[Ag7(H){E2P(OR)2}6] (E = Se, S): precursors for the fabrication of silver nanoparticles.

Reactions of Ag(I) salt, NH(4)(E(2)P(OR)(2)) (R = (i)Pr, Et; E = Se, S), and NaBH(4) in a 7:6:1 ratio in CH(2)Cl(2) at room temperature, led to the formation of hydride-centered heptanuclear silver clusters, [Ag(7)(H){E(2)P(OR)(2)}(6)] (R = (i)Pr, E = Se (3): R = Et; E = S(4). The reaction of [Ag(10)(E){E(2)P(OR)(2)}(8)] with NaBH(4) in CH(2)Cl(2) produced [Ag(8)(H){E(2)P(OR)(2)}(6)](PF(6)) (R = (i)Pr, E = Se (1): R = Et; E = S(2)), which can be converted to clusters 3 and 4, respectively, via the addition of 1 equiv of borohydride. Intriguingly clusters 1 and 2 can be regenerated via adding 1 equiv of Ag(CH(3)CN)(4)PF(6) to the solution of compounds 3 and 4, respectively. All complexes have been fully characterized by NMR ((1)H, (77)Se, (109)Ag) spectroscopy, UV-vis, electrospray ionization mass spectrometry (ESI-MS), FT-IR, thermogravimetric analysis (TGA), and elemental analysis, and molecular structures of 3(H) and 4(H) were clearly established by single crystal X-ray diffraction. Both 3(H) and 4(H) exhibit a tricapped tetrahedral Ag(7) skeleton, which is inscribed within an E(12) icosahedron constituted by six dialkyl dichalcogenophosphate ligands in a tetrametallic-tetraconnective (µ(2), µ(2)) bonding mode. Density functional theory (DFT) calculations on the models [Ag(7)(H)(E(2)PH(2))(6)] (E = Se: 3'; E = S: 4') yielded to a tricapped, slightly elongated tetrahedral silver skeleton, and time-dependent DFT (TDDFT) calculations reproduce satisfyingly the UV-vis spectrum with computed transitions at 452 and 423 nm for 3' and 378 nm for 4'. Intriguingly further reactions of [Ag(7)(H){E(2)P(OR)(2)}(6)] with 8-fold excess amounts of NaBH(4) produced monodisperse silver nanoparticles with an averaged particle size of 30 nm, which are characterized by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, X-ray diffraction (XRD), and UV-vis absorption spectrum.

Shape modulation of octanuclear Cu(I) or Ag(I) dichalcogeno template clusters with respect to the nature of their encapsulated anions: a combined theoretical and experimental investigation.

M8L6 clusters (M = Cu(I), Ag(I); L = dichalcogeno ligand) are known for their ability to encapsulate various kinds of saturated atomic anions. Calculations on the models [M8(E2PH2)6](2+) (M = Cu(I), Ag(I); E = S, Se) and the ionic or neutral [M8(X)(E2PH2)6](q) (X = H, F, Cl, Br, O, S, Se, N, P, C) indicate that the cubic M8L6 cage adapts its shape for maximizing the host-guest bonding interaction. The interplay between size, covalent and ionic bonding favors either a cubic, tetracapped tetrahedral, or bicapped octahedral structure of the metal framework. Whereas the large third- and fourth-row main group anions maintain the cubic shape, a distortion toward a tetracapped tetrahedral arrangement of the metals occurs in the case of hydride, fluoride, and oxide. The distortion is strong in the case of hydride, weak in the case of fluoride, and intermediate in the case of oxide. Density functional theory (DFT) calculations predict a bicapped octahedral architecture in the case of nitride and carbide. These computational results are supported by X-ray structures, including those of new fluorine- and oxygen-containing compounds. It is suggested that other oxygen-containing as well as so far unknown nitride-containing clusters should be feasible. For the first time, the dynamical behavior of the encapsulated hydride has been investigated by metadynamics simulations. Our results clearly demonstrate that the interconversion mechanism between two identical tetracapped tetrahedral configurations occurs through a succession of M-H bonds breaking and forming which present very low activation energies and which involve a rather large number of intermediate structures. This mechanism is full in accordance with (109)Ag and (1)H state NMR measurements.

Hydrido copper clusters supported by dithiocarbamates: oxidative hydride removal and neutron diffraction analysis of [Cu7(H){S2C(aza-15-crown-5)}6].

Reactions of Cu(I) salts with Na(S(2)CR) (R = N(n)Pr(2), NEt(2), aza-15-crown-5), and (Bu(4)N)(BH(4)) in an 8:6:1 ratio in CH(3)CN solution at room temperature yield the monocationic hydride-centered octanuclear Cu(I) clusters, [Cu(8)(H){S(2)CR}(6)](PF(6)) (R = N(n)Pr(2), 1(H); NEt(2), 2(H); aza-15-crown-5, 3(H)). Further reactions of [Cu(8)(H){S(2)CR}(6)](PF(6)) with 1 equiv of (Bu(4)N)(BH(4)) produced neutral heptanuclear copper clusters, [Cu(7)(H){S(2)CR}(6)] (R = N(n)Pr(2), 4(H); NEt(2), 5(H); aza-15-crown-5, 6(H)) and clusters 4-6 can also be generated from the reaction of Cu(BF(4))(2), Na(S(2)CR), and (Bu(4)N)(BH(4)) in a 7:6:8 molar ratio in CH(3)CN. Reformation of cationic Cu(I)(8) clusters by adding 1 equiv of Cu(I) salt to the neutral Cu(7) clusters in solution is observed. Intriguingly, the central hydride in [Cu(8)(H){S(2)CN(n)Pr(2)}(6)](PF(6)) can be oxidatively removed as H(2) by Ce(NO(3))(6)(2-) to yield [Cu(II)(S(2)CN(n)Pr(2))(2)] exploiting the redox-tolerant nature of dithiocarbamates. Regeneration of hydride-centered octanuclear copper clusters from the [Cu(II)(S(2)CN(n)Pr(2))(2)] can be achieved by reaction with Cu(I) ions and borohydride. The hydride release and regeneration of Cu(I)(8) was monitored by UV-visible titration experiments. To our knowledge, this is the first time that hydride encapsulated within a copper cluster can be released as H(2) via chemical means. All complexes have been fully characterized by (1)H NMR, FT-IR, UV-vis, and elemental analysis, and molecular structures of 1(H), 2(H), and 6(H) were clearly established by single-crystal X-ray diffraction. Both 1(H) and 2(H) exhibit a tetracapped tetrahedral Cu(8) skeleton, which is inscribed within a S(12) icosahedron constituted by six dialkyl dithiocarbamate ligands in a tetrametallic-tetraconnective (µ(2), µ(2)) bonding mode. The copper framework of 6(H) is a tricapped distorted tetrahedron in which the four-coordinate hydride is demonstrated to occupy the central site by single crystal neutron diffraction. Compounds 1-3 exhibit a yellow emission in both the solid state and in solution under UV irradiation at 77 K, and the structureless emission is assigned as a (3)metal to ligand charge transfer (MLCT) excited state. Density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations on model compounds match the experimental structures and provide rationalization of their bonding and optical properties.

Tetrahedral-shaped anions as a template in the synthesis of high-nuclearity silver(I) dithiophosphate clusters.

Novel Ag(32) clusters, [Ag(16)(EO(4)){S(2)P(OEt)(2)}(12)](2) (PF(6))(4) (E = S, 1; Se, 2) and [Ag(16)(MO(4)){S(2)P(OEt)(2)}(12)](2)(PF(6))(4) (M = Cr, 3; Mo, 4), were prepared in situ from the addition of a tetrahedral-shaped anion as a template to the pentanuclear extended chain [Ag(5){S(2)P(OEt)(2)}(4)](n)(PF(6))(n).

A copper(I) homocubane collapses to a tetracapped tetrahedron upon hydride insertion.

The hydrido copper(I) and silver(I) clusters incorporating 1,1-dicyanoethylene-2,2-dithiolate (i-MNT) ligands are presented in this paper. Reactions of M(I) (M = Cu, Ag) salts, [Bu(4)N](2)[S(2)CC(CN)(2)], with the anion sources ([Bu(4)N][BH(4)] for H(-), [Bu(4)N][BD(4)] for D(-)) in an 8:6:1 molar ratio in THF produce octanuclear penta-anionic Cu(I)/Ag(I) clusters, [Bu(4)N](5)[M(8)(X){S(2)CC(CN)(2)}(6)] (M = Cu, X = H, 1(H); X = D, 1(D); M = Ag, X = H, 2(H); X = D, 2(D)). They can also be produced from the stoichiometric reaction of M(8)(i-MNT)(6)(4-) with the ammonium borohydride. All four compounds have been fully characterized spectroscopically ((1)H and (13)C NMR, IR, UV-vis) and by elemental analyses. The deuteride-encapsulated Cu(8)/Ag(8) clusters of 1(D) and 2(D) are also characterized by (2)H NMR. X-ray crystal structures of 1(H) and 2(H) reveal a hydride-centered tetracapped tetrahedral Cu(8)/Ag(8) core, which is inscribed within an S(12) icosahedron formed by six i-MNT ligands, each in a tetrametallic-tetraconnective (µ(2), µ(2)) bonding mode. The encapsulated hydride in 2(H) is unequivocally characterized by both (1)H and (109)Ag NMR spectroscopies, and the results strongly suggest that the hydride is coupled to eight magnetically equivalent silver nuclei on the NMR time scale. Therefore, a fast interchange between the vertex and capping silver atoms in solution gives a plausible explanation for the perceived structural differences between the Ag(8) geometry deduced from the X-ray structure and the NMR spectra.

Dinuclear gold diselenophosphate complexes: structures and photoluminescence.

Structures of [AuSe(2)P(OR)(2)](2) (R = (i)Pr, 1; Et, 2), the first homoleptic dinuclear gold(I) bridged by phosphorodiselenoates, are reported along with their intriguing photoluminescent properties, which display multiple emissions as well as thermochromism.

Anion templating from a silver(i) dithiophosphate 1D polymer forming discrete cationic and neutral octa- and decanuclear silver(i) clusters.

We report on a Ag5 coordination polymer and discrete Ag8 and Ag10 dithiophosphate clusters. The cluster formation and structures were affected by the stoichiometric control of the M : L molar ratios used. The cluster [Ag5{S2P(O(i)Pr)2}4]n(PF6)n, , is a monomeric unit within a coordination polymer formed through the reaction between [Ag(CH3CN)4]PF6 and the dithiophosphate ligand, [S2P(O(i)Pr)2](-), used in a M : L molar ratio of 5 : 4. All other clusters formed in the study are discrete units with encapsulated anions within the metal framework. The clusters [Ag8(X){S2P(O(i)Pr)2}6](PF6) (X = F, , Cl, , Br, ) are all cationic and contain monoanionic halogens. The related cluster [Ag8(H/D){S2P(O(i)Pr)2}6](PF6) contains either a hydride or a deuteride ion, and , respectively. The cluster [Ag8(S){S2P(O(i)Pr)2}6], , is neutral due to the di-anionic nature of the encapsulated sulfide anion. Clusters were all formed by reacting [Ag(CH3CN)4]PF6 and [S2P(O(i)Pr)2](-) in a M : L molar ratio of 8 : 6 and stirring for 1 h in THF; thereafter the respective anions (one equiv.) were added in situ. The cluster [Ag10(I)4{S2P(O(i)Pr)2}6], , is also neutral due to the charge balancing of the additional metal and halogen. In this case the M : L : X molar ratio was 10 : 6 : 4. All new clusters were characterized by (1)H and (31)P NMR, and elemental analysis, and , , were characterized by single crystal X-ray diffraction.

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.

Phosphonate- and ester-substituted 2-cyanoethylene-1,1-dithiolate clusters of zinc: aerial CO2 fixation and unusual binding patterns.

Treatment of [Zn(tmeda)Cl2] (tmeda = N, N, N', N'-tetramethylethylenediamine) with a phosphonate-substituted 2-cyanoethylene-1,1-dithiolato ligand in air yields a tetranuclear zinc-carbonate complex 1 having the formula of [Zn4(tmeda)3(mu3-CO3){S2CC(CN)P(O)(OEt)2}3] in which four zinc atoms form a trigonal pyramid with the apical zinc atom in a hitherto unknown S3O3 coordination sphere. It is the first example of aerial CO2 fixation to afford a metal-carbonato compound incorporating 1,1-ethenedithiolate ligands. In sharp contrast, reaction with an isobutyl ester-substituted 2-cyanoethylene-1,1-dithiolate forms a trimeric zinc complex [Zn(tmeda){S2CC(CN)(CO2(i)Bu)}]3, 2, which does not contain the metal-bound carbonate. Compound 2 is the first example of a trinuclear zinc complex composed of four-, five-, and six-coordinated Zn atoms. The unsymmetrical ligand orientation around three zinc centers in 2 suggests that the other structural isomer, which would have an idealized C3 axis, may exist. The reaction of the ethyl ester derivative of 2-cyanoethylene-1,1-dithiolate with [Zn(tmeda)Cl2] affords [{Zn(tmeda)Cl}2{S2CC(CN)(CO2Et)}], 3. The ester-functionalized 1,1-dithiolate ligands in compounds 2 and 3 display a bimetallic, triconnective coordination mode, which is rare for these types of ligands. Some probable intermediates generated from the formation of compound 1 have also been proposed.