-
[show abstract]
[hide abstract]
ABSTRACT: Treatment of the (AuC2R)n acetylides with phosphine ligand 1,4-bis(diphenylphosphino)butane (PbuP) and Ag(+) ions results in self-assembly of the heterobimetallic clusters of three structural types depending on the nature of the alkynyl group. The hexadecanuclear complex [Au12Ag4(C2R)12(PbuP)6](4+) (1) is formed for R = Ph, and the octanuclear species [Au6Ag2(C2R)6(PbuP)3](2+) adopting two structural arrangements in the solid state were found for the aliphatic alkynes (R = Bu(t) (2), 2-propanolyl (3), 1-cyclohexanolyl (4), diphenylmethanolyl (5), 2-borneolyl (6)). The structures of the compounds 1-4 and 6 were determined by single crystal X-ray diffraction analysis. The NMR spectroscopic studies revealed complicated dynamic behavior of 1-3 in solution. In particular, complexes 2 and 3 undergo reversible transformation, which involves slow interconversion of two isomeric forms. The luminescence behavior of the titled clusters has been studied. All the compounds exhibit efficient sky-blue room-temperature phosphorescence both in solution and in the solid state with maximum quantum yield of 76%. The theoretical DFT calculations of the electronic structures demonstrated the difference in photophysical properties of the compounds depending on their structural topology.
Inorganic Chemistry 03/2013; · 4.60 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A new series of homoleptic alkynyl complexes, [{Au(2) Cu(2) (C(2) R)(4) }(n) ] (R=C(3) H(7) O (1), C(6) H(11) O (2), C(9) H(19) O (3), C(13) H(11) O (4)), were obtained from Au(SC(4) H(8) )Cl, Cu(NCMe)(4) PF(6) , and the corresponding alkyne in the presence of a base (NEt(3) ). Complexes 1-4 aggregate upon crystallization into polymeric chains through extensive metallophilic interactions. The cluster that contains fluorenolyl functionalities, C(13) H(9) O (5), crystallizes in its molecular form as a disolvate, [Au(2) Cu(2) (C(2) C(13) H(9) O)(4) ]⋅2 THF. The substitution of weakly bound THF molecules with pyridine molecules leads to the complex [Au(2) Cu(2) (C(2) C(13) H(9) O)(4) ]⋅2 py (6), thus giving two polymorphs in the solid state. Such structural diversity is established through metal-chain and hydrogen-bond formation, which depends on the stereochemical characteristics of the organic ligands. More interestingly, this solid-state structural arrangement affords good emission properties, such as intensity and spectroscopic profile, which are otherwise very weakly emissive in solution. Metallophilic aggregation of the {Au(2) Cu(2) } cluster units, as observed in the crystals, results in dramatic enhancement of the room-temperature phosphorescence, thereby reaching a maximum quantum efficiency of 95 % (4). A theoretical approach further indicates a synergistic effect of the array of the metal chain upon aggregation, which greatly enhances the spin-orbit coupling and, hence, the phosphorescence, thereby opening up a new direction in the field of aggregate-enhanced emission.
Chemistry 02/2013; · 5.93 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Treatment of Au(SC(4)H(8))Cl with a stoichiometric amount of hydroxyaliphatic alkyne in the presence of NEt(3) results in high-yield self-assembly of homoleptic clusters (AuC(2)R)(10) (R = 9-fluorenol (1), diphenylmethanol (2), 2,6-dimethyl-4-heptanol (3), 3-methyl-2-butanol (4), 4-methyl-2-pentanol (4), 1-cyclohexanol (6), 2-borneol (7)). The molecular compounds contain an unprecedented catenane metal core with two interlocked 5-membered rings. Reactions of the decanuclear clusters 1-7 with gold-diphosphine complex [Au(2)(1,4-PPh(2)-C(6)H(4)-PPh(2))(2)](2+) lead to octanuclear cationic derivatives [Au(8)(C(2)R)(6)(PPh(2)-C(6)H(4)-PPh(2))(2)](2+) (8-14), which consist of planar tetranuclear units {Au(4)(C(2)R)(4)} coupled with two fragments [AuPPh(2)-C(6)H(4)-PPh(2)(AuC(2)R)](+). The titled complexes were characterized by NMR and ESI-MS spectroscopy, and the structures of 1, 13, and 14 were determined by single-crystal X-ray diffraction analysis. The luminescence behavior of both Au(I)(10) and Au(I)(8) families has been studied, revealing efficient room-temperature phosphorescence in solution and in the solid state, with the maximum quantum yield approaching 100% (2 in solution). DFT computational studies showed that in both Au(I)(10) and Au(I)(8) clusters metal-centered Au → Au charge transfer transitions mixed with some π-alkynyl MLCT character play a dominant role in the observed phosphorescence.
Inorganic Chemistry 06/2012; 51(13):7392-403. · 4.60 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The structural characteristics of fully-hydrogenated carbon and boron nitride mono- and multilayer slabs, together with nanotubes derived from the slabs, are investigated mainly by means of periodic local second-order Møller-Plesset perturbation (LMP2) calculations and the results are compared with Hartree-Fock (HF), density functional theory (DFT), and dispersion function-augmented DFT (DFT-D) obtained ones. The investigated systems are structurally analogous to (111) and (110) slabs of diamond, where the hydrogenated (111) slab of diamond corresponds to the experimentally known graphane. Multilayering of monolayers and nanotubes is energetically favorable at the LMP2 level for both C and BN, while HF and DFT are not able to reproduce this behavior for CH systems. The work highlights the importance of utilizing methods capable of properly describing weak interactions in the investigation of dispersively-bound systems such as the multilayered graphanes and the corresponding nanotubes.
ChemPhysChem 05/2012; 13(9):2361-7. · 3.41 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We have investigated the structural and electronic characteristics of tetrahedral, octahedral, and icosahedral fullerenes
composed of group 15 elements phosphorus, arsenic, antimony, and bismuth. Systematic quantum chemical studies at the DFT and
MP2 levels of theory were performed to obtain periodic trends for the structural principles, stabilities, and electronic properties
of the elemental nanostructures. Calibration calculations for polyhedral clusters with up to 20 atoms showed the applied theoretical
approaches to be in good agreement with high-level CCSD(T)/cc-pVTZ results. By studying fullerenes up to P888, As540, Sb620, and Bi620, we found their structures and stabilities to converge smoothly toward their experimental bulk counterparts. The diameters
of the largest studied cages were 4.8, 3.7, 4.8, and 5.1nm for the P, As, Sb, and Bi fullerenes, respectively. Comparisons
with the experimentally known allotropes of the studied elements suggest the predicted polyhedral cages to be thermodynamically
stable. All studied group 15 polyhedral fullerenes were found to be semiconducting, and density of states analysis illustrated
clear periodic trends in their electronic structure. Relativistic effects become increasingly important when moving from P
to Bi and taking the spin–orbit effects into account by using a two-component procedure had a significant positive effect
on the relative stability of bismuth clusters.
KeywordsAb initio calculations–Antimony–Arsenic–Bismuth–Phosphorus–Fullerenes
Theoretical Chemistry Accounts 04/2012; 129(3):413-422. · 2.16 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We report a homoleptic Au-Cu alkynyl cluster that represents an unexplored class of luminescent materials with stimuli-responsive photophysical properties. The bimetallic complex formulated as [Au(2)Cu(2)(C(2)OHC(5)H(8))(4)](n) efficiently self-assembles from Au(SC(4)H(8))Cl, Cu(NCMe)(4)PF(6), and 1-ethynylcyclopentanol in the presence of NEt(3). This compound shows remarkably diverse polymorphism arising from the modulation of metallophilic interactions by organic solvents. Four crystalline forms, obtained from methanol (1a); ethanol, acetone, or choloroform (1b); toluene (1c); and diethyl ether or ethyl acetate (1d), demonstrate different photoluminescent characteristics. The solid-state quantum yields of phosphorescence (Φ) vary from 0.1% (1a) to 25% (1d), depending on the character of intermetallic bonding. The structures of 1b-d were determined by single-crystal X-ray diffraction. The ethanol (1b, Φ = 2%) and toluene (1c, Φ = 10%) solvates of [Au(2)Cu(2)(C(2)OHC(5)H(8))(4)](n) adopt octanuclear isomeric structures (n = 2), while 1d (Φ = 25%) is a solvent-free chain polymer built from two types of Au(4)Cu(4) units. Electronic structure calculations show that the dramatic enhancement of the emission intensity is correlated with the increasing role of metal-metal bonding. The latter makes the emission progressively more metal-centered in the order 1b < 1c < 1d. The metallophilic contacts in 1a-d show high sensitivity to the vapors of certain solvents, which effectively induce unusual solid-state isomerization and switching of the absorption and luminescence properties via non-covalent interactions. The reported polymorphic material is the first example of a gold(I) alkynyl compound demonstrating vapochromic behavior.
Journal of the American Chemical Society 04/2012; 134(15):6564-7. · 9.91 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We evaluate methods and models for the periodic quantum chemical treatment of defects in MgCl2 polymerization catalyst support and demonstrate the applicability of the approach for a study of chemical substitution of chlorine with bromine. Effects of the defects are evaluated through binding of methanol to catalytically relevant MgCl2 surfaces. Our results show that the hybrid density functional PBE0 method reproduces the MgCl2 crystal structure in good agreement with experiments and that a triple-ζ quality basis set is required to evaluate the donor binding properties. Furthermore, the effects of the defects depend on their position in the crystal lattice, and destabilization of the crystal lattice results in increased donor binding energy. Therefore, substitutions at the coordinatively unsaturated edges typically stabilize the crystallites and lower the donor binding energies, whereas substitutions at the coordinatively saturated bulk typically destabilize the crystallites and increase the donor binding energies. The effects are stronger on the (104) than on the (110) surface. The study is readily extendable to other kinds of defects occurring in crystallites.
The Journal of Physical Chemistry C 03/2012; 116(14):7957-7961. · 4.80 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A family of the diphosphines PPh(2)C(2)(C(6)H(4))(n)C(2)PPh(2) (n = 0-3), which possess a dialkynyl-arene spacer between the phosphorus atoms, was used for the synthesis of a series of bimetallic gold(I) complexes 1-7. Unlike the corresponding polynuclear Au(i) clusters, which show unique phosphorescence, 1-7 reveal dual emissions consisting of fluorescence and phosphorescence. The results are rationalized, in a semi-quantitative manner, by the trace (1-3) to zero (4-7) contribution of MLCT varying with the number of conjugated phenylene rings. As a result, unlike typical polynuclear Au(I) clusters with 100% triplet state population, the rate constant of the S(1)→T(1) intersystem crossing is drastically reduced to 10(9) s(-1) (4-7)-10(10) s(-1) (1-3), so that the fluorescence radiative decay rate can compete or even dominates. The drastic O(2) quenching of phosphorescence demonstrates the unprotected nature of the emission chromophores in 1-7, as opposed to the well protected, O(2) independent phosphorescence in most multimetallic Au(I) clusters.
Dalton Transactions 11/2011; 41(3):937-45. · 3.84 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Reactions of the homoleptic (AuC(2)R)(n) precursors with stoichiometric amount of diphosphine ligand PPh(2)C(6)H(4)PPh(2) (P^P) and Cu(+) ions lead to an assembly of a new family of bimetallic clusters [Au(6)Cu(2)(C(2)R)(6)(P^P)(2)](2+) (type I; R=9-fluorenolyl (1), diphenylmethanolyl (2), 2,6-dimethyl-4-heptanolyl (3), 1-cyclohexanolyl (4), Cy (5), tBu (6)). In the case of R=1-cyclohexanolyl, a structurally different complex [Au(6)Cu(2)(C(2)C(6)H(11)O)(6)(P^P)(3)](2+) (7, type II) could be obtained by treatment of 4 with one equivalent of the diphosphine, while for R=isopropanolyl only the latter type of cluster [Au(6)Cu(2)(C(2)C(3)H(7)O)(6)(P^P)(3)](2+) (8) was detected. Steric bulkiness of the alkynyl ligands and O···H-O hydrogen bonding are suggested to play an important role in stabilizing the type I and type II cluster structural motif, respectively. All the complexes exhibit intense photoluminescence in solution with emission parameters that depending on the geometrical arrangement of the octanuclear metal core. The clusters 1-4 and 6 show single emission band in a blue region (469-488 nm) with maximum quantum yield of 94% (4), while structurally different 7 and 8 emit yellow-orange (590 nm) with unity quantum efficiency. The theoretical DFT calculations of the electronic structures have been carried out to demonstrate that the metal-centered triplet emission within the heterometallic core plays a key role for the observed phosphorescence.
Chemistry 09/2011; 17(41):11456-66. · 5.93 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A method is presented to determine, individually and with minimal extra-thermodynamic assumptions, the Gibbs energy for anion transfer between two solvents using solid state electrochemistry of alkynyldiphosphine dinuclear Au(I) complexes (AuC2R)2PPh2C6H4PPh2 (L1, R = Fc; L2, R = C6H4Fc) and the heterometallic Au(I)–Cu(I) [{Au3Cu2(C2R)6}Au3(PPh2C6H4PPh2)3](PF6)2 (L3, R = Fc; L4, R = C6H4Fc) cluster complexes containing ferrocenyl units. These compounds exhibit a well-defined, essentially reversible solid-state oxidation in contact with different electrolytes, based on ferrocenyl-centered oxidation processes involving anion insertion. Voltammetric data can be used for a direct measurement of the free energy of ion transfer from one solvent to another using midpeak potentials in solutions of suitable salts in each one of the solvents separately or mixtures of the solvents. Excess Gibbs energy of solvation in solvent mixtures can also be directly measured using this procedure. Solvation data for different common inorganic oxoanions in water, MeOH, and MeCN and water–MeOH and water–MeCN mixtures are provided.
08/2011;
-
[show abstract]
[hide abstract]
ABSTRACT: The unprecedented, purely gold(I) alkynyl-diphosphine clusters 1-3 demonstrate intense room-temperature phosphorescence with maximum quantum efficiency of 92% in solution (3) and 86% in solid (2) and thermally dependent emission in the crystalline form, attributed to the crystal lattice arrangement.
Chemical Communications 04/2011; 47(19):5533-5. · 6.17 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Reactions between the diphosphino-gold cationic complexes [Au(2)(PPh(2)-C(2)-(C(6)H(4))(n)-C(2)-PPh(2))(2)](2+) (n = 0, 1, 2, 3) and polymeric acetylides (AuC(2)Ph)(n) and (AgC(2)Ph)(n) lead to the formation of a new family of heterometallic clusters with the general formula [Au(8+2n)Ag(6+2n)(C(2)Ph)(8+4n)(PPh(2)C(2)(C(6)H(4))(n)C(2)PPh(2))(2)](2+), n = 0 (1), 1 (2), 2 (3), 3 (4). Compounds 1-4 were characterized in detail by NMR and ESI-MS spectroscopy. Complex 1 (n = 0) crystallizes in two forms (orange (1a) and yellow (1b)), one of which (1a) has been analyzed by X-ray crystallography. The luminescence behavior of 1-4 has been studied. Compounds 2 and 3 exhibited orange-red phosphorescence with quantitative quantum efficiency in both aerated and degassed CH(2)Cl(2), implying O(2)-independent phosphorescence due to efficient protection of the emitting chromophore center by the organic ligands. Complex 3 exhibits reasonable two-photon absorption (TPA) property with a cross section of σ ≈ 45 GM (800 nm), which is comparable to the value of commercially available TPA dyes such as coumarin 151. Computational studies have been performed to correlate the structural and photophysical features of the complexes studied. The metal-centered triplet emission within the heterometallic core is suggested to play a key role in the observed phosphorescence. The luminescence spectrum of 1 in CH(2)Cl(2) shows dual phosphorescence maximized at 575 nm (the P(1) band) and 770 nm (the P(2) band). Both P(1) and P(2) bands possess identical excitation spectra, i.e., the same ground-state origin, and the same relaxation dynamics throughout the temperature range of 298-200 K. The dual emission of 1 arises from fast structural fluctuation upon excitation, perhaps forming two geometry isomers, which exhibit distinctly different P(1) and P(2) bands. The scrambling dynamics might require large-amplitude motion and, hence, is hampered in rigid media, as evidenced by the single emission for 1a (610 nm) and 1b (570 nm) observed in solid.
Inorganic Chemistry 02/2011; 50(6):2395-403. · 4.60 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We have performed a comprehensive theoretical investigation of the structural principles of semiconducting clathrate frameworks composed of the Group 14 elements carbon, silicon, germanium, and tin. We have investigated the basic clathrate frameworks, together with their polytypes, intergrowth clathrate frameworks, and extended frameworks based on larger icosahedral building blocks. Quantum chemical calculations with the PBE0 hybrid density functional method provided a clear overview of the structural trends and electronic properties among the various clathrate frameworks. In agreement with previous experimental and theoretical studies, the clathrate II framework proved to be the energetically most favorable, but novel hexagonal polytypes of clathrate II also proved to be energetically very favorable. In the case of silicon, several of the studied clathrate frameworks possess direct and wide band gaps. The band structure diagrams and simulated powder X-ray patterns of the studied frameworks are provided and systematic preliminary evaluation of guest-occupied frameworks is conducted to shed light on the characteristics of novel, experimentally feasible clathrate compositions.
Inorganic Chemistry 12/2010; 50(5):1733-42. · 4.60 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The novel heterobimetallic Au(I)-M(I) (M = Cu, Ag) alkynyl-diphosphine clusters were effectively prepared using a family of dialkynyl-based diphosphines, PPh(2)-C(2)-(C(6)H(4))(n)-C(2)-PPh(2) (n = 0-2). These compounds consist of [Au(x)M(y)(C(2)C(6)H(4)R)(2x)](y-x) clusters (x = (n + 2)(n + 3)/2; y = (n + 1)(n + 2)) "wrapped" in gold-diphosphine "belts" (M = Cu, n = 0, R = H (4); n = 1, R = H (6), OMe (8), NMe(2) (9). M = Ag, n = 0, 1, 2, R = H (5, 7, 10). The solid-state structures of 5 and 6 have been determined by X-ray crystallographic studies, other complexes were characterized by NMR spectroscopy and ESI-MS measurements. The luminescence behavior of these compounds has been studied both in the solid state and solution, and intense room-temperature emission in fluid medium with maximum quantum yield of 0.5 (6) was detected. Computational studies have been carried out and the theoretical results obtained are in good agreement with the experimental data. The calculations provided additional information on the structural and electronic properties of the aggregates under investigation and allowed for the rationalization of the difference in their photophysical behavior.
Dalton Transactions 10/2010; 39(38):9022-31. · 3.84 Impact Factor
-
Angewandte Chemie International Edition 10/2010; 49(47):8864-6. · 13.45 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We investigated the structural principles of novel germanium modifications derived by oxidative coupling of Zintl-type [Ge(9)](4-)clusters in various ways. The structures, stabilities, and electronic properties of the predicted {(2) (infinity)[Ge(9)](n)} sheet, {(1) (infinity)[Ge(9)](n)} nanotubes, and fullerene-like {Ge(9)}(n) cages were studied by using quantum chemical methods. The polyhedral {Ge(9)}(n) cages are energetically comparable with bulk-like nanostructures of the same size, in good agreement with previous experimental findings. Three-dimensional structures derived from the structures of lower dimensionality are expected to shed light on the structural characteristics of the existing mesoporous Ge materials that possess promising optoelectronic properties. Furthermore, 3D networks derived from the polyhedral {Ge(9)}(n) cages lead to structures that are closely related to the well-known LTA zeolite framework, suggesting further possibilities for deriving novel mesoporous modifications of germanium. Raman and IR spectra and simulated X-ray diffraction patterns of the predicted materials are given to facilitate comparisons with experimental results. The studied novel germanium modifications are semiconducting, and several structure types possess noticeably larger band gaps than bulk alpha-Ge.
ChemPhysChem 06/2010; 11(9):1944-50. · 3.41 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: An unprecedented Au-Ag alkynyl-diphosphine aggregate, obtained via CO-reduction of a mixture of simple reagents, exhibits intense room-temperature phosphorescence free from O(2) quenching, and serves as an excellent phosphorescence dye suited for both one- and two-photon imaging in human stem cells.
Chemical Communications 03/2010; 46(9):1440-2. · 6.17 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The novel heterometallic aggregates [Ag(8)Cu(2)(C(2)C(6)H(4)X)(6)(PPh(2)C(6)H(4)PPh(2))(6)][PF(6)](4) (X = H, 1; OMe, 2; NMe(2), 3) were prepared by the self-assembly reactions starting from simple precursors. These compounds consist of the central [Ag(6)Cu(2)(C(2)C(6)H(4)X)(6)](2+) clusters capped by two tripodal fragments [Ag(diphosphine)(3)](+). The solid state structures of complexes 1 and 3 have been determined by X-ray crystallographic studies, and NMR spectroscopy confirmed that the compounds remain intact in solution. In solution such as CH(3)CN, complexes 1-3 show a weak to moderate room-temperature phosphorescence in the blue region with a maximum quantum yield of 0.038 (2), while strong phosphorescence was recorded in the solid film of with a quantum yield of 0.26. Photophysical experiments revealed a relatively small effect of luminescence quenching by O(2) for 1, but more prominent quenching for 2 and 3 in solution. Computational approaches are in good agreement with the experimental data, supporting the proposed structural motif, and provide an additional insight into the electronic properties of these compounds to rationalize the different behavior of 1 compared to 2 and 3.
Dalton Transactions 03/2010; 39(9):2395-403. · 3.84 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Reaction of the polymeric alkynyl complexes (AuC(2)C(6)H(4)R)(n) (R = 4-NH(2) and 3-NH(2)) with the diphosphine PPh(2)C(6)H(4)PPh(2) in the presence of Cu(+) ions gave two novel heterometallic aggregates [{Au(3)Cu(2)(C(2)C(6)H(4)R)(6)}Au(3)(PPh(2)C(6)H(4)PPh(2))(3)](PF(6))(2) (R = 4-NH(2) (2), 3-NH(2) (3)). The compounds obtained were characterized by NMR spectroscopy and ESI-MS measurements. The solid-state structure of their 4-NMe(2) congener 1 is reported. The complexes 1-3 reversibly react with strong (HSO(3)Me and HSO(3)CF(3)) acids to give the adducts [{Au(3)Cu(2)(C(2)C(6)H(4)-R)(6)*(R'SO(3)H)(6)}Au(3)(PPh(2)C(6)H(4)PPh(2))(3)](PF(6))(2) (R = 4-NMe(2) (4), 4-NH(2) (5), 3-NH(2) (6)) with six acid molecules bound to the amine groups of the alkynyl ligands. Composition and structure of the adducts were established using ESI-MS and multinuclear ((31)P, (1)H and (1)H-(1)H COSY) NMR spectroscopy. It was found that formation of these adducts results in crucial changes of luminescence characteristics of the complexes 1-3 to give substantial (ca. 100 nm) blue shift of the emission maxima and a sharp increase (about an order of magnitude) in luminescence quantum yield for 4-NR(2) substituted derivatives. In the case of 3-substituted complex 3 the effect of adduct formation is much less pronounced and leads to blue-shift of emission maximum for 30 nm accompanied with a small drop in emission quantum yield. Computational studies have been performed to provide additional insight into the structural, electronic and photophysical properties of the starting complexes and their acid adducts. Interpretation of the photophysical effects induced by the adduct formation was suggested.
Dalton Transactions 03/2010; 39(10):2676-83. · 3.84 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Treatment of the polymeric alkynyl compounds (AuC2R)n (R = Fc, C6H4Fc; Fc = ferrocenyl) with the diphosphine PPh2C6H4PPh2 gave complexes (RC2Au)PPh2C6H4PPh2(AuC2R) (1, R = Fc; 2, R = C6H4Fc) with end-capped ferrocenyl groups. The reactions of 1 or 2 with Cu(NCMe)4PF6 result in formation of the heterotrimetallic aggregates [{Au3Cu2(C2R)6}Au3(PPh2C6H4PPh2)3](PF6)2 (3, R = Fc; 4, R = C6H4Fc), which consist of the alkynyl clusters [Au3Cu2(C2R)6]- wrapped by the cationic [Au3(PPh2C6H4PPh2)3]3+ belt. The novel compounds were characterized by NMR spectroscopy and ESI-MS measurements. The solid state structure of 3 is reported. Electrochemical properties of the complexes 1-4 have been studied. These data show that all six ferrocenyl units are oxidized in the clusters 3 and 4. The Fc groups of 3 are electronically coupled into each other, but in 4 behave essentially independently. Electronic structure calculations have been performed, showing good correlation with the X-ray and electrochemical studies.
Dalton Transactions 10/2009; · 3.84 Impact Factor
