Preparation and solid-state characterization of mixed-ligand coordination/organometallic oligomers and polymers of copper(I) and silver(I) using diphosphine and mono- and diisocyanide ligands

The dimers [Cu(2)(dppm)(2)(CN-t-Bu)(3)](BF(4))(2) and [Ag(2)(dppm)(2)(CN-t-Bu)(2)](X)(2) (X(-) = BF(4)(-), ClO(4)(-)) and the coordination polymers [[M(diphos)(CN-t-Bu)(2)]BF(4)](n) (M = Cu, Ag; diphos = bis(diphenylphosphino)butane (dppb), bis(diphenylphosphino)pentane (dpppen), bis(diphenylphosphino)hexane (dpph)), [[Ag(2)(dppb)(3)(CN-t-Bu)(2)](BF(4))(2)](n), and [[Ag(dpppen)(CN-t-Bu)]BF(4)](n) have been synthesized and fully characterized as model materials for the mixed bridging ligand polymers which exhibit the general formula [[M(diphos)(dmb)]BF(4)](n) (M = Cu, Ag; dmb = 1,8-diisocyano-p-menthane) and [[Ag(dppm)(dmb)]ClO(4)](n). The identity of four polymers ([[Ag(dppb)(CN-t-Bu)(x)]BF(4)](n) (x = 1, 2), [[Ag(2)(dppb)(3)(CN-t-Bu)(2)](BF(4))(2)](n), [[Ag(dppm)(dmb)]ClO(4)](n)) and the two dimers has been confirmed by X-ray crystallography. The structure of [[Ag(dppm)(dmb)]ClO(4)](n) exhibits an unprecedented 1-D chain of the type "[Ag(dmb)(2)Ag(dppm)(2)(2+)](n)", where d(Ag(.)Ag) values between tetrahedral Ag atoms are 4.028(1) and 9.609(1) A for the dppm and dmb bridged units, respectively. The [[Ag(dppb)(CN-t-Bu)(x)]BF(4)](n) polymers (x = 1, 2) form zigzag chains in which the Ag atoms are tri- and tetracoordinated, respectively. The [[Ag(2)(dppb)(3)(CN-t-Bu)(2)](BF(4))(2)](n) polymer, which is produced from the rearrangement of [[Ag(dppb)(CN-t-Bu)(2)]BF(4)](n), forms a 2-D structure described as a "honeycomb" pattern, where large [Ag(dppb)(+)](6) macrocycles each hosting two counterions and two acetonitrile guest molecules are observed. Properties such as glass transition temperature, morphology, thermal decomposition, and luminescence in the solid state at 293 K are reported. The luminescence bands exhibit maxima between 475 and 500 nm with emission lifetimes ranging between 6 and 55 micros. These emissions are assigned to a metal-to-ligand charge transfer (MLCT) of the type M(I) --> pi(NC)/pi(PPh(2)).     

Subtle role of polyatomic anions in molecular construction: structures and properties of AgX bearing 2,4'-thiobis(pyridine) (X(-) = NO(3)(-), BF(4)(-), ClO(4)(-), PF(6)(-), CF(3)CO(2)(-), and CF(3)SO(3)(-))

Studies on the subtle effects and roles of polyatomic anions in the self-assembly of a series of AgX complexes with 2,4'-Py(2)S (X(-) = NO(3)(-), BF(4)(-), ClO(4)(-), PF(6)(-), CF(3)CO(2)(-), and CF(3)SO(3)(-); 2,4'-Py(2)S = 2,4'-thiobis(pyridine)) have been carried out. The formation of products appears to be primarily associated with a suitable combination of the skewed conformers of 2,4'-Py(2)S and a variety of coordination geometries of Ag(I) ions. The molecular construction via self-assembly is delicately dependent upon the nature of the anions. Coordinating anions afford the 1:1 adducts [Ag(2,4'-Py(2)S)X] (X(-) = NO(3)(-) and CF(3)CO(2)(-)), whereas noncoordinating anions form the 3:4 adducts [Ag(3)(2,4'-Py(2)S)(4)]X(3) (X(-) = ClO(4)(-) and PF(6)(-)). Each structure seems to be constructed by competition between pi-pi interactions of 2,4'-Py(2)S spacers vs Ag.X interactions. For ClO(4)(-) and PF(6)(-), an anion-free network consisting of linear Ag(I) and trigonal Ag(I) in a 1:2 ratio has been obtained whereas, for the coordinating anions NO(3)(-) and CF(3)CO(2)(-), an anion-bridged helix sheet and an anion-bridged cyclic dimer chain, respectively, have been assembled. For a moderately coordinating anion, CF(3)SO(3)(-), the 3:4 adduct [Ag(3)(2,4'-Py(2)S)(4)](CF(3)SO(3))(3) has been obtained similarly to the noncoordinating anions, but its structure is a double strand via both face-to-face (pi-pi) stackings and Ag.Ag interactions, in contrast to the noncoordinating anions. The anion exchanges of [Ag(3)(2,4'-Py(2)S)(4)]X(3) (X(-) = BF(4)(-), ClO(4)(-), and PF(6)(-)) with BF(4)(-), ClO(4)(-), and PF(6)(-) in aqueous media indicate that a [BF(4)(-)] analogue is isostructural with [Ag(3)(2,4'-Py(2)S)(4)]X(3) (X(-) = ClO(4)(-) and PF(6)(-)). Furthermore, the anion exchangeability for the noncoordinating anion compounds and the X-ray data for the coordinating anion compounds establish the coordinating order to be NO(3)(-) > CF(3)CO(2)(-) > CF(3)SO(3)(-) > PF(6)(-) > ClO(4)(-) > BF(4)(-).     

Polymeric silver(I) complexes with pyridyl dithioether ligands: experimental and theoretical investigations on the coordination properties of the ligands

The reactions of four flexible tetradentate ligands, 1,3-bis(2-pyridylthio)propane (L1), 1,4-bis(2-pyridylthio)butane (L2), 1,5-bis(2-pyridylthio)pentane (L3) and 1,6-bis(2-pyridylthio)hexane (L4) with AgX (X = BF4-, ClO4-, PF6-, or CF3SO3-) lead to the formation of seven new complexes: [AgL1(BF4)]2 (1), [[AgL2](ClO4)]infinity (2), [[AgL2(CH3CN)](PF6)]infinity (3), [[AgL3](BF4)(CHCl3)]2 (4), [[AgL3(CF3SO3)](CH3OH)(0.5)]infinity (5), [[Ag2L4(2)](BF4)2]infinity (6), and [[AgL4](PF6)]infinity (7), which have been characterized by elemental analyses, IR spectroscopy, and X-ray crystallography. Single-crystal X-ray analyses show that complexes 1 and 4 possess dinuclear macrometallacyclic structures, and complexes 2, 3 and 5-7 take chain structures. In all the complexes, the nitrogen atoms of ligands preferentially coordinate to silver atoms to form normal coordination bonds, while the sulfur atoms only show weak interactions with silver atoms and the intermolecular AgS weak contacts connect the low-dimensional complexes into high-dimensional supramolecular networks. Additional weak interactions, such as pi-pi stacking, F...F weak interactions, Ag...O contacts or C-H...O hydrogen bonds, also help to stabilize the crystal structures. It was found that the parity of the -(CH2)n- spacers (n = 3-6) affect the orientation of the two terminal pyridyl rings, thereby significantly influence the framework formations of these complexes. The coordination features of ligands and their conformation changes between free and coordination states have been investigated by DFT calculations.     

Self-assembly, structures, and solution dynamics of emissive silver metallacycles and helices

Reactions of 9,10-bis(diphenylphosphino)anthracene (PAnP) and AgX (X = OTf-, ClO4-, PF6-, and BF4-) led to luminescent Ag-PAnP complexes with rich structural diversity. Helical polymers [Ag(mu-PAnP)(CH3CN)X]n (X = OTf-, ClO4-, and PF6-) and discrete binuclear [Ag2(mu-PAnP)2(CH3CN)4](PF6)2, trinuclear [Ag3(mu-PAnP)3 supersetBF4](BF4)2, and tetranuclear [Ag4(mu-PAnP)4 superset(ClO4)2](ClO4)2 metallacycles were isolated from different solvents. The tri- and tetranuclear metallacycles exhibited novel puckered-ring and saddlelike structures. Variable-temperature (VT) 31P{1H}-NMR spectroscopy of the complexes was solvent dependent. The dynamics in CD3CN involve two species, but the exchange processes in CD2Cl2 are more complicated. A ring-opening polymerization was proposed for the exchange mechanism in CD3CN.     

Metal Complexes of Mesitylphosphine: Synthesis, Structure, and Spectroscopy

A series of primary phosphine homoleptic complexes [ML(4)](n)()(+)X(n)() (1, M = Ni, n = 0; 2, M = Pd, n = 2, X = BF(4); 3, M = Cu, n = 1, X = PF(6); 4, M = Ag, n = 1, X = BF(4); L = PH(2)Mes, Mes = 2,4,6-Me(3)C(6)H(2)] was prepared from mesitylphosphine and Ni(COD)(2), [Pd(NCMe)(4)][BF(4)](2), [Cu(NCMe)(4)]PF(6), and AgBF(4), respectively. Reactions of 1-4 with MeC(CH(2)PPh(2))(3) (triphos) or [P(CH(2)CH(2)PPh(2))(3)] (tetraphos) afforded the derivatives [M(L')L](n)()(+)X(n)() (L' = triphos; 6, M = Ni, n = 0; 7, M = Cu, n = 1, X = PF(6); 8, M = Ag, n = 1, X = BF(4); L' = tetraphos; 9, M = Pd, n = 2, X = BF(4)). Addition of NOBF(4) to 1 yielded the nitrosyl compound [NiL(3)(NO)]BF(4), 5. The solution structure and dynamics of 1-9 were studied by (31)P NMR spectroscopy (including the first reported analyses of a 12-spin system for 1-2). Complexes 1, 3, 6, and 7.solvent were characterized crystallographically. The structural and spectroscopic studies suggest that the coordination properties of L are dominated by its relatively small cone angle and that the basicity of L is comparable to that of more commonly used tertiary phosphines.     

Self-assemblies based on [Cp2Mo2(CO)4(micro,eta2-P2)]-solid-state structure and dynamic behaviour in solution

Reaction of complex [Cp2Mo2(CO)4(micro,eta 2-P2)] (Cp=C5H5 (1)) with CuPF6, AgX (X=BF4, ClO4, PF6, SbF6, Al{OC(CF3)3}4) and [(Ph3P)Au(THF)][PF6] (THF=tetrahydrofuran), respectively, results in the facile formation of the dimers 3 b-h of the general formula [M2({Cp2Mo2 (CO)4(micro,eta 2:eta 2-P2)}2)({Cp2Mo2(CO)4 (micro,eta 2:eta 1:eta 1-P2)}2)][X]2 (M=Cu, Ag, Au; X=BF4, ClO4, PF6, SbF6, Al{OC(CF3)3}4). As revealed by X-ray crystallography, all these dimers comprise dicationic moieties that are well-separated from the weakly coordinating anions in the solid state. If 1 is allowed to react with AgNO2 and LAuCl (L=CO or tetrahydrothiophene), respectively, the dimer [Ag2{Cp2Mo2 (CO)4(micro,eta 2:eta 1:eta 1-P2)}2(eta 2-NO2)2] (5) and the complex [AuCl{Cp2Mo2(CO)4(micro,eta 2:eta 1-P2)}] (6) are formed, which have also been characterised by X-ray crystallography. In compounds 5 and 6, the anions remain coordinated to the Group 11 metal centres. Spectroscopic data suggest that the dimers 3 b-h display dynamic behaviour in solution and this is discussed by using the comprehensive results obtained for 3 g (M=Ag; X=Al{OC(CF3)3}4) as a basis. The interpretation of the experimental results is facilitated by density functional theory (DFT) calculations on 3 g (structures, energetics, NMR shielding tensors). The 31P magic angle spinning (MAS) NMR spectra recorded for the dimers 3 b (M=Cu; X=PF6) and 3c (M=Ag; X=BF4) as well as that of the previously reported one-dimensional (1 D) polymer [Ag2{Cp2Mo2(CO)4(micro,eta 2:eta 1:eta 1-P2)}3(micro,eta 1:eta 1-NO3)]n[NO3]n (4) are also discussed herein and the strong dependence of the chemical shift of the phosphorus atoms within each compound on subtle structural differences in the solid state is demonstrated. Furthermore, the X-ray crystallographic and 31P MAS NMR spectroscopic characterisation of a new polymorph of 1 is reported.     

Flexibility of inorganic tennis ball structures inducing anion selectivity

Inorganic tennis balls (ITBs), [[{Pt(betmp)(dach)}(2)Cu](2)(X)][X](3) (in which X=ClO(4) (-) (3), NO(3) (-) (4), Cl(-) (5) and Br(-) (6); dach=trans-1,2-diaminocyclohexane and betmp=bisethylthiomethylidenepropanedioate) and [[{Pt(dteym)(dach)}(2)Cu](2)(PF(6))][PF(6)](3) (7; dteym=1,3-dithiepane-2-ylidenemalonate), were prepared as crystals. Investigation of their X-ray crystal structures revealed that shapes of the cavities in ITBs show significant distortions that depend on the properties of the encapsulated anions. The CuCu* distance was observed to be longest in 7 and shortest in 5, the difference between them being 2.05 A. The flexibility of cavity structures of ITBs makes it possible to encapsulate various anions inside the cavity, while their distortions may be a reason for the difference in the encapsulating ability for anions, that is, anion selectivity. Especially, the distortions observed in 7 are so severe that the encapsulating ability of the cavity for PF(6) (-) is very low compared to other anions. The shapes of ITBs with ClO(4) (-) and BF(4) (-) ions inside their cavities are very similar; however, ClO(4) (-) is encapsulated by the cavity better than BF(4) (-), which is explicable by the difference of metal-anion interactions. This structural study on ITBs gives a clue to the origin of the anion selectivity of the cavity in ITBs previously investigated by (19)F NMR spectroscopy of the ITBs in methanol.     

Characterization of the [Ag(dmb)(2)(+)](n) oligomers (dmb = 1,8-diisocyano-p-menthane) in solution

The crystallographically characterized polymers [[Ag(dmb)(2)]Y](n) (Y = BF(4)(-), NO(3)(-), ClO(4)(-)) extensively dissociate in solution, contrarily to the Cu analogue, and common molecular weight determination techniques such as light scattering, osmometric, and intrinsic viscosity measurements fail to provide data allowing full characterization. Using pulsed NMR experiments, notably (13)C NMR T(1) (spin lattice relaxation time) and NOE (nuclear Overhauser enhancement) measurements on various ionic [[Ag(dmb)(2)]Y](n) materials (Y = BF(4)(-), NO(3)(-), ClO(4)(-)) and their related mononuclear [Ag (CN-t-Bu)(4)]Y salts in acetonitrile-d(3) (as comparative standards), the dipole-dipole spin lattice relaxation times (T(1)(DD)) of a selected quaternary (13)C probe are measured. These data allow us to extract the correlation times (tau(c)), which in turn permit us to estimate the volume of the tumbling species in solution. The comparison of the data between the [Ag(dmb)(2)(+)](n) and Ag(CN-t-Bu)(4)(+) species indicates the oligomeric nature of the former species, where the average number of Ag(dmb)(2)(+) approximately 8 (M(n) approximately 4000-5000).     

Anion-pi interactions as controlling elements in self-assembly reactions of Ag(I) complexes with pi-acidic aromatic rings

Reactions of 3,6-bis(2'-pyridyl)-1,2,4,5-tetrazine (bptz) and 3,6-bis(2'-pyridyl)-1,2-pyridazine (bppn) with the AgX salts (X = [PF6]-, [AsF6]-, [SbF6]-, and [BF4]-) afford complexes of different structural motifs depending on the pi-acidity of the ligand central ring and the outer-sphere anion. The bptz reactions lead to the polymeric [[Ag(bptz)][PF6]]infinity (1) and the dinuclear compounds [Ag2(bptz)2(CH3CN)2][PF6]2 (2) and [Ag2(bptz)2(CH3CN)2][AsF6]2 (3), as well as the propeller-type species [Ag2(bptz)3][AsF6]2 (4) and [Ag2(bptz)3][SbF6]2 (5a and 5b). Reactions of bppn with AgX produce the grid-type structures [Ag4(bppn)4][X]4 (6-9), regardless of the anion present. In 6-9, pi-pi stacking interactions are maximized, whereas multiple and shorter (therefore stronger) anion-pi interactions between the anions and the tetrazine rings are established in 1-5b. These differences reflect the more electron-rich character of the bppn pyridazine ring as compared to the bptz tetrazine ring. The evidence gleaned from the solid-state structures was corroborated by density functional theory calculations. In the electrostatic potential maps of the free ligands, a higher positive charge is present in the bptz as compared to the bppn central ring. Furthermore, the electrostatic potential maps of 3, 4, and 5b indicate an electron density transfer from the anions to the pi-acidic rings. Conversely, upon addition of the [AsF6]- ions to the cation of 7, there is negligible change in the electron density of the central pyridazine ring, which supports the presence of weaker anion-pi interactions in the bppn as compared to the bptz complexes. From the systems studied herein, it is concluded that anion-pi interactions play an important role in the outcome of self-assembly reactions.     

Chiral, Three-Dimensional Supramolecular Compounds: Homo- and Bimetallic Oxalate- and 1,2-Dithiooxalate-Bridged Networks. A Structural and Photophysical Study

In analogy to the [M(II)(bpy)(3)](2+) cations, where M(II) is a divalent transition-metal and bpy is 2,2'-bipyridine, the tris-chelated [M(III)(bpy)(3)](3+) cations, where M(III) is Cr(III) or Co(III), induce the crystallization of chiral, anionic three-dimensional (3D) coordination polymers of oxalate-bridged (&mgr;-ox) metal complexes with stoichiometries [M(II)(2)(ox)(3)](n)()(2)(n)()(-) or [M(I)M(III)(ox)(3)](n)()(2)(n)()(-). The tripositive charge is partially compensated by inclusion of additional complex anions like ClO(4)(-), BF(4)(-), or PF(6)(-) which are encapsulated in cubic shaped cavities formed by the bipyridine ligands of the cations. Thus, an elaborate structure of cationic and anionic species within a polymeric anionic network is realized. The compounds isolated and structurally characterized include [Cr(III)(bpy)(3)][ClO(4)] [NaCr(III)(ox)(3)] (1), [Cr(III)(bpy)(3)][ClO(4)][Mn(II)(2)(ox)(3)] (2), [Cr(III)(bpy)(3)][BF(4)] [Mn(II)(2)(ox)(3)] (3), [Co(III)(bpy)(3)][PF(6)][NaCr(III)(ox)(3)] (4). Crystal data: 1, cubic, P2(1)3, a = 15.523(4) ?, Z = 4; 2, cubic, P4(1)32, a = 15.564(3) ?, Z = 4; 3, cubic, P4(1)32, a = 15.553(3) ?, Z = 4; 4, cubic, P2(1)3, a = 15.515(3) ?, Z = 4. Furthermore, it seemed likely that 1,2-dithiooxalate (dto) could act as an alternative to the oxalate bridging ligand, and as a result the compound [Ni(II)(phen)(3)][NaCo(III)(dto)(3)].C(3)H(6)O (5) has successfully been isolated and structurally characterized. Crystal data: 5, orthorhombic, P2(1)2(1)2(1), a = 16.238(4) ?, b = 16.225(4) ?, c = 18.371(5) ?, Z = 4. In addition, the photophysical properties of compound 1 have been investigated in detail. In single crystal absorption spectra of [Cr(III)(bpy)(3)][ClO(4)][NaCr(III)(ox)(3)] (1), the spin-flip transitions of both the [Cr(bpy)(3)](3+) and the [Cr(ox)(3)](3)(-) chromophores are observed and can be clearly distinguished. Irradiating into the spin-allowed (4)A(2) --> (4)T(2) absorption band of [Cr(ox)(3)](3)(-) results in intense luminescence from the (2)E state of [Cr(bpy)(3)](3+) as a result of rapid energy transfer processes.     

Crucial role of the counteranion on the templation of metallomacrocycles and a 3D network: synthesis,characterization, and structural analysis

Two novel supramolecular architectures, [[Ag(2)L(1)(2)][X](2)] with X = CF(3)SO(3)(-) (2a) or X = NO(3)(-) (2b) and [[AgL(1)(2)][X]](n) with X = BF(4)(-) (3), were constructed by self-assembly and obtained in quantitative yields, using AgX as a building block and L(1) as the bridging ligand (L(1) = 1,3-bis(benzimidazol-1-ylmethyl)benzene). The X-ray molecular structures of 2a and 3 are reported. Complex 2a was identified as a metallomacrocycle in which one ligating triflate anion is coordinated to each of the two unsaturated Ag(I) ions. 2a crystallizes in monoclinic unit cell P2(1)/n with a = 9.728(6) A, b = 17.303(4) A, c = 13.268(3) A, beta = 92.52(4) degrees, V = 2231(2) A(3), and Z = 2. Remarkably, the X-ray structure of 2a shows a layered network structure consisting of infinite metallomacrocycles held together through pi-pi interactions between benzimidazole rings. In dramatic contrast, the product 3 prepared from AgBF(4) and L(1) lacks metal-counterion bonding, leading to a supramolecular 3D network with the following three outstanding features: (i) in one dimension, metallomacrocycles containing two Ag centers and two bridging ligands form infinite, double-stranded chains; (ii) neighboring chains are arranged by two distinct pi-pi interactions, one between substituted benzene rings and the other between benzimidazole rings, leading to a 3D structure; (iii) cavities within the 3D network contain BF(4)(-) counteranions. 3 crystallizes in monoclinic unit cell C2/c with a = 25.33(3) A, b = 11.655(6) A, c = 18.466(8) A, beta = 123.00(8) degrees, V = 4572(8) A(3), and Z = 4. Interestingly, electrospray mass spectroscopy suggests in either case that the identified elemental subunit [AgL(1)(2)](+) is the key building block which self-assembles and subsequent anion templation provides either the macrocycles 2a, b or the inorganic polymer 3. Remarkably, in dichloromethane solvent ligand-to-metal stoichiometries of 2:1 in 3 and 1:1 in 2a, b are obtained even with excess ligand, showing the power of metal-anion interactions in determining the overall supramolecular structure. Anion metathesis, showing supramolecular structural rearrangements from 2a to 2b and more spectacularly from 3 to 2b, smoothly occurred. The crucial effect and the nature of coordinating counteranions (BF(4)(-), CF(3)SO(3)(-), NO(3)(-)) on the supermolecule design are presented and discussed.     

Structures and related properties of AgX bearing 3,3'-thiobispyridine (X- = NO3-, BF4-, CLO4-, and PF6-

Infinite molecular helices [Ag(3,3'-Py2S)]X (3,3'-Py2S = 3,3'-thiobispyridine; X- = BF4-, ClO4-, and PF6-) have been rationally constructed or induced. Crystallographic characterization (X- = BF-, monoclinic P2(1)/n, a = 8.946(3) A, b = 14.130(2) A, c = 10.124(2) A, beta = 107.83(2) degrees, V = 1218.3(5) A3, Z = 4, R = 0.0351; X- = ClO4-, monoclinic P2(1)/n, a = 8.884(1) A, b = 14.305(3) A, c = 10.110(1) A, beta = 106.78(1) degrees, V = 1230.1(3) A3, Z = 4, R = 0.0417; X- = PF6-, monoclinic P2(1)/c, a = 10.959(2) A, b = 9.808(2) A, c = 14.065(3) A, beta = 112.03(2) degrees, V = 1401.4(5) A3, Z = 4, R = 0.0442) reveals that the skeletal structure is an oblong cylindrical cationic helix consisting of alternating Ag(I) and 3,3'-Py2S species and that its counteranions are pinched in two columns inside each helix. The formation of the helical coordination polymer appears to be primarily associated with a suitable combination of the skewed conformer of 3,3'-Py2S and the potential linear geometry of the N-Ag(I)-N bond. However, the framework of the nitrate analogue [Ag(3,3'-Py2S)NO3] (monoclinic P2(1)/c, a = 8.177(2) A, b = 10.291(1) A, c = 14.771(2) A, beta = 102.19(1) degrees, V = 1214.9(4) A3, Z = 4, R = 0.0300) is a two-dimensional network consisting of an 18-membered ring unit, where each 3,3'-Py2S acts as a N,N',S- tridentate ligand connecting three tetrahedral silver(I) ions with the monodentate nitrate weakly bonded to the silver (Ag.O = 2.65(1) A) rather than acting as a counteranion. The anion exchange of [Ag(3,3'-Py2S)NO3] with BF4-, ClO4-, or PF6- has been accomplished in aqueous media. The two-dimensional networks are easily converted into the helices via the anion exchange, but the reverse anion exchange proceeds slightly. Thermal analyses indicate a relationship between the thermal stabilities and the structural properties.     

Novel dithioether-silver(I) coordination architectures: structural diversities by varying the spacers and terminal groups of ligands

An investigation into the dependence of the framework formation of coordination architectures on ligand spacers and terminal groups was reported based on the self-assembly of AgClO4 and eight structurally related flexible dithioether ligands, RS(CH2)nSR (Lan, R = ethyl group; Lbn, R = benzyl group, n= 1-4). Eight novel metal-organic architectures, [Ag(La1)3/2ClO4]n (1a), [Ag2(La2)2(ClO4)2]2 (2a), [AgLa3ClO4]n (3a), {[Ag(La4)2]ClO4}n (4a), [AgLb1ClO4]2 (1b), [Ag(Lb2)2]ClO4 (2b), {[Ag(Lb3)3/2(ClO4)1/2](ClO4)1/2}n (3b) and [Ag(Lb4)3/2ClO4]n(4b), were synthesized and structurally characterized by X-ray crystallography. Structure diversities were observed for these complexes: 1a forms a 2-D (6,3) net, while 2a is a discrete tetranuclear complex, in which the AgI ion adopts linear and tetrahedral coordination modes, and the S donors in each ligand show monodentate terminal and mu2-S bridging coordination fashions; 3a has a chiral helical chain structure in which two homo-chiral right-handed single helical chains (Ag-La3-)n are bound together through mu2-S donors, and simultaneously gives rise to left-handed helical entity (Ag-S-)n. In 4a, left- and right-handed helical chains formed by the ligands bridging AgI centers are further linked alternately by single-bridging ligands to form a non-chiral 2-D framework. 1b has a dinuclear structure showing obvious ligand-sustained Ag-Ag interaction, while 2b is a mononuclear complex; 3b is a 3-D framework formed by ClO4- linking the 2-D (6,3) framework, which is similar to that of 1a, and 4b has a single, double-bridging chain structure in which 14-membered dinuclear ring units formed through two ligands bridging two AgI ions are further linked by single-bridging ligands. In addition, a systematic structural comparison of these complexes and other reported AgClO4 complexes of analogous dithioether ligands indicates that the ligand spacers and terminal groups take essential roles on the framework formation of the AgI complexes, and this present feasible ways for adjusting the structures of such complexes by modifying the ligand spacers and terminal groups.     

Synthesis, structures and reactivity of ruthenium nitrosyl complexes containing Kläui's oxygen tripodal ligand

Ruthenium nitrosyl complexes containing the Kl?ui's oxgyen tripodal ligand L(OEt)(-) ([CpCo{P(O)(OEt)(2)}(3)](-) where Cp = η(5)-C(5)H(5)) were synthesized and their photolysis studied. The treatment of [Ru(N^N)(NO)Cl(3)] with [AgL(OEt)] and Ag(OTf) afforded [L(OEt)Ru(N^N)(NO)][OTf](2) where N^N = 4,4'-di-tert-butyl-2,2'-bipyridyl (dtbpy) (2·[OTf](2)), 2,2'-bipyridyl (bpy) (3·[OTf](2)), N,N,N'N'-tetramethylethylenediamine (4·[OTf](2)). Anion metathesis of 3·[OTf](2) with HPF(6) and HBF(4) gave 3·[PF(6)](2) and 3·[BF(4)](2), respectively. Similarly, the PF(6)(-) salt 4·[PF(6)](2) was prepared by the reaction of 4·[OTf](2) with HPF(6). The irradiation of [L(OEt)Ru(NO)Cl(2)] (1) with UV light in CH(2)Cl(2)-MeCN and tetrahydrofuran (thf)-H(2)O afforded [L(OEt)RuCl(2)(MeCN)] (5) and the chloro-bridged dimer [L(OEt)RuCl](2)(μ-Cl)(2) (6), respectively. The photolysis of complex [2][OTf](2) in MeCN gave [L(OEt)Ru(dtbpy)(MeCN)][OTf](2) (7). Refluxing complex 5 with RNH(2) in thf gave [L(OEt)RuCl(2)(NH(2)R)] (R = tBu (8), p-tol (9), Ph (10)). The oxidation of complex 6 with PhICl(2) gave [L(OEt)RuCl(3)] (11), whereas the reduction of complex 6 with Zn and NH(4)PF(6) in MeCN yielded [L(OEt)Ru(MeCN)(3)][PF(6)] (12). The reaction of 3·[BF(4)](2) with benzylamine afforded the μ-dinitrogen complex [{L(OEt)Ru(bpy)}(2)(μ-N(2))][BF(4)](2) (13) that was oxidized by [Cp(2)Fe]PF(6) to a mixed valence Ru(II,III) species. The formal potentials of the RuL(OEt) complexes have been determined by cyclic voltammetry. The structures of complexes 5,6,10,11 and 13 have been established by X-ray crystallography.     

Halo- and azidodediazoniation of arenediazonium tetrafluoroborates with trimethylsilyl halides and trimethylsilyl azide and sandmeyer-type bromodediazoniation with Cu(I)Br in [BMIM][PF6] ionic liquid

Reaction of [ArN(2)][BF(4)] salts immobilized in [BMIM][PF(6)] ionic liquid (IL) with TMSX (X = I, Br) and TMSN(3) represents an efficient method for the preparation of iodo-, bromo-, and azido-derivatives via dediazoniation. The reactions can also be effected starting with ArNH(2) by in situ diazotization with [NO][BF(4)] followed by reaction with TMSX or TMSN(3). Depending on the substituents on the benzenediazonium cation, competing fluorodediazoniation (ArF formation) and hydrodediazoniation (ArH formation) were observed. Dediazoniation with TMSN(3) and with TMSI generally gave the highest chemoselectivity toward ArN(3) and ArI formation. The IL was recycled and reused up to 5 times with no appreciable decrease in the conversions. Multinuclear NMR monitoring of the interaction of [ArN(2)][BF(4)]/TMSX, [BMIM][PF6]/TMSX, and [BMIM][PF(6)]/TMSX/[ArN(2)][BF(4)] indicated that TMSF is formed primarily via [ArN(2)][BF(4)]/TMSX, generating [ArN(2)][X] in situ, which gives ArX on dediazoniation. Competing formation of ArF in Sandmeyer-type bromodediazoniation of [ArN(2)][BF(4)] with Cu(I)Br immobilized in the IL points to significant involvement of heterolytic dediazoniation.     

Three novel interpenetrating diamondoid networks from self-assembly of 1,12-dodecanedinitrile with silver(I) salts

The self-assembly of 1,12-dodecanedinitrile (ddn) with various silver salts (NO(3)(-), PF(6)(-), AsF(6)(-), ClO(4)(-)) afforded new polymeric coordination networks with the general formula [Ag(ddn)(2)]X. All these species contain interpenetrating diamondoid nets showing interesting features: with X=NO(3)(-) the cationic [Ag(ddn)(2)](+) network exhibits the highest interpenetration (tenfold) ever found within diamondoid nets exclusively based on coordinative bonds. When X=PF(6)(-) or AsF(6)(-) an eightfold diamondoid network is obtained that shows an unusual [4+4] mode of interpenetration, instead of the "normal" set of eight nets equally translated along a principal axis of the adamantanoid cages. The polymeric species that forms with X=ClO(4)(-) is a fourfold interpenetrating diamondoid network; the lower degree of interpenetration in this case is related to the conformation assumed by the flexible ddn ligands.     

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.     

Antibacterial Action of 4,4'-Bipyrazolyl-Based Silver(I) Coordination Polymers Embedded in PE Disks

Coupling the rigid spacer 4,4'-bipyrazole (H(2)BPZ), in its anionic or neutral form, to different silver(I) salts allowed isolation of the novel coordination polymers [Ag(2)(BPZ)] (1) and [Ag(H(2)BPZ)(X)] (X = NO(3), 2; ClO(4), 3; BF(4), 4; PF(6), 5; CH(3)SO(3), 6; CF(3)SO(3), 7), which were fully characterized by infrared and emission spectroscopies, thermal analysis, and X-ray powder diffraction. The crystal structure of 1 consists of 2-D layers containing 1-D chains of Ag(I) ions bridged by exo-tetradentate bipyrazolato moieties. The crystal structures of the [Ag(H(2)BPZ)(X)] species 2-7 feature 1-D chains of [Ag(H(2)BPZ)] stoichiometry, along which the metal centers are bridged by exo-bidentate bipyrazolyl spacers. Contacts among adjacent chains are mediated by the counterions through nonbonding interactions involving the Ag(I) ions and the pyrazolyl N-H groups. Thermogravimetric analyses disclosed the good thermal stability of these materials, decomposing in the range 200-300 °C. Under UV irradiation at room temperature, all the species showed a yellow-green emission centered in the range 520-522 nm. When embedded into polyethylene disks, 1, 2, and 4-7 demonstrated their activity as topical antibacterial agents against suspensions of E. coli, P. aeruginosa, and S. aureus: complete reduction of the three bacterial strains was achieved in 24 h, reduction of S. aureus reaching ca. 90% in only 2 h. Biocidal action was expressed also by contact susceptibility tests.     

Heterometallic polymeric clusters containing tetraselenotungstate anion: one-dimensional helical chain [[La(Me2SO)8

[PPh4]2[WSe4] reacts with an equivalent of [Ag(MeCN)4][ClO4] in DMF to afford a linear polymeric cluster [[Ph4P][(mu-WSe4)Ag]]n (1). Treatment of cluster 1 with excess La(NO3)3.3H2O in Me2SO solution resulted in the formation of a helical chain polymeric cluster [[La(Me2SO)8][(mu-WSe4)3Ag3]]n (2). Cluster 2 crystallizes in the monoclinic space group P2(1/n) with four formula units in a cell of dimensions a = 12.7642(5) A, b = 24.1725(9) A, c = 19.4012(7) A, and beta = 103.546(11) degrees. Refinement by full-matrix least-squares techniques gave final residuals R = 0.0540 and Rw = 0.1116 for 494 variables and 7593 reflections (Fo(2) > 2.0sigma(Fo(2))). The anion [[(mu-WSe4)3Ag3]]n(3n-) in 2 can be described as a butterfly-type SeWSe3Ag2 basic repeating unit linked through interactions with a Ag atom of one fragment and a Ag atom of another to form an intriguing helical array. The CuCN, KCN, and [Et4N]2[WSe4] reaction system resulted in the formation of a novel three-dimensional cluster [[Et4N]2[(mu4-WSe4)Cu4(CN)4]]n (4) either in DMF/2-picoline or in solid at 80 degrees C. Cluster 4 crystallizes in the orthorhombic space group Fddd with cell constants a = 11.090(2) A, b = 23.206(5) A, c = 23.910(5) A, and Z = 8. Anisotropic refinement with 1510 reflections (Fo(2) > 2.0sigma(Fo(2))) and 82 parameters for all non-hydrogen atoms yielded the values of R = 0.0428 and Rw = 0.0887. The anion structure of 4 is built up from a WSe4Cu4 unit bridged by cyanide ligands to form a three-dimensional cross framework. The air- and moisture-stable polymeric clusters easily decompose into small molecular clusters when treated with ligands such as PPh3 and pyridine (Py). Cluster 2 exhibits both strong optical absorption and an optical self-focusing effect (effective alpha2 = 2.2 x 10(-9) m2.W(-1), n2 = 6.8 x 10(-15) m2.W(-1); examined in a 0.13 mM DMF solution). Cluster 4 shows good photostability in the process of measurement and a large optical limiting effect (the limiting threshold is ca. 0.2 J.cm(-2)).     

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.