1 General Introduction
2 Ways of describing about organometallics and its constituents
3 Literature about organometallics
4 Preparation of organometallics
5 Usage of organometallics
Organometallic compounds are extensively explored and used from many years. This book will become a good source of understanding about organometallics.
I hope that this book will be useful to entire scientific community. First two chapters of this book give comprehensive coverage about fundamentals of organometallic compounds. The third chapter describes about the literature available to study this topic. Fourth chapter describes about the general methods for the preparation of organometallic compounds. Fifth chapter of the book is about the research work carried out in the field of organometallics. I hope that my book will serve as a reference source for the persons who are interested in the organometallic chemistry.
This book is also a guide to organometallic literature for various levels of students of organometallic chemistry.
I would like to receive your suggestions about this book.
(Mr.) Kiran V. Mehta
(M.Sc., Ph. D. and Prof. in Chemistry)
Palanpur-385001 (Gujarat) (India)
The compounds in which a metal or metalloid is bonded directly to carbon are called organometallics. Here, carbon is present in an organic group. In these compounds, there is a minimum one bond between a metal and carbon atom of an organic compound. In this way, one can say that a metal-carbon bond(R-M bond) is a characteristic of such compounds. In these kinds of compounds, interaction of a metal atom(s) and carbon atom(s) of organic group is important. Compounds of the d-block elements (transition elements), actinide group elements, lanthanide group elements, etc. are these kinds of compounds. Metal is electropositive and carbon is electronegative.
Organometallic have played a foremost role in the progress of Science. They are useful as catalysts and intermediates for the preparation of a large number of compounds.
Organometallic compounds of Lithium and Magnesium are known as Grignard reagents which are also organometallics.
CH3 CH2 CH2 CH2Li
Triethylborane(Et3B) is an organometallic compound of Boron. Titanocene dichloride, [Ti(η5-C5H5)2Cl2] is an organometallic compound of Titanium.
In these compounds, there is a σ bond between C atom and the metal. Grignard reagents and organolithiums are excessively alkaline for coupling reactions to prepare alkanes.
Organometallics of Sodium(Na) and Potassium(K) are generally ionics.
Ferrocenes are organometallics in which an iron atom is sandwiched between two hydrocarbon rings.
These compounds are useful for increasing rate of chemical reactions. Compounds like trimethylantimony, trimethylindium, trimethylgallium, trimethylaluminum, etc. are applied in the preparation of semiconductors. For the purification of metals or for the recovery of metals, these compounds are also used. Organometallics can be useful in organic synthesis.
History of Organometallics
In 1760, Louis Claude Cadet de Gassicourt found inks based on cobalt salts.
William Christopher Zeise produced Zeise's salt in 1827. It is the first platinum - olefin complex. The formula of Zeise's salt is as below:
Zeise's salt is one of the first examples of a transition metal alkene complex. The anion of this complex has η 2-ethylene ligand.
In 1848, Edward Frankland found diethylzinc(DEZ) (C2H5)2Zn. He prepared diethylzinc, by heating ethyl iodide in the presence of zinc metal. This is also called Frankland’s reagent.
Abbildung in dieser Leseprobe nicht enthalten
Organochlorosilanes were prepared by Charles Friedel and James Crafts in 1863.
Well known organo nickel complex Ni(CO)4 (tetracarbonylnickel) was found by Ludwig Mond in 1890. It is a toxic substance. In 1899, Grignard complexes were found.
In 1909, arsenic based complex Salvarsan was found by Paul Ehrlich.
In 1951, Walter Hieber was awarded the Alfred Stock prize for his work with metal carbonyl chemistry. Ferrocene has formula: Fe(η5-C5H5)2. In 1951, Ferrocene was found.
In 1973, Geoffrey Wilkinson and Ernst Otto Fischer were awarded Nobel Prize for their work on sandwich compounds. In 2005, Yves Chauvin, Robert Grubbs and Richard Schrock were awarded Nobel Prize for their work on metal catalyzed alkene metathesis.
 Shi L., Cai J. Y. Z., Application of organometallic compounds of groups 15 and 16 in organic synthesis, Highly stereoselective synthesis of Z, E conjugated diene-type sex pheromones , Journal of Organic Chemistry, 1987, 52(16), 3558-3560.
F.A. Cotton proposed the term hapticity which was derived from the prefix hapto (from the Greek haptein, to fasten denoting contact or combination) placed before the name of the olefin.
It is denoted by the Greek letter η (eta) is used to denote the number of contiguous atoms of a ligand which binds to a metal.
Ferrocene and Uranocene can be written as below with this kind of notations:
- Vasaka’s complex
η-notation is used when multiple atoms are coordinated. If a ligand coordinates by multiple atoms which are not contiguous, denticity is considered in the place of hapticity.
The number of donor groups in a single ligand bound to a metal center atom in a coordination complex is known as denticity.
The word denticity is derived from dentis (Latin word for tooth). The ligand is considered as biting the metal at one or more linkage points. The denticity of a ligand is denoted by the Greek letter K which is called kappa.
If one atom in the ligand is bound to the central metal, denticity is called one. These kinds of ligands are called monodentate ligands or unidentate ligands.
Ligand having more than one bonded atom is known as polydentate ligand. It is also known as multidentate ligand.
EDTA (Ethylenediaminetetraacetic acid) ligand coordinates by six contiguous ligands, so, it is described as K6 EDTA.
On the basis of denticity, ligands can be classified as below:
(1) Monodentate ligands
These ligands bind to the metal ion with one atom.
(2) Bidentate or didentate ligands
These ligands bind to the metal ion with two atoms.
Ethylene diamine(en) is a bidentate ligand.
(3) Tridentate ligands
These ligands bind to the metal ion with three atoms.
Terpyridine is a tridentate ligand.
These ligands generally bind through two connectivities:
It means meridian. In this type of connectivity, the donor atoms are stretched out around one half of the octahedron.
It means facial.
In this type of connectivity, the donor atoms are arranged on a triangle around one face of the octahedron.
1,4,7-triazacyclononane is acyclic ligand.
It is also called as TACN.
It has formula C6H12(NH)3.
Abbildung in dieser Leseprobe nicht enthalten
Fig.: Structure of TACN
It binds with fac manner. It is obtained from aziridine(C2H4NH).
(4) Tetradentate ligands
These ligands bind with four donor atoms to central metal atom.
Trien (Triethylenetetramine) is a tetra dentate ligand.
(5) Pentadentate ligands
These ligands bind with metal by five donor atoms.
Ethylene diaminetriacetic acid is such a ligand.
(6) Hexadentate ligands
These ligands bind with six donor atoms to central metal atom.
EDTA is this kind of ligand.
(7) Ligands having denticity higher than six
It is Diethylene triamine pentaacetate.
It is 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate.
These ligands are useful for lanthanide ions.
 F. A. Cotton, Proposed nomenclature for olefin-metal and other organometallic complexes, Journal of American Chemical Society, 1968, 90(22): 6230-6232.
Scientific Essay, 14 Pages
Textbook, 81 Pages
Research Paper (postgraduate), 7 Pages
Master's Thesis, 97 Pages
Term Paper, 18 Pages
Essay, 55 Pages
Term Paper (Advanced seminar), 23 Pages
Diploma Thesis, 115 Pages
Scientific Study, 4 Pages
Submitted Assignment, 19 Pages
Scientific Study, 17 Pages
GRIN Publishing, located in Munich, Germany, has specialized since its foundation in 1998 in the publication of academic ebooks and books. The publishing website GRIN.com offer students, graduates and university professors the ideal platform for the presentation of scientific papers, such as research projects, theses, dissertations, and academic essays to a wide audience.
Free Publication of your term paper, essay, interpretation, bachelor's thesis, master's thesis, dissertation or textbook - upload now!