RESUMO
The bottom-up synthesis of organometallic zinc clusters is described. The cation {[Zn10](Cp*)6 Me}(+) (1) is obtained by reacting [Zn2 Cp*2] with [FeCp2][BAr4 (F)] in the presence of ZnMe2. In the presence of suitable ligands, the high reactivity of 1 enables the controlled abstraction of single Zn units, providing access to the lower-nuclearity clusters {[Zn9 ](Cp*)6} (2) and {[Zn8 ](Cp*)5 ((t) BuNC)3}(+) (3). According to DFT calculations, 1 and 2 can be described as closed-shell species that are electron-deficient in terms of the Wade-Mingos rules because the apical ZnCp* units that constitute the cluster cage do not have three, but only one, frontier orbitals available for cluster bonding. Zinc behaves flexibly in building the skeletal metal-metal bonds, sometimes providing one major frontier orbital (like Groupâ 11 metals) and sometimes providing three frontier orbitals (like Groupâ 13 elements).
RESUMO
The synthesis and characterization of the cationic mixed metal Ga/Zn cluster [Zn2(GaCp*)6](2+) (1) is presented. The reaction of [Zn2Cp*2] with [Ga2Cp*][BAr4(F)] leads to the formation of the novel complex being the first example of a [Zn2](2+) core exclusively ligated by metalloid group-13 organyl-ligands. Compound 1 exhibits two different coordination modes: In the solid state, two of the six GaCp* ligands occupy bridging positions, whereas VT (1)H NMR indicates the coexistence of a second isomer in solution featuring six terminal GaCp* ligands. Quantum chemical calculations have been carried out to assign the gallium and zinc positions; the bonding situation in 1 is characterized and the importance of dispersion forces is discussed.
RESUMO
The triangular clusters [Zn3Cp*3](+) and [Zn2CuCp*3] were obtained by addition of the inâ situ generated, electrophilic, and isolobal species [ZnCp*](+) and [CuCp*] to Carmona's compound, [Cp*Zn-ZnCp*], without splitting the ZnZn bond. The choice of non-coordinating fluoroaromatic solvents was crucial. The bonding situations of the all-hydrocarbon-ligand-protected clusters were investigated by quantum chemical calculations revealing a high degree of σ-aromaticity similar to the triatomic hydrogen ion [H3](+). The new species serve as molecular building units of Cu(n)Zn(m) nanobrass clusters as indicated by LIFDI mass spectrometry.
RESUMO
The isoelectronic M7 clusters [Cu3Zn4](Cp*)5 (1) and {[Cu2Zn5](Cp*)5}+ (2) are described. While 1 can be isolated only as a minor side product from the reaction of Cu(CH3CO2) with equimolar amounts of [Zn2Cp*2] with the trigonal cluster [CuZn2](Cp*)3 as the major product, 2 is available in acceptable yields from the reaction of [CuZn2](Cp*)3 with the Cp*Zn2-transfer-reagent [Cp*Zn2(Et2O)3][BAr4 F]. The trigonal bipyramidal Cu/Zn-clusters exhibit exceptional bonding situations: with formally only one skeleton electron pair they can be regarded as highly electron deficient. However, a detailed DFT analysis reveals that the cluster bonding is supported by 3d orbital contributions of the trigonal metal base unit. The data contribute to the development of an advanced tool-box for synthesis of Hume-Rothery intermetallic (e.g. brass) inspired clusters.
RESUMO
A series of four Zn2+ metal-organic frameworks containing functionalised isophthalate linkers and 4,4'-bipyridine pillars have been prepared and characterised. Isophthalates which contain -OC3H2n+1 alkoxy side chains (with n = 1, 2 or 3) form frameworks with a 3D pillared-layer topology instead of the typical 2D layer topology of the renowned coordination polymers with an interdigitated structure (CIDs), which is found for shorter -OC2H5 side chains. The gas adsorption properties of the materials were analysed using N2, CO2 and O2 adsorption measurements at low temperatures.
RESUMO
The synthesis and characterisation of the solvent-stabilized salt [Zn2(THF)6](2+)[BAr4(F)]2(-) (1) is presented, which features the dizinc dication [Zn2](2+) as an analogue of the calomel dication [Hg2](2+). The labile tetrahydrofuran (THF) solvate molecules of 1 can be readily substituted by other ligands. Reaction with the strong donor ligand PMe3 (Me = CH3) leads to the Zn(ii) complex [Zn(PMe3)4](2+)[BAr4(F)]2(-) by disproportionation, while the π-acceptor-ligand phenylisocyanide (PhNC) gives the substitution product [Zn2(PhNC)6](2+)[BAr4(F)]2(-) (2) with an intact Zn-Zn bond.
RESUMO
The first example of ligand protected Cu-Zn clusters is described. Reaction of [CpCu(CN(t)Bu)] with [Zn2Cp*2] yields [(CuCN(t)Bu)4(ZnCp*)4] (1a) and [(CuCN(t)Bu)4(ZnCp*)3(ZnCp)] (1b). According to DFT calculations, the [Cu4Zn4] unit fulfils the unified superatom model for cluster valence shell closing.
RESUMO
Zn-Cp* bond cleavage reactions leading to novel monovalent cationic zinc species are presented (Cp* = pentamethylcyclopentadienyl). The treatment of [Zn2Cp*2] with two equiv. of [H(Et2O)2][BAr4(F)] (BAr4(F) = B{C6H3(CF3)2}4) yields the triple-decker complex [Cp*3Zn4(Et2O)2][BAr4(F)] (1) via protolytic removal of a Cp* ligand as Cp*H, whereas the reaction with an equimolar amount of [FeCp2][BAr4(F)] (Cp = cyclopentadienyl) results in the formation of [Cp*Zn2(Et2O)3][BAr4(F)] (2) under oxidative cleavage of a Cp* ring giving decamethylfulvalene, (Cp*)2, and [FeCp2] as by-products. The molecular structures of compounds 1 and 2 are established by single-crystal X-ray diffraction studies. A new synthetic pathway for the formation of [Zn2Cp*2] based on the reductive elimination of Cp*H from in situ formed Cp*ZnH is presented.