Reactivity In Substitution Reactions Research Articles

Apical Cyanide Ligand Substitution in Heterometallic Clusters [Re3Mo3Q8(CN)6]n– (Q = S, Se)

A number of transition metal cluster compounds can be obtained only in the melt of inorganic cyanides and, therefore, contain terminal cyanide ligands. Substitution of these ligands, which is often necessary to change the physicochemical properties of the clusters, is an urgent problem because of their low reactivity in substitution reactions. In this work, a synthetic approach has been developed for the substitution of CN‐ligands in the heterometallic cluster anions [Re3Mo3Q8(CN)6]n– (Q = S, n = 6; Q = Se, n = 5) by the 4‐tert‐butylpyridine (TBP) molecules. Two new compounds, namely [Re3Mo3S8(TBP)6] (1) and [Re3Mo3Se8(TBP)6] (2), were obtained with high yields and crystallized under solvothermal conditions. It has been shown that compounds 1 and 2 are based on the paramagnetic cluster cores {Re3Mo3Q8}0 containing 23 cluster valence electrons (CVE). The geometry of the new compounds has been investigated using X‐ray structural analysis. The electronic structure has been analyzed using the DFT calculations showing large distortion of M6 cluster core.

Explicitversusimplicit similarity – exploring relational conceptual understanding in organic chemistry

Learning to interpret organic structures not as an arrangement of lines and letters but, rather, as a representation of chemical entities is a challenge in organic chemistry. To successfully deal with the variety of molecules or mechanistic representations, a learner needs to understand how a representation depicts domain-specific information. Various studies that focused on representational competence have already investigated how learners relate a representation to its corresponding concept. However, aside from a basic connectional representational understanding, the ability to infer a comparable reactivity from multiple different functional groups in large molecules is important for undergraduate students in organic chemistry. In this quantitative study, we aimed at exploring how to assess undergraduate students’ ability to distinguish between conceptually relevant similarities and distracting surface similarities among representations. The instrument consisted of multiple-choice items in four concept categories that are generally used to estimate the reactivity in substitution reactions. This exploratory study shows that the item design for assessing students’ conceptual understanding influences students’ answering patterns. Insights and pitfalls gained from this investigation and future directions for research and teaching are provided.

Photochemical Reactions of Methanesulfonates. A New Deprotection Reaction

Abstract Although esters of methanesulfonic acid and E-toluene-sulfonic acid have similar reactivity in substitution reac-tions, their photochemical behavior is quite different, E-Toluenesulfonates experience photochemical desulfonation in the presence of amines, a reaction which regenerates the parent alcohols (eq 1) in good to excellent yields and thus allows the E-tolylsulfonyl group to become an effective photoremovable protecting group. 1–4 In contrast, photolysis of methanesulfonates is not regarded as a viable method for group deprotection since deprotection is accompanied by reduction (eq 2).5

Nucleophilic reactivity in substitution reactions at planar tetra-coordinate monocationic platinum(II) complexes. Kinetics of displacement of chloride from chloro[2,6-bis(methylthiomethyl)pyridine]platinum(II) cation

The kinetics of replacement of chloride in the [Pt(SNS)Cl] + cation [SNS = 2,6-bis(methylthiomethyl)pyridine] by a wide variety of nucleophiles [H 2O, OH −, Me 2SO, NO 2 −, NH 3, pyridine (py), C 5H 10NH (pip), N 3 −, Br −, (C 2H 5) 2S, (CH 2) 4S, I −, N,N,N′,N′-tetramethylthiourea (tmtu), SCN −, Ph 3As, SO 3 2−, thiourea (tu), SeCN − and CN −] have been studied in water at 25°C, μ = 0.50 mol dm −3 (LiClO 4). The log k 2° values ( k 2° is the second-order rate constant at μ = 0) do not follow the usual dependence upon the n Pt° scale, while there is a good linear relationship between log k 2° for the present mono-cationic substrate and log k 2° for the substitution reactions of a smaller number of nucleophiles with other mono-cationic platinum(II) substrates previously studied. A new more extensive nucleophilicity scale, based on [Pt(SNS)Cl] + as the standard substrate, that is appropriate to mono-cationic platinum(II) substrates, is proposed.

Synthesis and Solvolysis of [(ω-(Dimethylphenoxysilyl)alkyl]-diphenylphosphines, Phosphine Oxides and Phosphine Sulfides

Abstract Kinetics of base catalysed solvolytic cleavage of phenoxy group from compounds of general structure X (CH2)nSiMe2OPh, where n=1,2,3 and X=Me,Ph2P, Ph2P (p), Ph2P(s) has been investigated. The main purpose was to study the effect of phosphorus groups on the reactivity in substitution reaction at silicon. We wanted to answer the question whether there is any direct interaction of the phosphorus groups with silicon moiety, modifying this reactivity. Complementary NMR studies have also been performed for this purpose.

Nucleophilic reactivity in substitution reactions of square-planar metal complexes. III. Kinetic evidence for the accumulation of a reaction intermediate in nucleophilic substitutions in rhodium(I) complexes

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNucleophilic reactivity in substitution reactions of square-planar metal complexes. III. Kinetic evidence for the accumulation of a reaction intermediate in nucleophilic substitutions in rhodium(I) complexesL. Cattalini, R. Ugo, and A. OrioCite this: J. Am. Chem. Soc. 1968, 90, 18, 4800–4803Publication Date (Print):August 1, 1968Publication History Published online1 May 2002Published inissue 1 August 1968https://doi.org/10.1021/ja01020a009RIGHTS & PERMISSIONSArticle Views124Altmetric-Citations28LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (480 KB) Get e-Alerts Get e-Alerts

Nucleophilic reactivity in substitution reactions of square-planar metal complexes. II. A comparison of the kinetic behavior of platinum(II) and gold(III) complexes

Nucleophilic reactivity in substitution reactions of square-planar metal complexes. II. A comparison of the kinetic behavior of platinum(II) and gold(III) complexes

Nucleophilic Reactivity in Substitution Reactions of Square-Planar Metal Complexes. I. Effect of the Total Charge of the Substrate in Platinum(II) Complexes

Nucleophilic Reactivity in Substitution Reactions of Square-Planar Metal Complexes. I. Effect of the Total Charge of the Substrate in Platinum(II) Complexes