Abstract Rate constants are reported for ligand replacement in three pentacyanoferrate(III) complexes [Fe(CN)5L]3- with L = 4-cyanopyridine, 4,4'-bipyridyl, or 4-t-butyl-pyridine, in a range of aqueous salt solutions. These salts include chlorides and bromides of potassium, lithium, and calcium, and tetra-alkyl-ammonium bromides, at concentrations within the range 0.50 and 2.00 mol dm-3. The observed trends are compared with those for a selection of other inorganic reactions.
{"title":"Salt Effects on Reactivity for Substitution Reactions of Pentacyanoferrate(II) Complexes","authors":"S. Alshehri, J. Burgess","doi":"10.1515/irm-2003-0107","DOIUrl":"https://doi.org/10.1515/irm-2003-0107","url":null,"abstract":"Abstract Rate constants are reported for ligand replacement in three pentacyanoferrate(III) complexes [Fe(CN)5L]3- with L = 4-cyanopyridine, 4,4'-bipyridyl, or 4-t-butyl-pyridine, in a range of aqueous salt solutions. These salts include chlorides and bromides of potassium, lithium, and calcium, and tetra-alkyl-ammonium bromides, at concentrations within the range 0.50 and 2.00 mol dm-3. The observed trends are compared with those for a selection of other inorganic reactions.","PeriodicalId":8996,"journal":{"name":"BioInorganic Reaction Mechanisms","volume":"20 1","pages":"59 - 64"},"PeriodicalIF":0.0,"publicationDate":"2003-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74392756","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract The kinetics of the reaction of chromium(VI) with 2-mercaptoethanesulfonic acid (MESA) has been studied spectrophotometrically at wavelength, 435 nm, and ionic strength, I, of 0.50 mol dm-3 (NaClO4) over the ranges: 16.0 < θ < 29.5 °C, 2.6 < pH < 7.1 (citric acid-phosphate buffer), [Cr(VI)]T = 2.0 χ 10-4 mol dm-3, 1.0 χ 10-2 < [MESA]T < 4.0 χ 10-2 mol dm-3. The reaction occurs giving clear indication of the formation of an intermediate, which is assumed to be a typical Cr(VI)-thioester. The decay of the thioester then occurs via a series of electron transfer reactions to give Cr(III). The formation and decay rates of this intermediate have been investigated kinetically and a detailed mechanism for the overall reaction proposed. Experimental data were fitted to rate equations derived from this mechanism. The specific rate constants and corresponding activation parameters were also deduced. The results show that MESA without carboxylate groups, react differently when compared to other thiols having such groups present. This confirms the participating role of carboxylate groups in the formation of the Cr(VI)-thioester. The catalytic effect of added Zn2+ was investigated and its overall role in the reaction of Cr(VI) with MESA was explained.
{"title":"Kinetics and Mechanisms of the Reduction of Chromium(VI) by 2-Mercaptoethanesulfonic Acid in Aqueous Solution: Difference in the Mechanistic Process of Reduction with Noncarboxylate Thiols","authors":"Dwight C. Ramdon, D. Dixon, T. Dasgupta","doi":"10.1515/irm-2003-0106","DOIUrl":"https://doi.org/10.1515/irm-2003-0106","url":null,"abstract":"Abstract The kinetics of the reaction of chromium(VI) with 2-mercaptoethanesulfonic acid (MESA) has been studied spectrophotometrically at wavelength, 435 nm, and ionic strength, I, of 0.50 mol dm-3 (NaClO4) over the ranges: 16.0 < θ < 29.5 °C, 2.6 < pH < 7.1 (citric acid-phosphate buffer), [Cr(VI)]T = 2.0 χ 10-4 mol dm-3, 1.0 χ 10-2 < [MESA]T < 4.0 χ 10-2 mol dm-3. The reaction occurs giving clear indication of the formation of an intermediate, which is assumed to be a typical Cr(VI)-thioester. The decay of the thioester then occurs via a series of electron transfer reactions to give Cr(III). The formation and decay rates of this intermediate have been investigated kinetically and a detailed mechanism for the overall reaction proposed. Experimental data were fitted to rate equations derived from this mechanism. The specific rate constants and corresponding activation parameters were also deduced. The results show that MESA without carboxylate groups, react differently when compared to other thiols having such groups present. This confirms the participating role of carboxylate groups in the formation of the Cr(VI)-thioester. The catalytic effect of added Zn2+ was investigated and its overall role in the reaction of Cr(VI) with MESA was explained.","PeriodicalId":8996,"journal":{"name":"BioInorganic Reaction Mechanisms","volume":"349 1","pages":"47 - 58"},"PeriodicalIF":0.0,"publicationDate":"2003-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75707661","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract A trinuclear complex, [{(NH3)5Co(O2CCH2NH)}2Cu](ClO4)6.2H2O has been synthesised using mononuclear glycinato(pentaammine)cobalt(III) Perchlorate and characterised by various physicochemical methods. The kinetic study by stopped-flow spectrophotometer indicated that the dissociation of the trinuclear complex occurred mainly through an acid catalysed path.
{"title":"Synthesis, Characterisation and Dissociation of a Glycinate Bridged Trinuclear Co(III)-Cu(II)-Co(III) Complex","authors":"Ν. N. Das, A. Dash, G. S. Brahama, P. Mohanty","doi":"10.1515/irm-2003-0109","DOIUrl":"https://doi.org/10.1515/irm-2003-0109","url":null,"abstract":"Abstract A trinuclear complex, [{(NH3)5Co(O2CCH2NH)}2Cu](ClO4)6.2H2O has been synthesised using mononuclear glycinato(pentaammine)cobalt(III) Perchlorate and characterised by various physicochemical methods. The kinetic study by stopped-flow spectrophotometer indicated that the dissociation of the trinuclear complex occurred mainly through an acid catalysed path.","PeriodicalId":8996,"journal":{"name":"BioInorganic Reaction Mechanisms","volume":"10 1","pages":"73 - 78"},"PeriodicalIF":0.0,"publicationDate":"2003-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76399773","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract The kinetics of the interaction of glutathione (reduced) (GSH) with [Pt(en)(H2O)2](ClO4)2and [Pt(dmen)(H2O)2](ClO4)2 (en = ethylenediamine, dmen = N,N'-dimethylethylenediamine) have been studied spectrophotometrically as a function of [substrate complex], [glutathione] and temperature at a particular pH (4.0). The reaction was found to proceed via rapid outersphere association complex formation followed by two slow consecutive steps. The first step involves the transformation of the outersphere complex into the innersphere complex containing Pt-S bond, while the second step involves chelation when the second aqua ligand is displaced. The association equlibrium constant (KE) and the two rate constants k1 and k2 have been evaluated. Activation parameters for both the steps have been calculated using Eyring equation. The low enthalpy of activation and large negative values of entropy of activation indicate an associative mode of activation for both steps.
用分光光度法研究了谷胱甘肽(还原型)(GSH)与[Pt(en)(H2O)2](ClO4)2和[Pt(dmen)(H2O)2](ClO4)2 (en =乙二胺，dmen = N,N'-二甲基乙二胺)的相互作用动力学，并将其作为[底物配合物]，[谷胱甘肽]和温度在特定pH(4.0)下的函数。发现该反应是通过快速的外球缔合络合物形成，然后是两个缓慢的连续步骤进行的。第一步是将外层配合物转化为含有Pt-S键的内层配合物，第二步是当第二个水配体移位时的螯合作用。计算了缔合平衡常数(KE)和两个速率常数k1和k2。利用Eyring方程计算了这两个步骤的激活参数。低的激活焓和大的负值的激活熵表明两个步骤的激活模式是联合的。
{"title":"Substitution of aqua ligands from ds-[Pt(en)(H2O)2](ClO4)2 and cis-[Pt(dmen)(H2O)2](ClO4)2 (en = ethylenediamine, dmen = Ν,Ν′-dimethylethylenediamine) by glutathione (reduced) (GSH) in aqueous medium - A Kinetic And Mechanistic Study.","authors":"S. K. Bera, P. Sengupta, G. S. De","doi":"10.1515/irm-2003-0108","DOIUrl":"https://doi.org/10.1515/irm-2003-0108","url":null,"abstract":"Abstract The kinetics of the interaction of glutathione (reduced) (GSH) with [Pt(en)(H2O)2](ClO4)2and [Pt(dmen)(H2O)2](ClO4)2 (en = ethylenediamine, dmen = N,N'-dimethylethylenediamine) have been studied spectrophotometrically as a function of [substrate complex], [glutathione] and temperature at a particular pH (4.0). The reaction was found to proceed via rapid outersphere association complex formation followed by two slow consecutive steps. The first step involves the transformation of the outersphere complex into the innersphere complex containing Pt-S bond, while the second step involves chelation when the second aqua ligand is displaced. The association equlibrium constant (KE) and the two rate constants k1 and k2 have been evaluated. Activation parameters for both the steps have been calculated using Eyring equation. The low enthalpy of activation and large negative values of entropy of activation indicate an associative mode of activation for both steps.","PeriodicalId":8996,"journal":{"name":"BioInorganic Reaction Mechanisms","volume":"117 1","pages":"65 - 72"},"PeriodicalIF":0.0,"publicationDate":"2003-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79748999","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
G. Rauth, S. Jasimuddin, Ambikesh Mahapatra, C. Sinha
Abstract The reaction between Pd(N,N')Cl2 [(N,N'= l-methyl-2-(arylazo)imidazole (RaaiMe), p-RC6H4- N=N-C3H2NN-1 -Me; 2-(arylazo)pyridine (Raap), p-C6H4-N=N-C5H4N; 2- (arylazo)pyrimidine (Raapm), p-C6H4-N=N-C4H3N2; where R=H (a), Me (b), CI (c)] and apicolinic acid (α-picH) have been examined spectrophotometrically in MeCN solution at 298K. The product is Pd(a-pic)2 which has been supported by pure compound synthesis from Na2[PdCl4] and α-picH. The kinetics of the nucleophilic substitution reaction has been studied under pseudo-first-order condition. The reaction proceeds in a biphasic manner. The kinetic analysis confirms the nucleophilic association path. External addition of CI- (LiCl) suppresses the rate. On considering the consecutive reaction A-> B-> C the rate data have been evaluated. Each phase shows first-order dependence on [α-picH]. Rate-1 = {a1+k1[(α-picH]}[ Pd(N,N')Cl2]; rate-2 = {a1+k2[(α-picH]}[Pd(N,N')Cl2], with the k1 (first phase rate constant) > k2 (second phase rate constant). Increase in π-acidity of the ligand N,N' increases the rate and follows the order: Pd(RaaiMe)Cl2 < Pd(Raap)Cl2 < Pd(Raapm)Cl2 .
{"title":"Kinetics and mechanism of reaction of α-picolinic acid with dichloro-{2-(arylazo)- heterocycle}palladium(II) complexes","authors":"G. Rauth, S. Jasimuddin, Ambikesh Mahapatra, C. Sinha","doi":"10.1515/irm-2003-0104","DOIUrl":"https://doi.org/10.1515/irm-2003-0104","url":null,"abstract":"Abstract The reaction between Pd(N,N')Cl2 [(N,N'= l-methyl-2-(arylazo)imidazole (RaaiMe), p-RC6H4- N=N-C3H2NN-1 -Me; 2-(arylazo)pyridine (Raap), p-C6H4-N=N-C5H4N; 2- (arylazo)pyrimidine (Raapm), p-C6H4-N=N-C4H3N2; where R=H (a), Me (b), CI (c)] and apicolinic acid (α-picH) have been examined spectrophotometrically in MeCN solution at 298K. The product is Pd(a-pic)2 which has been supported by pure compound synthesis from Na2[PdCl4] and α-picH. The kinetics of the nucleophilic substitution reaction has been studied under pseudo-first-order condition. The reaction proceeds in a biphasic manner. The kinetic analysis confirms the nucleophilic association path. External addition of CI- (LiCl) suppresses the rate. On considering the consecutive reaction A-> B-> C the rate data have been evaluated. Each phase shows first-order dependence on [α-picH]. Rate-1 = {a1+k1[(α-picH]}[ Pd(N,N')Cl2]; rate-2 = {a1+k2[(α-picH]}[Pd(N,N')Cl2], with the k1 (first phase rate constant) > k2 (second phase rate constant). Increase in π-acidity of the ligand N,N' increases the rate and follows the order: Pd(RaaiMe)Cl2 < Pd(Raap)Cl2 < Pd(Raapm)Cl2 .","PeriodicalId":8996,"journal":{"name":"BioInorganic Reaction Mechanisms","volume":"48 1","pages":"31 - 38"},"PeriodicalIF":0.0,"publicationDate":"2003-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87869238","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract The kinetics of Mg2+ incorporation into the three water soluble porphyrin isomers of the relatively planar cationic tetrakis(N-Methyl-X-pyridyl)porphyrins (X = 2,3, or 4) were studied from pH 6.5 to 8.9 at 25 °C, I = 2.6. The reactions were first order in both porphyrin and magnesium ion concentrations, and the specific rate constants increased with an increase in pH. The proposed mechanism involves Mg2+ reacting with the differing centrally protonated forms of these porphyrins, in the order Ρ 2-> H-P-" > H2-P. Various other porphyrins were substantially less reactive. In contrast, Mg reacts orders of magnitude faster with the non-planar ß-octabromo-tetra(N-methyl-4-pyridyI) porphyrin, where the reaction proceeds almost exclusively through the Mg2+ + P2- pathway. As compared to other metal ions, the relatively slow incorporation of Mg2+ into porphyrins is in part a consequence of the comparatively slow water exchange rate constant for the aquo Mg2+ ion.
{"title":"Kinetics of Magnesium Incorporation into Water Soluble Porphyrins","authors":"Sabrina L. Bailey, P. Hambright","doi":"10.1515/irm-2001-0106","DOIUrl":"https://doi.org/10.1515/irm-2001-0106","url":null,"abstract":"Abstract The kinetics of Mg2+ incorporation into the three water soluble porphyrin isomers of the relatively planar cationic tetrakis(N-Methyl-X-pyridyl)porphyrins (X = 2,3, or 4) were studied from pH 6.5 to 8.9 at 25 °C, I = 2.6. The reactions were first order in both porphyrin and magnesium ion concentrations, and the specific rate constants increased with an increase in pH. The proposed mechanism involves Mg2+ reacting with the differing centrally protonated forms of these porphyrins, in the order Ρ 2-> H-P-\" > H2-P. Various other porphyrins were substantially less reactive. In contrast, Mg reacts orders of magnitude faster with the non-planar ß-octabromo-tetra(N-methyl-4-pyridyI) porphyrin, where the reaction proceeds almost exclusively through the Mg2+ + P2- pathway. As compared to other metal ions, the relatively slow incorporation of Mg2+ into porphyrins is in part a consequence of the comparatively slow water exchange rate constant for the aquo Mg2+ ion.","PeriodicalId":8996,"journal":{"name":"BioInorganic Reaction Mechanisms","volume":"13 1","pages":"51 - 62"},"PeriodicalIF":0.0,"publicationDate":"2001-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87841733","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Professor Peter Moore has accepted appointment as co-editor of Inorganic Reaction Mechanisms, effective from this first issue of Volume 3. Peter Moore is a B.Sc. and Ph.D. graduate of the University of Sheffield, where his doctoral research was supervised by R. G. Wilkins. Following his doctoral studies, he moved in the mid-1960s to a postdoctoral research post with F. Basolo and R. G. Pearson. In terms of a pedigree in inorganic reaction mechanisms, one couldn't ask for a better one! He returned from the USA to the UK and an academic position at the University of Warwick, where he now holds a personal chair in chemistry. Peter was formerly Secretary and Chairman of the Royal Society of Chemistry Inorganic Mechanisms Group, and a founder member and Chairman of the RSC Macrocycles and Supramolecular Chemistry Group, and (jointly with the late Bob Hay) the Coordination Chemistry Discussion Groups. He is currently Chairman of the latter group. He is author of more than 150 papers in learned society journals. Peter brings a depth and breadth of apposite knowledge and experience to the tasks of co-editor that will surely strengthen the journal as it enters the new century. It is fitting that Peter Moore has participated along with our foundation co-editor, the late Robert W. Hay, in expanding the footprint of inorganic chemistry. This is a linkage that provides continuity for the journal. Indeed, this issue commences with a further group of papers dedicated to our late co-editor, and in particular with a contribution co-authored by our new coeditor. I am looking forward to working with Peter on developing Inorganic Reaction Mechanisms further.
彼得·摩尔教授已接受任命为无机反应机制的共同编辑，从第3卷第一期开始生效。Peter Moore是谢菲尔德大学的学士和博士研究生，他的博士研究由R. G. Wilkins指导。在完成博士学业后，他于20世纪60年代中期跟随F. Basolo和R. G. Pearson进行博士后研究。就无机反应机制的谱系而言，没有比这更好的了!他从美国回到英国，在华威大学(University of Warwick)担任学术职务，现在是化学系的个人教授。Peter曾是皇家化学学会无机机制组的秘书和主席，皇家化学学会大环和超分子化学组的创始成员和主席，以及(与已故的Bob Hay一起)配位化学讨论组。他目前是后者的主席。他在学术学会期刊上发表了150多篇论文。彼得为联合编辑的任务带来了深度和广度的相关知识和经验，这必将在期刊进入新世纪时得到加强。彼得·摩尔与我们基金会的共同编辑，已故的罗伯特·w·海，一起参与了扩大无机化学的足迹，这是很合适的。这是一个为期刊提供连续性的链接。事实上，这期杂志从另一组论文开始，献给我们已故的共同编辑，特别是我们的新共同编辑共同撰写的一篇文章。我期待着与Peter一起进一步发展无机反应机制。
{"title":"Introducing The New Co-Editor Of Inorganic Reaction Mechanisms","authors":"G. Lawrance","doi":"10.1515/IRM-2001-0101","DOIUrl":"https://doi.org/10.1515/IRM-2001-0101","url":null,"abstract":"Professor Peter Moore has accepted appointment as co-editor of Inorganic Reaction Mechanisms, effective from this first issue of Volume 3. Peter Moore is a B.Sc. and Ph.D. graduate of the University of Sheffield, where his doctoral research was supervised by R. G. Wilkins. Following his doctoral studies, he moved in the mid-1960s to a postdoctoral research post with F. Basolo and R. G. Pearson. In terms of a pedigree in inorganic reaction mechanisms, one couldn't ask for a better one! He returned from the USA to the UK and an academic position at the University of Warwick, where he now holds a personal chair in chemistry. Peter was formerly Secretary and Chairman of the Royal Society of Chemistry Inorganic Mechanisms Group, and a founder member and Chairman of the RSC Macrocycles and Supramolecular Chemistry Group, and (jointly with the late Bob Hay) the Coordination Chemistry Discussion Groups. He is currently Chairman of the latter group. He is author of more than 150 papers in learned society journals. Peter brings a depth and breadth of apposite knowledge and experience to the tasks of co-editor that will surely strengthen the journal as it enters the new century. It is fitting that Peter Moore has participated along with our foundation co-editor, the late Robert W. Hay, in expanding the footprint of inorganic chemistry. This is a linkage that provides continuity for the journal. Indeed, this issue commences with a further group of papers dedicated to our late co-editor, and in particular with a contribution co-authored by our new coeditor. I am looking forward to working with Peter on developing Inorganic Reaction Mechanisms further.","PeriodicalId":8996,"journal":{"name":"BioInorganic Reaction Mechanisms","volume":"1 1","pages":"I - II"},"PeriodicalIF":0.0,"publicationDate":"2001-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85740056","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract The kinetics of oxidative deamination and decarboxylation of L-asparagine (L-Aspg) by aqueous alkaline permanganate at constant ionic strength of 0.50 mol dm-3 were studied spectrophotometrically. The reaction exhibits first-order kinetics in [permanganate ion] and fractional-order dependences in [L-Aspg] and [alkali]. Initially added products such as aldehyde, ammonia and manganate have no significant effect on the rate of reaction. An increase in ionic strength and a decrease in dielectric constant of the medium increase the rate. The oxidation process in alkaline medium has shown to proceed via two paths: One a substrate dependent path, the other a substrate independent path. The constants involved in the mechanism were evaluated. There is a good agreement between observed and calculated rate constants. The activation paramaters with respect to slow step of path I and path II were calculated.
{"title":"Kinetics of Oxidative Deamination and Decarboxylation of L-Asparagine by Alkaline Permanganate: a Mechanistic Approach","authors":"M. R. Kembhavi, A. L. Harihar, S. Nandibewoor","doi":"10.1515/irm-2001-0105","DOIUrl":"https://doi.org/10.1515/irm-2001-0105","url":null,"abstract":"Abstract The kinetics of oxidative deamination and decarboxylation of L-asparagine (L-Aspg) by aqueous alkaline permanganate at constant ionic strength of 0.50 mol dm-3 were studied spectrophotometrically. The reaction exhibits first-order kinetics in [permanganate ion] and fractional-order dependences in [L-Aspg] and [alkali]. Initially added products such as aldehyde, ammonia and manganate have no significant effect on the rate of reaction. An increase in ionic strength and a decrease in dielectric constant of the medium increase the rate. The oxidation process in alkaline medium has shown to proceed via two paths: One a substrate dependent path, the other a substrate independent path. The constants involved in the mechanism were evaluated. There is a good agreement between observed and calculated rate constants. The activation paramaters with respect to slow step of path I and path II were calculated.","PeriodicalId":8996,"journal":{"name":"BioInorganic Reaction Mechanisms","volume":"90 1","pages":"39 - 50"},"PeriodicalIF":0.0,"publicationDate":"2001-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84323584","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yakup Baran, P. Kau, G. Lawrance, Sutrisno, E. I. Nagy-Felsobuki
Abstract Acid dissociation constants for the aminoglycosides neomycin and neamine and of 2-deoxystreptamine are reported. Solution NMR studies indicate that complexation with copper(II) and zinc(II) involves principally the primary amine donors, and formation constants with both neamine and 2-deoxystreptamine (2-DOS) and these metal ions are reported (at 25°C, I = 0.5 mol dm-3). Complexation studies probed by electrospray mass spectrometry identify both 1:1 and 1:2 species for Cu(II) and Zn(II) with 2-DOS, but only 1:1 species with neamine, consistent with behaviour in bulk solution. Preliminary formation kinetics of Cu(II) with neamine indicate rapid complexation at high pH but slower two-step processes near pH 7, consistent with complications in the thermodynamic determinations in the intermediate pH regime. Reaction of 2-DOS and neamine with Cu(II) in methanol appears as a single process, with the former occurring ~103-fold faster
摘要本文报道了氨基糖苷新霉素和奈胺的酸解离常数以及2-脱氧链胺的酸解离常数。溶液核磁共振研究表明，与铜(II)和锌(II)的络合主要涉及伯胺供体，并报道了与邻胺和2-脱氧链胺(2-DOS)和这些金属离子的形成常数(在25°C, I = 0.5 mol dm-3)。电喷雾质谱检测的络合研究表明，Cu(II)和Zn(II)与2-DOS的络合态均为1:1和1:2，但与neamine的络合态仅为1:1，与体溶液中的络合态一致。Cu(II)与neamine的初步形成动力学表明，在高pH下，Cu(II)快速络合，但在pH 7附近的两步过程较慢，这与中间pH条件下热力学测定的复杂性一致。2-DOS和neamine与Cu(II)在甲醇中的反应表现为单一反应，前者反应速度快103倍
{"title":"Interactions of the Aminoglycoside Neamine and 2-Deoxystreptamine with Copper(II) and Zinc(II)","authors":"Yakup Baran, P. Kau, G. Lawrance, Sutrisno, E. I. Nagy-Felsobuki","doi":"10.1515/irm-2001-0104","DOIUrl":"https://doi.org/10.1515/irm-2001-0104","url":null,"abstract":"Abstract Acid dissociation constants for the aminoglycosides neomycin and neamine and of 2-deoxystreptamine are reported. Solution NMR studies indicate that complexation with copper(II) and zinc(II) involves principally the primary amine donors, and formation constants with both neamine and 2-deoxystreptamine (2-DOS) and these metal ions are reported (at 25°C, I = 0.5 mol dm-3). Complexation studies probed by electrospray mass spectrometry identify both 1:1 and 1:2 species for Cu(II) and Zn(II) with 2-DOS, but only 1:1 species with neamine, consistent with behaviour in bulk solution. Preliminary formation kinetics of Cu(II) with neamine indicate rapid complexation at high pH but slower two-step processes near pH 7, consistent with complications in the thermodynamic determinations in the intermediate pH regime. Reaction of 2-DOS and neamine with Cu(II) in methanol appears as a single process, with the former occurring ~103-fold faster","PeriodicalId":8996,"journal":{"name":"BioInorganic Reaction Mechanisms","volume":"58 1","pages":"31 - 38"},"PeriodicalIF":0.0,"publicationDate":"2001-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86956523","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fabian Benzo, Gabriel González, Manuel A Martínez, B. Sienra
Abstract The volumes of activation for the spontaneous, base-, and acid- catalysed path of the hydrolysis reaction of a series of trans-[Co(MeNH2)(NH3)4X](3-n)+ ions (X = Cl-, Br-, (ONO2)- (OSO3)2-) have been determined in order to establish analogies with the dissociative trends found in previous work with the spontaneous hydrolysis of neutral ligands from the same cores. While for the base catalysed path a significant decrease in the activation volume is found on going from the {Co(NH3)5} to the trans- {Co(MeNH2)(NH3)4} inert skeleton (i.e. 9.8, 12.5, 4.0 and 9.1 cm3 mol-1 for the chloro, bromo, nitrato and sulfato derivatives), no significant changes are observed for the same complexes in the spontaneous reaction. The trends are rationalized in terms of the important changes occurring in electrostriction factors for the DCB and Id intimate mechanisms operating and the important increase in the degree of dissociativeness due to the presence of a trans-methylamino ligand. For the acid catalysed path the differences are much more difficult to assess, specially taking into account the limited information available as well as the inherent errors involved in the rate constant determination.
{"title":"Activation Volumes for a Series of Spontaneous, Acidand Base-Catalysed Aquation Reactions of Aniono trans- [Co(MeNH2)(NH3)4X]2,1+ Complexes (X=Cl-, Br-,ΝO3-,SO42-)","authors":"Fabian Benzo, Gabriel González, Manuel A Martínez, B. Sienra","doi":"10.1515/irm-2001-0103","DOIUrl":"https://doi.org/10.1515/irm-2001-0103","url":null,"abstract":"Abstract The volumes of activation for the spontaneous, base-, and acid- catalysed path of the hydrolysis reaction of a series of trans-[Co(MeNH2)(NH3)4X](3-n)+ ions (X = Cl-, Br-, (ONO2)- (OSO3)2-) have been determined in order to establish analogies with the dissociative trends found in previous work with the spontaneous hydrolysis of neutral ligands from the same cores. While for the base catalysed path a significant decrease in the activation volume is found on going from the {Co(NH3)5} to the trans- {Co(MeNH2)(NH3)4} inert skeleton (i.e. 9.8, 12.5, 4.0 and 9.1 cm3 mol-1 for the chloro, bromo, nitrato and sulfato derivatives), no significant changes are observed for the same complexes in the spontaneous reaction. The trends are rationalized in terms of the important changes occurring in electrostriction factors for the DCB and Id intimate mechanisms operating and the important increase in the degree of dissociativeness due to the presence of a trans-methylamino ligand. For the acid catalysed path the differences are much more difficult to assess, specially taking into account the limited information available as well as the inherent errors involved in the rate constant determination.","PeriodicalId":8996,"journal":{"name":"BioInorganic Reaction Mechanisms","volume":"23 1","pages":"25 - 30"},"PeriodicalIF":0.0,"publicationDate":"2001-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76980305","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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