The supramolecular isomerism based on argentophilic interactions: the construction of helical chains with defined right-handed and left-handed helicity

The reactions of racemic and enantiopure macrocyclic compounds [Ni(alpha-rac-L)](ClO(4))(2) (containing equal amounts of SS and RR enantiomers), [Ni(alpha-SS-L)](ClO(4))(2), and [Ni(alpha-RR-L)](ClO(4))(2) with K[Ag(CN)(2)] in acetonitrile/water afford three 1D helical chains of {[Ni(f-rac-L)][Ag(CN)(2)](2)}(n) (1), {[Ni(f-SS-L)](2)[Ag(CN)(2)](4)}(n) (Delta-2), and {[Ni(f-RR-L)](2)[Ag(CN)(2)](4)}(n) (Lambda-2); one dimer of [Ni(f-rac-L)][Ag(CN)(2)](2) (3); and one trimer of [Ni(f-rac-L)Ag(CN)(2)](3).(ClO(4))(3) (4) (L = 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane). Compounds 1, Delta-2, Lambda-2, and 3, which are supramolecular isomers, are constructed via argentophilic interactions. In 1, [Ni(f-RR-L)][Ag(CN)(2)](2) enantiomers alternately connect with [Ni(f-SS-L)][Ag(CN)(2)](2) enantiomers through intermolecular argentophilic interactions to form a 1D meso-helical chain, and the 1D chains are further connected through the interchain hydrogen bonds to generate a 2D network. When chiral [Ni(alpha-SS-L)](ClO(4))(2) and [Ni(alpha-RR-L)](ClO(4))(2) were used as building blocks, two supramolecular stereoisomers of Delta-2 and Lambda-2 were obtained, which show the motif of homochiral right-handed and left-handed helical chains, respectively, and the 1D homochiral helical chains are linked by the interchain hydrogen bonds to form a 3D structure. In 3, a pair of enantiomers of [Ni(f-RR-L)][Ag(CN)(2)](2) and [Ni(f-SS-L)][Ag(CN)(2)](2) connect with each other through intermolecular argentophilic interactions to form a dimer. The reaction of [Ni(alpha-rac-L)](ClO(4))(2) with K[Ag(CN)(2)] in acetonitrile gives a trimer of 4; each trimer is chiral with unsymmetrical RR, RR, and SS, or RR, SS, and SS configurations. The homochiral nature of Delta-2 and Lambda-2 was confirmed by the results of solid circular dichroism spectra measurements. The solid samples of 1-4 show strong fluorescent emissions at room temperature.     

Two supramolecular isomers of molecular squares and 1D helical chains with alternating right- and left-handed chirality

The reaction of [Ni(alpha-rac-L)](ClO4)2 with K2[Ni(CN)4] gives a cyanide bridged [2+2] type of molecular square, {cis-[Ni(f-rac-L)][Ni(CN)4]}2 (1). By slightly changing the reaction conditions, the reaction of [Ni(alpha-rac-L)](ClO4)2 with KCN leads to a metastable compound, cis-[Ni(f-rac-L)(CN)2] (2), and an unexpected 1D helical chain, {cis-[Ni(f-rac-L)][Ni(CN)4]}n (3). In 3, the 1D helical chains are packed in an alternating right- and left-handed chirality due to the oppositely twisted arrangements of two adjacent [Ni(CN)4]2- anions. The metastable compound 2 can be converted to 3 in a CH3CN/CH3OH solution. Compounds 1 and 3 are classified as supramolecular isomers, and isomer 3 can be considered to be formed by the ring-opening polymerization of the square precursor 1. Magnetic susceptibility measurements of 1 and 3 show that the adjacent six-coordinated Ni(II) atoms are antiferromagnetically coupled through the bent -NC-Ni-CN- bridges of the diamagnetic [Ni(CN)4]2- anions, with g = 2.08 and J = -0.426 cm(-1) for 1 and g = 2.08 and J = -0.278 cm(-1) for 3. The correlation between the structures and the J values is discussed.     

Spontaneous resolution of a racemic nickel(II) complex and helicity induction via hydrogen bonding: the effect of chiral building blocks on the helicity of one-dimensional chains

The reactions of a racemic four-coordinated nickel(II) complex [Ni(alpha-rac-L)](ClO4)2 (containing equal amount of SS and RR enantiomers) with l- and d-phenylalanine in acetonitrile/water gave two less-soluble six-coordinated enantiomers of {[Ni( f-SS-L)(l-Phe)](ClO4)}n (Delta-1) and {[Ni(f- RR-L)(d-Phe)](ClO4)}n (Lambda-1), respectively. Evaporation the remaining solutions gave two six-coordinated diastereomers of {[Ni 3(f- RR-L)3(l-Phe)2(H 2O)](ClO4)4}n (a-2) and {[Ni3(f- SS-L)3(d-Phe)2(H2O)](ClO4)4}n (b-2), respectively (L = 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane, Phe(-) = phenylalanine anion). The reaction of [Ni(alpha-rac-L)](ClO4)2 with dl-Phe(-) gave a conglomerate of c-1; in which, the SS and RR enantiomers preferentially coordinate to l- and d-Phe(-) respectively to give a racemic mixture of Delta-1 and Lambda-1, and the spontaneous resolution occurs during the reaction, in which each crystal crystallizes to become enantiopure. Removing Phe(-) from Delta-1 and Lambda-1 using perchloric acid gave two enantiomers of [Ni(alpha-SS-L)](ClO4)2 (S-3) and [Ni(alpha-RR-L)](ClO4)2 (R-3). Dissolving S-3 and R-3 in acetonitrile gave two six-coordinated enantiomers of [Ni( f-SS-L)(CH3CN)2](ClO4)2 (S-4) and [Ni( f- RR-L)(CH3CN)2](ClO4)2 (R-4), while dissolving [Ni(alpha-rac-L)](ClO4)2 in acetonitrile gave a racemic twining complex [Ni(f-rac-L)(CH3CN)2](ClO4)2 (rac-4). Delta-1 and Lambda-1 belong to supramolecular stereoisomers, which are constructed via hydrogen bond linking of [Ni( f-SS-L)(l-Phe)](+) and [Ni(f-RR-L)(d-Phe)](+) monomers to form 1D homochiral right-handed and left-handed helical chains, respectively. The reaction of S-3 with d-Phe(-) gave {[Ni(f-SS-L)(d-Phe)](ClO4)}n (5), which shows a motif of a 1D hydrogen bonded zigzag chain instead of a 1D helical chain. Compound a-2/ b-2 contains dimers of [{Ni(f-RR-L)}2(l-Phe)(H2O)](3+)/[{Ni( f- SS-L)}2(d-Phe)(H2O)](3+) and 1D zigzag chains of {[Ni(f-RR-L)(l-Phe)](+)}n /{[Ni(f-SS-L)(d-Phe)](+) n . The homochiral nature of Delta-1/Lambda-1, a-2/b-2, S-3/R-3, and S-4/R-4 are confirmed by the results of circular dichroism (CD) spectra measurements.     

A cyanide-bridged 1-D helical chain involving both four- and six-coordinate nickel(II)

A cyanide-bridged coordination polymer, {[Ni(tren)][Ni(CN)₄]} _n (tren?=?tris(2-aminoethyl)amine), has been synthesized by self-assembly of cis-[Ni(tren)]²⁺ and [Ni(CN)₄]^2? building blocks. In the molecular structure, the paramagnetic cis-[Ni(tren)]²⁺ cations are bridged by diamagnetic [Ni(CN)₄]^2? anions through two cis-cyanides to form a 1-D helical chain of {[Ni(tren)][Ni(CN)₄]} _n . The compound crystallizes with a centrosymmetrical space group, P2₁ /n, in which the helical chains are packed in alternating right- and left-handed chiralities with a helical pitch of 10.2566(3)?Å (equal to the length of the b-axis), leading to the formation of a racemic compound. The crystal packing is stabilized by moderately strong hydrogen-bonding between primary amines of tren and nitrogens of terminal cyanide.     

Coordination solids derived from Cp*M(CN)3- (M = Rh,Ir)

Solutions of Rh2(OAc)4 and Et4N[Cp*Ir(CN)3] react to afford crystals of the one-dimensional coordination solid [Et4N[Cp*Ir(CN)3][Rh2(OAc)4]]. This reaction is reversed by coordinating solvents such as MeCN. The structure of the polymer consists of helical anionic chains containing Rh2(OAc)4 units linked via two of the three CN ligands of Cp*Ir(CN)3-. Use of the more Lewis acidic Rh2(O2CCF3)4 in place of Rh2(OAc)4 gave purple [(Et4N)2[Cp*Ir(CN)3]2[Rh2(O2CCF3)4]3], whose insolubility is attributed to stronger Rh-NC bonds as well as the presence of cross-linking. The species [[Cp*Rh(CN)3][Ni(en)n](PF6)] (n = 2, 3) crystallized from an aqueous solution of Et4N[Cp*Rh(CN)3] and [Ni(en)3](PF6)2; [[Cp*Rh(CN)3][Ni(en)2](PF6)] consists of helical chains based on cis-Ni(en)(2)2+ units. Aqueous solutions of Et4N[Cp*Ir(CN)3] and AgNO3 afforded the colorless solid Ag-[Cp*Ir(CN)3]. Recrystallization of this polymer from pyridine gave the hemipyridine adduct [Ag[Ag(py)][Cp*Ir(CN)3]2]. The 13C cross-polarization magic-angle spinning NMR spectrum of the pyridine derivative reveals two distinct Cp* groups, while in the pyridine-free precursor, the Cp*'s appear equivalent. The solid-state structure of [Ag[Ag(py)][Cp*Ir(CN)3]2] reveals a three-dimensional coordination polymer consisting of chains of Cp*Ir(CN)3- units linked to alternating Ag+ and Ag(py)+ units. The network structure arises by the linking of these helices through the third cyanide group on each Ir center.     

Heterobimetallic coordination polymers incorporating [M(CN)(2)](-) (M = Cu,Ag) and [Ag(2)(CN)(3)](-) units: increasing structural dimensionality via M-M' and M...NC interactions

A series of new heterometallic coordination polymers has been prepared from the reaction of metal-ligand cations and KAg(CN)(2) units. Many of these contain silver-silver (argentophilic) interactions, analogous to gold-gold interactions, which serve to increase supramolecular structural dimensionality. Compared to [Au(CN)(2)](-) analogues, these polymers display new trends specific to [Ag(CN)(2)](-), including the formation of [Ag(2)(CN)(3)](-) and the presence of Ag...N interactions. [Cu(en)(2)][Ag(2)(CN)(3)][Ag(CN)(2)] (1, en = ethylenediamine) forms 1-D chains of alternating [Ag(CN)(2)](-) and [Ag(2)(CN)(3)](-) units via argentophilic interactions of 3.102(1) A. These chains are connected into a 2-D array by strong cyano(N)-Ag interactions of 2.572(3) A. [Cu(dien)Ag(CN)(2)](2)[Ag(2)(CN)(3)][Ag(CN)(2)] (2, dien = diethylenetriamine) forms a 1-D chain of alternating [Cu(dien)](2+) and [Ag(CN)(2)](-) ions with the Cu(II) atoms connected in an apical/equatorial fashion. These chains are cross-linked by [Ag(2)(CN)(3)](-) units via argentophilic interactions of 3.1718(8) A and held weakly in a 3-D array by argentophilic interactions of 3.2889(5) A between the [Ag(CN)(2)](-) in the 2-D array and the remaining free [Ag(CN)(2)](-). [Ni(en)][Ni(CN)(4)].2.5H(2)O (4) was identified as a byproduct in the reaction to prepare the previously reported [Ni(en)(2)Ag(2)(CN)(3)][Ag(CN)(2)] (3). In [Ni(tren)Ag(CN)(2)][Ag(CN)(2)] (5, tren = tris(2-aminoethyl)amine), [Ni(tren)](2+) cations are linked in a cis fashion by [Ag(CN)(2)](-) anions to form a 1-D chain similar to the [Au(CN)(2)](-) analogue. [Cu(en)Cu(CN)(2)Ag(CN)(2)] (6) is a trimetallic polymer consisting of interpenetrating (6,3) nets stabilized by d(10)-d(10) interactions between Cu(I)-Ag(I) (3.1000(4) A). Weak antiferromagnetic coupling has been observed in 2, and a slightly stronger exchange has been observed in 6. The Ni(II) complexes, 4 and 5, display weak antiferromagnetic interactions as indicated by their relatively larger D values compared to that of 3. Magnetic measurements on isostructural [Ni(tren)M(CN)(2)][M(CN)(2)] (M = Ag, Au) show that Ag(I) is a more efficient mediator of magnetic exchange as compared to Au(I). The formation of [Ni(CN)(4)](2)(-), [Ag(2)(CN)(3)](-), and [Cu(CN)(2)](-) are all attributed to secondary reactions of the dissociation products of the labile KAg(CN)(2).     

Helical Coordination Polymers Based on Keggin-type POMs and N-donor Ligand

Two new 1D helical coordination polymers based on polyoxometalate were synthesized by self-assembly of Keggin-type POMs and copper salts in the presence of triangular N-heterocyclic derivatives or long-chain N-containing carboxylate ligand, that are, (H₃O)[{Cu(H₂tpim)₂}{SiMo₁₂O₄₀}] · 0.5H₂O [Htpim = 2,4,5-tri(4-pyridyl)-imidazole] ( 1 ) and [Cu₂(Hcpp)₃(cpp)(H₂O)][PMo₁₂O₄₀] · 2H₂O [Hcpp = 1-(4-cyanobenzyl)-3–2-yl)pyrazole] ( 2 ). Their structures were determined by single-crystal X-ray diffraction and further characterized by elemental analyses and TG analyses. Compounds 1 and 2 exhibit (1D→2D) interdigitated architectures assembled from 1D helical chains. In compound 1 , the achiral 2D interdigitated nets containing left- and right-handed helixes are further interdigitated with each other to form a 3D supramolecular framework. In compound 2 , adjacent 2D interdigitated layers with opposite chirality are further extended by supramolecular interactions into a 3D supramolecular network, in which non-coordinating Keggin-type POMs as guests are encapsulated.     

Effect of the semirigid capping ligand on the structure formation of cyano-bridged bimetallic assemblies: syntheses, crystal structures, and magnetic properties

The syntheses, crystal structures, and magnetic properties of three novel cyano-bridged bimetallic assemblies, [Ni(bpm)(2)](3)[Co(CN)(6)](2)x3.5H(2)O (1), [Co(bpm)(2)][Fe(CN)(5)NO]x2H(2)O (2), and [Co(bpm)(2)][Ni(CN)(4)] (3) (bpm = bis(1-pyrazolyl)methane), are reported. Complex 1 crystallizes in the tetragonal space group P4(3)2(1)2 with a = 12.800(5) A, b = 12.800(5) A, c = 42.80(3) A, V = 7012(6) A(3), and Z = 8. Complex 2 crystallizes in the chiral trigonal space group P3(2)21 with a = 11.9961(19) A, b = 11.9961(19) A, c = 16.062(5) A, gamma = 120 degrees , V = 2001.7(8) A(3), and Z = 3. Complex 1 is a trigonal bipyramidal complex in which three [Ni(bpm)(2)](2+) units are situated in the equatorial plane and are connected to the two apical [Co(CN)(6)](3)(-) units via three N ends of the cyanide groups. Complex 2 possesses a triangular left-handed helical chain structure composed of [Co(bpm)(2)](2+) linked by [Fe(CN)(5)NO](2)(-); the shortest intramolecular Co...Fe distance is 5.162 A. To the best of our knowledge, this is the first observation of a heteronuclear helical chain structure based on pentacyanonitrosylferrate(II). The structure of complex 3 is roughly determined by X-ray crystallograhy analysis to be a 1D zigzag chain. These structure variations, from a discrete cluster to a 1D helical chain and a 1D zigzag chain, rely on the semirigidity of the capping ligand bpm. Magnetic susceptibility measurements indicate that complex 1 has an intramolecular ferromagnetic interaction (J = 4.06 cm(-)(1)) between the nickel(II) ions; this is further confirmed by the magnetization measurements. In complexes 2 and 3, the cobalt(II) ions are located in a moderately strong field.     

A series of chiral coordination polymers containing helicals assembled from a new chiral (R)-2-(4'-(4'-carboxybenzyloxy)phenoxy)propanoic acid: syntheses, structures and photoluminescent properties

Ten new chiral coordination polymers, namely, [Ni(L)(H(2)O)(2)] (1), [Co(L)(H(2)O)(2)] (2), [Cd(L)(H(2)O)] (3), [Cd(L)(phen)] (4), [Mn(2)(L)(2) (phen)(2)]·H(2)O (5), [Cd(2)(L)(2)(biim-4)(2)] (6), [Zn(2)(L)(2)(biim-4)(2)] (7), [Cd(L)(pbib)] (8), [Cd(L)(bbtz)] (9) and [Cd(L)(biim-6)] (10), where phen = 1,10-phenathroline, biim-4 = 1,1'-(1,4-butanediyl)bis(imidazole), pbib = 1,4-bis(imidazole-1-ylmethyl)benzene, bbtz = 1,4-bis(1,2,4-triazol-1-ylmethyl)benzene, biim-6 = 1,1'-(1,6-hexanedidyl)bis(imidazole), and H(2)L = (R)-2-(4'-(4'-carboxybenzyloxy)phenoxy)propanoic acid, have been synthesized under hydrothermal conditions. Their structures have been determined by single-crystal X-ray diffraction analyses and further characterized by infrared spectra (IR), powder X-ray diffraction (PXRD), elemental analyses and thermogravimetric (TG) analyses. Compounds 1 and 2 exhibit similar 1D left-handed helical chains, which are further extended into 3D supramolecular structures through O-H···O hydrogen-bonding interactions, respectively. Compound 3 shows a 2D double-layer architecture containing helical chains. Compound 4 features two types of 2D undulated sheets with helical chains, which are stacked in an ABAB fashion along the c direction. Compound 5 possesses a 1D double chain ribbon structure containing unusual meso-helical chains, which is linked by π-π interactions into a 2D supramolecular layer. These layers are further extended by hydrogen-bonding interactions to form a 3D supramolecular assembly. Compounds 6 and 7 are isostructural and exhibit 2D (4(4))-sql networks with helical chains. Neighboring sheets are further linked by C-H···O hydrogen-bonding interactions to generate 3D supramolecular architectures. Compounds 8-10 are isostructural and display 3D 3-fold interpenetrating diamond frameworks with helical chains. The effects of coordination modes of L anions, metal ions and N-donor ligands on the structures of the coordination polymers have been discussed. The luminescent properties of 3, 4 and 6-10 have also been investigated in detail.     

Aggregation of [Au(CN)4]- anions: examination by crystallography and 15N CP-MAS NMR and the structural factors influencing intermolecular Au···N interactions

To investigate the factors influencing the formation of intermolecular Au···NC interactions between [Au(CN)(4)](-) units, a series of [cation](n+)[Au(CN)(4)](n) double salts was synthesized, structurally characterized and probed by IR and (15)N{(1)H} CP-MAS NMR spectroscopy. Thus, [(n)Bu(4)N][Au(CN)(4)], [AsPh(4)][Au(CN)(4)], [N(PPh(3))(2)][Au(CN)(4)], [Co(1,10-phenanthroline)(3)][Au(CN)(4)](2), and [Mn(2,2';6',2'-terpyridine)(2)][Au(CN)(4)](2) show [Au(CN)(4)](-) anions that are well-separated from one another; no Au-Au or Au···NC interactions are present. trans-[Co(1,2-diaminoethane)(2)Cl(2)][Au(CN)(4)] forms a supramolecular structure, where trans-[Co(en)(2)Cl(2)](+) and [Au(CN)(4)](-) ions are found in separate layers connected by Au-CN···H-N hydrogen-bonding; weak Au···NC coordinate bonds complete octahedral Au(III) centers, and support a 2-D (4,4) network motif of [Au(CN)(4)](-)-units. A similar structure-type is formed by [Co(NH(3))(6)][Au(CN)(4)](3)·(H(2)O)(4). In [Ni(1,2-diaminoethane)(3)][Au(CN)(4)](2), intermolecular Au···NC interactions facilitate formation of 1-D chains of [Au(CN)(4)](-) anions in the supramolecular structure, which are separated from one another by [Ni(en)(3)](2+) cations. In [1,4-diazabicyclo[2.2.2]octane-H][Au(CN)(4)], the monoprotonated amine cation forms a hydrogen-bond to the [Au(CN)(4)](-) unit on one side, while coordinating to the axial sites of the gold(III) center through the unprotonated amine on the other, thereby generating a 2-D (4,4) net of cations and anions; an additional, uncoordinated [Au(CN)(4)](-)-unit lies in the central space of each grid. This body of structural data indicates that cations with hydrogen-bonding groups can induce intermolecular Au···NC interactions, while the cationic charge, shape, size, and aromaticity have little effect. While the ν(CN) values are poor indicators of the presence or absence of N-cyano bridging between [Au(CN)(4)](-)-units (partly because of the very low intensity of the observed bands), (15)N{(1)H} CP-MAS NMR reveals well-defined, ordered cyanide groups in the six diamagnetic compounds with chemical shifts between 250 and 275 ppm; the resonances between 260 and 275 ppm can be assigned to C-bound terminal ligands, while those subject to CN···H-N bonding resonate lower, around 250-257 ppm. The (15)N chemical shift also correlates with the intermolecular Au···N distances: the shortest Au-N distances also shift the (15)N peak to lower frequency. This provides a real, spectroscopically measurable electronic effect associated with the crystallographic observation of intermolecular Au···NC interactions, thereby lending support for their viability.     

具有双螺旋链的新型二维无机-有机骨架晶体材料Ni(PDC)(H2O)2的合成与结构

本文报道由H2PDC合成的新型维层状无机-有机骨架晶体Ni(PDC)(H2O)2(H2PDC=吡啶-2,5-二羧酸), 该化合物的一层是由右手螺旋Ni—O—C链与左手螺旋Ni-pdc链组成, 而邻近的一层则是由左手螺旋Ni—O—C链与右手螺旋Ni-pdc链组成, 层与层之间通过氢键作用形成了三维超分子结构. 用ICP、TG、IR和X射线单晶衍射分析等手段对其结构进行表征.     

cis-[Ni(NCS)_2tren]的镜面对称性破缺: 螯环的特殊手性构象

为了探究cis-[Ni(NCS)2tren][tren:三(2-氨基乙基)胺]的手性来源,本文采用单晶X射线衍射、溶液紫外-可见-近红外(UV-Vis-NIR)光谱、固体紫外圆二色(CD)光谱和粉末X射线衍射(XRD)等对cis-[Ni(NCS)2tren]的一对手性晶体进行了表征.研究结果表明:该手性晶体由结晶过程中的镜面对称性破缺而形成;三角架型配体tren配位后的特殊手性构象(δδλ,λλδ)是cis-[Ni(NCS)2tren]的主要手性来源.络合物固体紫外CD谱所呈现的Cotton效应可能来自其螯环手性构象以及手性金属中心对NCS-配体的π-π*跃迁和荷移跃迁生色团的手性微扰.对20批次合成产物进行固体CD检测的统计结果表明:它们的对映体过量(ee)值在39%-100%之间.     

Bimetallic cyanide-bridged complexes based on the photochromic nitroprusside anion and paramagnetic metal complexes. Syntheses, structures, and physical characterization of the coordination compounds [Ni(en)2]4[Fe(CN)5NO]2[Fe(CN)6]x5H2O, [Ni(en)2][Fe(CN)5NO]x3H2O, [Mn(3-MeOsalen)(H2O)]2[Fe(CN)5NO], and [Mn(5-Brsalen)]2[Fe(CN)5NO

The synthesis, crystal structure, and physical characterization of the coordination compounds [Ni(en)2]4[Fe(CN)5NO]2[Fe(CN)6]x5H2O (1), [Ni(en)2][Fe(CN)5NO]x3H2O (2), [Mn(3-MeOsalen)(H2O)]2[Fe(CN)5NO] (3), and [Mn(5-Brsalen)]2[Fe(CN)5NO] (4) are presented. 1 crystallizes in the monoclinic space group P2(1)/n (a = 7.407(4) A, b = 28.963(6) A, c = 14.744(5) A, alpha = 90 degrees, beta = 103.26(4) degrees, gamma = 90 degrees, Z = 2). Its structure consists of branched linear chains formed by cis-[Ni(en)2]2+ cations and ferrocyanide and nitroprusside anions. The presence of two kinds of iron(II) sites has been demonstrated by M?ssbauer spectroscopy. 2 crystallizes in the monoclinic space group P2(1)/c (a = 11.076(3) A, b = 10.983(2) A, c = 17.018(5) A, alpha = 90 degrees, beta = 107.25(2) degrees, gamma = 90 degrees, Z = 4). Its structure consists of zigzag chains formed by an alternated array of cis-[Ni(en)2]2+ cations and nitroprusside anions. 3 crystallizes in the triclinic space group P1 (a = 8.896(5) A, b = 10.430(5) A, c = 12.699(5) A, alpha = 71.110(5) degrees, beta = 79.990(5) degrees, gamma = 89.470(5) degrees, Z = 1). Its structure comprises neutral trinuclear bimetallic complexes in which a central [Fe(CN)5NO]2- anion is linked to two [Mn(3-MeOsalen)]+ cations. 4 crystallizes in the tetragonal space group P4/ncc (a = 13.630(5) A, c = 21.420(8) A, Z = 4). Its structure shows an extended 2D neutral network formed by cyclic octameric [-Mn-NC-Fe-CN-]4 units. The magnetic properties of these compounds indicate the presence of quasi-isolated paramagnetic Ni2+ and Mn3+. Irradiated samples of the four compounds have been studied by differential scanning calorimetry to detect the existence of the long-lived metastable states of nitroprusside.     

Synthesis, crystal structures, and magnetic properties of cyano-bridged heterobimetallic chains based on [(Tp)Fe(CN)3]-

With the use of the tailored cyanometalate precursor, (Bu4N)[(Tp)Fe(CN)3] (Tp = Tris(pyrazolyl)hydroborate) as the building block to react with fully solvated Cu(II), Co(II), and Ni(II) cations, four one-dimensional (1D) heterobimetallic cyano-bridged chain complexes of squares, [(Tp)2Fe(III)2(CN)6Cu(CH3OH).2CH3OH]n (1), [(Tp)2Fe(III)2(CN)6Cu(DMF).DMF]n (2), [(Tp)2Fe(III)2(CN)6M(CH3OH)2.2CH3OH]n (M = Co (3) and Ni (4)), have been prepared. In complexes 1 and 2, the Cu(II) ions are pentacoordinated in the form of a slightly distorted square-based pyramid, and they are linked by distorted octahedrons of [(Tp)Fe(CN)3]- to form 1D chains of squares. In complexes 3 and 4, both the central Co(II) and Ni(II) ions have a slightly distorted octahedral coordination geometry, and they are bridged by [(Tp)Fe(CN)3]- to form similar 1D chains of squares. There are weak interchain pi-pi stacking interactions through the pyrazolyl groups of the Tp ligands for complexes 3 and 4. The crystal structures and magnetic studies demonstrate that complexes 1 and 2 exhibit intrachain ferromagnetic coupling and single-chain magnets behavior, and the blocking temperature is ca. 6 K for complex 1 and ca. 3 K for complex 2. Complexes 3 and 4 show significant metamagnetic behavior, where the cyanides mediate the intrachain ferromagnetic coupling between Fe(III) and Co(II) or Ni(II) ions and the interchain pi-pi stacking interactions lead to antiferromagnetic couplings. The field dependence of the magnetization measurements shows that the critical field is around 1 kOe for complex 3 and 0.8 kOe for complex 4 at 1.8 K.     

Syntheses and Crystal Structures of Two Copper~Ⅱ Complexes with Tetracyanonickelate~Ⅱ

Two copper-nickel complexes, {[Cu(i-Pr3TACN)][Ni(CN)4]}2·2H2O (1) and {[Cu(DACH)][Ni(CN)4]}n (2), have been synthesized by the self-assembly reactions of K2[Ni(CN)4] with CuCl2 and the corresponding chelating ligand 1,4,7-triisopropyl-1,4,7- triazacyclononane (i-Pr3TACN) or 1,4-diazacycloheptane (DACH), respectively. The complexes were structurally characterized by single-crystal X-ray diffraction, elemental analyses, IR spectra and magnetic properties. Complex 1 presents a [2+2] type of molecular square structure and 2 features a 2D β-pucker structure. The magnetic susceptibility measurements reveal a weak antiferromagnetic interaction between the Cu(Ⅱ) ions, with the J values of-22.11 and -32.50 cm-1 for 1 and 2. Moreover, by changing the size of macrocyclic ligands we have successfully constructed two different strictures, which may provide useful information for the construction of the structure.     

Synthesis and characterization of a novel two-dimensional layered vanadate complex containing double helical chains

A novel two-dimensional layered vanadate complex 1 [Ni(phen)H₂O][V₂O₆] has been hydrothermally synthesized and characterized by elemental analyses, i.r., x.p.s., t.g. and single crystal X-ray diffraction. The single crystal X-ray diffraction analysis reveals that compound 1 consists of the chains covalently linked by [Ni(phen)H₂O]²⁺ subunits to form two-dimensional layered polyoxovanadate. It is interesting that the compound 1 consists of left-handed and right-handed helical chains, which are further interconnected to produce the double helical chains. The adjacent two-dimensional layers interact with each other via extensive hydrogen bonds and π–π stacking interactions to form a three-dimensional supramolecular framework.     

Zipped-up chain-type coordination polymers: unsymmetrical amide-containing ligands inducing beta-sheet or helical structures. kazu-u@yamaguchi-u.ac.jp

The crystal structures of thirteen AgI coordination polymers involving py-CONH-(CH2)n-py (py=pyridine; n=0, 1) derivatives were determined by means of single-crystal X-ray analyses. All of the compounds form one-dimensional chains composed of AgI atoms and bridging ligands with formulas [[Ag(py-CONH-(CH2)n-py)][X]]n (X=PF6 -, ClO4 -, BF4 -, and NO3 - with solvent molecules). The unsymmetrical coordination environments around AgI atoms induce direction in the chains, that is, -[NH-(CH2)n-py-Ag-py-CO]-, which resembles the alignment of amino acid chains in proteins. In compounds [[Ag(4-pia)][X]]n (1 supersetX; 4-pia=N-(4-pyridyl)isonicotinamide; X=PF6 -, ClO4 -, BF4 -, and NO3 -), [[Ag(4-pmia)][X]]n (2 supersetX; 4-pmia=N-(pyridin-4-ylmethyl)isonicotinamide; X=PF6 -, ClO4 -H2O, and NO3 -H2O), and [[Ag(3-pmia)][X]]n (3 supersetX; 3-pmia=N-(pyridin-3-ylmethyl)isonicotinamide; X=PF6 -, ClO4 -, BF4 -, and NO3 -H2O), each chain is aligned parallel to neighboring chains, but adjacent chains run in the opposite direction. Particularly in [[Ag(3-pmia)][PF6]]n (3 supersetPF6 -), [[Ag(3-pmia)][ClO4]]n (3 supersetClO4 -), and [[Ag(3-pmia)][BF4]]n (3 supersetBF4 -), amide moieties of 3-pmia ligands are complementarily hydrogen bonded to amide moieties in neighboring chains, as in the beta-sheet motif in proteins. On the other hand, in [[Ag(4-pmna)][PF6]MeOH]n (4-pmna=N-(pyridin-4-ylmethyl)nicotinamide), all chains in the crystal form left-handed (4 a supersetPF6 -MeOH) and right-handed (4 b supersetPF6 -MeOH) helical structures with a helical pitch of 28 A. Heterogeneous anion exchanges proceed reversibly in 2, but not in 3, which provides information about the thermal stabilities of the crystals.     

A bridge between pillared-layer and helical structures: a series of three-dimensional pillared coordination polymers with multiform helical chains

Rational self-assembly of a long V-shaped 3,3',4,4'-benzophenonetetracarboxylate (bptc) ligand and metal salts in the presence of linear bidentate ligand yield a series of novel pillared helical-layer complexes, namely, [Cu2(bptc)(bpy)2] (1), [M3(Hbptc)2(bpy)3(H2O)4].2 H2O (M = Fe(2) and Ni(3)), [Co2(bptc)(bpy)(H2O)].0.5 bpy (4), [Cd2(bptc)(bpy)(H2O)2].H2O (5), [Mn2(bptc)(bpy)1.5(H2O)3] (6) and [M2(bptc)(bpy)0.5(H2O)5].0.5 bpy (M = Mn(7), Mg(8) and Co(9), bpy=4,4'-bipyridine). Their structures were determined by single-crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectra, and thermogravimetric (TG) analyses. The structure of 1 consists of two types of chiral layers, one left-handed and the other right-handed, which are connected by bpy pillars to generate a novel 3D open framework featuring four distinct helical chains. Compounds 2 and 3 are isostructural and feature 3D structures formed from the interconnection of arm-shaped helical layers with bpy pillars. Compound 4 is a pillared helical double-layer complex containing four different types of helices, among which the nine-fold interwoven helices constructed from triple-stranded helical motifs are unprecedented. Compound 5 exhibits a novel 3D covalent framework which features nanosized tubular channels. These channels are built from helical layers pillared by bptc ligands. The structure of 6 is constructed from {Mn(bptc)(H2O)}n2n- layers, which consist of left- and right-handed helical chains, pillared by [Mn2(bpy)3(H2O)4]4+ complexes into a 3D framework. To the best of our knowledge, compounds 1-6 are the first examples of pillared helical-layer coordination polymers. Compounds 7-9 are isostructural and exhibit interesting 2D helical double-layer structures, which are constructed from {M(bptc)(H2O)2}n2n- ribbons cross-linked by [M2(bpy)(H2O)6]4+ complexes. Furthermore, the 3D supramolecular structures of 7-9 are similar to the 3D structure of 6, and the 2D structure of 7 can be transformed into the 3D structure of 6 at higher reaction temperature. By inspection of the structures of 1-9, it is believed that the V-shaped bptc ligand and V-shaped phthalic group of the bptc ligand are important for the formation of the helical structures. The magnetic behavior of compounds 1, 2, 4, 6, and 9 was studied and indicated the existence of antiferromagnetic interactions. Moreover, compound 5 shows intense photoluminescence at room temperature.     

Silver coordination complexes as room-temperature multifunctional materials

A series of bischelate ionic silver complexes [Ag(L*)(2)][X] was prepared by complexation of a newly synthesized 2,2'-bipyridine containing chiral alkoxy chains in the 4,4' positions. The appropriate choice of the construction motifs allows the preparation of new materials in which several functionalities can be introduced. Indeed, when the anion X(-) is a triflate or a dodecylsulfate group, the right combination of intermolecular interactions promotes the production of liquid crystalline mesophases. Therefore, the presence of coordinating anions, which drives the supramolecular assembly, is essential to generate, at the same time, room-temperature columnar hexagonal mesomorphism, the columnar helical supramolecular structure, and excimeric emission.     

Aurophilicity-coordination interplay in the design of cyano-bridged nickel(II)-Gold(I) bimetallic assemblies: structural and computational studies of the gold(I)-gold(I) interactions

Two polymorphic cyano-bridged Au(I)-Ni(II) bimetallic complexes of formulas [Ni(en)2Au(CN)2][Au(CN)2] (1) and [Ni(en)2[Au(CN)2]2] (2) have been prepared from the 1:2 reaction between [Au(CN)2]- and either [Ni(en)2Cl2]Cl or [Ni(en)3]Cl2.2H2O, respectively. The structure of 1 consists of polymeric cationic chains of alternating [Au(CN)2]- and [Ni(en)2]2+ units running along the a axis and [Au(CN)2]- anions lying between the chains. The noncoordinated dicyanoaurate anions are aligned perpendicular to the ac plane and involved in aurophilic interactions with the bridging dicyanoaurate groups, ultimately leading to a 2D bimetallic grid. The structure of 2 consists of trinuclear molecules made of two [Au(CN)2]- anions linked to [Ni(en)2]2+ unit in trans configuration. Trinuclear units are joined by aurophilic interactions to form 1D zigzag chains. The magnetic properties of these compounds are strongly dominated by the local anisotropy of the octahedral Ni(II) ions, thus indicating that the magnetic exchange interaction mediated by dicyanoaurate bridging groups, if it exists, is very weak. To get insight into the electronic properties of the inter- and intramolecular interactions of the [Au(CN)2]- building blocks, the structures of different aggregates of dicyanogold units were optimized and then analyzed by making use of atoms-in-molecules (AIM) theory. Moreover, bond indices were calculated by methods based upon nonlinear population analysis.