Silver cages with encapsulated acetylenediide as building blocks for hydrothermal synthesis of supramolecular complexes with n-cyanopyridine and pyridine-n-carboxamide (n=3, 4)

New silver(i) double salts (Ag(2)C(2))(AgCF(3)CO(2))(8)(3-pyCONH(2))(2)(H(2)O)(4) (1), [(Ag(2)C(2))(AgCF(3)CO(2))(4)(4-pyCONH(2))(H(2)O)].H(2)O (2), (Ag(2)C(2))(AgCF(3)CO(2))(6)(3-pyCONH(2))(4) (3), (Ag(2)C(2))(AgCF(3)CO(2))(6)(3-pyCN)(2) (4) and (Ag(2)C(2))(AgCF(3)CO(2))(4)(4-pyCN)(2) (5) (n-pyCONH(2) is pyridine-n-carboxamide, n-pyCN is n-cyanopyridine; n=3, 4) have been synthesized by the hydrothermal method. All five compounds contain polyhedral silver(i) cages each encapsulating a C(2)(2-) dianion. Compounds 1, 3 ,4 and 5 exhibit three-dimensional structures, whereas compound 2 is a two-dimensional network. The structure of 1 is constructed from the linkage of a branched-tree architecture via hydrogen bonds. Unlike 4 and 5, which involve the connection of n-cyanopyridine (n=3, 4) with silver columns, 3 results from the linkage of discrete silver cages via pyridine-3-carboxamide.     

Polyhedral C2@Agn cages distorted by ancillary pyridine N-oxide ligands in silver-acetylenediide complexes

Reactions of the pyridine N-oxide ligands L, L2 and L3 with the silver acetylenediide-containing system under hydrothermal conditions gave rise to four silver-acetylenediide complexes bearing interesting C2@Agn motifs: (Ag2C2)2(AgCF3CO2)8(L1)3.5 (1), (Ag2C2)2(AgCF3CO2)8(L2)2 (2), (Ag2C2)(AgCF3CO2)4(L3) (3) and [(Ag7(C2)(CF3SO3)3(L3)2(H2O)2] x 2CF3SO3 (4) (L = nicotinic acid N-oxide, L(1) = pyridine N-oxide, L2 = 1,2-bis(4-pyridyl)ethane N,N'-dioxide, L3 = 1,3-bis(4-pyridyl)propane N,N'-dioxide), which exhibit new distorted polyhedral C2@Agn cage motifs. Complex 1 has a pair of acetylenediide dianions encapsulated in a Ag(14) aggregate composed of three polyhedral parts, whereas 2 contains an irregular (C2)2@Ag13 double cage. In 3, the basic building unit is a centrosymmetric (C2)2@Ag12 double cage with each component single cage taking the shape of a highly distorted triangulated dodecahedron with one missing vertex. As to complex 4, the core is a C2@Ag7 single cage in the form of a slightly distorted monocapped trigonal prism with four cleaved edges that include all three vertical sides. Furthermore, in the silver-rich environment, the pyO-type ligands are induced to exhibit unprecedented coordination modes, such as the mu(5)-O,O,O,O',O' ligation mode of L2 in 2 and the mu4-O,O,O',O' mode of L3 in 3 and 4.     

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.     

Structures of [(CO2)n(H2O)m]- (n=1-4, m=1,2) cluster anions. I. Infrared photodissociation spectroscopy

The infrared photodissociation spectra of [(CO(2))(n)(H(2)O)(m)](-) (n=1-4, m=1, 2) are measured in the 3000-3800 cm(-1) range. The [(CO(2))(n)(H(2)O)(1)](-) spectra are characterized by a sharp band around 3570 cm(-1) except for n=1; [(CO(2))(1)(H(2)O)(1)](-) does not photodissociate in the spectral range studied. The [(CO(2))(n)(H(2)O)(2)](-) (n=1, 2) species have similar spectral features with a broadband at approximately 3340 cm(-1). A drastic change in the spectral features is observed for [(CO(2))(3)(H(2)O)(2)](-), where sharp bands appear at 3224, 3321, 3364, 3438, and 3572 cm(-1). Ab initio calculations are performed at the MP2/6-311++G(**) level to provide structural information such as optimized structures, stabilization energies, and vibrational frequencies of the [(CO(2))(n)(H(2)O)(m)](-) species. Comparison between the experimental and theoretical results reveals rather size- and composition-specific hydration manner in [(CO(2))(n)(H(2)O)(m)](-): (1) the incorporated H(2)O is bonded to either CO(2) (-) or C(2)O(4) (-) through two equivalent OH...O hydrogen bonds to form a ring structure in [(CO(2))(n)(H(2)O)(1)](-); (2) two H(2)O molecules are independently bound to the O atoms of CO(2) (-) in [(CO(2))(n)(H(2)O)(2)](-) (n=1, 2); (3) a cyclic structure composed of CO(2) (-) and two H(2)O molecules is formed in [(CO(2))(3)(H(2)O)(2)](-).     

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.     

Syntheses, structures, and properties of intercalation compounds of silver(I) complex with [2.2]paracyclophane

Reaction of [2.2]paracyclophane (pcp) with silver(I) trifluoroacetate (AgCF(3)CO(2)) and silver(I) pentafluoroproprionate (AgC(2)F(5)CO(2)) has led to isolation of three novel intercalation polymers: [Ag(4)(pcp)(CF(3)CO(2))(4)](C(6)H(6)) (1), [Ag(4)(pcp)(CF(3)CO(2))(4)](C(6)H(3)Me(3)) (2), and [Ag(4)(pcp)(C(2)F(5)CO(2))(4)](pcp) (3). Structure studies using single crystal X-ray diffraction have shown that all compounds contain two-dimensional layered frameworks based on cation-pi interactions, in which pcp exhibits an unprecedented micro-tetra-eta(2) coordination mode. Guest molecules which weakly interact with the host pcp via C-H.pi interactions are intercalated between layers. The guest-eliminated complexes (1a and 2a) and guest-reincorporated ones (1b or 1c and 2b or 2c), accompanied by small structural changes, were confirmed by (1)H NMR, thermogravimetric analysis, mass spectra, and X-ray powder diffraction patterns. The structural changes from 1 --> 1a --> 1c (=1) can take place reversibly in the process of exposure of 1a to benzene vapor. The original framework of complex 2 is also completely recovered by immersing 2a in mesitylene as well as exposing it to mesitylene vapor.     

Crown ethers as ancillary ligands in the assembly of silver(i) aggregates containing embedded acetylenediide

Five silver(I) double salts containing embedded acetylenediide, [Ag([12]crown-4)(2)][Ag(10)(C(2))(CF(3)CO(2))(9)([12]crown-4)(2)(H(2)O)(3)] x H(2)O (2), [Ag(2)C(2) x 5 AgCF(3)CO(2) x (benzo[15]crown-5) x 2 H(2)O] x 0.5 H(2)O (3), [Ag(4)([18]crown-6)(4)(H(2)O)(3)][Ag(18)(C(2))(3)(CF(3)CO(2))(16)(H(2)O)(2.5)] x 2.5 H(2)O (4), [Ag(2)C(2) x 6 AgC(2)F(5)CO(2) x 2([15]crown-5)](2) (5), and [(Ag(2)C(2))(2) x (AgC(2)F(5)CO(2))(9) x ([18]crown-6)(2) x (H(2)O)(3.5)] x H(2)O (6), have been isolated by varying the types of crown ethers and anions employed. Single-crystal X-ray analysis has shown that complex 2 is composed of winding anionic chains with sandwiched [Ag([12]crown-4)(2)](+) ions accommodated in the concave cavities between them. In 3, silver(I) double cages each sandwiched by a couple of benzo[15]crown-5 ligands are linked by [Ag(2)(CF(3)CO(2))(2)] bridges to form a one-dimensional structure. For 4, an anionic silver column is generated through fusion of two kinds of silver polyhedra (triangulated dodecahedron and bicapped trigonal antiprism), and the charge balance is provided by aqua-ligated [Ag([18]crown-6)](+) ions. Complex 5 is a centrosymmetric hexadecanuclear supermolecule composed of two [(eta(5)-[15]crown-5)(2)(C(2)@Ag(7))(mu-C(2)F(5)CO(2))(5)] moieties connected through a [Ag(2)(C(2)F(5)CO(2))(2)] bridge. Compound 6 is a discrete supermolecule containing an asymmetric (C(2))(2)@Ag(13) cluster core capped by two [18]crown-6 ligands in mu(3)-eta(5) and mu(4)-eta(6) ligation modes.     

Self-assembled silver polyhedra with embedded acetylide dianion stabilized by perfluorocarboxylate and 4-hydroxyquinoline ligands

Four new silver(I) double salts (L(2)H)(4)[Ag(10)(C(2))(CF(3)CO(2))(12)(L)(2)].5H(2)O (1), [Ag(8)(C(2))(CF(3)CO(2))(6)(L)(6)] (2), [(Ag(2)C(2))(AgC(2)F(5)CO(2))(6)(L)(3)(H(2)O)].H(2)O (3), and (L.H(3)O)(2)[Ag(11)(C(2))(2)(C(2)F(5)CO(2))(9)(H(2)O)(2)].H(2)O (4) incorporating the hitherto unexplored ligand 4-hydroxyquinoline (L) have been synthesized by the hydrothermal method. Compound 1 features an unprecedented bicapped square-antiprismatic Ag(10) silver cage with an embedded C(2)(2-) moiety, whereas the discrete supermolecule 2 bears a rhombohedral Ag(8) core similar to that previously found in Ag(2)C(2).6AgNO(3). Compound 3 contains a discrete supramolecular complex whose core is a (C(2))(2)@Ag(16) double cage constructed from the edge-sharing of two monocapped square antiprisms, which is completely surrounded by 12 pentafluoropropionate, 6 4-hydroxyquinoline, and 2 aqua ligands. The layer structure in 4 is constructed from a sinuous anionic silver column composed of fused irregular monocapped trigonal antiprisms each encapsulating a C(2)(2-) dianion, with L.H(3)O(+) species serving as hydrogen-bond connectors to adjacent columns.     

Systematic investigations on magneto-structural correlations of copper(II) coordination polymers based on organic ligands with mixed carboxylic and nitrogen-based moieties

Reaction of copper(II) tetrazolate-5-carboxylate with different neutral N-donor spacer ligands under hydrothermal conditions leads to the formation of five new coordination polymers, [Cu(tzc)(pyz)(0.5)(H(2)O)(2)](n)·H(2)O (1), [Cu(tzc)(pyz)](n) (2), [Cu(tzc)(pym)(H(2)O)](n) (3), [Cu(tzc)(dpe)(0.5)(H(2)O)](n) (4) and [Cu(tzc)(azpy)(0.5)(H(2)O)](n) (5) (tzc = tetrazolate-5-carboxylate, pyz = pyrazine, pym = pyrimidine, dpe = 1,2-di(4-pyridyl)ethylene and azpy = 4,4'-azopyridine). All five structures were characterized by X-ray single-crystal measurements and bulk material can be prepared phase pure in high yields. The crystal structures of the hydrates 1, 3, 4 and 5 show dimeric [Cu(2)(N(tzc)-N(tzc))(2)] building units formed by μ(2)-N1,O1:N2 bridging tzc ligands as the characteristic structural motif. These six-membered entities in 1, 4 and 5 are connected by μ(2)-N,N' bridging N-donor ligands into 1D chains and in 3 into 2D layers. In the crystal structure of compound 2 adjacent Cu(II) cations are connected by μ(2)-N1,O1:N4,O2 bridging tzc ligands into chains, which are further connected by μ(2)-N,N' bridging pyz ligands forming 2D layers. Extensive hydrogen bonds in all compounds play an important role in the construction of their supramolecular networks. Investigations of their thermal properties reveal water release upon heating according to the formation of anhydrates before starting decomposing above 220 °C. Furthermore, the magnetic properties have been studied leading to consistent global antiferromagnetic exchange interactions with coupling constants of J = 3 ± 1 cm(-1) and long-range antiferromagnetic ordering states at lower temperatures.     

New family of silver(I) complexes based on hydroxyl and carboxyl groups decorated arenesulfonic acid: syntheses, structures, and luminescent properties

Self-assembly of silver(I) salts and three ortho-hydroxyl and carboxyl groups decorated arenesulfonic acids affords the formation of nine silver(I)-sulfonates, (NH(4))·[Ag(HL1)(NH(3))(H(2)O)] (1), {(NH(4))·[Ag(3)(HL1)(2)(NH(3))(H(2)O)]}(n) (2), [Ag(2)(HL1)(H(2)O)(2)](n) (3), [Ag(2)(HL2)(NH(3))(2)]·H(2)O (4), [Ag(H(2)L2)(H(2)O)](n) (5), [Ag(2)(HL2)](n) (6), [Ag(3)(L3)(NH(3))(3)](n) (7), [Ag(2)(HL3)](n) (8), and [Ag(6)(L3)(2)(H(2)O)(3)](n) (9) (H(3)L1 = 2-hydroxyl-3-carboxyl-5-bromobenzenesulfonic acid, H(3)L2 = 2-hydroxyl-4-carboxylbenzenesulfonic acid, H(3)L3 = 2-hydroxyl-5-carboxylbenzenesulfonic acid), which are characterized by elemental analysis, IR, TGA, PL, and single-crystal X-ray diffraction. Complex 1 is 3-D supramolecular network extended by [Ag(HL1)(NH(3))(H(2)O)](-) anions and NH(4)(+) cations. Complex 2 exhibits 3-D host-guest framework which encapsulates ammonium cations as guests. Complex 3 presents 2-D layer structure constructed from 1-D tape of sulfonate-bridged Ag1 dimers linked by [(Ag2)(2)(COO)(2)] binuclear units. Complex 4 exhibits 3-D hydrogen-bonding host-guest network which encapsulates water molecules as guests. Complex 5 shows 3-D hybrid framework constructed from organic linker bridged 1-D Ag-O-S chains while complex 6 is 3-D pillared layered framework with the inorganic substructure constructing from the Ag2 polyhedral chains interlinked by Ag1 dimers and sulfonate tetrahedra. The hybrid 3-D framework of complex 7 is formed by L3(-) trianions bridging short trisilver(I) sticks and silver(I) chains. Complex 8 also presents 3-D pillared layered framework, and the inorganic layer substructure is formed by the sulfonate tetrahedrons bridging [(Ag1O(4))(2)(Ag2O(5))(2)](∞) motifs. Complex 9 represents the first silver-based metal-polyhedral framework containing four kinds of coordination spheres with low coordination numbers. The structural diversities and evolutions can be attributed to the synthetic methods, different ligands and coordination modes of the three functional groups, that is, sulfonate, hydroxyl and carboxyl groups. The luminescent properties of the nine complexes have also been investigated at room temperature, especially, complex 1 presents excellent blue luminescence and can sensitize Tb(III) ion to exhibit characteristic green emission.     

Trinuclear pyrazine-bridged ruthenium complexes: syntheses, electrochemistry, NIR-Vis spectra, and their interpretation in terms of a 5-orbital-3-parameter model

A study of absorption spectra in the near-infrared (NIR) and visible (vis) regions of trinuclear Ru complexes containing pyrazine (pyz) as bridging ligand, trans-[(Ru(NH(3))(5)pyz)(2)Ru(NH(3))(4)](m+)(m = 6-9), is reported. The spectra were recorded on aqueous solutions containing the described species formed in situ by stoichiometric additions of a standard solution of Ce(SO(4))(2). They were interpreted in terms of a simple 5-orbital-3-parameter model which includes the effects of d-pi interaction and electronic correlation. The model is shown to account for the observed NIR-vis spectra of the complex ions. The 6+ parent species was synthesized by an improved literature method and fully characterized. The novel 8+ complex was also prepared and characterized. The 9+ ion was established to be slowly reduced by water, with dioxygen formation. Electrochemical (CV and DPV) studies were performed on the trinuclear 6+ complex, as well as on its constituent fragments [Ru(NH(3))(5)(pyz)](2+) and trans-[Ru(NH(3))(4)(pyz)(2)](2+).     

Supramolecular structural variations with changes in anion and solvent in silver(I) complexes of a semirigid, bitopic tris(pyrazolyl)methane ligand

The bitopic ligand p-C(6)H(4)[CH(2)OCH(2)C(pz)(3)](2) (pz = pyrazolyl ring) that contains two tris(pyrazolyl)methane units connected by a semirigid organic spacer reacts with silver(I) salts to yield [p-C(6)H(4)[CH(2)OCH(2)C(pz)(3)](2)(AgX)(2)]( infinity ), where X = CF(3)SO(3)(-) (1), SbF(6)(-) (2), PF(6)(-) (3), BF(4)(-) (4), and NO(3)(-) (5). Crystallization of the first three compounds from acetone yields [p-C(6)H(4)[CH(2)OCH(2)C(pz)(3)](2)(AgCF(3)SO(3))(2)]( infinity ) (1a), [p-C(6)H(4)[CH(2)OCH(2)C(pz)(3)](2)(AgSbF(6))(2)[(CH(3))(2)CO](2)]( infinity ) (2b), and [p-C(6)H(4)[CH(2)OCH(2)C(pz)(3)](2)AgPF(6)]( infinity ) (3a), where the stoichiometry for the latter compound has changed from a metal:ligand ratio of 2:1 to 1:1. The structure of 1a is based on helical argentachains constructed by a kappa(2)-kappa(1) coordination to silver of the tris(pyrazolyl)methane units. These chains are organized into a tubular 3D structure by cylindrical [(CF(3)SO(3))(6)](6)(-) clusters that form weak C-H...O hydrogen bonds with the bitopic ligand. The same kappa(2)-kappa(1) coordination is present in the structure of 2a, but the structure is organized by six different tris(pyrazolyl)methane units from six ligands bonding with six silvers to form a 36-member argentamacrocycle core. The cores are organized in a tubular array by the organic spacers where each pair of macrocycles sandwich six acetone molecules and one SbF(6)(-) counterion. The structure of 3a is based on a kappa(2)-kappa(0) coordination mode of each tris(pyrazolyl)methane unit forming a helical coordination polymer, with two strands organized in a double stranded helical structure by a series of C-H...pi interactions between the central arene rings. Crystallization of 2-4 from acetonitrile yields complexes of the formula [p-C(6)H(4)[CH(2)OCH(2)C(pz)(3)](2)[(AgX)(2)(CH(3)CN)(n)]]( infinity ) where n = 2 for X = SbF(6)(-) (2b), X = PF(6)(-) (3b) and n = 1 for X = BF(4)(-) (4b). All three structures contain argentachains formed by a kappa(2)-kappa(1) coordination mode of the tris(pyrazolyl)methane units linked by the organic spacer and arranged in a 2D sheet structure with the anions sandwiched between the sheets. Crystallization of 5 from acetonitrile yields crystals of the formula [p-C(6)H(4)[CH(2)OCH(2)C(pz)(3)](2)(AgNO(3))(2)(CH(3)CN)(4)]( infinity ), where the nitrate is bonded to the silver. The argentachains, again formed by kappa(2)-kappa(1) coordination, are arranged in W-shaped sheets that have an overall configuration very different from 2b-4b. Treating [p-C(6)H(4)[CH(2)OCH(2)C(pz)(3)](2)(AgSbF(6))(2)]( infinity ) with a saturated aqueous solution of KPF(6) or KO(3)SCF(3) slowly leads to complete exchange of the anion. Crystallization of a sample that contains an approximately equal mixture of SbF(6)(-)/PF(6)(-) from acetonitrile yields [p-C(6)H(4)[CH(2)OCH(2)C(pz)(3)](2)[Ag(2)(PF(6))(0.78(1))(SbF(6))(1.22(1))(CH(3)CN)(2)][(CH(3)CN)(0.25) (C(4)H(10)O)(0.25)]]( infinity ), a compound with a sheet structure analogous to 2b-4b. Crystallization of the same mixture from acetone yields [p-C(6)H(4)[CH(2)OCH(2)C(pz)(3)](2)(AgSbF(6))[(CH(3))(2)CO](1.5)]( infinity ), where the metal-to-ligand ratio is 1:1 and the [C(pz)(3)] units are kappa(2)-kappa(0) bonded forming a coordination polymer. The supramolecular structures of all species are organized by a combination of C-H...pi, pi-pi, or weak C-H-F(O) hydrogen bonding interactions.     

Enlargement of globular silver alkynide cluster via core transformation

The multinuclear metal-ligand supramolecular synthon R-C≡C?Ag(n) (R = alkyl, cycloalkyl; n = 3, 4, 5) has been employed to construct two high-nuclearity silver ethynide cluster compounds, [Cl(6)Ag(8)@Ag(30)((t)BuC≡C)(20)(ClO(4))(12)]·Et(2)O (1) and [Cl(6)Ag(8)@Ag(30)(chxC≡C)(20)(ClO(4))(10)](ClO(4))(2)·1.5Et(2)O (chx = cyclohexyl) (2), that bear the same novel Cl(6)Ag(8) central core. The synthesis of 1 made use of [Cl@Ag(14)((t)BuC≡C)(12)]OH as a precursor, and its reaction with AgClO(4) in CH(2)Cl(2) resulted in an increase in nuclearity from 14 to 38. The results presented here strongly suggest that the formation of multinuclear silver ethynide cage complexes 1 and 2 proceeds by a reassembly process in solution that involves transformation of the encapsulated chloride template within a Ag(14) cage into a cationic pseudo-O(h) Cl(6)Ag(8) inner core, leading to the generation of a much enlarged Cl(6)Ag(8)@Ag(30) cluster within a cluster. To our knowledge, this provides the first example of the conversion of a silver cluster into one of higher nuclearity via inner-core transformation.     

Syntheses and structures of photochromic silver(I) coordination polymers with cis-1,2-dicyano-1,2-bis(2,4,5-trimethyl-3-thienyl)ethene

Five novel silver(I) coordination polymers with cis-1,2-dicyano-1,2-bis(2,4,5-trimethyl-3- thienyl)ethene (cis-dbe) were synthesized and are characterized in this paper. Treatment of AgCF(3)SO(3) or AgCF(3)CO(2) with cis-dbe afforded [Ag(2)(cis-dbe)(CF(3)SO(3))(2)] (1) and [Ag(2)(cis-dbe)(CF(3)CO(2))(2)] (2), and both complexes exhibit a 1-D infinite chain structure with two cyano groups and two thienyl groups of the ligand bridging four metal ions. Reaction of AgC(n)()F(2)(n)(+1)CO(2) with cis-dbe gave rise to an unprecedented cocrystallization of a 2-D sheet structure, [Ag(2)(cis-dbe)(C(n)F(2)(n)(+1)CO(2))(2)], where n = 2 (3), 3 (4), and 4 (5). Upon irradiation with 450 nm light, these five silver(I) complexes turned orange or red from yellow, and the color reverted to yellow on exposure to 560 nm light, indicative of the reversible cyclization/ring-opening reaction occurring in the crystalline phase. Furthermore, different anions gave not only the different structural dimensions but also the different photoresponsive patterns. The correlation between the crystal structures and the photochromic reactivity is discussed.     

Luminescent platinum(II) dimers with a cyclometallating aryldiamine ligand

Triflate salts of three (Pt(pip2NCN))2(mu-L)2+ (pip2NCNH = 1,3-bis(piperidylmethyl)benzene) dimers bridged by a series of nitrogen-donor ligands (L = pyrazine (pyz), 1,2-bis(4-pyridyl)ethane (bpa), trans-1,2-bis(4-pyridyl)ethylene (bpe)) are reported. These complexes have been fully characterized by 1H NMR spectroscopy and elemental analysis. The X-ray crystal structures of [(Pt(pip2NCN))2(mu-pyz)](CF3SO3)2 and [(Pt(pip2NCN))2(mu-bpe)](CF3SO3)2 x 2CH2Cl2 are reported. [(Pt(pip2NCN))2(mu-pyz)](CF3SO3)2: triclinic, P, a = 12.5240(5) A, b = 14.1570(6) A, c = 14.2928(6) A, alpha = 106.458(1) degrees , beta = 92.527(1) degrees , gamma = 106.880(1) degrees , V = 2303.46(17) A(3), Z = 2. [(Pt(pip2NCN))2(mu-bpe)](CF3SO3)2 x 2CH2Cl2: monoclinic, P21/c, a = 10.1288(6) A, b = 16.3346(9) A, c = 17.4764(10) A, beta = 90.882(2) degrees , V = 2891.1(3) A3, Z = 2. These structures and solution measurements provide evidence for the strong trans-directing properties of the pip2NCN- ligand. The electronic structures of these complexes and those of the 4,4'-bipyridine (bpy) dimer, (Pt(pip2NCN))2(mu-bpy)2+, also have been investigated by UV-visible absorption and emission spectroscopies, as well as cyclic voltammetry. The accumulated data indicate that variations in the bridging ligands provide remarkable control over the electronic structures and photophysics of these complexes. Notably, the bpa dimer exhibits a broad, low-energy emission from a metal-centered 3LF excited state, whereas the bpe and bpy dimers exhibit structured emission from a lowest pyridyl-centered 3(pi-pi*) excited state. In contrast, the pyz dimer exhibits remarkably intense yellow emission tentatively assigned to a triplet metal-to-ligand charge-transfer excited state.     

Silver(I)-ethynide clusters constructed with phosphonate-functionized polyoxovanadates

Two neutral silver(I)-phenylethynide clusters incorporating the [((t)BuPO(3))(4)V(4)O(8)](4-) unit as an integral shell component, namely {(NO(3))(2)@Ag(16)(C≡CPh)(4)[((t)BuPO(3))(4)V(4)O(8)](2)(DMF)(6)(NO(3))(2)}·DMF·H(2)O and {[(O(2))V(2)O(6)](3)@Ag(43)(C≡CPh)(19)[((t)BuPO(3))(4)V(4)O(8)](3)(DMF)(6)}·5DMF·2H(2)O, have been isolated and characterized by X-ray crystallography. The central cavities of the Ag(16) and Ag(43) clusters are occupied by two NO(3)(-) and three [(O(2))V(2)O(6)](4-) template anions, respectively.     

Solution and mechanochemical syntheses, and spectroscopic and structural studies in the silver(I) (bi-)carbonate: triphenylphosphine system

Syntheses of a number of adducts of silver(I) (bi-)carbonate with triphenylphosphine, both mechanochemically, and from solution, are described, together with their infra-red spectra, (31)P CP MAS NMR and crystal structures. Ag(HCO(3)):PPh(3) (1:4) has been isolated in the ionic form [Ag(PPh(3))(4)](HCO(3))·2EtOH·3H(2)O. Ag(2)CO(3):PPh(3) (1:4) forms a binuclear neutral molecule [(Ph(3)P)(2)Ag(O,μ-O'·CO)Ag(PPh(3))(2)](·2H(2)O), while Ag(HCO(3)):PPh(3) (1:2) has been isolated in both mononuclear and binuclear forms: [(Ph(3)P)(2)Ag(O(2)COH)] and [(Ph(3)P)(2)Ag(μ-O·CO·OH)(2)Ag(PPh(3))(2)] (both unsolvated). A more convenient method for the preparation of the previously reported copper(I) complex [(Ph(3)P)(2)Cu(HCO(3))] is also reported.     

Pseudorotaxane-type n-hydrocarbon container. Metallacyclodimer of ionic palladium(II) complexes containing 1,3-bis(4-pyridyl)tetramethyldisiloxane

An unusual "pseudorotaxaned n-alkane within a metalla-cyclodimer" system, C(n)H(2n+2)@[(Me(4)en)Pd(L)](2)(CF(3)SO(3))(4) (n = 5, 6, 7; Me(4)en = N,N,N',N'-tetramethylethylenediamine; L = 1,3-bis(4-pyridyl)tetramethyldisiloxane), was constructed. This system is the first pseudorotaxane-type petroleum container achieved via the appropriate size effect.     

Tuning the coordination geometry of silver in bis(pyrazolyl)alkane complexes

Silver(I) complexes of the bis(pyrazolyl)methane ligands Ph(2)C(pz)(2), PhCH(pz)(2), and PhCH(2)CH(pz)(2) (pz = pyrazolyl ring) have been prepared in an attempt to explore how sterically hindered poly(pyrazolyl)methane ligands influence the variable coordination geometries exhibited by silver(I) complexes, especially its ability to participate in cation...pi interactions. The complex (Ag[(pz)(2)CPh(2)](2))(PF(6)).C(3)H(6)O adopts an unusual square planar coordination environment as indicated by the sum of the four N-Ag-N angles being 360 degrees. The proximity of phenyl groups above and below the AgN(4) core enforces the unusual coordination geometry about the metal center. This arrangement is not a result of silver(I)...pi arene interactions but rather of the constraints imposed by the steric crowding caused by (aryl)(2)C(pz)(2) ligands. In contrast, the complexes of the other two ligands, (Ag[(pz)(2)CHPh](2))(PF(6)).0.5CH(2)Cl(2) and (Ag[(pz)(2)CH(CH(2)Ph)](2))(PF(6)).CH(2)Cl(2), show normal tetrahedral geometry about the silver(I), also with no indication of silver(I)...pi arene interactions. All three new complexes have extended supramolecular structures supported by a combination of CH...pi and CH...F interactions.     

Sensitised near-infrared luminescence from lanthanide(III) centres using Re(I) and Pt(II) diimine complexes as energy donors in d-f dinuclear complexes based on 2,3-bis(2-pyridyl)pyrazine

The luminescent transition metal complexes [Re(CO)(3)Cl(bppz)] and [Pt(CC-C(6)H(4)CF(3))(2)(bppz)] [bppz = 2,3-bis(2-pyridyl)pyrazine], in which one of the diimine binding sites of the potentially bridging ligand bppz is vacant, have been used as 'complex ligands' to make heterodinuclear d-f complexes by attachment of a {Ln(dik)(3)} fragment (dik = a 1,3-diketonate) at the vacant site. When Ln = Pr, Nd, Er or Yb the lanthanide centre has low-energy f-f excited states capable of accepting energy from the (3)MLCT excited state of the Pt(II) or Re(I) centre, quenching the (3)MLCT luminescence and affording sensitised lanthanide(III)-based luminescence in the near-IR region. UV/Vis and luminescence spectroscopic titrations allowed measurement of (i) the association constants for binding of the {Ln(dik)(3)} fragment at the vacant diimine site of [Re(CO)(3)Cl(bppz)] or [Pt(CC-C(6)H(4)CF(3))(2)(bppz)], and (ii) the degree of quenching of the (3)MLCT luminescence according to the nature of the Ln(III) centre. In all cases Nd(III) was found to be the most effective of the series at quenching the (3)MLCT luminescence of the d-block component because the high density of f-f excited states of the appropriate energy make it a particularly effective energy-acceptor.