Tetranuclear silver(I) clusters showing high ionic conductivity in a bicontinuous cubic mesophase.

The synthesis and characterization of tetranuclear silver triazole metallomesogens, [Ag4(L(4)-C(n))6][BF4]4 (L(4)-C(n) = 4-alkyl-1,2,4-triazoles where C(n) stands for C(n)H(2n+1) with n = 12, 14, 16, and 18), are reported. Upon heating, a phase transition sequence of Cr → SmC → Cub → SmA → isotropic liquid is observed for all of these compounds. Depending on the alkyl chain length, two types of cubic phases are found in this series of compounds. Those with shorter alkyl chains (n = 12 and 14) exhibit a micellar cubic phase, whereas long alkyl chains (n =16 and 18) show a bicontinuous cubic phase. Superior ionic conductivity at the bicontinuous cubic mesophase for [Ag4(L4-C16)6][BF4]4 is observed because of the presence of a three-dimensional ion-transporting channel. Doping a small amount of AgBF4 enhances the ionic conduction dramatically, presumably via promotion of the migration of Ag(I) ions in the channels.

Oxygenation of ruthenium carbene complexes containing naphthothiophene or naphthofuran: spectroscopic and DFT studies.

The aryl propargylic alcohol 1-[2-(thiophen-3-yl)phenyl]prop-2-yn-1-ol (1a) is readily prepared from 2-(thiophen-3-yl)benzaldehyde. In the presence of visible light, treatment of 1a with one-half mole equivalent of [Ru]Cl ([Ru]=Cp(dppe)Ru) (dppe=1,2-bis(diphenylphosphino)ethane) and NH4PF6 in O2 affords the naphtha[2,1-b]thiophene-4-carbaldehyde (4a) in high yields. The cyclization reaction of 1a proceeds through the formation of the carbene complex 2a that contains the naphtha[2,1-b]thiophene ring, which is isolated in a 1:1 stoichiometric reaction. The C-C bond formation between the inner carbon of the terminal triple bond and the heterocyclic ring is confirmed by structure determination of 2a using single-crystal X-ray diffraction analysis. Facile oxygenation of 2a by O2 yields the aldehyde product 4a accompanied by the formation of phosphine oxide of dppe. Oxygen is most likely activated by coordination to the ruthenium center when one PPh2 unit of the dppe ligand dissociates. This dissociated PPh2 unit then reacts with the coordinated oxygen nearby to generate half-oxidized dppe ligand and an unobserved oxo-carbene intermediate. Coupling of the oxo/carbene ligands followed by demetalation then yields 4a. Presumably the resulting complex with the half-oxidized dppe ligand continuously promotes cyclization/oxygenation of 1a to yield the second aldehyde molecule. In alcohol such as MeOH or EtOH, the oxygenation reaction affords a mixture of 4a and the corresponding esters 5a or 5a'. Four other aryl propargylic alcohols 1b-e, which contain thiophen-2-yl, isopropenyl, fur-3-yl, and fur-2-yl, respectively, on the aryl ring are also prepared. Analogous aldehydes 4b-e are similarly prepared from 1b-e, respectively. For oxygenations of 1b, 1d, and 1e in alcohol, mixtures of aldehyde 4, ester 5, and acetal 8 are obtained. The carbene complex 2b obtained from 1b was also characterized by single-crystal X-ray diffraction analysis. The UV/Vis spectra of 2a and 2b consist of absorption bands with a high extinction coefficient. From DFT calculations on 2a and 2b, the visible light is found to populate the LUMO antibonding orbital of mainly Ru=C bonds, thereby weakening the Ru=C bond and promoting the oxygenation/demetalation reactions of 2.

Tetra-kis[µ-1,3-bis-(4,5-dihydro-1,3-oxazol-2-yl)benzene-κ(2)N:N']tris-ilver(I) tris-(hexa-fluoridophosphate).

In the title compound, [Ag(3)(C(12)H(12)N(2)O(2))(4)](PF(6))(3), one Ag(I) ion, lying on a twofold rotation axis, is coordinated by four N atoms from four 1,3-bis-(4,5-dihydro-1,3-oxazol-2-yl)benzene (L) ligands in a distorted tetra-hedral geometry and the other Ag(I) ion is coordinated by two N atoms from two L ligands in a bent arrangement [N-Ag-N = 169.03 (17)°]. Two L ligands adopt a syn conformation, while the other two adopt an anti conformation. They bridge adjacent Ag(I) ions, forming a trinuclear complex. One of the PF(6) (-) anions is half-occupied, with the P atom located on a twofold rotation axis. The PF(6) (-) anions link the complex mol-ecules via Ag⋯F inter-actions [2.80 (2) and 2.85 (2) Å] into a polymeric chain along [100].

catena-Poly[[bis-(nitrato-κO)copper(II)]-µ-1,4-bis-(4,5-dihydro-1,3-oxazol-2-yl)-benzene-κN:N'].

In the title coordination polymer, [Cu(NO(3))(2)(C(12)H(12)N(2)O(2))](n), the Cu(II) ion, situated on an inversion center, is coordinated by two O atoms from two nitrate anions and two N atoms from two 1,4-bis-(4,5-dihydro-1,3-oxazol-2-yl)benzene (L) ligands in a distorted square-planar geometry. Each L ligand also lies across an inversion center and bridges two Cu(II) ions, forming a polymeric chain running along the [101] direction. The three O atoms of the nitrate group are disordered over two positions in a 3:2 ratio.

An eleven-vertex deltahedron with hexacapped trigonal bipyramidal geometry.

The first elemental cluster with hexacapped trigonal bipyramidal geometry is revealed in the luminescent undecanuclear silver complex which is stabilized by nine dithiocarbamate ligands and has an interstitial hydride. The hydride position within the Ag(11) cage is confirmed by a DFT investigation.

Anion-templated syntheses of octanuclear silver clusters from a silver dithiophosphate chain.

Extended chain polymers [Ag(5){S(2)P(OEt)(2)}(4)(PF(6))](n), (1) could be converted to clusters of the type, [Ag(8)(X){S(2)P(OEt)(2)}(6)](PF(6)) [X = F (2); Cl (3); H (4)], by the addition of appropriate anions, of which [Ag(8)(H){S(2)P(OEt)(2)}(6)](+) showed a unique tetracapped-tetrahedral Ag(8) core and contained Ag-mu-H-Ag linkages.

Structure, photophysical properties, and DFT calculations of selenide-centered pentacapped trigonal prismatic silver(I) clusters.

Undecanuclear silver clusters [Ag(11)(mu(9)-Se)(mu(3)-Br)(3){Se(2)P(OR)(2)}(6)] (R = Et, (i)Pr, (2)Bu) were isolated from the reaction of [Ag(CH(3)CN)(4)](PF(6)), NH(4)[Se(2)P(OR)(2)], and Bu(4)NBr in a molar ratio of 4:3:1 in CH(2)Cl(2) at -20 degrees C. Clusters were characterized by elemental analysis, NMR spectroscopy ((1)H, (31)P, and (77)Se), positive FAB mass spectrometry, and X-ray crystallography of the isopropyl derivative. Structural elucidations revealed that the Ag(11)Se core geometry of clusters is a selenide-centered, slightly distorted 3,3,4,4,4-pentacapped trigonal prism surrounded by six diselenophosphato ligands, each in a tetrametallic tetraconnective (mu(2), mu(2)) coordination mode, and three mu(3)-bromide anions. All compounds exhibited orange luminescence both as a solid and in solution. The electronic structure of these clusters was studied by DFT calculations, and their optical properties were rationalized through a TDDFT investigation. The computed metrical parameters of the clusters were consistent with the corresponding X-ray data of [Ag(11)(mu(9)-Se)(mu(3)-Br)(3){Se(2)P(O(i)Pr)(2)}(6)] . The theoretical investigations affirmed that the low-energy absorptions as well as emissions were due to transitions from an orbital mostly of a selenophosphate ligand/central Se atom character to an orbital of metal character.

Tetra-butyl-ammonium bis-[4,4'-dimethyl-2,2'-(3,7-dimethyl-1H-4,2,1-benzothiaza-siline-1,1-di-yl)dibenzene-thiol-ato]vanadium(III) acetonitrile tetra-solvate.

In the title compound, [N(C(4)H(9))(4)][V(C(23)H(21)NS(3)Si)(2)]·4CH(3)CN, the V(III) atom (site symmetry ) is coordinated by two N,S,S'-tridentate 4,4'-dimethyl-2,2'-(3,7-dimethyl-1H-4,2,1-benzothiaza-siline-1,1-di-yl)dibenzene-thiol-ate ligands in a distorted trans-VN(2)S(4) octa-hedral geometry. The complete cation is generated by crystallographic twofold symmetry, with the V atom lying on the rotation axis. The unusual ligand arose from nucleophilic attack on the coordinated nitrile by the thiol-ate precursor and reduction of nitrile to the imidate.

Octanuclear copper(I) clusters inscribed in a Se(12) icosahedron: anion-induced modulation of the core size and symmetry.

Synthesis and structural characterization of an octanuclear Cu(I) cluster [Cu(8){Se(2)P(O(i)Pr)(2)}(6)](PF(6))(2) (1) with an empty Cu(8) cubic core involving diisopropyl diselenophosphate (dsep) ligand has been demonstrated despite its high tendency to abstract anions even from the traces of impurities in the solvent. Reaction of 1 with anion sources (Bu(4)NF for F(-); NaBH(4) for H(-), and NaSH for S(2-)) in a 1:1 ratio produced anion-centered Cu(8) clusters with a formula [Cu(8)(X){Se(2)P(O(i)Pr)(2)}(6)](PF(6)) (X = F, 2a; H, 3a; D, 3a') and [Cu(8)(S){Se(2)P(O(i)Pr)(2)}(6)] (4) in high yields. In addition, fluoride- and hydride-centered Cu(8)(I) clusters [Cu(8)(X){Se(2)P(OEt)(2)}(6)](PF(6)) (X = F, 2b; H, 3b) could be generated in approximately 80% yield by direct reaction of [Cu(CH(3)CN)(4)](PF(6)), NH(4)Se(2)P(OEt)(2), and the anion sources (Bu(4)NF for F(-); NaBH(4) for H(-)) in 8:6:1 ratio. Whereas the structural elucidation of complexes 2 and 4 revealed an anion-centered cubic Cu(8) core surrounded by six dsep ligands, it was a tetracapped tetrahedral copper framework with a hydride in the center in compounds 3. All Cu...Cu distances along either the edge of the cube in 2 and 4 or the tetracapped tetrahedron in 3 are shorter than those identified in 1. Although the cubic (or spherical) contraction of the copper framework that was identified in a series of closed-shell anion-centered (except a hydride) Cu(8) cube having T(h) symmetry could be explained by the existence of strong anion-cation attractions, it was definitely a surprise that the hydride, which is the smallest closed-shell anion and spherical too, induced a tetrahedral contraction of four out of the eight Cu atoms in the empty cube 1, resulting in a tetracapped-tetrahedral geometry and reducing the symmetry to T from T(h). Furthermore the fact that the encapsulated anion induced modulation of the copper core size and symmetry was fully reproduced by DFT calculations on model compounds. To the best of our knowledge, this demonstrated the first example of the reduction of molecular symmetry (from T(h) to T) simply by changing the encapsulated species without altering the general bonding pattern of the surrounding ligands. We also demonstrated that the hydride can easily replace other anions (Cl(-), Br(-), F(-), S(2-), Se(2-)) in a very facile manner to produce hydride-centered species. Eventually, compounds 3 were stable in the presence of other anions, and hydride/deuteride exchange could not be achieved.

Conjugate base of a secondary phosphine selenide [P(Se)(O(i)Pr)2]- as the bridging unit for the construction of heterometallic Fe(II)-Hg(II)/Cd(II) complexes.

Reactions of perchlorate salts of Hg(II)/Cd(II) with [CpFe(CO)(2)P(Se)(O(i)Pr)(2)] (denoted as L) produced dicationic clusters [HgL(2)](ClO(4))(2), 1; [HgL(3)](ClO(4))(2), 2; and [CdL(3)(H(2)O)](ClO(4))(2), 11. However, the reactions of L with Hg(II)/Cd(II) halides yielded neutral complexes. For instance, HgI(2) produced [Hg(3)I(6)L(2)], 3, or [HgI(2)L(2)], 4, depending on the metal-to-ligand ratio used. Reaction of L with any of the Hg(II)/Cd(II) halides in a 1:1 ratio produced neutral clusters [HgX(mu-X)L](2) (M = Hg; X = Cl, 5; Br, 6; I, 7; M = Cd; X = Cl, 8; Br, 9; I, 10). Thus, variation of the M-to-L ratio made it possible for the formation of compounds with different metal/ligand stoichiometries only when ClO(4)(-) and I(-) salts of Hg(II) were used. Single-crystal X-ray crystallography revealed that two and three L units were connected to a Hg(II) via its Se atom in 1 and 2, respectively, whereas Hg(II) in 4 was connected to two "I" and two "L" units. An L (through its Se) and a terminal halogen were attached to each of the Hg(II)'s of the Hg(2)X(2) parallelogram core in 5 and 6. The cadmium complex 8, with a Cd(2)Cl(2) parallelogram core, was isostructural with the mercury complex 5. Although bonding and connectivity in 8 were similar to those in 9 and 10, the conformation of the bulky L ligands was unusually syn in 9 and 10, unlike the anti orientation in 5, 6, and 8. The syn conformation of L was also observed in compounds 1 and 2. Secondary interactions, namely, Se...Se interaction, the X...H-C type of H-bonding (X = halogen or Se), and pi-stacking, revealed in the structures played a role in determining the ligand conformation. The [P(Se)(O(i)Pr)(2)](-), the conjugate base of secondary phosphine selenide [HP(Se)(O(i)Pr)(2)], acted as a bridge with P bonded to Fe and Se bonded to Hg (or Cd) in these heterometallic clusters. Compound 5 further demonstrated a longer P-Se bond in the secondary phosphine selenide compared to that in isostructural, tertiary phosphine selenide metal complexes.

Facile entrapment of a hydride inside the tetracapped tetrahedral Cu(I)8 cage inscribed in a S12 icosahedral framework.

Reaction of [Cu(CH(3)CN)(4)](PF(6)) and NH(4)[S(2)P(OR)(2)] in a 4:3 ratio in acetone at room temperature produces octanuclear dicationic copper complexes [Cu(8){S(2)P(OR)(2)}(6)](PF(6))(2) (R = (i)Pr, 1; Et, 3) in 81 and 83% yields, respectively. On the other hand, reaction of [Cu(CH(3)CN)(4)](PF(6)), NH(4)[S(2)P(OR)(2)], and NaBH(4) in an 8:6:1 molar ratio in THF for 1 h yields [Cu(4)(H)(mu(3)-Cu)(4){S(2)P(OR)(2)}(6)](PF(6)) (R = (i)Pr, 2a; Et, 4a) in 87 and 82% yields, respectively. In a similar reaction when NaBD(4) is used instead of NaBH(4), [Cu(4)(D)(mu(3)-Cu)(4){S(2)P(OR)(2)}(6)](PF(6)) (R = (i)Pr, 2b; Et, 4b) are obtained in 83 and 78% yields, respectively. Structural elucidations of 2a and 4a reveal the tetracapped tetrahedral Cu(8) cage with an interstitial hydride. Each of the Cu(I) centers is trigonally coordinated by three S atoms, and each of the six dithiophosphate ligands is connected to a Cu(4) butterfly, where the hinge positions are occupied by two copper atoms situated at the vertex of the central tetrahedron and the wingtips are two capping Cu atoms. The 12 S atoms out of the six ligands constitute an icosahedron around the hydride-centered tetracapped tetrahedral Cu(8) framework. Surprisingly, empty Cu(8) clusters 1 and 3 can abstract hydride (or deuteride) from NaBH(4) (or NaBD(4)) in THF to form 2a and 4a (or 2b and 4b), respectively. Apparently the cubic Cu(8) core, which is known to be formed in the reaction of Cu(I) salt and dichalcogenophosph(in)ate ligands, undergoes a tetrahedral contraction due to the strong Cu...H interactions. Interestingly, the chloride can also be replaced from the chloride-centered Cu(8) complex of [Cu(8)(Cl){S(2)P(OEt)(2)}(6)](PF(6)) by hydride (or deuteride) to form 2a and 4a (or 2b and 4b). However, the hydride- and deuteride-centered compounds 2a,b and 4a,b do not allow the guest exchange.

A novel cyclometalated dimeric iridium complex, [(dfpbo)2Ir]2 [dfpbo = 2-(3,5-difluorophenyl)benzoxazolato-N,C2'], containing an unsupported Ir(II)-Ir(II) bond.

An unusual iridium complex, [(dfpbo)(2)Ir](2) [dfpbo = 2-(3,5-difluorophenyl)benzoxazolato-N,C(2')], which is the first dimeric iridium complex composed of two bis-cyclometalated Ir(II) structures connected by an unsupported Ir(II)-Ir(II) bond, has been synthesized and fully characterized. Under mild conditions of neutral pH at room temperature, this complex dissociated spontaneously to form the stable radical [Ir(dfpbo)(2)]*.

N,N-Bis(2-pyrid-yl)formamidine.

In the crystal structure of the title compound, C(11)H(10)N(4), the dihedral angle between the two pyridyl rings is 36.1 (1)°. The mol-ecules are connected via two strong N-H⋯N and two weak C-H⋯N hydrogen bonds into dimers, which are located on centers of inversion. This compound adopts the s-trans-anti-s-cis conformation in the solid state.

2-{5-[N-(2-Pyridyl)carbamo-yl]pentan-amido}pyridinium hexa-fluoro-phosphate.

In the crystal structure of the title compound, C(16)H(19)N(4)O(2) (+)·PF(6) (-), the cations and anions are situated on centres of inversion. Thus, the N-H H atom is disordered over both N atoms due to symmetry. In the crystal, mol-ecules are connected via N-H⋯F and N-H⋯O hydrogen bonds. The cation adopts the ⋯AAA⋯ trans conformation in the solid state.

N,N-Bis(6-methyl-2-pyrid-yl)formamidine.

In the crystal structure of the title mol-ecule, C(13)H(14)N(4), the two pyridyl rings are not coplanar but twisted about the C-N bond with an inter-planar angle of 71.1 (1)°. In the crystal, the mol-ecules form dimers, situated on crystallographic centres of inversion, which are connected via a pair of N-H⋯N hydrogen bonds. C-H⋯π-electron ring inter-actions are also present in the crystal structure. The title mol-ecule adopts an s-cis-anti-s-cis conformation in the solid state.

Syntheses, structures and magnetism of linear tri- and tetra-copper chains containing anions of N,N'-bis(pyrimidine-2-yl)formamidine.

Reaction of Kpmf (pmf(-) = anion of N,N'-bis(pyrimidyl-2-yl)formamidine, Hpmf) with divalent copper salt CuX2 afforded the linear trinuclear complexes of the type [Cu3(pmf)4](X)2 (X = BF4, 1; NO3, 2; ClO4, 3), while reaction of Kpmf with monovalent copper salt CuX gave the linear tetranuclear complexes of the type Cu4(pmf)4X2 (X = Cl, 4; Br, 5). The copper atoms of complexes 1-5 are helically bridged by four pmf(-) ligands, resulting in three different coordination modes for the pmf(-) ligands. In complexes 1-3, one pmf(-) ligand adopts a new coordination mode with the two amine nitrogen atoms chelating to the central copper atom, while the other three feature chelation by one pyrimidyl and one adjacent amine nitrogen atoms. The Cu(II)...Cu(II) distances are 2.729(2) and 2.825(2) A for 1, 2.762(1) and 2.832(1) A for 2 and 2.732(1) and 2.827(1) A for 3. In complexes 4 and 5, the pmf(-) ligands are coordinated to the copper atoms in tetradentate fashion with each nitrogen atom coordinating to one Cu atom. The Cu...Cu distances are 2.580(1) and 2.549(1) A for 4 and 2.582(1) and 2.561(1) A for 5. Antiferromagnetic interactions between the copper ions are observed with calculated g and J values of 2.03(1) and -188(2) cm(-1) for 1, 2.09(1) and -268(3) cm(-1) for 2, and 2.09(1) and -486(2) cm(-1) for 5. By comparing the magnetic data it can be shown that the bonding mode of the pmf(-) ligand is one of the important factors in determining the strengths of the Cu...Cu interactions in linear trinuclear and tetranuclear copper complexes.

Toward quartz and cristobalite: spontaneous resolution, structures, and characterization of chiral silica-mimetic silver(I)-organic materials.

An alpha-quartz-mimetic chiral coordination network of [Ag(L1)(CF3SO3)]n (L1=5,5'-bipyrimidine), after treatment with PF6- anions, undergoes a solution-state structural transformation toward [Ag(L1)(PF6)]n with a cristobalite-mimetic chiral structures. This structural transformation is accompanied by substantial enhancement in the fluorescent intensity and in the second-harmonic-generation response. The results also demonstrate an effective design strategy based on the spontaneous resolution route for the preparation of chiral architectures.

Crystal structures and solution behaviors of dinuclear d(10)-metal complexes containing anions of N,N'-bis(pyrimidine-2-yl)formamidine.

The salts of Zn(II), Cd(ii) and Hg(II) react instantaneously with Kpmf (pmf(-) = anion of N,N'-bis(pyrimidine-2-yl)formamidine, Hpmf) in THF, producing bimetallic complexes of the types [M(2)(pmf)(3)](X) (M = Zn(II), X = I(3)(-), ; M = Zn(II), X = NO(3)(-), ; M = Zn(II), X = ClO(4)(-), ; M = Cd(II), X = NO(3)(-), ; M = Cd(II), X = ClO(4)(-), ) and Hg(2)(pmf)(2)X(2) (X = Cl, ; Br, ; I, ). New tridentate and tetradentate coordination modes were observed for the pmf(-) ligands and their fluxional behaviors investigated by measuring variable-temperature (1)H NMR spectra. Complexes and , which possess only tetradentate coordination modes for the pmf(-) ligands in the solid state show larger free energy of activation (DeltaG(c)( not equal)) for the exchange than complexes and with tetradentate and/or tridentate coordination modes. Complexes and are the first dinuclear Zn(II) and Hg(II) complexes containing formamidinate ligands. Moreover, the separation between the two Hg(II) atoms are 3.4689(9), 3.4933(13) and 3.5320(10) A for complexes , respectively, similar to the sum of van der Waals radii of two Hg(II) atoms which is 3.50(7) A. All the complexes exhibit emissions and the nature of the anions hardly change the emission wavelengths of the complexes with the same metal centers. The emission bands may be tentatively assigned as intraligand (IL) pi-->pi* transitions.

Novel metalloreagent Cp(CO)2FeP(Se)(OR)2 produced from P-Se bond cleavage in the thermal reaction of [CpFe(CO)2]2 with phosphor-1,1-diselenolates.

The reaction of [CpFe(CO)2]2 with NH4Se2P(OR)2 yields a novel reagent Cp(CO)2FeP(Se)(OR)2, which has demonstrated coordination properties at the Se center to form heterometallic clusters as well as reactivity at the Se site toward C-based electrophiles.

Selenium-centered, undecanuclear silver cages surrounded by iodo and dialkyldiselenophosphato ligands. Syntheses, structures, and photophysical properties.

Three clusters [Ag11(mu9-Se)(mu3-I)3{Se2P(OR)2}6] (R = Et, 1; iPr, 2; 2Bu, 3) were isolated from the reaction of [Ag(CH3CN)4](PF6), NH4[Se2P(OR)2], and Bu4NI in a molar ratio of 4:3:1 in CH2Cl2 in 47-55% yield. Compounds 1 and 2 can also be synthesized with high yield from the reaction of Ag10(Se)[Se2P(OR)2]8 with 8 equiv of Bu4NI. In the positive fast atom bombardment mass spectra of 1-3, two major peaks that correspond to the intact molecule with the loss of an iodide ion, [Ag11(mu9-Se)(mu3-I)(2){Se2P(OR)2}6]+, and a diselenophosphate ligand, [Ag11(mu9-Se)(mu3-I)3{Se2P(OR)2}5]+, were identified. Single-crystal X-ray analyses of 2 and 3 reveal an Ag11Se core stabilized by three iodide anions and six diselenophosphato ligands in a tetrametallic tetraconnective (mu2,mu2) coordination mode. The central core adopts the geometry of a 3,3,4,4,4-pentacapped trigonal prism with a selenium atom in the center. In addition, weak intermolecular Se...I interactions exist in 2 and form a one-dimensional polymeric chain structure. Furthermore, all compounds exhibit orange-red luminescence in both the solid state and solution.