ordered and aligned lamellar phase structure of the synthesized monolithic silica. The SAXS pattern demonstrates that the order lamellar nanostructure of the prepared super-microporous silica does not collapse after removal of the template. Further work will be undertaken to employ the high robustness of the RTIL liquid-crystals for the generation of other mesoporous materials. ExperimentalPreparation of 1: The synthetic procedure of 1 followed a route reported in the literature [10]. 1-Chlorohexadecane (0.25 mol, 65.22 g) was mixed with 1-methylimidazole (0.25 mol, 20.53 g). The mixture was put into a 200 mL flask, refluxed at 90 C for 24 h, and then cooled down to room temperature. A white waxy solid was obtained. The product was dispersed into 200 mL THF, in which 1 was crystallized. After washing several times with THF, the crystalline powder of 1 was collected by centrifugation, and dried in vacuum at room temperature.Preparation of Monolithic Ordered Super-microporous Lamellar Silica with 1 as Template: In a typical synthesis, TMOS was used as the sol±gel precursor. 0.36 g of 1 was mixed with 1.0 mL of TMOS under mild magnetic stirring. After homogenization of the mixture, 0.5 mL of an aqueous solution of 0.01 M HCl, acting as an acid catalyst, was added dropwise. The resulting mixture was stirred at 40 C for 30 min, allowing pre-condensation of the silica, followed by mild vacuum exposure at 40 C for removal of the methanol formed due to the hydrolysis of TMOS. Complete gelation was accomplished by leaving the sample in an open flask at 40 C for 48 h. A transparent colorless silica monolith was obtained with no visible cracks and very high mechanical stability. The transparency of the hybrid materials strongly suggests the homogeneity of 1 in the silica matrix and the absence of phase separation between the RTIL and silica. 1 was removed from the silica by calcination of the sample at 550 C for 3 h at with a temperature ramp of 20 C min ±1 from room temperature to 250 C and from 350 C to 550 C, and 2 C min ±1 from 250 C to 350 C. The final product was ground into a powder for further characterization.Characterization: The TEM image was recorded on a Zeiss EM 912 X apparatus at an acceleration voltage of 120 kV. The sample was prepared by applying a drop of a diluted suspension of silica powder on a carbon-covered copper grid. The phase behavior of 1 in the reaction medium was studied by POM with a Leica DMR optical microscope. TGA was taken on a Netzsch 209. The sample was examined at a heating rate of 10 C min ±1 in an oxygen atmosphere. The powder SAXS curve was recorded on a rotating-anode instrument with pinhole collimation. A Nonius rotating anode device (P = 4 kW, Cu Ka) and an imageplate detector system were used. With the image plates placed at a distance of 40 cm from the sample, a scattering vector range from s = 0.05 to 1.0 nm ±1 was available [s = (2 sinh)/k, 2h scattering angle, k = 0.154 nm]. Nitrogen sorption data was obtained with a Micromeritics Tristar 3000 automated gas adsorption analyz...
Copper(I) carbonyl complexes with a series of hindered L R1,R2 ligands (L: hydrotris(pyrazolyl)borate, R1 and R2 are substituents at the 3-and 5-positions of the pyrazole ring, respectively), L R1,R2 CuCO [R1, R2 ) Me, Me (1), i-Pr, i-Pr (2), t-Bu, Me (3), t-Bu, i-Pr (4), Ph, i-Pr (5), Ph, Ph (6)] have been synthesized and characterized by 1 H NMR and IR spectroscopy and elemental analysis. The molecular structures of 3 and 6 have been determined by X-ray crystallography. The electronic structures of copper(I) sites are characterized by means of 63 Cu NMR spectroscopy and by the CtO stretching vibration. The sharp 63 Cu NMR signals are observed for L R1,R2 CuCO complexes in toluene at room temperature. The 63 Cu NMR signals of copper(I) complexes with alkyl-substituted ligands (1-4) are observed in lower field than those of the phenyl derivatives (5, 6) correlating with the electrondensity at the copper center. This argument is supported by the good correlation between the δ( 63 Cu) value and CtO stretching vibration which is a sensitive indicator of the extent of back-donation of the Cu d electrons to the antibonding CtO orbitals.
A series of hydrocarbyl complexes supported only by hydrotris(pyrazolyl)borato ligands (Tp R′ ) 3,5-diisopropylpyrazolyl (Tp iPr2 ) and 3,4,5-trimethylpyrazolyl derivatives (Tp Me3 )), Tp R′ M-R (M/R/R′ ) Ni/η 3 -allyl/iPr 2 (2 iPr2 Ni), Co/η 3 -allyl/iPr 2 (2 iPr2 Co), Fe/η 1 -allyl/iPr 2 (2 iPr2 Fe), Ni/η 3 -prenyl/iPr 2 (3 iPr2 Ni), Co/η 1 -p-methylbenzyl/iPr 2 (4 iPr2 Co), Fe/η 1 -p-methylbenzyl/iPr 2 (4 iPr2 Fe), Co/η 1 -p-methylbenzyl/Me 3 (4 Me3 Co), Fe/η 1 -p-methylbenzyl/Me 3 (4 Me3 Fe), Co/η 1 -R-naphthylmethyl/iPr 2 (5 iPr2 Co), Co/η 1 -ethyl/iPr 2 (6 iPr2 Co), Fe/η 1 -ethyl/iPr 2 (6 iPr2 Fe)) is prepared by reaction of the corresponding precursors,, with appropriate Grignard reagents. η 1 -Hydrocarbyl complexes are obtained when M ) Fe, Co, and the thermally unstable η 1 -ethylnickel derivative 6 iPr2 Ni is characterized via conversion to the acyl derivative Tp iPr2 Ni(CO)C(dO)Et ( 12). Characterization by a combination of various spectroscopic methods (IR, NMR, UV, and ESR), magnetic susceptibility, X-ray crystallography, and chemical reactions reveals that the η 1 -hydrocarbyl complexes 2 iPr2 Fe and 4-6 are tetrahedral, highly coordinatively unsaturated species with 14 (M ) Fe) and 15 (M ) Co) valence electrons. It is remarkable that the ethyl complexes 6 are thermally stable even at higher temperatures (70 °C (Co); 110 °C (Fe)), although they contain β-hydrogen atoms. The presence of a metal-carbon bond in 4-6 has been confirmed by protonation and hydrogenolysis, giving alkane (R-H) and carbonylation leading to acyl-carbonyl species (Tp R′ M(CO) n C(dO)R: M/n ) Fe/2 (7), Co/1 (8)). Despite the coordinative unsaturation at the metal centers complexes 4-6 turn out to be sluggish toward unsaturated organic compounds such as olefin, internal acetylene, ketone, and nitrile. Only phenylacetylene reacted with the ethyl complexes 6 iPr2 to result in insertion of the CtC bond into the M-C bond (6 iPr2 Co) or protonolysis of the M-C bond to afford the acetylide complex Tp iPr2 FeCtCPh, which was characterized after carbonylation, giving Tp iPr2 Fe(CO) 2 CtCPh (12). The magnetic susceptibility of η 1 -hydrocarbyl complexes combined with the results of EHMO calculations for the model complexes Tp H M-CH 3 (M ) Fe, Co) reveals the high-spin configuration of d electrons, which leads to occupation of all five frontier orbitals by electron pairs or unpaired electrons. The lack of a vacant d orbital is concluded to be the origin of the thermal stability of the electron-deficient hydrocarbyl complexes.
Coordinatively unsaturated hydrocarbyl complexes bearing b-hydrogen atoms, Tp iPr M-CH 2 CH 3 [M = Fe, Co; Tp iPr = hydrotris(3,5-diisopropylpyrazolyl)borate], 14e and 15e species, respectively, are prepared; they are resistant to bhydride elimination.
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