Quadrupolar [14](meta-ortho)2azolophanes. Intramolecular C-H…N and to Water C-H…O hydrogen bonding revealed by X-ray diffraction

The first X-ray crystallographic diffraction of an example of the title heterophanes built up from heterocyclic betaine subunits is reported and its quadrupolar character is confirmed. The crystal packing of 2·4H₂O is mainly governed by hydrogen-bonding networks, strong intermolecular interactions with water together with weak interactions, either intramolecular or with water.     

Binuclear copper(I) macrocycles synthesized via the weak-link approach

The weak-link approach has been employed to synthesize a series of bimetallic Cu(I) macrocycles in high yield. Addition of phosphinoalkylether or -thioether ligands to [Cu(MeCN)4]PF6 produces "condensed" intermediates, [mu-(1,4-(PPh2CH2CH2X)2Y)2Cu2][PF6]2 (X = S, O; Y = C6H4, C6F4), containing strong P-Cu bonds and weaker O-Cu or S-Cu bonds. The weak bonds of these intermediates can be cleaved through ligand substitution reactions to generate macrocyclic structures, [mu-(1,4-(PPh2CH2CH2X)2Y)2(Z)nCu2][PF6]2 (X = S, O; Y = C6H4, C6F4; Z = pyridine, acetonitrile, diimines, isocyanide) in nearly quantitative yields. The incorporation of tetrahedral Cu(I) metal centers into these macrocycles provides a pathway to complexes that differ from analogous d8 square planar macrocycles generated via this approach in their increased air stability, small molecule reactivity, and ability to form multiple structural isomers. Solid-state structures, as determined by single-crystal X-ray diffraction studies, are presented for condensed intermediates and an open macrocycle     

Surprising photochemical reactivity and visible light-driven energy transfer in heterodimetallic complexes

The bis(bidentate) phosphine cis,trans,cis-1,2,3,4-tetrakis(diphenylphosphino)cyclobutane (dppcb) has been used for the synthesis of a series of novel heterodimetallic complexes starting from [Ru(bpy)(2)(dppcb)]X(2) (1; X = PF(6), SbF(6)), so-called dyads, showing surprising photochemical reactivity. They consist of [Ru(bpy)(2)](2+)"antenna" sites absorbing light combined with reactive square-planar metal centres. Thus, irradiating [Ru(bpy)(2)(dppcb)MCl(2)]X(2) (M = Pt, 2; Pd, 3; X = PF(6), SbF(6)) dissolved in CH(3)CN with visible light, produces the unique heterodimetallic compounds [Ru(bpy)(CH(3)CN)(2)(dppcb)MCl(2)]X(2) (M = Pt, 7; Pd, 8; X = PF(6), SbF(6)). In an analogous reaction the separable diastereoisomers (ΔΛ/ΛΔ)- and (ΔΔ/ΛΛ)-[Ru(bpy)(2)(dppcb)Os(bpy)(2)](PF(6))(4) (5/6) lead to [Ru(bpy)(CH(3)CN)(2)(dppcb)Os(bpy)(2)](PF(6))(4) (9), where only the RuP(2)N(4) moiety of 5/6 is photochemically reactive. By contrast, in the case of [Ru(bpy)(2)(dppcb)NiCl(2)]X(2) (4; X = PF(6), SbF(6)) no clean photoreaction is observed. Interestingly, this difference in photochemical behaviour is completely in line with the related photophysical parameters, where 2, 3, and 5/6, but not 4, show long-lived excited states at ambient temperature necessary for this type of photoreaction. Furthermore, the photochemical as well as the photophysical properties of 2-4 are also in accordance with their single crystal X-ray structures presented in this work. It seems likely that differences in "steric pressure" play a major role for these properties. The unique complexes 7-9 are also fully characterized by single-crystal X-ray structure analyses, clearly showing that the stretching vibration modes of the ligand CH(3)CN, present only in 7-9, cannot be directly influenced by "steric pressure". This has dramatic consequences for their photophysical parameters. The trans-[Ru(bpy)(CH(3)CN)(2)](2+) chromophore of 9 acts as efficient "antenna" for visible light-driven energy transfer to the Os-centred "trap" site, resulting in k(en) ≥ 2 × 10(9) s(-1) for the energy transfer. Since electron transfer is made possible by the use of this intervening energy transfer, in dyads like 2-4 highly reactive M(0) species (M = Pt, Pd, Ni) could be generated. These species are not stable in water and M(II) hydride intermediates are usually formed, further reacting with H(+) to give H(2). Thus, derivatives of 3, namely [M(bpy)(2)(dppcb)Pd(bpy)](PF(6))(4) (M = Os, Ru) dissolved in 1:1 (v/v) H(2)O-CH(3)CN produce H(2) during photolysis with visible light.     

Rates of electronic excitation hopping in anisotropic ionic crystals of [Ru(2,2'-bipyridine)3]X2 (X = ClO4-, PF6-, SbF6-); Monte Carlo simulation of single- and multi-exponential emission decays

Emission decays of triplet metal-to-ligand charge transfer states in anisotropic crystals of [Ru(1 - x)Os(x)(bpy)(3)]X(2) (bpy = 2,2'-bipyridine, X = PF(6)-, ClO(4)-, SbF(6)-, and 0.115 > x > 0.001) at approximately 300 K were measured by means of time-correlated single-photon counting. Rates of excitation hopping calculated on the basis of an interaction between transition dipoles of a donor cation and an acceptor cation are insufficient to simulate the single-exponential decays (x = 0.0099) and the multiexponential decays (x = 0.060 and 0.115) of the PF(6)- salt crystals. A limiting rate of excitation hopping to an imaginary cation at the van der Waals distance via a super-exchange interaction between d orbitals through the bpy ligands was determined to be 0.83 x 10(10) s(-1) on average by means of a step-by-step Monte Carlo simulation, assuming an distance-attenuation factor, beta, of the exchange interaction of 10 nm-1. The total rate of excitation hopping via both a dipole-dipole mechanism and a super-exchange mechanism to the neighboring sites of the cation was calculated to be 5.4 x 10(9) s(-1) for the PF(6)- crystal. Anisotropic diffusion constants estimated from the hopping rates and lengths in the PF(6)- crystal are 9.3 x 10(-6), 9.1 x 10(-6), and 1.4 x 10(-6) cm(2)s(-1) along the a axis, the b axis, and the c axis, respectively, which are compared with an isotropic diffusion constant, 1.3 x 10(-6) cm(2) s(-1), estimated from the pseudo-bimolecular rate constant of excitation transfer to [Os(bpy)(3)](2+), using an isotropic Smoluchowski equation. A multiexponential emission decay of [Ru(0.885)Os(0.115)(bpy)(3)](PF(6))(2) was also simulated to determined the limiting rate of excitation transfer to [Os(bpy)(3)](2+) at the van der Waals distance (2.6 x 10(11) s(-1)). The magnitude of beta determined is 6.5 and 11.5 nm(-1) for the ClO(4)- and the SbF(6)- salt crystals, respectively, on reference to that of beta (10 nm(-1)) for the PF(6)- salt crystal.     

Cyanide-bridge Fe-Fe and Fe-Co molecular squares: structures and electrochemistry of

Cyanide-bridged iron-iron and iron--cobalt molecular squares of [Fe(II/4)(mu-CN)4(bpy)8[(PF6)4 x 4H2O (1), [Fe(II/2)Co(II/2)(mu-CN)4(bpy)8](PF6)4 x 3CHCl3 x 2CH3CN (2), and [Fe(II/2)Co(III/2)(mu-CN)4(bpy)8](PF6)6 x 2CHCl3 x 4CH3NO2 (3) (bpy =2,2'-bipyridine) were prepared. X-ray structure analyses for 1-3 were performed and their electrochemistry was studied. In 1-3, four metal ions are bridged by cyanide groups to form tetranuclear macrocycles ("molecular squares"). Each metal ion in the square is six-coordinate: four of the coordination sites are occupied by the nitrogen atoms of two of bpy ligands and the remaining cis coordination sites are occupied by cyanide-carbon or cyanide-nitrogen atoms. In 1, Fe-C (cyanide) (1.899(4)-1.927(4)A) and Fe-N(cyanide) (1.929(4)-1.950(4)A) distances are typical of low-spin Fe2+ ions. In 2, Fe-C(cyanide) and Co(2+)-N(cyanide) bond lengths are in the range 1.919(5)-1.963(5)A and 1.850(5)-2.017(5) A, respectively: in contrast, shorter bond lengths are observed for the metal to cyanide-carbon and cyanide-nitrogen (1.878(7)- 1.893(7) A) in 3. As a result, the molecular squares in 1. 2, and 3 have sides of 4.947(1)4.986(1) A, 5.001(1)-5.053(1) A, and 4.910(1)-4.918(1) A, respectively. Magnetic susceptibility measurements revealed that the Fe2+ and Co3- ions in 1 and 3 are diamagnetic, while the high-spin Co2+ ions in 2 are weakly coupled through the low-spin Fe2 ions. Cyclic voltammograms of the squares are presented, and the electrochemically generated mixed-valent species [Fe(II/2)Fe(III/2)(mu-CN)4(bpy)8]6+ was discussed in terms of the intervalence transfer band.     

Syntheses and characterization of oxygen/sulfur-bridged incomplete cubane-type clusters, [Mo3S4Tp3]+ and [Mo3OS3Tp3]+, and a mixed-metal cubane-type cluster, [Mo3FeS4ClTp3]. X-ray structures of [Mo3S4Tp3]Cl, [Mo3OS3Tp3]PF6, and [Mo3FeS4ClTp3

The reaction of [Mo3S4(H2O)9]4+ (1) with hydrotris(pyrazolyl)borate (Tp) ligands produced [Mo3S4Tp3]Cl x 4 H2O ([3]Cl x 4 H2O) in an excellent yield. An X-ray structure analysis of [3]Cl x 4 H2O revealed that each molybdenum atom bonded to the Tp ligand. We report four salts of 3, [3]Cl x 4 H2O, [3]tof x 2 H2O, [3]PF6 x H2O, and [3]BF4 x 2 H2O in this paper. The solubility and stability of the chloride salt in organic solvents differ completely from those of the other salts. We have also prepared a new compound, [Mo3OS3Tp3]PF6 x H2O ([4]PF6 x H2O), via the reaction of [Mo3OS3(H2O)9]4+ (2) with KTp in the presence of NH4PF6. All the molybdenum atoms bonded to Tp ligand. 1H NMR signals corresponding to nine protons bonded to three pyrazole rings in one Tp were observed in a spectrum (at 253 K) of [3]BF4 x 2 H2O. It shows that cluster 3 has a 3-fold rotation axis in CD2Cl2 solution. Twenty-one 1H NMR signals corresponding to twenty-seven protons bonded to nine pyrazole rings in three Tp ligands were observed in a spectrum (at 233 K) of [4]PF6 x H2O; obviously, 4 has no 3-fold rotation axis, in contrast to 3. The short CH...mu3S distance caused large upfield chemical shifts in the 1H NMR spectra of 3 and 4. The reaction of 3 with metallic iron in CH2Cl2 produced [Mo3FeS4XTp3] (X = Cl (5), Br (6)). X-ray structure analysis of 5 has revealed the existence of a cubane-type core Mo3FeS4. Complex 3 functions as a metal-complex ligand for preparing a novel mixed-metal complex even in nonaqueous solvents. The cyclic voltammogram of 5 shows two reversible one-electron couples (E(1/2) = -1.40 and 0.52 V vs SCE) and two irreversible one-electron oxidation processes (E(pc) = 1.54 and 1.66 V vs SCE).     

Disilver(I) macrocycles: variation of cavity size with anion binding

Reaction of the N-methylated bis(amidopyridine) ligand, LL = C6H4(1,3-CONMe-4-C5H4N)2, with the silver salts AgNO3, AgO2CCF3, AgO3SCF3, AgBF4, and AgPF6 gave the corresponding cationic disilver(I) macrocycles [Ag2(micro-LL)2]X2, 2a-e. The transannular silver...silver distance in the macrocycles varies greatly from 2.99 to 7.03 A, and these differences arise through a combination of different modes ofanion binding and from the presence or absence of silver...silver secondary bonding. In all complexes, the ligand adopts a conformation in which the methyl group and oxygen atom of the MeNCO units are mutually cis, but the overall macrocycle can exist in either boat (X = PF6 only) or chair conformation. Short transannular silver...silver distances are found in complexes 2b,c, in which the anions CF3CO2- and CF3SO3- bind above and below the macrocycle, but longer silver...silver distances are found for 2a,d,e, in which the anions are present, at least in part, inside the disilver macrocycle. Easy anion exchange occurs in solution, and studies using ESI-MS indicate that the anion binding to form [Ag2X(micro-LL)2]+ follows the sequence X = CF3CO2- > NO3- > CF3SO3-.     

Novel charged [1(4)]ăzolophanes: associative behaviour revealed by electrospray ionization

Electrospray ionization mass spectrometry has been used to investigate simple multicharged [1(4)]heterophanes containing heterocyclic betaine subunits as building blocks. The formation of stable noncovalent polymolecular self-assembled structures in the gas phase is reported.     

Novel[1n]-meta-heterophane frameworks with a bis-betaine nature

A convergent "5 + 1" and "5 + 3" synthetic strategy allowed the synthesis of the first examples of bis-betaines 2 and 3, a prototype of phanes that incorporate heterocyclic betaines. The structure of the quadrupolar macrocyclic systems 2 and 3 together with the dicationic [1(6)]- and [1(8)] meta-heterophane precursors 5*2X and 6*2X were examined by spectroscopy using 1H and 13C NMR techniques together with 1H-DNMR studies and electrospray ionization mass spectrometry.     

Synthesis and structure of the incomplete cuboidal clusters [W3Se4H3(dmpe)3]+, [W3Se4H(3-x)(OH)x(dmpe)3]+ and [W3Se4(OH)3(dmpe)3]+, and the mechanism of the acid-assisted substitution of the coordinated hydrides

The novel incomplete cuboidal cluster [W3Se4H3(dmpe)3](PF6), [1](PF6), has been prepared by reduction of [W3Se4Br3(dmpe)3](PF6) with LiBH4 in THF solution. The trihydroxo complex [W3Se4(OH)3(dmpe)3](PF6), [2](PF6), was obtained by reacting [W3Se4Br3(dmpe)3](PF6) with NaOH in MeCN-H2O solution. The complexes [1](PF6) and [2](PF6) were converted to their BPh4- salts by treatment with NaBPh4. Recrystallisation of [1](BPh4) in the presence of traces of water affords the mixed dihydride hydroxo complex [W3Se4H2(OH)(dmpe)3](BPh4). The crystal structures of [1](BPh4), [2](BPh4) and [W3Se4H2(OH)(dmpe)3](BPh4) have been resolved. Although the [1]+ trihydride does not react with an excess of halide salts, reaction with HX leads to [W3Se4X3(dmpe)3]+ (X = Cl, Br). The kinetics of this reaction has been studied at 25 degrees C in MeCN-H2O solution (1:1, v/v) and found to occur with two consecutive kinetic steps. The first step is independent of the nature and concentration of the X(-) anion but shows a first order dependence on the concentration of acid (k1 = 12.0 mol(-1) dm(3) s(-1)), whereas the second one is independent of the nature and concentration of both the acid and added salts (k2 = 0.024 s(-1)). In contrast, the reaction of [2]+ with acids occurs in a single step with kobs = 0.63 s(-1)(HCl) and 0.17 s(-1)(HBr). These kinetic results are discussed on the basis of the mechanism previously proposed for the reactions of the analogous [W3S4H3(dmpe)3]+ cluster, with special emphasis on the effects caused by the change of S by Se on the rate constants for the different processes involved.     

Silver coordination networks and cages based on a semi-rigid bis(isoxazolyl) ligand

The semi-rigid ligand 1,4-bis((3,5-dimethylisoxazol-4-yl)methyl)benzene (bisox) reacts with a range of silver(i) salts to give products in which the anions dictate the structure. The reactions with AgNO(3) and AgO(2)CCF(3) both lead to compounds in which the anions are coordinated to the silver centres. Thus, the structure of [Ag(2)(NO(3))(2)(bisox)] 1 contains helical silver-nitrate chains that are linked into sheets by bridging bisox ligands, whereas the structures of [Ag(O(2)CCF(3))(bisox)]·0.5X (2a, X = MeOH; 2b, X = MeCN) consist of sheets in which Ag(2)(μ-O(2)CCF(3))(2) dimers act as 4-connecting nodes. In these structures bisox adopts the S-conformation, with the nitrogen donor atoms anti to each other. The reactions of bisox with AgClO(4) and AgBF(4) in methanol give the compounds [Ag(2)(bisox)(3)]X(2) (3, X = ClO(4); 5, X = BF(4)), the structures of which contain triply-interpenetrated sheets with Borromean links and ligands in the S-conformation. Recrystallisation of these compounds from acetonitrile-diethyl ether gives [Ag(2)(bisox)(3)]X(2)·xEt(2)O (4, X = ClO(4), x = 1; 6, X = BF(4), x = 1.2). The structures of 4 and 6 contain similar triply-interpenetrated sheets to those in 3 and 5, though these are sandwiched between sheets of discrete Ag(2)(bisox)(3) cages, in which the bisox ligands are in the C-conformation, with the nitrogen donor atoms syn to each other. Diethyl ether molecules project through the faces of the cages and template cage formation. Both 4 and 6 lose diethyl ether on heating in vacuum, and convert into 3 and 5, respectively. This solid state transformation requires a change in conformation of half the bisox ligands, with conversion of 6 into 5 occurring more readily than conversion of 4 into 3. The reactions of bisox with AgPF(6) and AgSbF(6) in methanol give mixtures of products from which [Ag(bisox)(2)]X·0.5bisox (7, X = PF(6); 8, X = SbF(6)) can be isolated. Both 7 and 8 have structures containing one-dimensional chains, in which the bisox ligands adopt C-conformations and interconnect distorted tetrahedral silver centres in a pairwise manner generating macrocycles. Additional uncoordinated bisox molecules lie within half of these macrocyclic rings. Recrystallisation of the crude AgSbF(6)/bisox reaction mixture from acetonitrile-diethyl ether gives [Ag(bisox)(2)]SbF(6)9, the structure of which consists of a triply-interpenetrated flattened diamondoid network. A similar structure was observed for [Ag(bisox)(2)]CF(3)SO(3)10, which is formed from the reaction of AgO(3)SCF(3) and bisox in methanol.     

Examination of the mixed-valence state of the doubly boron-bridged diferrocene cation [(FeCp)2{mu-C10H6(BPh)2}]+

A series of mixed-valent (MV) complexes [(FeCp)2(mu-C10H6(BPh)2)]+X ([1+]X; X=I 5, PF6, SbF6, B(C6F5)4) were prepared by oxidation of diboradiferrocene [(FeCp)2(mu-C10H6(BPh)2)] (1) with I 2, AgPF6, and AgSbF6, respectively, and through anion exchange of the I 5(-) salt with [Li(Et2O)x][B(C6F5)4] in the case of X=B(C6F5)4. The MV state of the cation was investigated in solution by multinuclear NMR spectroscopy, CV, and UV/Vis-NIR absorption spectroscopy, and in the solid state by IR spectroscopy, single-crystal X-ray crystallography, and M?ssbauer spectroscopy. The cyclic voltammogram of 1 shows two distinct redox waves with a large redox splitting of Delta E=510 mV in CH2Cl2 and the NIR spectrum for the mono-oxidized species displays an intervalence charge-transfer band at around 1500 to 1700 nm depending on the specific counterion present. The X-ray crystal structures of [1+]X show inversion-symmetric cations with X=I 5 and B(C6F5)4 and unsymmetric valence-trapped structures composed of one ferrocene and one ferrocenium moiety with X=PF6 and SbF6. M?ssbauer data for X=PF6 are consistent with valence trapping at all temperatures between 90 and 343 K. In comparison, fast electron transfer is evident on the M?ssbauer timescale for X=I 5 and temperature-dependent behavior is observed for X=B(C6F5)4. The anion dependence of the X-ray structural and M?ssbauer data is discussed in the context of crystal symmetry and the possibility of static and dynamic disorder effects is considered.     

Solid-state 129Xe and 131Xe NMR study of the perxenate anion XeO(6)4-

Results of the first solid-state 131Xe NMR study of xenon-containing compounds are presented. The two NMR-active isotopes of xenon, 129Xe (I=1/2) and 131Xe (I=3/2), are exploited to characterize the xenon magnetic shielding and quadrupolar interactions for two sodium perxenate salts, Na4XeO6.xH2O (x=0, 2), at an applied magnetic field strength of 11.75 T. Solid-state 129/131Xe NMR line shapes indicate that the local xenon environment in anhydrous Na4XeO6 adopts octahedral symmetry, but upon hydration, the XeO6(4-) anion becomes noticeably distorted from octahedral symmetry. For stationary, anhydrous samples of Na4XeO6, the heteronuclear 129/131Xe-23Na dipolar interaction is the principal contributor to the breadth of the 129/131Xe NMR lines. For stationary and slow magic-angle-spinning samples of Na4XeO(6).2H2O, the anisotropic xenon shielding interaction dominates the 129Xe NMR line shape, whereas the 131Xe NMR line shape is completely dominated by the nuclear quadrupolar interaction. The xenon shielding tensor is approximately axially symmetric, with a skew of -0.7+/-0.3, an isotropic xenon chemical shift of -725.6+/-1.0 ppm, and a span of 95+/-5 ppm. The 131Xe quadrupolar coupling constant, 10.8+/-0.5 MHz, is large for a nucleus at a site of approximate Oh symmetry, and the quadrupolar asymmetry parameter indicates a lack of axial symmetry. This study demonstrates the extreme sensitivity of the 131Xe nuclear quadrupolar interaction to changes in the local xenon environment.     

Self-assembly of dialkyltin moieties and mercaptobenzoic acid into macrocyclic complexes with hydrophobic "pseudo-cage" or double-cavity structures: supramolecular infrastructures involving intermolecular C-H...S weak hydrogen bonds and pi-pi interactions

Four novel organotin complexes of two types--[R2Sn(o-SC6H4CO2)]6 (R = Me, 1 x H2O; nBu, 2) and {[R2Sn(m-CO2C6H4S)R2Sn(m-SC6H4CO2)SnR2]O}2 (R = Me, 3; nBu, 4)--have been prepared by treatment of o- or m-mercaptobenzoic acid and the corresponding R2SnCl2 (R = Me, nBu) with sodium ethoxide in ethanol (95%). All the complexes were characterized by elemental analysis, FT-IR and NMR (1H, (3C, 119Sn) spectroscopy, TGA, and X-ray crystallography diffraction analysis. The molecular structure analyses reveal that both 1 and 2 are hexanuclear macrocycles with hydrophobic "pseudo-cage" structures, while 3 and 4 are hexanuclear macrocycles with double-cavity structures. Furthermore, the supramolecular structure analyses show that looser and more intriguing supramolecular infrastructures were also found in complexes 1-4, which exist either as one-dimensional chains of rings or as two-dimensional networks assembled from the organometallic subunits through intermolecular C-H...S weak hydrogen bonds (WHBs) and pi-pi interactions.     

Influence of anions on the dimensionality of extended networks based on Cu I cations and 1,4,5,8,9,12-hexaazatriphenylene (HAT) ligands

Reactions of Cu I salts with 1,4,5,8,9,12-hexaazatriphenylene (HAT) afford three types of cationic coordination polymers depending on the anion present in the reaction solution. In the crystal structure of {[Cu(HAT)][BF4]x1/3(C6H6)}infinity, (1), Cu ions and HAT molecules form extended layers that are best described as strongly distorted honeycomb nets. The space between the layers is occupied by [BF4]- anions and solvent molecules. {[Cu(HAT)][PF6]}infinity, (2), crystallizes as a chiral (10,3)-a net with [PF6]- anions residing in the cavities of the three-dimensional metal-organic framework. The crystal structure of {[Cu4(HAT)3][SbF6]4x3C6H6}infinity, (3), is based on unique extended [Cu4(HAT)3]infinity "nanotubules" filled with solvent molecules and [SbF6]- anions.     

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.     

Efficient synthesis of a chiral [4]pseudocatenane and its derivatives: a novel ship's wheel-like interlocked structure

A novel chiral[4]pseudocatenane 5H(3)[PF(6)](3) was synthesized efficiently by treatment of a solution of chiral triptycene-based tri(crown ether) 1 and three equivalents of a bis[p-(but-3-enyloxy)benzyl]ammonium salt in CH(2)Cl(2) with a Grubbs II catalyst, followed by hydrogenation. It was found that the ammonium groups in 5H(3)[PF(6)](3) could be deprotonated by 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in acetonitrile or dimethyl sulfoxide (DMSO). Consequently, N-acylation of the ammonium groups was easily performed in the presence of DBU, which resulted in a new class of neutral highly ordered interlocked molecules in good yields. In particular, the incorporation of stopper units, for example, diethyl phosphoramidate, lead to the isolation of the interlocked molecule 10 with an interesting ship's wheel-like structure, which was structurally studied with the help of detailed NMR experiments. Compared with 1, it was further found that the Cotton effect of (R)-1,1'-binaphthyl chromophore at 241 nm was greatly reduced in 5H(3)[PF(6)](3) and its derivatives. Moreover, a new positive Cotton effect at 248 nm appeared in the interlocked molecules; this observation could be attributed to the chirality transfer from the binaphthyl units to the macrocycles lying in the cavities of 1.     

Framework engineering by anions and porous functionalities of Cu(II)/4,4'-bpy coordination polymers

A combination of framework-builder (Cu(II) ion and 4,4'-bipyridine (4,4'-bpy) ligand) and framework-regulator (AF(6) type anions; A = Si, Ge, and P) provides a series of novel porous coordination polymers. The highly porous coordination polymers ([Cu(AF(6))(4,4'-bpy)(2)].8H(2)O)(n)(A = Si (1a.8H(2)O), Ge (2a.8H(2)O)) afford robust 3-dimensional (3-D), microporous networks (3-D Regular Grid) by using AF(6)(2-) anions. The channel size of these complexes is ca. 8 x 8 A(2) along the c-axis and 6 x 2 A(2) along the a- or b-axes. When compounds 1a.8H(2)O or 2a.8H(2)O were immersed in water, a conversion of 3-D networks (1a.8H(2)O or 2a.8H(2)O) to interpenetrated networks ([Cu(4,4'-bpy)(2)(H(2)O)(2)].AF(6))(n)(A = Si (1b) and Ge (2b)) (2-D Interpenetration) took place. This 2-D interpenetrated network 1b shows unique dynamic anion-exchange properties, which accompany drastic structural conversions. When a PF(6)(-) monoanion instead of AF(6)(2)(-) dianions was used as the framework-regulator with another co-counteranion (coexistent anions), porous coordination polymers with various types of frameworks, ([Cu(2)(4,4'-bpy)(5)(H(2)O)(4)].anions.2H(2)O.4EtOH)(n)(anions = 4PF(6)(-) (3.2H(2)O.4EtOH), 2PF(6)(-) + 2ClO(4)(-) (4.2H(2)O.4EtOH)) (2-D Double-Layer), ([Cu(2)(PF(6))(NO(3))(4,4'-bpy)(4)].2PF(6).2H(2)O)(n)(5.2PF(6).2H(2)O) (3-D Undulated Grid), ([Cu(PF(6))(4,4'-bpy)(2)(MeCN)].PF(6).2MeCN)(n)(6.2MeCN) (2-D Grid), and ([Cu(4,4'-bpy)(2)(H(2)O)(2)].PF(6).BF(4))(n) (7) (2-D Grid), were obtained, where the three modes of PF(6)(-) anions are observed. 5.2PF(6).2H(2)O has rare PF(6)(-) bridges. The PF(6)(-) and NO(3)(-) monoanions alternately link to the Cu(II) centers in the undulated 2-D sheets of [Cu(4,4'-bpy)(2)](n)() to form a 3-D porous network. The free PF(6)(-) anions are included in the channels. 6.2MeCN affords both free and terminal-bridged PF(6)(-) anions. 3.2H(2)O.4EtOH, 4.2H(2)O.4EtOH, and 7 bear free PF(6)(-) anions. All of the anions in 3.2H(2)O.4EtOH and 4.2H(2)O.4EtOH are freely located in the channels constructed from a host network. Interestingly, these Cu(II) frameworks are rationally controlled by counteranions and selectively converted to other frameworks.     

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)(-).     

Synthesis and characterization of ethylbis(2-pyridylethyl)amineruthenium complexes and two different types of C-H bond cleavage at an ethylene arm

Ruthenium complexes bearing ethylbis(2-pyridylethyl)amine (ebpea), which has flexible -C(2)H(4)- arms between the amine and the pyridyl groups and coordinates to a metal center in facial and meridional modes, have been synthesized and characterized. Three trichloro complexes, fac-[Ru(III)Cl(3)(ebpea)] (fac-[1]), mer-[Ru(III)Cl(3)(ebpea)] (mer-[1]), and mer-[Ru(II)Cl(3){η(2)-N(C(2)H(5))(C(2)H(4)py)═CH-CH(2)py}] (mer-[2]), were synthesized using the Ru blue solution. Formation of mer-[2] proceeded via a C-H activation of the CH(2) group next to the amine nitrogen atom of the ethylene arm. Reduction reactions of fac- and mer-[1] afforded a triacetonitrile complex mer-[Ru(II)(CH(3)CN)(3)(ebpea)](PF(6))(2) (mer-[3](PF(6))(2)). Five nitrosyl complexes fac-[RuX(2)(NO)(ebpea)]PF(6) (X = Cl for fac-[4]PF(6); X = ONO(2) for fac-[5]PF(6)) and mer-[RuXY(NO)(ebpea)]PF(6) (X = Cl, Y = Cl for mer-[4]PF(6); X = Cl, Y = CH(3)O for mer-[6]PF(6); X = Cl, Y = OH for mer-[7]PF(6)) were synthesized and characterized by X-ray crystallography. A reaction of mer-[2] in H(2)O-C(2)H(5)OH at room temperature afforded mer-[1]. Oxidation of C(2)H(5)OH in H(2)O-C(2)H(5)OH and i-C(3)H(7)OH in H(2)O-i-C(3)H(7)OH to acetaldehyde and acetone by mer-[2] under stirring at room temperature occurred with formation of mer-[1]. Alternative C-H activation of the CH(2) group occurred next to the pyridyl group, and formation of a C-N bond between the CH moiety and the nitrosyl ligand afforded a nitroso complex [Ru(II)(N(3))(2){N(O)CH(py)CH(2)N(C(2)H(5))C(2)H(4)py}] ([8]) in reactions of nitrosyl complexes with sodium azide in methanol, and reaction of [8] with hydrochloric acid afforded a corresponding chloronitroso complex [Ru(II)Cl(2){N(O)CH(py)CH(2)N(C(2)H(5))C(2)H(4)py}] ([9]).