Synthesis of cationic indenyl- and fluorenyl-arene complexes of ruthenium

Interaction of [Ru(-C ₆ H ₆ )Cl ₂ ] ₂ with indenyl- or fluorenyllithium in THF gives, together with cationic benzene complexes [Ru( ⁵ -C ₉ H ₇ )(-C ₆ H ₆ )]⁺ and [Ru( ⁵ -C ₁₃ H ₉ )(-C ₆ H ₆ )]⁺, the neutral cyclohexadienyl derivatives Ru( ⁵ -C ₉ H ₆ -C ₉ H ₇ ) and Ru( ⁵ -C ₁₃ H ₉ )( ⁵ -C ₆ H ₆ -C ₁₃ H ₉ ), respectively. Interaction of the cyclohexadienyl complexes with Al ₂ O ₃ , Ph ₃ C⁺, and CF ₃ CO ₂ H has been studied. Reaction of Ru( ⁵ -C ₁₃ H ₉ )( ⁵ -C ₆ H ₇ ) with CF ₃ CO ₂ H in the presence of an arene yields cationic cyclohexadienylarene complexes: [Ru( ⁵ -C ₁₃ H ₉ )( ⁶ -arene)]⁺ (arene=C ₆ H ₆ or 1,3,5-Me ₃ C ₆ H ₃ ).A. N. Nesmeyanov Institute of Organoelemental Compounds, Russian Academy of Sciences, 117813 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 3, pp. 699–706, March, 1992.     

Influence of interparticle interactions on the kinetics of self-assembly and mechanical strength of nanoparticulate aggregates

Computer simulations based on Discrete Element Method have been performed in order to investigate the influence of interparticle interactions on the kinetics of self-assembly and the mechanical strength of nanoparticle aggregates.Three different systems have been considered.In the first system the interaction between particles has been simulated using the JKR (Johnson,Kendall and Roberts) contact theory,while in the second and third systems the interaction between particles has been simulated using van der Waals and electrostatic forces respectively.In order to compare the mechanical behaviour of the three systems,the magnitude of the maximum attractive force between particles has been kept the same in all cases.However,the relationship between force and separation distance differs from case to case and thus,the range of the interparticle force.The results clearly indicate that as the range of the interparticle force increases,the self-assembly process is faster and the work required to produce the mechanical failure of the assemblies increases by more than one order of magnitude.     

Photochemical oxidation of hydrocarbons by atmospheric oxygen in acetonitrile catalyzed by cyclopentadienyliron complexes

[(-ArH)Fe(-C₅H₅)]⁺BF₄ ^–, where ArH is benzene or toluene, catalyzes the photochemical oxidation of hydrocarbons by oxygen in acetonitrile. Cyclohexane and ethylbenzene are oxidized to the alcohol and ketone derivatives, which are formed in different amounts (after gas-liquid chromatography); benzaldehyde is obtained from styrene. The proposed mechanism involves the formation of a peroxide radical from the organometallic complex, which is capable of hydrogen atom abstraction from the alkane.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1680–1683, July, 1991.     

Hydrocarbon oxygenation with Oxone catalyzed by complex [Mn2L2O3]2+ (L=1,4,7-trimethyl-1,4,7-triazacyclononane) and oxalic acid

Oxone (peroxysulphate) very efficiently oxidizes benzene to p-quinone (TON 1140) and alkanes to the corresponding alcohols and ketones (aldehydes) in aqueous acetonitrile 50 °C if catalytic amounts of complex [Mn₂L₂O₃]²⁺ (L=1,4,7-trimethyl-1,4,7-triazacyclononane) and oxalic acid are present in the solution. In contrast to the similar reaction with H₂O₂, the alkane oxidation with Oxone does not afford the corresponding alkyl hydroperoxides. Phenol was quantitatively oxidized to a mixture of p-quinone and pyrocatechol (9:1 ratio). Cyclohexanol gave cyclohexanone (TON 400). The proposed mechanism includes the formation of an oxidizing species containing the Mn(V)O fragment. A kinetic study demonstrated that an adduct of [Mn₂L₂O₃]²⁺ and oxalic acid is formed in the initial stage. This adduct reacts with Oxone to generate the oxidizing species.     

Cage‐like Copper(II) Silsesquioxanes: Transmetalation Reactions and Structural,Quantum Chemical,and Catalytic Studies

The transmetalation of bimetallic copper–sodium silsesquioxane cages, namely, [(PhSiO_1.5)₁₀(CuO)₂(NaO_0.5)₂] (“Cooling Tower”; 1 ), [(PhSiO_1.5)₁₂(CuO)₄(NaO_0.5)₄] (“Globule”; 2 ), and [(PhSiO_1.5)₆(CuO)₄(NaO_0.5)₄(PhSiO_1.5)₆] (“Sandwich”; 3 ), resulted in the generation of three types of hexanuclear cylinder‐like copper silsesqui‐ oxanes, [(PhSiO_1.5)₁₂(CuO)₆(C₄H₉OH)₂(C₂H₅OH)₆] ( 4 ), [(PhSiO_1.5)₁₂(CuO)₆(C₄H₈O₂)₄(PhCN)₂(MeOH)₄] ( 5 ), and [(PhSiO_1.5)₁₂(CuO)₆(NaCl)(C₄H₈O₂)₁₂(H₂O)₂] ( 6 ). The products show a prominent “solvating system–structure” dependency, as determined by X‐ray diffraction. Topological analysis of cages 1 – 6 was also performed. In addition, DFT theory was used to examine the structures of the Cooling Tower and Cylinder compounds, as well as the spin density distributions. Compounds 1 , 2 , and 5 were applied as catalysts for the direct oxidation of alcohols and amines into the corresponding amides. Compound 6 is an excellent catalyst in the oxidation reactions of benzene and alcohols.     

Cage‐like Fe,Na‐Germsesquioxanes: Structure,Magnetism, and Catalytic Activity

A series of four unprecedented heterometallic metallagermsesquioxanes were synthesized. Their cage‐like architectures have a unique type of molecular topology consisting of the hexairon oxo {Fe₆O₁₉} core surrounded in a triangular manner by three cyclic germoxanolates [PhGe(O)O]₅. This structural organization induces antiferromagnetic interactions between the Fe^III ions through the oxygen atoms. Evaluated for this first time in catalysis, these compounds showed a high catalytic activity in the oxidation of alkanes and the oxidative formation of benzamides from alcohols.     

Performance of slotted pores in particle manufacture using rotating membrane emulsification

This paper addresses the use of different slotted pores in rotating membrane emulsification technology.Pores of square and rectangular shapes were studied to understand the effect of aspect ratio (1-3.5) and their orientation on oil droplet formation.Increasing the membrane rotation speed decreased the droplet size,and the oil droplets produced were more uniform using slotted pores as compared to circular geometry.At a given rotation speed,the droplet size was mainly determined by the pore size and the fluid velocity of oil through the pore (pore fluid velocity).The ratio of droplet diameter to the equivalent diameter of the slotted pore increased with the pore fluid velocity.At a given pore fluid velocity and rotation speed,pore orientation significantly influences the droplet formation rate: horizontally disposed pores (with their longer side perpendicular to the membrane axis) generate droplets at double the rate of vertically disposed pores.This work indicates practical benefits in the use of slotted membranes over conventional methods.     

Predicting thermal conductivity of liquid suspensions of nanoparticles (nanofluids) based on rheology

A methodology is proposed for predicting the effective thermal conductivity of dilute suspensions of nanoparticles (nanofluids) based on rheology.The methodology uses the rheological data to infer microstructures of nanoparticles quantitatively,which is then incorporated into the conventional Hamilton-Crosser equation to predict the effective thermal conductivity of nanofluids.The methodology is experimentally validated using four types of nanofluids made of titania nanoparticles and titanate nanotubes dispersed in water and ethylene glycol.And the modified Hamilton-Crosser equation successfully predicted the effective thermal conductivity of the nanofluids.     

Nanoporous metal organic framework materials for hydrogen storage

Hydrogen is expected to play an important role in future transportation as a promising alternative clean energy source to carbon-based fuels.One of the key challenges to commercialize hydrogen energy is to develop appropriate onboard hydrogen storage systems,capable of charging and discharging large quantities of hydrogen with fast enough kinetics to meet commercial requirements.Metal organic framework (MOF) is a new type of inorganic and organic hybrid nanoporous particulate materials.Its diverse networks can enhance hydrogen storage through tuning the structure and property of MOFs.The MOF materials so far developed adsorb hydrogen through weak disperston interactions,which allow significant quantity of hydrogen to be stored at cryogenic temperatures with fast kinetics.Novel MOFs are being developed to strengthen the interactions between hydrogen and MOFs in order to store hydrogen under ambient conditions.This review surveys the development of such candidate materials,their performance and future research needs.     

Synthesis of triple-decker iron and cobalt complexes with a central tetramethylphospholyl ligand

30-Electron triple-decker complexes [(η-C₅H₅)Fe(μ-η:η-C₄Me₄P)Fe(η-C₅Me₅)]PF₆ and [(η-C₄Me₄)Co(μ-η:η-C₄Me₄P)Fe(η-C₅Me₅)]PF₆ with a central tetramethylphospholyl ligand were synthesized by stacking reactions of cationic fragments [(η-C₅H₅)Fe]⁺ and [(η-C₄Me₄)Co]⁺ with nonamethylphosphaferrocene (η-C₄Me₄P)Fe(η-C₅Me₅). Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1647–1649, September, 2000.