Based on hsab parameters, calculated using quantum mechanical methods, hd is a relatively hard low. Based on the strength of the metalligand bonds, the energy of the system is altered. Although there have been numerous attempts to make the theory quantitative by assigning numbers representing hardness and softness to acids and bases, these have not been particularly. At the end of the class discussion, they turned in either a printed or an electronic copy of the annotated paper. Copper and goldcatalyzed 1,3phosphatyloxy and 1,3halogen migration relay to 1,3dienes. Hsab theoryrelative nucleophilicity and electrophilicity 5. We believe the new theory we established here, the socalled 2b theory that combines the hsab and bifunctional mechanisms, is a fundamental principle of electrochemistry underscoring the interface. Introduction the hsab concept is an acronym for hard and soft acids and bases. An interaction of co 2 and amino groups is explained by the hard soft acid base hsab theory 21, 22. This may lead to a change in magnetic properties as well. The hsab principle and extended solubility theory alan beerbower energy center, university of california, san diego, lajolla, calif. Abstract based on the density functional theory dft, the stability of molecular complexes has been predicted according to hardsoft acid base hsab theory. Lack of space prevents further discussion of many new applications. The impact of the new idea was immediate, however, over the years the hsab principle has rather fallen by the wayside.
Hard soft acids bases hsab principle and organic chemistry. Introduction to inorganic chemistryacidbase chemistry. Hard and soft acids and bases hsab theory hard and soft acids and bases hsab theory is a qualitative concept introduced by ralph pearson to explain the stability of metal complexes and the mechanisms of their reactions. Week of september 26th mredi tour, september 28th strain and stability ch 2. If youre seeing this message, it means were having trouble loading external resources on our website. However it is possible to quantify this concept based on klopmans fmo analysis using interactions between homo and lumo. However, for those who wish to learn more about density functional theory. A polyhedronbased heterometallic mof constructed by hsab theory and sbb strategy.
How to decide which part reacts in an ambident nucleophile. Pearson 1963 hard acids prefer to associate with hard bases, and soft acids prefer to associate with soft bases. Applications of bases in transition metal catalyzed. Cft qualitatively describes the strength of the metalligand bonds. On opening the book cover you will find a periodic table and a list of elements and atomic masses. An introduction to the quantum theory for chemists. Crystal field theory cft describes the breaking of orbital degeneracy in transition metal complexes due to the presence of ligands. It forms stable complexes with border line metals like co,ni,zn,cu of type concs 4 2by cordinating through n and softer acid cations rh,ir,pd,pt,au tends to form complexes of type pdscn 4 2by coordinating through s. First we point out the important link between the absolute hardness of acidandbase and the average energy gap. Synthesis, structure, and adsorption properties dongmei wanga, yuxiao zhanga, jiali gaoa, genwu geb, and chunxia lia a key laboratory of the ministry of education for advanced catalysis materials. Also known as the pearson acid base concept, hsab is widely used in chemistry for explaining stability of compounds, reaction mechanisms and pathways.
Applications of the hardsoft acidbase hsab principle. Hsab is an extremely useful qualitative theory that enables predictions of what adducts will form in a complex mixture of potential lewis acids and bases. Using e and c numbers for cdnsich 3 3 2 and zntpp calculate the enthalpies for these two acids interacting with ch 2 4 o and ch 2 4 s and show that the hsab. Pearsons hsab theory is in direct contradiction with fajans rules. Hardsoft acidbase hsab principle and difference in. If these condensed acids contain only one type of acid anhydride, they abd called isopoly acids, and their salts are called isopoly salts. The major aim is to show how various bases work, and from there, how we might optimize the reaction conditions by using different type of bases, according to the specific demands in transition metal catalyzed reactions. Introduction to acidbase chemistry a chem1 reference text stephen k.
Chemical hardness is one of the highly useful concepts which enable chemists to understand reactivities without reference to large supercomputers and databases. Ambidentate ligand is a mono dentate ligand which can coordinate to metal through more than one coordinating atoms. Hsab theory classifies reacting species as either relatively hard or soft, based on polarizability. We attempt to extend the hardsoft acidbase hsab principle for the reactions in solutions to interactions in solids. It assigns the terms hard or soft, and acid or base to chemical species. Also known as the pearson acidbase concept, hsab is widely used in chemistry for explaining stability of compounds, reaction mechanisms and pathways. For example, the later predict the nature of beryllium salts to be more covalent. Lower simon fraser university contents 1 acids 2 1.
Ralph pearson introduced the hard soft lewis acid base hsab principle in the early nineteen sixties, and in doing so attempted to unify inorganic and organic reaction chemistry. In this article, the notorious negative occupation problem afflicting the ekt. Syllabus and tentative course outline for ch 451551. View notes lecture 11 lewis hsab theory from chem 2030 at rensselaer polytechnic institute.
Polarizability is an inherent characteristic of electron distribution in atoms or molecules. Iso poly and heteropoly acids and salts pdf download lazheawal interactions between two hard or soft acids or bases are stronger than ones between one hard and one soft acid or base. Hsab principleapplicationspearsons hard soft acid base. The pdf file you selected should load here if your web browser has a pdf reader plugin installed for example, a recent version of adobe acrobat reader if you would like more information about how to print, save, and work with pdfs, highwire press provides a helpful frequently asked questions about pdfs alternatively, you can download the pdf file directly to your computer, from where it. Theory to,download application of hard soft acid base hsab theory to,free download application of hard soft acid base hsab theory to,application of hard soft acid base hsab theory to pdf ebooks, read application of hard soft acid base hsab theory to. Originally developed as an intuitive, qualitative concept, it is today firmly based on and justifed by quantum chemistry. This can be refined further by noting that for some metal ions, their chemistry is dominated by size and charge, while for others it is. In this study, density functional theory dft based reactivity descriptors have been used to understand site and regioselective reactions79. Geochemical ore classification nickel ni, zinc zn, and copper cu ores are exclusively found as sulfides, whilst aluminum al and calcium ca are usually found as oxide and carbonate, respectively. Hard applies to species which are small, have high charge states the charge criterion applies. The journal of organic chemistry 2015, 80 3, 16611671. Also known as the pearson acid base concept, hsab is widely used in chemistry for explaining stability of. The hsab principle more quantitative aspects sciencedirect.
Received april 18, 1983 193 a semiquantitative approach to the prediction of. Week of october 2nd strain and stability ch 2 thermochemistry. Several studies have been reported the applicability of local hardsoft acidbase hsab principle in examining the site selectivity in a molecule9. A coherent picture of the hydrogen oxidation and evolution. The base ch 2 4 o is considered hard while ch 2 4 s is soft. Determination of relative reactivity of hsab complexes. Jensen department of chemistry, university of wisconsin, madison, wis.
Determination of relative reactivity of hsab complexes using dft theory salah aldin jassim humadi department of chemistry, college of science, university of diyala. Pdf hardsoft acidbase hsab principle and difference. Scheme vii the outcome of fc reactions on the basis of hard and soft acid base principle hsab. The c3 and o2ethylations were examined to find out whether the marcus or hsab theory can explain the ambident reactivity of this nucleophile. For some of these questions, you need data from the appendices of inorganic chemistry, fourth edition by c. Hsab concept is an initialism for hard and soft lewis acids and bases. If youre behind a web filter, please make sure that the domains. Co 2 is considered as a hard acid, while primary and secondary amines are hard bases. Hsab welcome bbq sept 02 come celebrate labor day weekend with hsab we are hosting our annual welcome bbq. The hsab concept has been widely used to study the physics and chemistry of the solid state, see, for example, ref. Hsab theory the hsab concept is an initialism for hard and soft lewis acids and bases.
Theory of hard and soft acid and bases hsab sruthi p k 2. The pdf file was posted to the course moodle, and students were asked to annotate their copy either in printed or electronic form to highlight terms or sections of text that they did not understand. We have already pointed out that the affinity that metal ions have for ligands is controlled by size, charge and electronegativity. Accordingly, cysteine is an unfavorable candidate for hd adduction since the corresponding sulfhydryl thiol group is a soft nucleophile. There is a theory named as hard and soft acidbase theoryhsab.
203 126 510 719 1058 537 533 263 34 1474 1223 87 1317 1119 938 1041 175 331 739 720 1306 814 441 935 665 19 813 1450 134 115 418 1321 953 515 190 1414