1,721,112 research outputs found
Electric–field assisted growth of highly oriented DAST nano-crystals in polymeric matrix for non linear optical application
No full textSurface-Mediated Organometallic Synthesis: High-Yield Syntheses of [Ir4(CO)12], [Ir6(CO)15]2−, and [Ir8(CO)22]2− by Controlled Reduction of Silica-Supported IrCl3 or [Ir(cyclooctene)2(μ-Cl)]2 in the Presence of Na2CO3 or K2CO3
No full textThe controlled reductive carbonylation under 1 atm. of CO of [Ir(cyclooctene)2(μ-Cl)]2, supported on a silica surface added with an alkali carbonate such as Na2CO3 or K2CO3, can be directed toward the formation of [Ir4(CO)12], K2[Ir6(CO)15] or K2[Ir8(CO)22] by controlling (i) the nature and amount of alkali carbonate, (ii) the amount of surface water, and (iii) the temperature. [Ir4(CO)12] can also be prepared by direct controlled reductive carbonylation of IrCl3 supported on silica in the presence of well controlled amounts of Na2CO3. These efficient silica-mediated syntheses are comparable to conventional synthetic methods carried out in solution or on the MgO surface. Like in strongly basic solution or on the MgO surface, the initially formed [Ir4(CO)12], the first step of nucleation which does not require a strong basicity of the silica surface, gives in a second time sequentially [Ir8(CO)22]2- and [Ir6(CO)15]2- according to reaction conditions and basicity of the silica surface
Solvent- and vapor-induced isomerization between the luminescent solids [CuI(4-pic)](4) and [CuI(4-pic)](infinity) (pic = methylpyridine). The structural basis for the observed luminescence vapochromism
No full textExposure of the polymeric solid [CuI(4-pic)](infinity) (pic = picoline = methyl pyridine) to liquid or vapor toluene leads to disappearance of its room-temperature blue emission (lambda (max) 437 nm) and the appearance of a yellow emission (lambda (max) 580 nm) characteristic of the [CuI(4-pic)](4) tetramer. The process is reversed when the latter is exposed to liquid or vapor n-pentane. Analogous transformations between the tetrameric and polymeric forms do not occur when the 3-picoline analogues [CuI(3-pic)](x) are similarly treated. Single-crystal X-ray diffraction studies on the compounds [CuIL](infinity) and [CuIL](4) (L = 3-, 4-pic) indicate that the 4-pic tetranuclear isomer incorporates toluene into its solid phase to give a material with the composition [CuI(4-pic)](4). 2C(6)H(5)CH(3), but the other three phases are solvent-free. The chains in the two polymeric phases exhibit double-zigzag configurations, also commonly observed in zeolitic tetrahedral structures. In both polymeric phases, the chains propagate along the monoclinic b axis. The 3-pic tetrameric phase can be described as a close-packed structure of [CuIL](4) units, whereas tetramers in the 4-pic phase form infinite columns along the unique tetragonal c axis segregated by four columns of toluene pairs. These structural differences explain the different behaviors during the phase transformation between tetrameric and polymeric polymorphs of the 3-pic and 4-pic compounds
Luminescence response of the solid state polynuclear copper(I) iodide materials [CuI(4-picoline)](x) to volatile organic compounds
No full textExposure of the polymeric solid [CuI(4-pic)](infinity) to either liquid or vapor toluene leads to disappearance of this material's characteristic room temperature blue emission (lambda(max) 437 nm) and the appearance of the yellow emission (lambda(max) 580 nm) indicative of the [CuI(4-pic)](4) tetramer; the process is reversed when the latter is exposed to liquid or vapor n-pentane
Surface organometallic chemistry: the potential involvement of surface-bound [HOs3(CO)10(OSi≡)] and physisorbed [HOs3(CO)10(OH)] as intermediates in the silica-mediated synthesis of various neutral and anionic osmium carbonyl clusters
No full textReproducible high-yield syntheses of [Ru3(CO)12], [H4Ru4(CO)12], and [Ru6C(CO)16]2− by a convenient two-step methodology involving controlled reduction in ethylene glycol of RuCl3·nH2O
No full textRu3CO12 [H4Ru4(CO)12], and [Ru6C(CO)16]2- have been synthesized in reproducible high yields and under mild conditions (1 atm) by a two-step methodology involving (i) first carbonylation of RuCl3·nH2O dissolved in ethylene glycol to give a mixture of tri- and di-carbonyl ruthenium(II) species, probably of the kind [Ru(CO)3Cl2(ethylene glycol)] and [Ru(CO)2Cl2(ethylene glycol)x ] (x = 1, 2), and (ii) addition of specific amounts of alkali carbonates and further reductive carbonylation to give the desired ruthenium carbonyl cluster. The selectivity of the second step is controlled by the: (i) nature and quantity of the alkali carbonate (Na2CO3 or K2CO3); (ii) gas-phase composition (CO or CO+H2); (iii) temperature
Surface mediated organometallic synthesis: Formation of [H5Os10(CO)(24)](-) by hydrogenation of silica-supported [Os(CO)(3)(OH)(2)](n) as a springboard for a high-yield synthesis of [H4Os10(CO)(24)](2-) starting from alpha-[Os(CO)(3)Cl-2](2) and working in ethylene glycol solution
No full textNew high yield routes to the high nuclearity hydrido carbonyl clusters [H5OS10(CO)24]- and [H4OS10(CO)24]2-, model systems for the chemisorption of CO and H2 on metal surfaces, are reported. [H5OS10(CO)24]- is obtained in good yields by hydrogenation (1 atm) at 200°C of physisorbed [Os(CO)3(OH)2]n whereas in refluxing ethylene glycol solution, that is less acidic than the silica surface, [H4OS10(CO)24]2- is obtained in high yield start-ing from [Os(CO)3(OH)2]n or, more conveniently, from α-[Os(CO)3Cl2]2 in the presence of the stoichiometric amount of sodium carbonate. The quantitative equilibrium [H4OS10(CO)24]2- +OH-⇄+H+ [H5OS10(CO)24]- is confirmed
New water-soluble ruthenium(II) and osmium(II) hydroxo carbonyl complexes
No full textA high-yield procedure is described for the preparation, from [M(CO)3Cl2]2 (M = Ru, Os) and aqueous NaOH, of the new water-soluble and air-stable species [Ru(CO)2Cl(OH)]n, [Ru(CO)2(OH)2]n, [Os(CO)3Cl-(OH)]2, and [Os(CO)3(OH)2]x (x = 2 or n)
Surface-mediated organometallic synthesis: high-yield syntheses of [Rh4(CO)12], [Rh6(CO)16], [Rh5(CO)15]− and [Rh12(CO)30]2− by controlled reduction of silica-supported RhCl3 or [Rh(CO)2Cl]2 in the presence of CH3CO2Na, Na2CO3 or K2CO3
No full textThe reductive carbonylation under 1 atm of CO of [Rh(CO)2Cl]2 supported on a silica surface added with a base such as CH3CO2Na, Na2CO3 or K2CO3, can be directed toward the formation of [Rh4(CO)12], [Rh6(CO)16] or K2[Rh12(CO)30] by controlling (i) the nature and amount of base; (ii) the amount of surface water; (iii) the reaction time; (iv) the temperature. Physisorbed [Rh6(CO)16] can also be prepared by direct controlled reductive carbonylation of RhCl3·nH2O supported on silica in the presence of well controlled amounts of CH3CO2Na. The neutral clusters [Rh4(CO)12] and [Rh6(CO)16] are easily recovered by extraction with dichloromethane whereas treatment of the generated silica-supported K2[Rh12(CO)30] with tetrahydrofuran affords K2[Rh12(CO)30] (by working under N2) or K[Rh5(CO)15] (by working under CO) in agreement with the easy conversion of these two clusters in solution. These efficient silica-mediated syntheses are comparable to conventional synthetic methods carried out in solution
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