In this work, novel oxidative coupling complexes, [(Pip)<sub>4n</sub>Cu<sub>4</sub>X<sub>4</sub>(CO<sub>3</sub>)<sub>2</sub>] (n = 1 or 2, X = Cl or Br, Pip ...In this work, novel oxidative coupling complexes, [(Pip)<sub>4n</sub>Cu<sub>4</sub>X<sub>4</sub>(CO<sub>3</sub>)<sub>2</sub>] (n = 1 or 2, X = Cl or Br, Pip = piperidine), are synthesized from the reaction of well characterized Lewis base [(Pip)<sub>4n</sub>Cu<sub>4</sub>X<sub>4</sub>O<sub>2</sub>] with carbon dioxide as a Lewis acid in CH<sub>2</sub>Cl<sub>2</sub>. These carbonato-derivatives are isolated as stable solids. They are easily soluble in aprotic solvents as CH<sub>2</sub>Cl<sub>2</sub>or phNO<sub>2</sub>. Cryoscopic measurements support tetranuclear structure for all of them. Electronic spectra in the near infrared with high molecular absorptivity may be explained for tetranuclear cuban structure to fulfil 3 halo-ligands for each copper centre in [(Pip)<sub>4n</sub>Cu<sub>4</sub>X<sub>4</sub>(CO<sub>3</sub>)<sub>2</sub>]. The EPR spectra for [(Pip)<sub>4n</sub>Cu<sub>4</sub>X<sub>4</sub>(CO<sub>3</sub>)<sub>2</sub>] complexes are axial type of spectra (d<sub>x2-y2</sub> G.S) suggesting elongated tetragonal distortion for all of them. Cyclic voltammograms for [(Pip)<sub>4n</sub>Cu<sub>4</sub>X<sub>4</sub>(CO<sub>3</sub>)<sub>2</sub>] are irreversible in character. These tetranuclear carbonato complexes show catalytical activity. They initiate the oxidation of 2,6-dimethylphenol (DMP) to 3,3’,5,5’-tetramethyl-4,4’-diphenoquinone (DPQ).展开更多
Theoretical investigation on the structures of the octacoordinated [Nd(CO3)4]5-and the nonacoordinated [Nd(CO3)4.OH2]5-complexes, using the SPARKLE parameters of the lanthanides within MOPAC, revealed that they posses...Theoretical investigation on the structures of the octacoordinated [Nd(CO3)4]5-and the nonacoordinated [Nd(CO3)4.OH2]5-complexes, using the SPARKLE parameters of the lanthanides within MOPAC, revealed that they possessed dodecahedral and square antiprismatic structures respectively with an average Nd-O distance of 0.249 nm. These structures and the Nd-O distances agreed well with those experimentally found in the crystal structures. Replacing the water molecule with a fluoride ion or a mondentatecarbonato ligand resulted in a nonacoordinated distorted square antiprismatic structures where the trans-carbonato groups were twisted. The corresponding decacoordinated structures with two fluoride ions or a bidentatecarbonato group, [Nd(CO3)4·F2]7-and [Nd(CO3)5]7-, were also investigated. In both cases considerable twisting of the transcarbonato groups was observed.展开更多
This paper represents the interaction of well characterized Lewis base [（Pyr）nCuX]4O2, n = 1 or 2, X = Cl, Br or I, Pyr = pyrrolidine with CO2 as a Lewis acid to produce new series of oxidative coupling and catechol...This paper represents the interaction of well characterized Lewis base [（Pyr）nCuX]4O2, n = 1 or 2, X = Cl, Br or I, Pyr = pyrrolidine with CO2 as a Lewis acid to produce new series of oxidative coupling and catechol oxidase initiators [（Pyr）nCuX]4（CO3）2. These carbonato derivatives are isolated as stable solids. They are easily soluble in aprotic solvents as CH2Cl2 or PhNO2. Cryoscopic measurements support tetranuclear core structure for all of them. Infrared spectra show differences from their oxo analogous in the carbonato domains but those differences did not distinguish between tridentate bridging carbonato and bidentate one. Rate of oxidation of 2,6-dimethylphenol （DMP） by [（Pyr）CuCl]4（CO3）2, supports coordination number six for Cu（Ⅱ） centers in [（Pyr）CuCl]4（CO3）2. In order to fulfill coordination number six, for n = 1, carbonate will act as tridentate while for n = 2, it will act as bidentate, as shown in Scheme 4. Near infrared spectra indicate a [（3 halo） Cu（Ⅱ） charge transfer] for [（Pyr）nCuX]4（CO3）2, n = 1 or 2, X = Cl or Br. Low molecular absorptivities of the maxima at 825 nm and 730 nm for [（Pyr）nCuI]4（CO3）2, n = 1 or 2 with a minimum of high molecular absorptivities at 600 nm, comparing to X= CI or Br analogous, support a step structure for [（Pyr）,Cul]4（CO3）2, as shown in Scheme 5. Cyclic voltammograms for [（Pyr）nCuX]4（CO3）2; n = 1 or 2, X = CI or Br, are irreversible in characters.展开更多
The violet polycrystalline (NH4)5[(VO)6(CO3)4(OH)9]·10H2O(NVCO) was simply sy nthesized by solution reaction using V2O5, HCl, N2H4·2HCl and NH4HCO3 as the st arting materials. The results of TGA and DTA of N...The violet polycrystalline (NH4)5[(VO)6(CO3)4(OH)9]·10H2O(NVCO) was simply sy nthesized by solution reaction using V2O5, HCl, N2H4·2HCl and NH4HCO3 as the st arting materials. The results of TGA and DTA of NVCO under H2(99.999%) atmosphe re show that V2O3 forms at 620℃. The data of TG/DTG and DTA of NVCO under N2(99 .999%) atmosphere indicate that VO2 forms at 367℃and crystallizes at 390℃. In air atmosphere, the TG/DTG and DTA of NVCO show that V2O5 forms at 354℃, cryst allizes at 366℃and melts at 664℃. The three thermolysis processes of NVCO show that a large amount of H2O, CO2 and NH3 gases fast releases during the thermoly sis of NVCO, causing that the particles of the materials split and atomize stron gly, thus to obtain V2O3, VO2 and V2O5 nano-powders finally. According to the a bove of thermoanalytical results, V2O3, VO2 and V2O5 powders were prepared respe ctively under H2, N2 and oxygen in a tube furnace. Chemical analysis and XRD exp eriments of the powders identify that pure V2O3 is obtained at 800℃for 0.5h und er H2 atmosphere; crystalline VO2 is obtained at 480℃for 0.5h in N2; amorphous VO2 is obtained at 350℃for 20min under N2 atmosphere, this has been first repor ted to prepare amorphous VO2 powder so far; pure V2O5 is obtained at 400℃for 10 min under oxygen. From the micrographs of the powders, the particle size of the V2O3, the crystalline VO2 or the V2O5 powders is 35nm, 24nm or < 40nm, respectiv ely. Above-mentioned results prove that NVCO is a good precursor for preparatio n of pure V2O3, VO2 and V2O5 nano-powders under mild conditions.展开更多
基金the National Natural Science Foundation of China (20001007 20131020)Natural Science Foundation of the Chinese Academy of Sciences (KJCX2-H3) and Fujian province (2000F006)
文摘In this work, novel oxidative coupling complexes, [(Pip)<sub>4n</sub>Cu<sub>4</sub>X<sub>4</sub>(CO<sub>3</sub>)<sub>2</sub>] (n = 1 or 2, X = Cl or Br, Pip = piperidine), are synthesized from the reaction of well characterized Lewis base [(Pip)<sub>4n</sub>Cu<sub>4</sub>X<sub>4</sub>O<sub>2</sub>] with carbon dioxide as a Lewis acid in CH<sub>2</sub>Cl<sub>2</sub>. These carbonato-derivatives are isolated as stable solids. They are easily soluble in aprotic solvents as CH<sub>2</sub>Cl<sub>2</sub>or phNO<sub>2</sub>. Cryoscopic measurements support tetranuclear structure for all of them. Electronic spectra in the near infrared with high molecular absorptivity may be explained for tetranuclear cuban structure to fulfil 3 halo-ligands for each copper centre in [(Pip)<sub>4n</sub>Cu<sub>4</sub>X<sub>4</sub>(CO<sub>3</sub>)<sub>2</sub>]. The EPR spectra for [(Pip)<sub>4n</sub>Cu<sub>4</sub>X<sub>4</sub>(CO<sub>3</sub>)<sub>2</sub>] complexes are axial type of spectra (d<sub>x2-y2</sub> G.S) suggesting elongated tetragonal distortion for all of them. Cyclic voltammograms for [(Pip)<sub>4n</sub>Cu<sub>4</sub>X<sub>4</sub>(CO<sub>3</sub>)<sub>2</sub>] are irreversible in character. These tetranuclear carbonato complexes show catalytical activity. They initiate the oxidation of 2,6-dimethylphenol (DMP) to 3,3’,5,5’-tetramethyl-4,4’-diphenoquinone (DPQ).
文摘Theoretical investigation on the structures of the octacoordinated [Nd(CO3)4]5-and the nonacoordinated [Nd(CO3)4.OH2]5-complexes, using the SPARKLE parameters of the lanthanides within MOPAC, revealed that they possessed dodecahedral and square antiprismatic structures respectively with an average Nd-O distance of 0.249 nm. These structures and the Nd-O distances agreed well with those experimentally found in the crystal structures. Replacing the water molecule with a fluoride ion or a mondentatecarbonato ligand resulted in a nonacoordinated distorted square antiprismatic structures where the trans-carbonato groups were twisted. The corresponding decacoordinated structures with two fluoride ions or a bidentatecarbonato group, [Nd(CO3)4·F2]7-and [Nd(CO3)5]7-, were also investigated. In both cases considerable twisting of the transcarbonato groups was observed.
文摘This paper represents the interaction of well characterized Lewis base [（Pyr）nCuX]4O2, n = 1 or 2, X = Cl, Br or I, Pyr = pyrrolidine with CO2 as a Lewis acid to produce new series of oxidative coupling and catechol oxidase initiators [（Pyr）nCuX]4（CO3）2. These carbonato derivatives are isolated as stable solids. They are easily soluble in aprotic solvents as CH2Cl2 or PhNO2. Cryoscopic measurements support tetranuclear core structure for all of them. Infrared spectra show differences from their oxo analogous in the carbonato domains but those differences did not distinguish between tridentate bridging carbonato and bidentate one. Rate of oxidation of 2,6-dimethylphenol （DMP） by [（Pyr）CuCl]4（CO3）2, supports coordination number six for Cu（Ⅱ） centers in [（Pyr）CuCl]4（CO3）2. In order to fulfill coordination number six, for n = 1, carbonate will act as tridentate while for n = 2, it will act as bidentate, as shown in Scheme 4. Near infrared spectra indicate a [（3 halo） Cu（Ⅱ） charge transfer] for [（Pyr）nCuX]4（CO3）2, n = 1 or 2, X = Cl or Br. Low molecular absorptivities of the maxima at 825 nm and 730 nm for [（Pyr）nCuI]4（CO3）2, n = 1 or 2 with a minimum of high molecular absorptivities at 600 nm, comparing to X= CI or Br analogous, support a step structure for [（Pyr）,Cul]4（CO3）2, as shown in Scheme 5. Cyclic voltammograms for [（Pyr）nCuX]4（CO3）2; n = 1 or 2, X = CI or Br, are irreversible in characters.
文摘The violet polycrystalline (NH4)5[(VO)6(CO3)4(OH)9]·10H2O(NVCO) was simply sy nthesized by solution reaction using V2O5, HCl, N2H4·2HCl and NH4HCO3 as the st arting materials. The results of TGA and DTA of NVCO under H2(99.999%) atmosphe re show that V2O3 forms at 620℃. The data of TG/DTG and DTA of NVCO under N2(99 .999%) atmosphere indicate that VO2 forms at 367℃and crystallizes at 390℃. In air atmosphere, the TG/DTG and DTA of NVCO show that V2O5 forms at 354℃, cryst allizes at 366℃and melts at 664℃. The three thermolysis processes of NVCO show that a large amount of H2O, CO2 and NH3 gases fast releases during the thermoly sis of NVCO, causing that the particles of the materials split and atomize stron gly, thus to obtain V2O3, VO2 and V2O5 nano-powders finally. According to the a bove of thermoanalytical results, V2O3, VO2 and V2O5 powders were prepared respe ctively under H2, N2 and oxygen in a tube furnace. Chemical analysis and XRD exp eriments of the powders identify that pure V2O3 is obtained at 800℃for 0.5h und er H2 atmosphere; crystalline VO2 is obtained at 480℃for 0.5h in N2; amorphous VO2 is obtained at 350℃for 20min under N2 atmosphere, this has been first repor ted to prepare amorphous VO2 powder so far; pure V2O5 is obtained at 400℃for 10 min under oxygen. From the micrographs of the powders, the particle size of the V2O3, the crystalline VO2 or the V2O5 powders is 35nm, 24nm or < 40nm, respectiv ely. Above-mentioned results prove that NVCO is a good precursor for preparatio n of pure V2O3, VO2 and V2O5 nano-powders under mild conditions.
