Li17Ag3Sn6: a polar intermetallic pi-system with carbonate-like [AgSn3]11- anions and trefoil aromatic [Ag2Sn3]6- layers

A new lithium silver stannide, Li17Ag3Sn6, was synthesized from high-temperature reactions of the pure elements in tantalum containers. Its crystal structure, in the space group, P31m, with a = 8.063(3) A, c = 8.509(4) A, Z = 1, features two distinct AgSn-based anionic layers. Defect graphitic layers of Ag2Sn3, with ordered vacancies at one-third of the Ag sites, are alternately stacked with Kagome-like nets of isolated trigonal planar AgSn3 units. Double layers of Li ions are sandwiched between the stacked AgSn-based layers. Theoretical calculations show unusual pi-interactions within both anionic layers, with the trigonal planar [AgSn3]11- units being isoelectronic with CO(3)2-. In addition, the chemical bonding of the layered [Ag2Sn3]6- pi-network features incompletely filled lone-pair Sn states involved in in-plane trefoil aromatic interactions. Transport and magnetic susceptibility measurements on Li17Ag3Sn6 indicate excellent metallic behavior and temperature-independent paramagnetism consistent with results from band structure calculations. The "trefoil" aromaticity, previously postulated for aromatic molecular systems, is finally observed, albeit in a polar intermetallic solid-state structure that lies at the border between metals and nonmetals.     

Structural features of Ag[AuF4] and Ag[AuF6] and the stuctural relationship of Ag[AgF4]2 and Au[AuF4]2 to Ag[AuF4]2

Synchrotron radiation X-ray powder diffraction data (SPDD) have been obtained for Ag[AgF4]2, Au[AuF4]2, Ag[AuF4], and Ag[AuF6]. Ag[AgF4]2 and Au[AuF4]2 are isostructural with Ag[AuF4]2, space group (SG) P2(1)/n, Z = 2, with the following: for Ag[AgF4]2 a = 5.04664(8), b = 11.0542(2), c = 5.44914(9) A, beta = 97.170(2) degrees; for Au[AuF4]2 a = 5.203(2), b = 11.186(3), c = 5.531(2) A, beta = 90.55(2) degrees. The structure of Ag[AgF4]2 was refined successfully (SPDD) applying the Rietveld method, yielding the following interatomic distances (A): AgII-F = 2.056(12), 2.200(13), 2.558(13); AgIII-F = two at 1.846(12), others = 1.887(12), 1.909(13), 2.786-(12), 2.796(12), 2.855(12). AgAuF4, like other AA'F4 salts (A = Na-Rb; A' = Ag, Au), crystallizes in the KBrF4 structure type, SG I4/mcm (140), Z = 4 with a = 5.79109(6), c = 10.81676(7) A. SPDD gave (in A) four AuIII-F = 1.89(1) and eight AgI-F = 2.577(7). SPDD for AgAuF6 confirmed that it has the LiSbF6 structure, SG R3, Z = 3, with a = 5.2840(2), c = 15.0451(6) A.     

Crown compounds for anions: sandwich and half-sandwich complexes of cyclic trimetric perfluoro-o-phenylenemercury with polyhedral closo-[B10H10]2- and closo-[B12H12]2- anions

It has been shown by IR and NMR spectroscopy that cyclic trimeric perfluoro-o-phenylenemercury (o-C6F4-Hg)3 (1) is capable of binding closo-[B10H10]2- and closo-[B12H12]2- anions to form complexes [[(o-C6F4Hg)3](B10-H10)]2- (2), [[(o-C6F4Hg)3]2(B10H10)]2-(3), [[(o-C6F4Hg)3](B12H12)]2- (4), and [[(o-C6F4Hg)3]2(B12H12)]2- (5). According to IR data, the bonding of the [B10H10]2- and [B12H12]2- ions to the macrocycle in these complexes is accomplished through the formation of B-H-Hg bridges. Complexes 2, 3, and 5 have been isolated in analytically pure form and have been characterized by spectroscopic means. X-ray diffraction studies of 3 and 5 have revealed that these compounds have unusual sandwich structures, in which the polyhedral di-anion is located between the planes of two molecules of 1 and is bonded to each of them through two types of B-H-Hg bridges. One type is the simultaneous coordination of a B-H group to all three Hg atoms of the macrocycle. The other type is the coordination of a B-H group to a single Hg atom of the cycle. According to X-ray diffraction data, complex 2 has an analogous but half-sandwich structure. The obtained complexes 2-5 are quite stable; their stability constants in THF/acetone (1:1) at 20 degrees C have been determined as 1.0 x 10(2)Lmol(-1), 2.6 x 10(3)L(2)mol(2), 0.7 x 10(2)Lmol(-1), and 0.98 x 10(3)L(2)mol(-2), respectively.     

Ring-opening polymerisation of silver-diphosphine [M2L3] coordination cages to give [M2L3]infinity coordination polymers

[M2L3] coordination cages and linear [M2L3]infinity polymers of the rigid, bridging diphosphines bis(diphenylphosphino)acetylene (dppa) and trans-1,2-bis(diphenylphosphino)ethylene (dppet) with silver(I) salts have been investigated in the solution and solid states. Unlike flexible diphosphines, 1:1 dppa/AgX mixtures do not selectively form discrete [Ag2(diphos)2(X)2] macrocycles; instead dynamic mixtures of one-, two- and three-coordinate complexes are formed. However, 3:2 dppa/AgX ratios (X = SbF6. BF4, O3SCF3 or NO3) do lead selectively to new [M2L3] triply bridged cage complexes [Ag2(dppa)3(X)2] 1a-d (X = SbF6 a, BF4 b, O3SCF3 c, NO3 d), which do not exhibit Ag-P bond dissociation at room temperature on the NMR time scale (121 MHz). Complexes la-d were characterised by X-ray crystallography and were found to have small internal cavities, helical conformations and multiple intramolecular aromatic interactions. The nucleophilicity of the anion subtly influences the cage shape: Increasing nucleophilicity from SbF6 (1a) through BF4 (1b) and O3SCF3 (1c) to NO3 (1d) increases the pyramidal distortion at the AgP3 centres, stretching the cage framework (with Ag...Ag distances increasing from 5.48 in 1a to 6.21 A in 1d) and giving thinner internal cavities. Crystal packing strongly affected the size of the helical twist angle, and no correlation between this parameter and the Ag-Ag distance was observed. When crystalline 1c was stored in its supernatant for 16 weeks, conversion occured to the isostoichiometric [M2L3]infinity coordination polymer [Ag(dppa)2Ag(dppa)(O3SCF3)2]infinity (1c'). X-ray crystallography revealed a structure with ten-membered Ag2(dppa)2 rings linked into infinite one-dimensional chains by a third dppa unit. The clear structural relationship between this polymer and the precursor cage 1c suggests a novel example of ring-opening polymerisation. With dppet, evidence for discrete [M2L3] cages was also found in solution, although 31P NMR spectroscopy suggested some Ag-P bond dissociation. On crystallisation, only the corresponding ring-opened polymeric structures [M2L3]infinity could be obtained. This may be because the greater steric bulk of dppet versus dppa destabilises the cage and favours the ring-opening polymerisation.     

K2Ag6Sn3S10: a quaternary sulfide composed of silver sulfide layers pillared by zigzag chains 1infinity[SnS3]2-

A novel framework K(2)Ag(6)Sn(3)S(10) was synthesized solvothermally and characterized by single-crystal diffraction. The framework comprises [Ag(6)SnS(4)](2+) cationic layers pillared by [SnS(3)](2)(-) zigzag chains formed by vertex-sharing SnS(4) tetrahedra, and potassium ions are located in 1D channels. This compound crystallizes in the orthorhombic Pbcn space group with a = 24.0201(2) A, b = 6.4017(3) A, c = 13.3056(4) A, Z = 4. Its thermal and optical properties are studied.     

氮杂环卡宾银碘化物[Ag(MEIm)2]+[AgI2]-的合成、结构与催化性能(MEIm=1-methyl-3-ethyl-imidazolyl)

常温下(MEIm)+I-(MEIm=1-methyl-3-ethyl-imidazolyl)与Ag2O按照物质的量比为1∶2在DMSO中反应成功的合成了线型氮杂环卡宾银碘化物[Ag(MEIm)2]+[AgI2]-,化合物通过了元素分析,1H NMR,X-ray衍射表征。配合物属于单斜晶系,空间群为C2/m,a=1.592 5(4)nm,b=0.679 07(14)nm,c=0.927 1(2)nm,β=110.247(5)°,V=0.940 7(4)nm3,Mr=689.86,Z=8,Dc=2.436 g.cm-3,μ(Mo Kα)=5.36 mm-1,F(000)=640,R=0.036,wR=0.105。配合物由阴阳离子对构成,配阳离子中2个卡宾碳原子与银原子呈线型结构。目标化合物对L-lactide的聚合具有高的催化活性。     

新型离子型有机锡化合物{[Ph~2Sn]~2[2,6-Py(CO~2)]~3H~2O}^2^-.[HNEt~3]^+~2的合成、表征、性质及晶体结构

利用三苯基氯化锡和2,6-吡啶二甲酸在三乙胺存在下以1:1摩尔比反应,合成了离子型有机锡化合物{[Ph~2Sn]~2[2,6-Py(CO~2)]~3H~2O}^2^-[HNEt~3]^+~2。通过元素分析、红外光谱和核磁共振氢谱对其结构进行了表征。用X射线单晶衍射测定了该化合物的晶体结构。化合物为单斜晶系,空间群P2~1/n,a=1.7073(7)nm,b=1.7447(7)nm,c=2.5333(10)nm,β=109.694(7)°,Z=4,V=6.824(5)nm^3,D~c=1.282g/cm^3,μ=0.793mm^-^1,F(000)=2696,R~1=0.0563,WR~2=0.1539。化合物中两个锡原子呈七配位畸变五角双锥构型。生物活性测试结果表明,该化合物具有较强的体外抗肿瘤活性。     

Preparation and characterization of the argentates: [Ag[P(CF(3))(2)](2)](-), [Ag[(micro-P(CF(3))(2))M(CO)(5)](2)](-) (M = Cr, W), and [Ag[(micro-P(C(6)F(5))(2))W(CO)(5)](2)](-): X-ray crystal structure of [K(18-crown-6)][Ag[(micro-P(CF(3))(2))Cr(CO)(5)](2)

The first example of a mononuclear diphosphanidoargentate, bis[bis(trifluoromethyl)phosphanido]argentate, [Ag[P(CF(3))(2)](2)](-), is obtained via the reaction of HP(CF(3))(2) with [Ag(CN)(2)](-) and isolated as its [K(18-crown-6)] salt. When the cyclic phosphane (PCF(3))(4) is reacted with a slight excess of [K(18-crown-6)][Ag[P(CF(3))(2)](2)], selective insertion of one PCF(3) unit into each silver phosphorus bond is observed, which on the basis of NMR spectroscopic evidence suggests the [Ag[P(CF(3))P(CF(3))(2)](2)](-) ion. On treatment of the phosphane complexes [M(CO)(5)PH(CF(3))(2)] (M = Cr, W) with [K(18-crown-6)][Ag(CN)(2)], the analogous trinuclear argentates, [Ag[(micro-P(CF(3))(2))M(CO)(5)](2)](-), are formed. The chromium compound [K(18-crown-6)][Ag[(micro-P(CF(3))(2))Cr(CO)(5)](2)] crystallizes in a noncentrosymmetric space group Fdd2 (No. 43), a = 2970.2(6) pm, b = 1584.5(3) pm, c = 1787.0(4), V = 8.410(3) nm(3), Z = 8. The C(2) symmetric anion, [Ag[(micro-P(CF(3))(2))Cr(CO)(5)](2)](-), shows a nearly linear arrangement of the P-Ag-P unit. Although the bis(pentafluorophenyl)phosphanido compound [Ag[P(C(6)F(5))(2)](2)](-) has not been obtained so far, the synthesis of its trinuclear counterpart, [K(18-crown-6)][Ag[(micro-P(C(6)F(5))(2))W(CO)(5)](2)], was successful.     

Synthesis and characterization of bis[bis(pentafluoroethyl)phosphinyl]imides, M(+)N[(C2F5)2P(O)]2(-), M = H, Na, K, Cs, Ag, Me4N

A convenient synthesis and a full characterization of the strong acid bis[bis(pentafluoroethyl)phosphinyl]imide and some of its salts M (+)N[(C 2F 5) 2P(O)] 2 (-), M = Na, K, Cs, Ag, Me 4N, are presented. Their thermal (mp, T dec.) and spectroscopic (IR, Raman, NMR) properties are discussed. A single crystal structure of [Me 4N][N{P(O)(C 2F 5) 2} 2] has been obtained, and the structural parameters of the anion are compared with the results of quantum-chemical calculations. The observed properties are comparable to those of bis((trifluoromethyl)sulfonyl)imide and their derivatives.     

Structural chemistry of "defect" cyanometalate boxes: (Cs subset [CpCo(CN)3]4[Cp*Ru]3) and (M subset [Cp*Rh(CN)3]4[Cp*Ru]3) (M = NH4, Cs)

A series of heptametallic cyanide cages are described; they represent soluble analogues of defect-containing cyanometalate solid-state polymers. Reaction of 0.75 equiv of [Cp*Ru(NCMe)3]PF6, Et(4)N[Cp*Rh(CN)3], and 0.25 equiv of CsOTf in MeCN solution produced (Cs subset [CpCo(CN)3]4[Cp*Ru]3)(Cs subset Rh4Ru3). 1H and 133Cs NMR measurements show that Cs subset Rh4Ru3 exists as a single Cs isomer. In contrast, (Cs subset [CpCo(CN)3]4[Cp*Ru]3) (Cs subset Co4Ru3), previously lacking crystallographic characterization, adopts both Cs isomers in solution. In situ ESI-MS studies on the synthesis of Cs subset Rh4Ru3 revealed two Cs-containing intermediates, Cs subset Rh2Ru2+ (1239 m/z) and Cs subset Rh3Ru3+ (1791 m/z), which underscore the participation of Cs+ in the mechanism of cage formation. 133Cs NMR shifts for the cages correlated with the number of CN groups bound to Cs+: Cs subset Co4Ru4+ (delta 1 vs delta 34 for CsOTf), Cs subset Rh4Ru3 where Cs+ is surrounded by ten CN ligands (delta 91), Cs subset Co4Ru3, which consists of isomers with 11 and 10 pi-bonded CNs (delta 42 and delta 89, respectively). Although (K subset [Cp*Rh(CN)3]4[Cp*Ru]3) could not be prepared, (NH4 subset [Cp*Rh(CN)3]4[Cp*Ru]3) (NH4 subset Rh4Ru3) forms readily by NH4+-template cage assembly. IR and NMR measurements indicate that NH4+ binding is weak and that the site symmetry is low. CsOTf quantitatively and rapidly converts NH4 subset Rh4Ru3 into Cs subset Rh4Ru3, demonstrating the kinetic advantages of the M7 cages as ion receptors. Crystallographic characterization of CsCo4Ru3 revealed that it crystallizes in the Cs-(exo)1(endo)2 isomer. In addition to the nine mu-CN ligands, two CN(t) ligands are pi-bonded to Cs+. M subset Rh4Ru3 (M = NH4, Cs) crystallizes as the second Cs isomer, that is, (exo)2(endo)1, wherein only one CN(t) ligand interacts with the included cation. The distorted framework of NH4 subset Rh4Ru3 reflects the smaller ionic radius of NH4+. The protons of NH4+ were located crystallographically, allowing precise determination of the novel NH4...CN interaction. A competition experiment between calix[4]arene-bis(benzocrown-6) and NH4 subset Rh4Ru3 reveals NH4 subset Rh4Ru3 has a higher affinity for cesium.     

The cyclic "silver-diphos" motif [Ag2(mu-diphosphine)2]2+ as a synthon for building up larger structures

The dinuclear, cyclic structural motif [Ag2(diphosphine)2](2+), here termed the "silver-diphos" motif, previously observed in many diphosphine-silver complexes, has been investigated as a synthon for building up larger structures such as coordination cages and polymers. A series of ligands containing one to four meta-substituted diphosphine groups, attached via a central core, has been synthesized from the corresponding fluoroarenes by reaction with KPPh2. Upon reaction with silver salts, the target synthon is adopted by meta-substituted diphosphines 1,3-bis(diphenylphosphino)benzene (L1), 2,6-bis(diphenylphosphino)benzonitrile (L2), and 3,5-bis(diphenylphosphino)benzamide (L3), each of which gives a single species in solution consistent with the expected dimeric complexes [Ag2L2(anion)2]. X-ray crystal structures of [Ag2(L1)2(OTf)2] and [Ag2(L2)2(SbF6)2] confirm the adoption of the silver-diphos motif in the solid state. Amide-functionalized diphosphine L3 forms a hydrogen-bonded chain structure in the solid state via the amide group. A discrete boxlike cage [Ag4(L4)2][SbF6]4 based on two silver-diphos synthons is formed when the tetraphosphine Ph2Sn{3,5-bis(diphenylphosphino)benzene}2 (L4) reacts with silver(I). Its single-crystal X-ray structure reveals a central cavity of minimum diameter, ca. 5.0 A, which contains a single SbF6(-) counterion disordered over two sites. In contrast to the highly selective behavior of the di- and tetra-phosphines L1-L4, the heptaphosphine P{3,5-bis(diphenylphosphino)benzene}3 L5 and the hexaphosphine PhSn{3,5-bis(diphenylphosphino)benzene}3 L6 give dynamic mixtures upon reaction with silver salts in solution. This nonspecific behavior is rationalized by the fact that their diphosphine groups are not appropriately disposed to form stable discrete structures based on the silver-diphos synthon. By contrast, the octaphosphine Sn{3,5-bis(diphenylphosphino)benzene}4 L7 does selectively form a single, discrete, highly symmetrical product in solution, [Ag4(L7)(OTf)4]. In this case, the ligand unexpectedly adopts an interarm tetra-chelating coordination mode, resulting in a continuous 24-membered ring around the periphery of the molecule. To understand the adoption of this unusual coordination mode, the alternative diphosphine Ph2Sn(3-diphenylphosphinobenzene)2 L8, which models a single interarm chelating site of L7, was also investigated. By contrast to L7, its coordination was nonspecific, giving mixtures of silver complexes upon reaction with AgOTf. The selective interarm chelation by L7 may therefore be stabilized by the continuous coordination ring in [Ag4(L7)(OTf)4]; that is, the four chelating sites can be thought of as acting in a cooperative manner. Alternatively, interarm steric repulsions between phenyl groups may favor interarm chelation. Overall, we conclude that, if the diphosphine groups are appropriately articulated to act independently (i. e., they are adequately separated and oriented), the silver-diphos synthon can be a useful tool for the coordination-based self-assembly of larger structures.     

Copper hydroxydiphosphate with a one-dimensional arrangement of copper polyhedra: Cu3[P2O6OH]2

A new copper hydroxydiphosphate Cu3(P2O6OH)2 was synthesized, by soft chemistry. The crystal structure was solved ab initio from X-ray powder diffraction data in the triclinic space group P. The structure is built up from [Cu3O10]infinity zigzag chains linked by P2O6(OH) groups to form a tridimensional framework. The [Cu3O10]infinity chains consist of edge-sharing polyhedra. The structure contains two sorts of copper polyhedra: one CuO6 octahedron and two CuO5 pyramids. Magnetization measurements confirm the presence of divalent copper and suggest antiferromagnetic interactions at low temperature.     

STRUCTURE STUDIES OF [Et_4N]_4[Cu_8(i-mnt)_6] (i-mnt=S_2C=C(CN)_2) AND [Me_4N]_4[Cu_5Ag_3(i-mnt)_6]·H_2O

<正> [Me4N]6[Ag6(i-mnt)6].H2O(1),[Et4N]4[Cu8(i-mnt)6](2) and [Me4N]4-[Cu5Ag3(i-mnt)6].H2O(3)(i-mnt=S2C=C(CN)2) were synthesized. The crystal and molecular structure of the complex 1 was reported by us.The structure of the complex 2 was determined from single crystal X-ray diffraction data. [Et4N]4[Cu8(i-mnt)s] 2, Mr=1870.46, monoclinic, P21/n, a=14.724(6), b = 17.228(3), c=15.59(1)A,β= 100.75(7)°,V=3886.3A3;Z = 2,Dc= 1.598 g/cm3. Complex 3 has been characterized by ICP elemental analyses and IR spectrum.     

Betaine-induced assembly of neutral infinite columns and chains of linked silver(I) polyhedra with embedded acetylenediide

Ten polymeric silver(I) double salts containing embedded acetylenediide: [(Ag2C2)2(AgCF3CO2)9(L1)3] (1), [(Ag2C2)2(AgCF3CO2)10(L2)3]H2O (2), [(Ag2C2)(AgCF3CO2)4(L3)(H2O)]0.75 H2O (3), [(Ag2C2)(1.5)(AgCF3CO2)7(L4)2] (4), [(Ag2C2)(AgCF3CO2)7(L5)2(H2O)] (5), [(Ag2C2) (AgC2F5CO2)7(L1)3(H2O)] (6), [(Ag2C2)(AgCF3CO2)7(L1)3(H2O)]2 H2O (7), [(Ag2C2)(AgC2F5CO2)6(L3)2] (8), [(Ag2C2)2(AgC2F5CO2)12(L4)2(H2O)4]H2O (9), and [(Ag2C2)(AgCF3CO2)6(L3)2(H2O)]H2O (10) have been isolated by varying the types of betaines, the perfluorocarboxylate ligands employed, and the reaction conditions. Single-crystal X-ray analysis has shown that 1-4 all have a columnar structure composed of fused silver(I) double cages, with C2(2-) species embedded in its stem and an exterior coat comprising anionic and zwitterionic carboxylates. For 5 and 6, single silver(I) cages are linked into a beaded chain through both types of carboxylate ligands. In 7, two different coordination modes of L1 connect the silver(I) polyhedra into a chain. For 8, the mu(2)-O,O' coordination mode of L3 connects the silver(I) double cages into a chain. Compound 9 exhibits a two-dimensional architecture generated from the cross-linkage of double cages by C2F5CO2-, L4, and [Ag2(C2F5CO2)2] units. Similar to 9, 10 is also a two-dimensional structure, which is formed by connecting the chains of linked double cages through [Ag2(CF3CO2)2] bridging.     

Synthesis and Structure of a Mixed Phosphine-Thiolato Polymer with a Linear Chain Network [Ag2 (μ2-dppe)3 (S-mbo)2]n · 2nDMF [dppe = 1,2-Bis (diphenylphosphino)ethane, mbo= 2-Mercaptobenzoxazole]

Diphosphino organochalcogenide metal complexes have been investigated presently fortheir possible use as anti-cancer agents[1-3]. However, the area of silver complexes withmixed phosphine-thiolato ligands has scarcely been touched[4]. As a heterocyclic thiolato lig-and with potential S and N donors, 2-mercaptobenzoxazole (Hmbo) is interesting because ofthe structural chemistry of its multifunctional coordination modes (unidentate-N, unidentate-S or bidentate-N : S)[5-8]. Until now, Ag-mbo complex has been unknown to our knowl-edge, despite the fact that its complexes of Sn[5] , Au[6] and Li[7,8] have been reported. Hereinwe report the X-ray crystal structure of a self-assembled coordination polymer[Ag2(μ2-dppe)3(S-mbo)2]n · 2nDMF(dppe=1,2-bis(diphenylphosphino)ethane, Hmbo=2-mercaptobenzoxazole, DMF = dimethyl formamide).     

Synthesis and Crystal Structure of a Novel Complex [Ag(NIT3Py)3]·((ClO4)(H2O)

A novel complex [Ag(NIT3Py)3]·((ClO4)(H2O) has been synthesized and structurally characterized by X-ray diffraction method. It crystallizes in the rhombohedral system, space group R3 with a = 15.8227(17), b = 15.8227(17), c = 31.445(3) (A),γ = 120°, V = 6817.8(12) (A)3, Dc = 1.370 g/cm3, Z = 6, μ= 0.566 mm-1, Mr = 937.18, F(000) = 2916, R = 0.0715, wR = 0.2115 and GOF = 1.086. The structure consists of Ag(NIT3Py)3+ cation moiety, one water molecule and one perchloric ion. The Ag(I) ion is in a trigonal planar coordination environment formed by three nitrogen atoms from three NIT3Py ligand molecules.     

Cs3AgAs4Se8 and CsAgAs2Se4: selenoarsenates with infinite 1 infinity[AsSe2]- chains in different Ag+ coordination environments

Two quaternary silver selenoarsenates Cs3AgAs4Se8 (I) and CsAgAs2Se4 (II) have been discovered by methanothermal reaction of Li3AsSe3 with AgBF4 in the presence of the respective alkali metal sources Cs2CO3 and CsCl. Orange crystals of Cs3AgAs4Se8 (I) were formed after reaction at 120 degrees C for 72 h, whereas red CsAgAs2Se4 (II) was obtained under slightly different conditions at 140 degrees C for 70 h. Both compounds possess novel two-dimensional (2D) polyanions consisting of infinite 1 infinity[AsSe2]- chains that are interconnected by Ag+ ions in different coordination patterns. In I, a double layer of 1 infinity[AsSe2]- chains is bridged by distorted trigonal planar coordinated Ag+ atoms to form a 2 infinity[AgAs4Se8]3- layer with a thickness of about 11.3 A. The nonbonding Ag...Ag distances are about 4.220 A, and large cavities within the layers accommodate for three of the four crystallographic Cs+ cations. The double amount of Ag+ atoms per AsSe2 chain unit in II leads to simple layers 2 infinity[AgAs2Se4]- [=[Ag2As4Se8]2-] in which the Ag+ atoms are arranged in rows between the 1 infinity[AsSe2]- chains, with alternating Ag...Ag distances of 3.053(3) and 3.488(3) A. Hereby the 1 infinity[AsSe2]- polyanions show a disorder within the central (-As-Seb)- chain (b = bridging), while the positions of the terminal Se atoms (Set) remain unaffected. The thermal, optical, and spectroscopic properties of the compounds are reported. Both I and II melt with decomposition and are wide band gap semiconductors with values of 2.07 and 1.79 eV, respectively. Raman spectroscopic data show typical band patterns expected for infinite [AsSe2]- chains. Crystal Data: Cs3AgAs4Se8 (I), monoclinic, C2/c, a = 25.212(2) A, b = 8.0748(7) A, c = 22.803(2) A, beta = 116.272(2) degrees, Z = 8; CsAgAs2Se4 (II), monoclinic, P2(1)/n, a = 10.9211(1) A, b = 6.5188(2) A, c = 13.7553(3) A, beta = 108.956(1) degrees, Z = 4.     

Inclusion complexation of diquat and paraquat by the hosts cucurbit[7]uril and cucurbit[8]uril

The binding interactions in aqueous solution between the dicationic guest diquat (DQ(2+)) and the cucurbit[7]uril (CB7) and cucurbit[8]uril (CB8) hosts were investigated by (1)H NMR, UV/Vis, and fluorescence spectroscopy; mass spectrometry; single-crystal X-ray diffraction; and electrochemical techniques. The binding data were compared with previously reported results for the related paraquat guest (PQ(2+)). DQ(2+) was found to bind poorly (K=350 m(-1)) inside CB7 and more effectively (K=4.8 x 10(4) m(-1)) inside CB8. One-electron reduction led to increased binding affinity with both hosts (K(r)=1 x 10(4) m(-1) with CB7 and K(r)=6 x 10(5) m(-1) for CB8). While (1)H NMR spectroscopic data revealed that DQ(2+) is not fully included by CB7, the crystal structure of the CB8DQ(2+) complex-obtained from single-crystal X-ray diffraction-clearly establishes its inclusion nature. Overall, both diquat and its one-electron reduced radical cation are bound more effectively by CB8 than by CB7. In contrast to this, paraquat exhibits selectivity for CB7, but its radical cation forms a highly stable dimer inside CB8. These differences highlight the pronounced sensitivity of cucurbit[n]uril hosts to guest features such as charge, charge distribution and shape.     

Photochemical Preparation of Highly Water-Soluble Pendant [60]Fullerene-Aminopolymers

Abstract— In order to introduce fullerene cages into an aqueous environment, pendant [60]fullerene-poly(propionylethyle-neimine-co-ethyleneimine) was prepared photochemical-ly. The pendant polymer is highly water soluble, with equivalent aqueous solubilities of the polymer-bound [60]fullerene much higher than the solubility of [60]ful-lerene in toluene. The photochemical reaction between [60]fullerene and secondary amine moieties in the ami-nopolymers likely follows a photoinduced electron transfer-proton transfer mechanism. The pendant polymer structures, which are represented by dehydrogenated di-and tetra-aminofullerene linkages, were characterized by use of proton and 13C NMR, Fourier transform-infrared spectroscopy, gel-permeation chromatography and optical spectroscopic methods.