyl substituents from the complex anion or co-crystallised ethyl acetate alternate with TTF(+) units. Solution spectroscopic and cyclic voltammetric evidence points to the formation of soluble assemblies between TTF(+) and the counterion which correspond to the stoichiometry observed by crystallography and other methods in the solid state.     

Hydrothermal synthesis, structure, and luminescent properties of selected Zn(II)/Cd(II) coordination polymers constructed from 3,5-bis(x-pyridyl)-1,2,4-triazole (x = 3, 4)

Utilizing 3,5-bis(x-pyridyl)-1,2,4-triazole (x-Hpytz, x = 3; x = 4) as multidentate ligands, six novel coordination polymers with Zn(II) or Cd(II) metal ions were prepared: [Zn(3-pytz)(0.5)(OH)(0.5)Cl](n) (1, 1D ladder), {[Zn(3-Hpytz)(H(2)O)(4)] [Zn(3-Hpytz)(H(2)O)(3)·SO(4)]SO(4)·5H(2)O}(n) (2·5H(2)O, 1D chain), [Cd(3-Hpytz)(SO(4))](n) (3, 3D framework), {[Cd(3-Hyptz)SO(4)·3H(2)O]·2H(2)O}(n) (4·2H(2)O, 1D chain), [Zn(4-pytz)Cl](n) (5, 3D framework) and [Zn(2)(4-pytz)(SO(4))(OH)](n) (6, 3D framework). All compounds were obtained from hydrothermal reactions, with the exception of compound 4 which was obtained by solvent diffusion at room temperature. All compounds were characterized by FTIR, elemental analysis and TGA analysis and their structures were determined by X-ray diffraction. All compounds exhibited substantial thermal stability and showed photofluorescent properties that resulted from ligand π-π* transition.     

A series of single, double, and triple Me2biim-bridged dinuclear, trinuclear, and polymeric complexes: syntheses, crystal structures, and luminescent properties

Reaction of ZnCl(2) and Me(2)biim (Me(2)biim = N,N'-dimethyl-2,2-'-biimidazole) in acidic or neutral aqueous solutions gave the noncoordinated ZnCl(4).H(2)Me(2)biim (1) or the double Me(2)biim bridged [Zn(2)Cl(4)(mu-Me(2)biim)(2)] (2). Use of CdX(2) (X = Cl, Br, I) instead of ZnCl(2) yielded the single Me(2)biim bridged one-dimensional coordination polymer [CdX(2)(mu-Me(2)biim)](n) (X = Cl, 3; Br, 4; I, 5). The stacking of the infinite chains are dominated by C-H...X interactions in 3 and 4 but by I...I interactions in 5, responsible for their different crystal structures. Use of Zn(NO(3))(2) instead of ZnCl(2) produced the novel triple Me(2)biim-bridged [Zn(2)(mu-Me(2)biim)(3)(H(2)O)(2)](NO(3))(4).H(2)O (6). The unprecedented hexa-Me(2)bim bridged trinuclear [Cd(3)(mu-Me(2)biim)(8)](2)(ClO(4))(12)(H(2)O)(6) (7) was obtained by using Cd(CH(3)CO(2))(2) in the presence of NaClO(4). Compounds 1-7 were characterized by X-ray crystallography and IR. Examination of photophysical properties of 1-7 indicates that the fluorescence emission of Me(2)biim has been effectively enhanced, quenched, or shifted in its metal complexes 1-7.     

Synthesis,Structure and Luminescent Properties of [Zn(btzb)2Cl2]·2H2O[btzb=1,2-Bis(5-tetrazolyl)benzene]

The title compound[Zn(btzb)2Cl2]·2H2O(1·2H2O,btzb=1,2-bis(5-tetrazolyl)benzene)was synthesized in situ by the[2 3] cycloaddition reaction of phthalonitrile with NaN3 in water in the presence of ZnCl2 under refluxing conditions.1·2H2O crystallizes in the monoclinic system,space group P21/c with a=9.0119(18),b=7.5566(15),c=18.076(5)(A),β=114.67(2)°,V=1118.6(4)(A)3,Z=2,Dc=1.784 g/cm3 T=223(2)K,C16H16N16O2Cl2Zn,Mr=600.74,F(000)=608,μ(MoKα)=1.393 mm-1,S=1.081,R=0.0306 and wR=0.0669 for 1896 observed reflections with Ⅰ ＞2σ(Ⅰ).The Zn2 ion of 1 is coordinated by four N atoms from two btzb ligands and two Cl atoms,forming a distorted octahedral coordination geometry.A number of intermolecular hydrogen bonding interactions between molecules 1 and/or the solvated water molecules result in a 3D hydrogen-bonded structure.The luminescent property of 1·2H2O was also investigated.     

Lasagna-type arrays with halide-nitromethane cluster filling. The first recognition of the Hal(-)···HCH2NO2 (Hal = Cl, Br, I) hydrogen bonding

The previously predicted ability of the methyl group of nitromethane to form hydrogen bonding with halides is now confirmed experimentally based on X-ray data of novel nitromethane solvates followed by theoretical ab initio calculations at the MP2 level of theory. The cationic (1,3,5-triazapentadiene)Pt(II) complexes [Pt{HN=C(NC(5)H(10))N(Ph)C(NH(2))=NPh}(2)](Cl)(2), [1](Hal)(2) (Hal = Cl, Br, I), and [Pt{HN=C(NC(4)H(8)O)N(Ph)C(NH(2))=NPh}(2)](Cl)(2), [2](Cl)(2), were crystallized from MeNO(2)-containing systems providing nitromethane solvates studied by X-ray diffraction. In the crystal structure of [1][(Hal)(2)(MeNO(2))(2)] (Hal = Cl, Br, I) and [2][(Cl)(2)(MeNO(2))(2)], the solvated MeNO(2) molecules occupy vacant spaces between lasagna-type layers and connect to the Hal(-) ion through a weak hydrogen bridge via the H atom of the methyl thus forming, by means of the Hal(-)···HCH(2)NO(2) contact, the halide-nitromethane cluster "filling". The quantum-chemical calculations demonstrated that the short distance between the Hal(-) anion and the hydrogen atom of nitromethane in clusters [1][(Hal)(2)(MeNO(2))(2)] and [2][(Cl)(2)(MeNO(2))(2)] is not just a consequence of the packing effect but a result of the moderately strong hydrogen bonding.     

Poly(pyrazolyl)aluminate complexes containing aluminum-hydrogen bonds

The treatment of LiAlH(4) with 2, 3, or 4 equiv of the 3,5-disubstituted pyrazoles Ph(2)pzH or iPr(2)pzH afforded [Li(THF)(2)][AlH(2)(Ph(2)pz)(2)] (97%), [Li(THF)][AlH(Ph(2)pz)(3)] (96%), [Li(THF)(4)][Al(Ph(2)pz)(4)] (95%), and [Li(THF)][AlH(iPr(2)pz)(3)] (89%). The treatment of ZnCl(2) with [Li(THF)][AlH(Ph(2)pz)(3)] afforded Zn(AlH(Ph(2)Pz)(3))H (70%). X-ray crystal structures of these complexes demonstrated κ(2) or κ(3) coordination of the aluminum-based ligands to the Li or Zn ions. The treatment of [Li(THF)][AlH(Ph(2)pz)(3)] with MgBr(2) or CoCl(2) in THF/Et(2)O solutions, by contrast, afforded the pyrazolate transfer products Mg(2)Br(2)(Ph(2)pz)(2)(THF)(3)·2THF (25%) and Co(2)Cl(2)(Ph(2)pz)(2)(THF)(3)·THF (23%) as colorless and blue crystalline solids, respectively. An analogous treatment of [Li(THF)][AlH(Ph(2)pz)(3)] with MCl(2) (M = Mn, Fe, Ni, Cu) afforded metal powders and H(2), illustrating hydride transfer from Al to M as a competing reaction path.     

一个由咪唑衍生物构筑的二重穿插的锌配位聚合物的合成、结构及荧光性质

以ZnCl2、H3IDC(咪唑-4,5-二羧酸)和bix(1,4-双(咪唑基-1-甲基)-苯)为原料,在水热条件下得到了1个新的二重穿插的三维层-柱状金属-有机框架结构的配位聚合物{[Zn3(IDC)(bix)1.5Cl3].0.25H2O}n(1),并通过元素分析、红外光谱、热重分析以及单晶X-射线结构分析对其组成和结构进行了表征。单晶X-射线结构分析表明,配合物1的晶体属于单斜晶系,P21/c空间群,a=1.158 44(17)nm,b=1.088 75(16)nm,c=2.391 7(3)nm,β=96.835(2)°,V=2.995 1(8)nm3,Z=4,Dc=1.813 g.cm-3,F(000)=1 638,对于4 772个可观测点(I>2σ(I)),最终残差因子R1=0.037 9,wR2=0.089 6。在配合物1中,每个IDC3-分别桥联4个锌(Ⅱ)离子形成一维锯齿形链状结构,一维链通过cis-μ2-bix的2个氮原子连接形成二维网状结构,相邻的二维层之间再通过trans-μ2-bix的2个氮原子进一步连接形成了二重穿插的三维层-柱状金属-有机框架结构。固体室温荧光测试结果表明,配合物1在波长为400 nm的光激发下于468 nm处出现强烈的荧光发射。     

二{桥-2，4，6-三[二(2-吡啶基)胺]-1，3，5-三嗪-N，N′，N ″，N′′′}·四氯合二锌(Ⅱ)的合成与晶体结构(英)

A dinuclear Zn(Ⅱ) complex C₆₆H₄₈Cl₄N₂₄Zn₂·2CH₃OH·2H₂O (1) was synthesized and characterized by X-ray crystallography. In the complex, two 2,4,6-tris[bis(2-pyridyl)amino]-1,3,5-triazine ligands are bridged together by two zinc(Ⅱ) ions and stacked in a parallel manner. CCDC: 267649.     

The donor ability of the chelated carbonate ligand: protonation and metallation of [(L)Co(O2CO)]+ complexes in aqueous solution

The syntheses and X-ray structures of [Co(Me-tpa)O(2)COZnCl(3)], [Co(pmea)O(2)COZnCl(3)].H(2)O [Co(trpyn)O(2)COZn(OH(2))(4)OCO(2)Co(trpyn)](ZnCl(4))(2).H(2)O, [Co(trpyn)(O(2)COH)]ZnCl(4).3H(2)O and [Co(trpyn)(O(2)CO)]ClO(4) are reported (Me-tpa = [(6-methyl-2-pyridyl)methyl]bis(2-pyridylmethyl)amine, pmea = bis(2-pyridylmethyl)-2-(2-pyridylethyl)amine, trpyn = tris(2-(1-pyrazolyl)ethyl)amine). The chelated bicarbonate complex [Co(trpyn)(O(2)COH)]ZnCl(4).3H(2)O is isolated as a crystalline solid from an acidic solution of the parent carbonate [Co(trpyn)(O(2)CO)]ClO(4), and X-ray structural analysis shows that lengthening of the C[double bond, length as m-dash]O(exo) bond and shortening of the C-O(endo) bond accompanies protonation. The bimetallic complex [Co(Me-tpa)O(2)COZnCl(3)] results from the unexpected coordination of ZnCl(3)(-) to the exo O atom of a chelated carbonate ligand. This complex is obtained from both acidic and neutral solutions in which [Zn(2+)] = 1.0 M, while the structurally similar complex [Co(pmea)O(2)COZnCl(3)].H(2)O is isolated from an analogous neutral solution. The trimetallic complex [Co(trpyn)O(2)COZn(OH(2))(4)OCO(2)Co(trpyn)](ZnCl(4))(2).H(2)O crystallises on prolonged standing of [Co(trpyn)(O(2)CO)]ClO(4) in a neutral solution having [Zn(2+)] = 1.0 M. The Zn-O bond lengths in all three complexes are indicative of bonds of significant strength. DFT calculations show that the nature of the bonding interaction between the Co(iii) ion and the endo O atoms of the carbonate ligand remain essentially unaffected by coordination of Zn(2+) to the exo O atom. They also show that such coordination of Zn(2+) decreases the C-O(exo) bond order.     

Group 6 complexes with iron and zinc heterometals: understanding the structural, spectroscopic, and electrochemical properties of a complete series of M≡M···M' compounds

Binuclear quadruply bonded complexes Cr(2)(dpa)(4) (1, dpa = 2,2'-dipyridylamide), Mo(2)(dpa)(4) (2), and W(2)(dpa)(4) (3) react with anhydrous FeCl(2), yielding heterometallic compounds CrCrFe(dpa)(4)Cl(2) (4), MoMoFe(dpa)(4)Cl(2) (5), and WWFe(dpa)(4)Cl(2) (6). These molecules are structurally similar, having a linear M≡M···Fe chain that is axially capped by chloride ions and is equatorially supported by the helically twisted dpa ligands. A structurally related zinc analog, CrCrZn(dpa)(4)Cl(2) (7), can be prepared upon metalation of 1 with ZnCl(2). This reaction also persistently produces a 2:1 adduct of ZnCl(2) with 1, [Cr(2)(dpa)(4)](ZnCl(2))(2) (8), which is in equilibrium with 7 and has the two zinc ions bound externally to the Cr(2) core and axial bridging chloro ligands attached to each Cr ion. The sole isolable product of the addition of ZnCl(2) to 3 is a 1:1 adduct, [W(2)(dpa)(4)]ZnCl(2) (9). The structurally related chain complexes 4, 5, 6, and 7 are characterized by X-ray crystallography, UV-vis spectroscopy, cyclic voltammetry, and (57)Fe Mo?ssbauer spectroscopy for the iron complexes in order to gain insights into the nature of heterometallic interactions, electronic excited states, and redox properties of these compounds, which have implications for all other M≡M···M' molecules. Additionally, NMR spectroscopy has been used to gain insight into the mechanism of the metalation of 1 by Zn(II).     

2-(N，N-二羧甲基氨甲基)氢醌金属配合物(钴、镍、锌)的合成、晶体结构及电化学性质研究

合成了3个新的氢醌金属配合物:[Co(H2cah)(H2O)2].H2O(1),Ni(H2cah)(H2O)2].H2O(2),[Zn(H2cah)(CH3OH)(H2O)].H2O(3)(H4cah=2-(N,N-二羧甲酸氨甲基)氢醌),通过X-射线单晶衍射,红外光谱,元素分析对它们进行了表征。这些配合物均为单核结构,并且通过分子间的氢键形成了无限的超分子网状结构。电化学研究显示配合物1中的Co2+/Co+对和配合物2中的Ni2+/Ni+对的氧化还原是一个不可逆的过程,但是氢醌到半醌之间的转换是一个准可逆的过程。     

Reactions of a gold(I) thiolate complex [Au(Tab)(2)](2)(PF(6))(2) (Tab = 4-(trimethylammonio)benzenethiolate) with diphosphine ligands

Reactions of a gold(i) thiolate complex [Au(Tab)(2)](2)(PF(6))(2) (Tab = 4-(trimethylammonio)benzenethiolate) with equimolar 1,2-bis(diphenylphosphine)ethane (dppe), 1,3-bis-(diphenylphosphine)propane (dppp) or 1,4-bis-(diphenylphosphine)butane (dppb) in MeOH-DMF-CH(2)Cl(2) gave rise to three polymeric complexes [Au(2)(Tab)(2)(dppe)](2)(PF(6))(4)·2MeOH (1·2MeOH), [Au(2)(Tab)(2)(dppp)]Cl(2)·0.5MeOH·4H(2)O (2·0.5MeOH·4H(2)O), and [Au(4)(μ-Tab)(2)(Tab)(2)(dppb)](PF(6))(4)·4DMF (3·4DMF), respectively. Analogous reaction of 1 with dppb in DMF/C(2)H(4)Cl(2) produced one tetranuclear complex [Au(2)(μ-Tab)(Tab)(2)](2)Cl(4)·2DMF·4H(2)O (4·2DMF·4H(2)O). Complexes 1-4 were characterized by elemental analysis, IR spectra, UV-vis spectra, (1)H and (31)P{(1)H} NMR and single crystal X-ray analysis. Compounds 1 and 2 consist of [Au(Tab)](2) dimeric fragments that are bridged by dppe or dppp ligands to form a 1D linear chain extending along the a axis. For 3, each [Au(4)(Tab)(2)(μ-Tab)(2)] fragment is linked by a pair of dppb ligands to afford another 1D chain extending along the c axis. For 4, the four [Au(Tab)](+) fragments are linked by two Au-Au bonds and two doubly bridging Tab ligands to form a {[Au(Tab)](4)(μ-Tab)(2)} chair-like cyclohexane structure. Hydrogen-bonding interactions in 2 and 4 lead to the formation of interesting 2D hydrogen-bonded networks. The luminescent properties of 1-4 in solid state were also investigated.     

Nine non-symmetric pyrazine-pyridine imide-based complexes: reversible redox and isolation of [M(II/III)(pypzca)2](0/+) when M = Co, Fe

The non-symmetric imide ligand Hpypzca (N-(2-pyrazylcarbonyl)-2-pyridinecarboxamide) has been deliberately synthesised and used to produce nine first row transition metal complexes: [M(II)(pypzca)(2)], M = Zn, Cu, Ni, Co, Fe; [M(III)(pypzca)(2)]Y, M = Co and Y = BF(4), M = Fe and Y = ClO(4); [Cu(II)(pypzca)(H(2)O)(2)]BF(4), [Mn(II)(pypzca)(Cl)(2)]HNEt(3). These are the first deliberately prepared complexes of a non-symmetric imide ligand. X-ray crystal structures of [Cu(II)(pypzca)(2)]·H(2)O, [Co(II)(pypzca)(2)], [Co(III)(pypzca)(2)]BF(4), [Cu(II)(pypzca)(H(2)O)(2)]BF(4)·H(2)O and [Mn(II)(pypzca)Cl(2)]HNEt(3) show that each of the (pypzca)(-) ligands binds in a meridional fashion via the N(3) donors. In the first three complexes, two such ligands are bound such that the 'spare' pyrazine nitrogen atoms are positioned approximately orthogonally to one another and also to the imide oxygen atoms. In MeCN the [M(II/III)(pypzca)(2)](0/+) complexes, where M = Ni, Co or Fe, exhibit one reversible metal based M(II/III) process and two distinct, quasi-reversible ligand based reduction processes, the latter also observed for M(II) = Zn. [Mn(II)(pypzca)Cl(2)]HNEt(3) displays a quasi-reversible oxidation process in MeCN, along with several irreversible processes. Both copper(II) complexes show only irreversible processes. Variable temperature magnetic measurements show that [Fe(III)(pypzca)(2)]ClO(4) undergoes a gradual spin crossover from partially high spin at 298 K (3.00 BM) to fully low spin at 2 K (1.96 BM), and that [Co(II)(pypzca)(2)] remains high spin from 298 to 4 K. All of the complexes are weakly coloured, other than [Fe(II)(pypzca)(2)] which is dark purple and absorbs strongly in the visible region.     

Isopolyoxometalates derived from arylstibonic acids with "reverse-Keggin ion" structures based on [M(RSb)(12)O(28)] cores, M = Co(ii) or Zn(ii)

The preparations and structures are described of four new polyoxostibonates, [Co(p-MeC(6)H(4)Sb)(12)O(28){Co(H(2)O)(3)}(4)]Cl(2)·6H(2)O, [Co(p-ClC(6)H(4)Sb)(12)O(28){Co(H(2)O)(3)}(4)]Cl(2)·22H(2)O, (PhCH(2)NMe(3))(2)[Zn(p-ClC(6)H(4)Sb)(12)O(28)Zn(4)Cl(2.54)Br(1.46)]·8MeCN·H(2)O and [BaCoH(4)(p-MeC(6)H(4)Sb)O(28)]·5H(2)O. Each of these has a framework of 12 (RSb) groups linked by 28 O atoms, with one transition metal ion in a tetrahedral site in the centre. Other metal ions are coordinated to the polyhedral faces. Three of the complexes have the ε Keggin ion geometry, while the fourth is a δ isomer.     

Reversible Solvatomagnetic Effect in Novel Tetranuclear Cubane-Type Ni(4) Complexes and Magnetostructural Correlations for the [Ni(4)(μ(3)-O)(4)] Core

A new family of tetranuclear nickel cube complexes [Ni(4)L(4)(solv)(4)] (1, solv = MeOH; 2, solv = H(2)O; H(2)L = pyrazole-based tridentate {ONO} ligand) has been studied in detail, in particular by X-ray diffraction and superconducting quantum interference device (SQUID) magnetometry. Different solvates 1·H(2)O, 2·4C(3)H(6)O, 2·CH(2)Cl(2), and 2·H(2)O were obtained in crystalline form. Only small structural variations were found for the Ni-O-Ni angles of the [Ni(4)O(4)] cores of those compounds, but these slight variations have dramatic consequences for the magnetic properties. [Ni(4)L(4)(MeOH)(4)]·H(2)O (1·H(2)O) and [Ni(4)L(4)(H(2)O)(4)]·H(2)O (2·H(2)O) can be reversibly interconverted in the solid state by exposure to the respective solvent, MeOH or H(2)O, and this goes along with a switching of the spin ground state from magnetic (S(T) = 4) to diamagnetic (S(T) = 0). Likewise the (irreversible) loss of lattice solvent in [Ni(4)L(4)(H(2)O)(4)]·4C(3)H(6)O (2·4C(3)H(6)O) to give 2·2C(3)H(6)O changes the ground state from S(T) = 4 to S(T) = 0. In view of these dramatic solvatomagnetic effects for the present [Ni(4)L(4)(solv)(4)] complexes, which occur upon extrusion of lattice solvent or facile exchange of coordinated solvent molecules while keeping the robust [Ni(4)O(4)] core intact, a note of care is issued: whenever magnetic data are obtained for powdered material or for crystals that easily loose lattice solvent molecules, the magnetic properties may not necessarily reflect the situation observed in the corresponding single crystal diffraction study. Finally, a thorough analysis of the present series of complexes as well as other {Ni(4)(μ(3)-OR)(4)} cubes reported in the literature confirms that a correlation between the (Ni-O-Ni)(av) bond angle and J in [Ni(4)O(4)] cubane complexes does indeed exist.     

由MCl2(M=Zn，Cd)与咪唑-4，5-二羧酸和1，4-双(咪唑-1-基)丁烷构筑的两个二重穿插二维配位聚合物的合成、结构和性质

以2∶1∶4物质的量比的咪唑-4,5-二羧酸(H3IDC),1,4-双(咪唑-1-基)丁烷(bib)和ZnCl2或CdCl2为反应物,在水热条件下分别得到了1个二重穿插的二维锌(Ⅱ)配位聚合物{[Zn2(IDC)(bib)Cl].H2O}n(1)和1个二重穿插的二维镉(Ⅱ)配位聚合物[Cd2(HIDC)(bib)1.5Cl2]n(2)。用元素分析、红外光谱以及单晶X-射线衍射结构分析对它们的组成和结构进行了表征,并对它们的热稳定性和荧光性质进行了初步的研究。