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1.
目的: 构建α 1亚基诱导表达、β 2和γ 2L亚基稳定表达的人源α 1β 2γ 2L-GABA AR-CHO(Chinese hamster ovary)细胞株。方法: 从人cDNA文库中扩增α 1、β 2、γ 2L亚基编码基因,分别构建亚基表达载体;将三个亚基表达载体共转染CHO-K1细胞,通过抗性筛选、膜电位检测法进行稳定表达克隆筛选;通过qPCR、Western blot对亚基表达进行鉴定;以激动剂GABA、阳性变构调节剂地西泮(diazepam,Dia)、拮抗剂荷包牡丹碱(bicuculine)为工具药,采用全细胞膜片钳方法及膜电位检测法对稳定表达细胞的药理学功能进行鉴定。结果: 经克隆筛选获得表达量较高的α 1β 2γ 2L-GABA AR-CHO并对其亚基表达鉴定,结果显示该细胞稳定表达α 1、β 2、γ 2L亚基,构建的α 1β 2γ 2L-GABA AR-CHO细胞仅在加入四环素(tetracyclin)诱导的情况下表达α 1亚基并与β 2、γ 2L组装成具有功能活性的α 1β 2γ 2L-GABA AR;对其进行全细胞膜片钳检测研究发现,GABA可对其产生激动效应,引起α 1β 2γ 2L-GABA AR-CHO细胞产生氯离子通道特征性电流变化,Dia可剂量依赖性地增强GABA对α 1β 2γ 2L-GABA AR的激动效应;在膜电位检测研究中,获得GABA激动效应EC 50为(177.72 ± 15.92)nmol/L,Dia变构效应EC 50为(3.63±0.52)μmol/L,拮抗剂Bicuculine拮抗效应IC 50为(538.83±29.55)nmol/L。结论: 通过采用诱导表达策略,成功构建了α 1β 2γ 2L-GABA AR-CHO稳定表达细胞株,该细胞株具有对激动剂、阳性变构剂、拮抗剂特异性检测的药理学功能。 相似文献
2.
L-苏氨酸醛缩酶(L-Threonine aldolase,L-TA)可以催化甘氨酸和醛合成β-羟基-α-氨基酸。β-羟基-α-氨基酸具有两个手性中心,是多种手性药物的中间体。但是,游离的L-TA难以重复利用,分离纯化困难,严重阻碍了工业化应用。固定化技术可以有效解决这些问题。利用氨基树脂NAA固定化来源于 Bacillus nealsonii的L-苏氨酸醛缩酶,采用戊二醛作为交联剂,经过条件优化确定最佳固定化条件为:加酶量13 U、载体量0.6 g、0.4%( V/V)戊二醛、活化时间2 h、pH 8.5、35℃、固定化5 h。在此条件下,固定化酶酶活回收率为85.7%。在30℃下半衰期可达59天,为游离酶的6.5倍。将其应用于合成L- syn-对甲砜基苯丝氨酸,使用460 h后,残余酶活为79.4%。进一步开发了载体再利用策略,将失活固定化酶表面的氨基用戊二醛活化后,再与新的游离酶进行固定化,实现载体的再利用。利用该方法载体可重复利用两次,制备的固定化酶仍能使用460 h。该方法大大降低了固定化成本,为固定化L-TA的工业化应用打下坚实的基础。 相似文献
3.
为了实现糖苷类物质的高效转化,将来源于副干酪乳杆菌( Lactobacillus paracasei)TK1501 β-葡糖苷酶基因连接于表达载体pET28a(+)上,在 E. coli BL21中表达,重组酶经镍离子亲和层析分离得到纯酶,其分子质量和比酶活分别为86.63kDa和675.56U/mg。最适作用温度和pH分别为30℃和6.5。 Mg 2+和Ca 2+对β-葡糖苷酶酶活抑制作用最小,Cu 2+几乎使其丧失催化活性。其底物特异性较宽泛,对大豆异黄酮、栀子苷、水杨苷、七叶苷、虎杖苷、熊果苷均有降解作用。以β-pNPG为底物时,该酶的 Km和 Vmax分别为1.44mmol/L和58.32mmol/(L·s),催化系数 kcat为3 982/s。结果与分析表明,来源于副干酪乳杆菌TK1501 β-葡糖苷酶对水解大豆异黄酮和合成糖苷将会发挥重要作用。 相似文献
4.
目的: 研究蛋白质精氨酸甲基转移酶5(protein arginine methyltransferase 5,Prmt5)在小鼠脑血管发育、稳态维持中的功能,并考察脑血管内皮细胞特异性敲除 Prmt5后对中枢神经系统的影响。方法: 利用脑血管内皮细胞特异性表达 SP-A-Cre转基因小鼠和 Prmt5条件基因打靶小鼠交配,构建脑血管内皮细胞特异性 Prmt5敲除小鼠。利用H-E染色、免疫荧光染色、激光散斑成像、Sulfo-NHS-Biotin染料灌注等方法评价脑血管内皮细胞特异性 Prmt5敲除小鼠脑血管结构、脑血流量、血脑屏障渗透性等;利用实时定量PCR进一步检测补体C1q(complement C1q,C1q)、肿瘤坏死因子-α(tumor necrosis factor-α,TNF-α)和白细胞介素-1β(interleukin 1β,IL-1β)等细胞因子的表达水平。通过免疫荧光、Western blot等检测胶质纤维酸性蛋白(glial fibrillary acidic protein,GFAP)、S100钙结合蛋白β(S100 calcium-binding protein β protein,S100β)和补体C3(complement C3,C3)的表达,检测小鼠皮层、丘脑和小脑中星形胶质细胞活化水平。结果: 脑血管内皮细胞特异性敲除 Prmt5导致血管损伤, C1q、TNF-α和IL-1β等炎症因子表达水平上调,活化星形胶质细胞比例明显增加。结论: 脑血管内皮细胞中 Prmt5在小鼠脑血管稳态维持中发挥了重要功能。 相似文献
5.
17α-羟基黄体酮(17α-OH-PROG)是甾体激素类药物的关键中间体,其生物合成主要由细胞色素单加氧酶(CYP17)催化生成。在此过程中,细胞色素 P450还原酶(cytochrome P450 reductase,CPR)作为细胞色素P450 酶电子传递链的重要组成部分,直接影响CYP17的催化效率。为研究不同来源CPR与17α-羟化酶的适配性,首先以人源17α-羟化酶作为研究对象,构建了表达质粒pPIC3.5k-hCYP17,获得了重组毕赤酵母菌株。其次筛选获得3种不同来源CPR,构建了表达质粒 pPICZX-CPR,获得17α-羟化酶与CPR共表达菌株,并在毕赤酵母中进行转化实验,对转化产物进行薄层色谱(TLC)和高效液相色谱(HPLC)分析。结果显示,重组菌株具有17α-羟化酶活性,能够催化黄体酮生成目标产物17α-OH-PROG 以及副产物16α-羟基黄体酮(16α-OH-PROG)。不同来源的CPR与17α-羟化酶共表达与仅表达17α-羟化酶的产率相比均有所提高,其中hCPR-CYP17共表达菌株表现出最高的转化水平,17α-OH-PROG产率提高42%。上述结果表明:17α-羟化酶基因与CPR共表达能够提高其黄体酮17α-羟基化水平。为甾体黄体酮17α-羟基化的生物催化研究提供思路,对甾体药物的工业生产具有重要意义。 相似文献
6.
将 B. circulans 251 β-CGTase应用于海藻糖制备,海藻糖转化率从50.4%提高至71.9%。为进一步提高底物的转化率,运用易错PCR-高通量筛选技术筛选对以麦芽糖为歧化反应受体的亲和性提高的 B. circulans 251 β-CGTase突变体。利用低底物浓度的96孔板4,6-亚乙基-对硝基苯-α-D-麦芽七糖苷(EPS)显色法,最终筛选得到了一株对麦芽糖亲和性提高的突变体M234I。将野生型β-CGTase和突变体酶M234I进行蛋白质纯化,测定其酶学性质。结果表明,突变体的比活为345.25U/mg,野生型则为357.63U/mg;突变体M234I对麦芽糖的 Km为0.258 2mmol/L,仅为野生型(0.474 9mmol/L)的54.4%,对麦芽糖的亲和性显著提高;突变体的最适温度、最适pH较野生型未发生较大变化。以麦芽糊精(DE值16)为底物,将突变体M234I用于多酶复配体系生产海藻糖,酶反应结果表明海藻糖的转化率最高达74.9%,较野生型β-CGTase提高约3%。 相似文献
7.
从地衣芽孢杆菌( Bacillus licheniformis)中克隆到耐高温α-淀粉酶基因全长, 构建了原核表达载体, 转入大肠杆菌( Escherichia coli)中, 使用IPTG于28°C诱导6小时后, 通过SDS-PAGE检测到目的蛋白, 分子量约为55 kDa, 并通过酶活力检测实验证明该蛋白具有耐高温α-淀粉酶活性。同时构建了该基因融合GFP的植物表达载体, 通过农杆菌( Agro- bacterium tumefaciens)介导瞬时转化烟草( Nicotiana tabacum)下表皮细胞并在荧光显微镜下观察, 发现在烟草下表皮细胞的细胞质和液泡中均有绿色荧光。使用I 2-KI溶液对乙醇脱色后的烟草叶片进行染色, 显色反应表明在烟草中表达的耐高温α-淀粉酶具有酶活性。最后, 采用农杆菌介导的花蕾浸泡法将重组载体转化到拟南芥( Arabidopsis thaliana)中, 筛选到稳定遗传的耐高温α-淀粉酶基因的拟南芥纯合子。研究结果为后期开展表达耐高温α-淀粉酶的转基因植物的相关研究奠定了实验基础。 相似文献
8.
目的: GM1神经节苷脂贮积症是一种由半乳糖苷酶beta 1(galactosidase beta 1, GLB1)基因突变引起的β-半乳糖苷酶(β-galactosidase,β-gal)活性降低导致的严重的溶酶体贮积病。该病以进行性、致命性神经退行性病变为特征,目前尚无有效的治疗手段, AAV载体介导的基因治疗被认为是最有希望的治疗方法。通过基因定点突变获得具有较高β-gal活性的 GLB1突变体,以期用于后续 AAV介导的基因治疗。方法: 对人类和其他6种脊椎动物 GLB1基因进行多序列比对分析,筛选出部分氨基酸位点进行定点突变,采用携带突变位点的重组质粒和AAV9载体转染或感染HEK-293细胞,比较突变体与未突变体的活性差异。对GM1模型鼠注射携带coGLB1-R299L的rAAV9病毒,探究该突变体的体内活性表达。结果: 从15个突变体中筛选出coGLB1-R299L突变体,经质粒转染导入细胞后,其β-gal活性比具有野生型氨基酸序列的coGLB1增加了30%~40%。AAV体外感染实验中,rAAV9-coGLB1-R299L组的β-gal活性较未感染的细胞对照组提升了约2.2倍。体内结果显示,rAAV9-coGLB1-R299L在模型鼠体内广泛表达,心脏、肝脏、脾脏、肺、脑组织中β-gal活性显著提升。结论: 获得了具有更高β-gal活性的突变体coGLB1-R299L,初步探究了rAAV9-coGLB1-R299L的体外表达效果和模型鼠体内β-半乳糖苷酶的表达与分布,为该突变体应用于AAV介导的GM1神经节苷脂病治疗奠定基础。 相似文献
9.
目的: 原核表达盐穗木( Halostachys caspica C. A. Mey.)金属硫蛋白HcMT并探究其抗氧化活性。方法: 构建原核表达载体pET-32a- HcMT,转化至大肠杆菌 Escherichia coli BL21,加入Zn 2+胁迫培养(终浓度为200 μmol/L),分离纯化得到Zn-HcMT,测定Zn-HcMT自由基清除活性和总抗氧化能力,制备复合物Zn-HcMT/TiO 2并做FTIR表征。结果: 通过原核表达获得融合蛋白Zn-HcMT,对·OH、O 2· -、DPPH自由基具有较强的清除活性,对·OH、O 2· -的IC 50分别为0.386 mg/mL、0.038 mg/mL。融合蛋白浓度为0.01 mg/mL时,对DPPH清除率达(37.43 ± 0.006 8)%,浓度为0.3mg/mL时TEAC(trolox-equivalent antioxidant capacity)值为(1.023 ± 0.01)mmol/L,融合蛋白还原力A 700为0.142 ± 0.055,FTIR图谱同时表现了Zn-HcMT和TiO 2吸收特性。结论: Zn-HcMT具有良好的清除ROS活性及较强的抗氧化能力,在化妆品领域有潜在应用前景。 相似文献
10.
环氧化物水解酶可催化外消旋环氧化物的动力学拆分或对映归一性水解制备手性环氧化物或邻二醇,具有广阔的应用前景.为提高宇佐美曲霉环氧化物水解酶 ( AuEH2) 催化外消旋对甲基苯基缩水甘油醚 ( rac-pMPGE) 的对映体选择率 ( E).通过分子动力学模拟 (MD) 选取相互作用频率最高的位点A250替换为其他19种氨基酸;选取对映选择性显著提高的突变体测定其动力学参数 ( Km和 kcat) 及区域选择性系数 (β S和β R),并利用重组大肠杆菌全细胞拆分 rac-pMPGE.突变体 AuEH2 A250H的 E值从12.7提高至38.4,重组菌比活力为51.9U/g湿细胞;其水解 ( S) -pMPGE的 kcat/ Km从10.0mmol/(L·s)提高至12.8 mmol/(L·s),而水解 ( R) -pMPGE的 kcat/ Km从1.13mmol/(L·s)降低至0.35mmol/(L·s);全细胞拆分20mmol/L rac-pMPGE获得 ( R) -pMPGE的 ees为>99%,产率从33.0% 提高至40.7%.A250位点的突变对 AuEH2的对映选择性和酶活力具有显著影响;高对映选择性的 AuEH2突变体在制备高光学纯的 ( R) -pMPGE中具有应用潜力. 相似文献
11.
The effect of oxygen transfer rate (OTR) on β-carotene production by Blakelsea trispora in shake flask culture was investigated. The results indicated that the concentration of β-carotene (704.1 mg/l) was the highest in culture grown at maximum OTR of 20.5 mmol/(l h). In this case, the percentage of zygospores was over 50.0% of the biomass dry weight. On the other hand, OTR level higher than 20.5 mmol/(l h) was found to be detrimental to cell growth and pigment formation. To elucidate the effect of oxidative stress on β-carotene synthesis, the accumulation of hydrogen peroxide during fermentation under different OTRs was determined. A linear response of β-carotene synthesis to the level of H 2O 2 was observed, indicating that β-carotene synthesis is stimulated by H 2O 2. However, there was an optimal concentration of H 2O 2 (2400 μM) in enhancing β-carotene synthesis. At a higher concentration of H 2O 2, β-carotene decreased significantly due to its toxicity. 相似文献
12.
New mixed metal complexes SrCu 2(O 2CR) 3(bdmap) 3 (R = CF 3 (1a), CH 3 (1b)) and a new dinuclear bismuth complex Bi 2(O 2CCH 3) 4(bdmap) 2(H 2O) (2) have been synthesized. Their crystal structures have been determined by single-crystal X-ray diffraction analyses. Thermal decomposition behaviors of these complexes have been examined by TGA and X-ray powder diffraction analyses. While compound 1a decomposes to SrF 2 and CuO at about 380°C, compound 1b decomposes to the corresponding oxides above 800°C. Compound 2 decomposes cleanly to Bi 2O 3 at 330°C. The magnetism of 1a was examined by the measurement of susceptibility from 5–300 K. Theoretical fitting for the susceptibility data revealed that 1a is an antiferromagnetically coupled system with g = 2.012(7), −2 J = 34.0(8) cm −1. Crystal data for 1a: C 27H 51N 6O 9F 9Cu 2Sr/THF, monoclinic space group P2 1/ m, A = 10.708(6), B = 15.20(1), C = 15.404(7) Å, β = 107.94(4)°, V = 2386(2) Å 3, Z = 2; for 1b: C 27H 60N 6O 9Cu 2Sr/THF, orthorhombic space group Pbcn, A = 19.164(9), B = 26.829(8), C = 17.240(9) Å, V = 8864(5) Å 3, Z = 8; for 2: C 22H 48O 11N 4Bi 2, monoclinic space group P2 1/ c, A = 17.614(9), B = 10.741(3), C = 18.910(7) Å, β = 109.99(3)°, V = 3362(2) Å 3, Z = 4. 相似文献
13.
Glucose oxidase (GOD) was covalently immobilized on amorphous AlPO 4 as well as on an AlPO 4/clay mineral Sepiolite system. Immobilization of the enzyme was carried out through the -amino group of lysine residues through an aromatic Schiff's-base. Activation of the support was obtained after reaction of appropriate molecules with support surface –OH groups. The enzymatic activities of native, and different immobilized GOD systems and filtrates, were followed by the amount of liberated
-gluconic acid obtained in the enzymatic β-
-glucose oxidation with the aid of an automatic titrator. The kinetic properties of native and immobilized GOD were obtained for glucose concentrations in the range of physiological conditions and at different working conditions such as reaction temperature, reaction pH, and enzyme concentration. The binding percentage of enzymes was in the 50–80% range, with residual and specific activities in the 65–80% and 90–150% ranges, respectively. No change in the pH optimum and only slight changes in the Vmax and KM kinetic parameters with respect to native GOD were observed, so that not only was little deactivation of enzyme obtained throughout the immobilization process but also that the stability of the covalently bound enzyme in the two supports appeared to have increased with respect to the soluble enzyme. GOD immobilization also increased its efficiency and operational stability in repeated uses on increasing the amount of immobilized enzyme. 相似文献
14.
The reaction of N,N,N′,N′-tetrakis(2-pyridylmethyl)ethylenediamine (tpen) with VCl 3 in CH 3CN yields Cl 3V(tpen)VCl 3 which was hydrolyzed in water in the presence of oxygen affording [V 2O 2(μ-OH) 2(tpen)]I 2·2H 2O, the crystal structure of which has been determined. A syn-{OV(μ-OH) 2VO} 2+ core has been identified where the V(IV) centers are antiferromagnetically coupled ( J = −150 cm −1; g = 1.80). 相似文献
15.
The reaction of RuCl 3(H 2O), with C 5Me 4CF 3J in refluxing EtOH gives [Ru 2(η 5-C 5Me 1CF 2) 2 (μ-Cl 2] (20 in 44% yield. Dimer 2 antiferromagnetic (−2 J=200 cm 1). The crystal structures of 2 (rhombohedral system, R3 space group, Z=9, R=0.0589) and [Rh 2(η 5-C 5Me 4CF 3( 2Cl 2(μ-Cl) 2] (3) (rhombohedral system.
space group, Z = 9, R = 0.0641) were solved; both complexes have dimeric structures with a trans arrangement of the η 5-C 5Me 4CF 4 rings. Comparison of the geometry of 2 and 3 with those of the corresponding η 5-C 5Me 5 complexes shows that lowering the ring symmetry causes significant distortion of the M 2(μ-Cl) 2 moiety. The analysis of the MCl 3 fragment conformations in 2 and 3 and in the η 5-C 5ME 5 analogues shows that they are correlated with the M---M distances. The Cl atoms are displaced by Br on reaction of 2 with KBr in MeOH to give the diamagnetic dimer [Ru 2(η 5-C 5Me 4CF 3) 2Br 2 (μ-Br 2] (4). Complex 2 reacts with O 2 in CH 2Cl 2 solution at ambient temperature to form a mixture of isomeric η 6-fulvene dimers [Ru 2(η 6-C 5Me 3CF 3 = CH 2) 2Cl 2(μ-Cl) 2] (5). Reactions of 5 with CO and allyl chloride give Ru(η 5-C 5Me 3CF 3CH 2Cl)(CO) 2Cl (6) and Ru(η 5-C 5Me 3CF 3CF 3CH 2Cl)(η 3-C 3H 5)Cl 2 (7) respectively. 相似文献
16.
With exposure to trace amounts of air and moisture, the Cr 2(II, II) complex Cr 2(μ-3,5Cl 2-form) 4, where 3,5Cl 2-form is [(3,5-Cl 2C 6H 3)NC(H)N(3,5-Cl 2C 6H 3) −], undergoes an oxidative addition reaction. Structural information from the X-ray crystal structure of the edge-sharing bioctahedral (ESBO) Cr 2(III, III) product Cr 2(μ-OH) 2(μ-3,5Cl 2-form) 2(η 2-3,5Cl 2-form) 2 (1) indicates 1 has a significantly longer Cr–Cr distance [2.732(2) Å] than Cr 2(μ-3,5Cl 2-form) 4 [1.9162(10) Å], but the shortest Cr–Cr distance in an ESBO Cr 2(III, III) complex recorded to date. 相似文献
17.
The phosphinoalkenes Ph 2P(CH 2) nCH=CH 2 ( n= 1, 2, 3) and phosphinoalkynes Ph 2P(CH 2) n C≡CR (R = H, N = 2, 3; R = CH 3, N = 1) have been prepared and reacted with the dirhodium complex (η−C 5H 5) 2Rh 2(μ−CO) (μ−η 2−CF 3C 2CF 3). Six new complexes of the type (ν−C 5H 5) 2(Rh 2(CO) (μ−η 1:η 1−CF 3C 2CF 3)L, where L is a P-coordinated phosphinoalkene, or phosphinoalkyne have been isolated and fully characterized; the carbonyl and phosphine ligands are predominantly trans on the Rh---Rh bond, but there is spectroscopic evidence that a small amount of the cis-isomer is formed also. Treatment of the dirhodium-phosphinoalkene complexes with (η−CH 3C 5H 4)Mn(CO) 2thf resulted in coordination of the manganese to the alkene function. The Rh 2---Mn complex [(η−C 5H 5) 2Rh 2(CO) (μ−η 1:η 1−CF 3C 2CF 3) {Ph 2P(CH 2) 3CH=CH 2} (η−CH 3C 5H 4)Mn(CO) 2] was fully characterized. Simi treatment of the dirhodium-phosphinoalkyne complexes with Co 2(CO) 8 resulted in the coordination of Co 2(CO) 6 to the alkyne function. The Rh 2---Co 2 complex [(η−C 5H 5) 2Rh 2(CO) (μ−η 1:η 1−CF 3C 2CF 3) {Ph 2PCH 2C≡CCH 3}Co 2(CO) 2], C 37H 25Co 2F 6O 7PRh 2, was fully characteriz spectroscopically, and the molecular structure of this complex was determined by a single crystal X-ray diffraction study. It is triclinic, space group
( Ci1, No. 2) with a = 18.454(6), B = 11.418(3), C = 10.124(3) Å, = 112.16(2), β = 102.34(3), γ = 91.62(3)°, Z = 2. Conventional R on | F| was 0.052 fo observed ( I > 3σ( I)) reflections. The Rh 2 and Co 2 parts of the molecule are distinct, the carbonyl and phosphine are mutually trans on the Rh---Rh bond, and the orientations of the alkynes are parallel for Rh 2 and perpendicular for Co 2. Attempts to induce Rh 2Co 2 cluster formation were unsuccessful. 相似文献
18.
The reaction of TiCl 4 with Li 2[(SiMe 2) 2(η 5-C 5H 3) 2] in toluene at room temperature afforded a mixture of cis- and trans-[(TiCl 3) 2{(SiMe 2) 2(η 5-C 5H 3) 2}] in a molar ratio of 1/2 after recrystallization. The complex trans-[(TiCl 3) 2{(SiMe 2) 2(η 5-C 5H 3) 2}] was hydrolyzed immediately by the addition of water to THF solutions to give trans-[(TiCl 2) 2(μ-O){(SiMe 2) 2(η 5-C 5H 3) 2}] as a solid insoluble in all organic solvents, whereas hydrolysis of cis-[(TiCl 3) 2{(SiMe 2) 2(η 5-C 5H 3) 2}] under different conditions led to the dinuclear μ-oxo complex cis-[(TiCl 2) 2)(μ-O){(SiMe 2) 2(η 5-C 5H 3) 2}] and two oxo complexes of the same stoichiometry [(TiCl) 2(μ-O){(SiMe 2) 2(η 5-C 5H 3) 2}] 2(μ-O) 2 as crystalline solids. Alkylation of cis- and trans-[(TiCl 3) 2{(SiMe 2) 2(η 5-C 5H 3) 2}] with MgCIMe led respectively to the partially alkylated cis-[(TiMe 2Cl) 2{(SiMe 2) 2(η 5-C 5H 3) 2}] and the totally alkylated trans-[(TiMe 3) 2{(SiMe 2) 2(η 5-C 5H 3) 2}] compounds. The crystal and molecular structure of the tetranuclear oxo complex [(TiCl) 2(μ-O){(SiMe 2) 2(η 5-C 5H 3) 2}] 2(μ-O) 2 was determined by X-ray diffraction. 相似文献
19.
The reactions of the polysulfur and selenium cationic clusters S 82+ and Se 82+ with various iron carbonyls were investigated. Several new chalcogen containing iron carbonyl cluster cations were isolated, depending on the nature of the counteranion. In the presence of SbF 6− as a counterion, the cluster [Fe 3(E 2) 2(CO) 10] [SbF 6] 2·SO 2 (E = S, Se) could be isolated from the reaction of E 82+ and excess iron carbonyl. The cluster is a picnic-basket shaped molecule of two iron centers linked by two Se 2 groups, with the whole fragment capped by an Fe(CO) 4 group. Crystallographic data for C 10O 12Fe 3Se 4Sb 2F 12S (I): space group monoclinic P2 1/ c, A = 11.810(9), b = 24.023(6), c = 10.853(7) Å, β = 107.15(5)°, V = 2942(3) Å 3, Z = 4, R = 0.0426, Rw = 0.0503. When Sb 2F 11− is present as the counterion, or Se 4[Sb 2F 11] 2 is used as the cluster cation source, a different cluster can be isolated, which has the formula [Fe 4(Se 2) 3(CO) 12] [SbF 6] 2·3SO 2. The dication contains two Fe 2Se 2 fragments bridged by an Se 2 group. Crystallographic data for C 12O 18Fe 4Se 6Sb 2F 12S 3 (III): space group triclinic
, b = 18.400(9), C = 10.253(4) Å, = 93.10(4), β = 103.74(3), γ = 93.98(3)°, V = 1995(1) Å 3, Z = 2, R = 0.0328, Rw = 0.0325. The CO stretches in the IR spectrum all show a large shift to higher wavenumbers, suggesting almost no τ backbonding from the metals. This also correlates with the observed bond distances. All the compounds are extremely sensitive to air and water, and readily lose SO 2 when removed from the solvent. Thus all the crystals were handled at −100°C. The clusters seem to be either insoluble or unstable in all solvents investigated. 相似文献
20.
Reaction of RuCl(η 5-C 5H 5( pTol-DAB) with AgOTf (OTf = CF 3SO 3) in CH 2Cl 2 or THF and subsequent addition of L′ (L′ = ethene (a), dimethyl fumarate (b), fumaronitrile (c) or CO (d) led to the ionic complexes [Ru(η 5-C 5H 5)( pTol-DAB)(L′)][OTf] 2a, 2b and 2d and [Ru(η 5-C 5H 5)( pTol-DAB)(fumarontrile- N)][OTf] 5c. With the use of resonance Raman spectroscopy, the intense absorption bands of the complexes have been assigned to MLCT transitions to the iPr-DAB ligand. The X-ray structure determination of [Ru(η 5-C 5H 5)( pTol-DAB)(η 2-ethene)][CF 3SO 3] (2a) has been carried out. Crystal data for 2a: monoclinic, space group P2 1/ n with A = 10.840(1), b = 16.639(1), C = 14.463(2) Å, β = 109.6(1)°, V = 2465.6(5) Å 3, Z = 4. Complex 2a has a piano stool structure, with the Cp ring η 5-bonded, the pTol-DAB ligand σN, σN′ bonded (Ru-N distances 2.052(4) and 2.055(4) Å), and the ethene η 2-bonded to the ruthenium center (Ru-C distances 2.217(9) and 2.206(8) Å). The C = C bond of the ethene is almost coplanar with the plane of the Cp ring, and the angle between the plane of the Cp ring and the double of the ethene is 1.8(0.2)°. The reaction of [RuCl(η 5-C 5H 5)(PPh) 3 with AgOTf and ligands L′ = a and d led to [Ru(η 5-C 5H 5)(PPh 3) 2(L′)]OTf] (3a) and (3d), respectively. By variable temperature NMR spectroscopy the rottional barrier of ethene (a), dimethyl fumarate (b and fumaronitrile (c) in complexes [Ru(η 5-C 5H 5)(L 2)(η 2-alkene][OTf] with L 2 = iPr-DAB (a, 1b, 1c), pTol-DAB (2a, 2b) and L = PPh 3 (3a) was determined. For 1a, 1b and 2b the barrier is 41.5±0.5, 62±1 and 59±1 kJ mol −1, respectively. The intermediate exchange could not be reached for 1c, and the Δ G# was estimated to be at least 61 kJ mol −. For 2a and 3a the slow exchange could not be reached. The rotational barrier for 2a was estimated to be 40 kJ mol −. The rotational barier for methyl propiolate (HC≡CC(O)OCH 3) (k) in complex [Ru(η 5-C 5H 5)(iPr-DAB) η 2-HC≡CC(O)OCH 3)][OTf] (1 k) is 45.3±0.2 kJ mol −1. The collected data show that the barrier of rotational of the alkene in complexes 1a, 2a, 1b, 2b and 1c does not correlate with the strength of the metal-alkene interaction in the ground state. 相似文献
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