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Styx Numbers and Rules of Boron Hydrides
(Institute of Chemistry Ceylon, 2023-06) Perera K. Sarath D
Boron hydrides are a class of electron deficient compounds that have unusual bonding behavior and form cages and clusters. The electron deficient BH3 is the simplest boron hydride which exists as a dimer B2 H6 (diborane). The structure of B2 H6 contains bridging B-H-B (or BHB) bonds; quite different to those of carbon hydrides.
Agostic interaction and metallacycles
(Institute of Chemistry Ceylon, 2023-06) Perera K. Sarath D
An interaction that occurs between an unsaturated metal center and a C-H bond of a group attached to that metal center is called an agostic interaction. These interactions are denoted by a half-headed arrow ( ) as given in following examples.
Diels-Alder Reaction
(Institute of Chemistry Ceylon, 2023-06) Perera K. Sarath D
Diels-Alder (D-A) reaction is a (4π+2π) cycloaddition reaction. It is used to generate six-membered rings by combining two π-systems. The key components of this reaction are a conjugated diene (an alkene with two π-bonds) and a dienophile (simple alkene or alkyne). During this concerted reaction, two new sigma bonds are formed and change of two π-bonds into sigma bonds takes place.
Chirality of Molecules
(Institute of Chemistry Ceylon, 2019-09) Gunaratna,Medha.J
Chirality is the existence of different configurations (three dimensional arrangements) of a substance with an identical chemical formula. The word Chirality is derived from the Greek word chéri meaning hand.
The Transistor
(Institute of Chemistry Ceylon, 2019-09) Jayaweera,Hiran. H. E
Transistor the building block of the modern processor was invented by Physicists John Bardeen, Walter Brattain, and William Shockley in 1947 at Bell Laboratories, USA. Considering the importance of the invention, the inventors were awarded the Nobel Prize in Physics in 1956 .
IUPAC Nomenclature of Coordination Compounds
(Institute of Chemistry Ceylon, 2019-01) Karunarathne,Mahesh.C
Systematic naming of chemical compounds is of utmost importance due to the fact that nonsystematic trivial names, common names, industrial trade names, and other names create chaos within the scientific community.
Dihydrogen Complexes
(Institute of Chemistry Ceylon, 2024-05) Perera K. Sarath D
Neutral ligands such as H2 O, NMe3 and PPh3 donate a pair of electrons on the heteroatom to a metal center when coordinate bond is formed. Transition metal hydrides contain at least one M-H bond where a pair of electrons is shared between hydrogen and the metal center. In this article, syntheses and properties of complexes with molecular hydrogen (H2 ) are presented.
Theory behind Radiocarbon Dating
(Institute of Chemistry Ceylon, 2019-01) Lamabadusuriya,M.R
Radiocarbon dating is a method of finding the age of a fossile (a dead plant or an animal) or an ancient artifact containing carbon. This dating method is based on the amount of radioactive 14C isotope remaining in the sample.
Protecting Groups in Organic Synthesis
(Institute of Chemistry Ceylon, 2019-01) Weerasinghe,Laksiri
Creating a complex target molecule with a sequence of reactions, including intermediary re-functionalization with a correctly placed skeleton, is often a challenging task. One of the key issues in such endeavor is chemoselectivity. Protecting groups play an important role in multistep organic synthesis to improve the chemoselectivity in subsequent steps.
Bonding in Organometallic Complexes
(Institute of Chemistry, 2024-05) Perera K. Sarath D
Neutral ligands (:L) and monoanionic ligands (X–) donate a pair of electrons or a lone-pair to a vacant orbital in a transition metal centre (M) to form a covalent σ-bond between them. Ligands such as :C≡O, :C≡NR (isonitrile or isocyanide) and :PR3 (tertiary phosphine or phosphite) can donate a pair of electrons to a metal centre to form a σ-bond. These ligands are considered as σ-donors.
Nucleophilic Attack on Coordinated Ligands
(Institute of Chemistry Ceylon, 2024-05) Perera K. Sarath D
Reactions of nucleophiles with transition metal complexes are useful in the preparation of new metal complexes. Unsaturated ligands such as C≡O, isonitriles, olefins, dienes, and arenes are not normally reactive towards nucleophiles. When these ligands or molecules are coordinated to an electron-deficient metal they become activated towards nucleophilic attack. The factors which facilitate nucleophilic attack on a coordinated ligands are (i) formal positive charge on the metal, (ii) coordination of π acceptor ligands, (iii) the metal should be coordinatively saturated. and (iv) high reactivity of the nucleophile
Supercritical Fluid Chromatography
(Institute of Chemistry Ceylon, 2023-09) Ariyasena J. A. Thiloka C
In supercritical fluid chromatography, a supercritical fluid is used as the mobile phase and the stationary phase is usually a thin liquid film which is bonded to the surface of support materials or the capillary column wall. Super critical fluid chromatography inherits the best features of the gas and liquid chromatography and results in efficient separations.
Elements in Biology
(Institute of Chemistry Ceylon, 2023-09) Perera K. Sarath D
Research findings suggest that eleven elements are predominantly present in all biological systems. However, hydrogen, carbon, oxygen and nitrogen correspond to 99% of the total. Hydrogen constitutes 62.8% of the atoms in a human body. The percentage of oxygen, carbon and nitrogen are 25.4, 9.4 and 1.4%, respectively. Other essential elements make up the remaining 1% {sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), phosphorus (P), sulphur (S) and chlorine (Cl)}. Very large percentages of hydrogen and oxygen arise from the high-water content present in living systems. Regarding our health and well-being, it is important to know about the elements found in biological systems, their functions and the level of toxicity.
Opium Alkaloids
(Institute of Chemistry Ceylon, 2020-01) Weerasiri,Kushan
Alkaloids constitute a class of nitrogen containing organic compounds that possess significant pharmacological properties.
Valence Bond Theory
(Institute of Chemistry Ceylon, 2020-01) Perera,K. Sarath D
Metal centres of d-block form coordination compounds with ligands which can donate a pair of electrons.
Isomerism in Coordination Compounds
(Institute of Chemistry Ceylon, 2020) Perera,K. Sarath D
Isomers (compounds with the same chemical formula) can be broadly classified into (i) stereoisomers (e.g. geometrical and optical) with the same connectivity but having different spatial arrangements and (ii) structural isomers with different connections between atoms.
Introduction to Coordination Chemistry
(Institute of Chemistry Ceylon, 2022-09) Perera,K. Sarath D
Coordination chemistry of transition metals is very important as it helps students to understand various industrial, chemical and biological processes.
Introduction to Polymer Chemistry
(Institute of Chemistry Ceylon, 2022-09) Perera,K. Sarath D
Polymers play an important role in our day-to-day life. In Greek, poly means “many” and mer means “parts”. Polysaccharides, proteins and nucleic acids are the main bio-polymers/macromolecules.
Metathesis and Polymerization of Olefins
(Institute of Chemistry Ceylon, 2022-09) Perera,K. Sarath D
Metathesis of simple salts is a double replacement reaction as shown below.
Beauty of Physical Chemistry – Part 2 New definitions of SI Units and Physical Chemistry
(Institute of Chemistry Ceylon, 2022-06) Ratnaweera,Chinthaka Nadun
In the previous article we learnt how fixed values of hyperfine transition frequency of Cs, speed of light, Planck constant, and Avogadro constant are used to define SI units of time, length, mass and amount of substances (mole) respectively under the new definitions. In this article we will discuss the remaining three new definitions of SI units.

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