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Coordination Compound - One Shot Lecture | CHAMPIONS - JEE/NEET CRASH COURSE 2022

PW English Medium・141 minutes read

The importance and properties of coordination compounds in inorganic chemistry are discussed, along with theories, nomenclature, and classification of salts. The focus is on coordination numbers, central metal behavior, ligands, hybridization, isomerism, and naming conventions in coordination chemistry.

Insights

Coordination compounds are crucial in inorganic chemistry, focusing on their identification, properties, behavior in solutions, and nomenclature.
Different types of salts, including simple, double, and complex salts, have distinct dissociation behaviors in aqueous solutions, affecting ion identification.
Ligands in coordination compounds act as electron donors through coordinate bonds, classified based on charge as negatively charged, neutral, or positively charged.
Naming coordination compounds involves specific rules, starting with ligands' names followed by the metal name and oxidation state, ensuring clarity in nomenclature.
The Valence Bond Theory and Crystal Field Theory provide insights into the interactions between metal ions and ligands, explaining electron pairing, magnetic properties, and stability in coordination complexes.

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Recent questions

What are coordination compounds?
Coordination compounds involve central metals and ligands forming coordinate bonds, essential in inorganic chemistry.
How do ligands behave in coordination compounds?
Ligands donate electrons through coordinate bonds, acting as electron-rich species in coordination compounds.
What determines the coordination number in a complex?
The coordination number is determined by the number of monodentate ligands bonded to the central metal by sigma bonds in a complex.
What is the significance of hybridization in coordination compounds?
Hybridization involves intermixing orbitals to form equal energy orbitals, determining the geometry and properties of coordination complexes.
How is isomerism exhibited in coordination compounds?
Isomerism in coordination compounds includes coordination, ionization, solvate, geometrical, and optical isomerism, affecting the arrangement and properties of complexes.

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Summary

00:00

Importance of Coordination Compounds in Chemistry

Coordination compounds are the focus of the session, with an emphasis on their importance and interest in inorganic chemistry.
The discussion will cover the identification of coordination compounds, their properties, behavior in aqueous solutions, and nomenclature.
Various theories related to coordination compounds will be explored, along with different types of isomerisms.
Different types of salts are introduced: simple salt (e.g., NaCl), double salt (e.g., KCl·MgCl2·6H2O), and complex salt (e.g., K4Fe(CN)6).
Double salts completely dissociate into individual ions in aqueous solutions, while complex salts only partially dissociate, requiring specific tests to identify the ions present.
Molecular or addition compounds are formed when simple salts combine in fixed proportions, leading to the classification of double salts and complex salts.
Representation of coordination compounds includes a central metal (M), ligands (L) donating electrons, the number of ligands (N), and the charge (X) of the compound.
The coordination entity consists of the central metal and ligands forming coordinate bonds.
The central atom or ion in a coordination compound acts as a Lewis acid, accepting electron pairs from ligands acting as Lewis bases.
D-block metals are commonly used as central metals due to their vacant d orbitals, essential for accepting electrons in coordination compounds.

18:51

Ligands and Atom Interactions in Coordination Chemistry

Small size atoms tend to accept electrons more readily due to high nuclear charge and availability of vacancy orbitals.
Ligands are Lewis bases that donate electrons through coordinate bonds, behaving as electron-rich species.
Ligands can be negatively charged, neutral with lone pairs of electrons, or even positively charged.
Negatively charged ligands include O2-, NH2-, F-, O-, Cl-, and others.
Neutral ligands like NH3, CO, and PH3 are common examples.
Positively charged ligands such as NO+ and X- can also act as ligands.
Ligands are classified based on charge as negatively charged, neutral, or positively charged.
Dentisticity refers to the number of lone pairs of electrons donated by a ligand to a central metal atom.
Chelate rings form when a ligand has multiple donating sites, enhancing the stability of the complex.
Ambidentate ligands have two donating sites but donate from only one site at a time, unlike chelate complexes.

35:50

Coordination Chemistry: Bonds, Numbers, and Nomenclature

Coordination number is 6, with Fe and ethylene diamine forming 6 coordinate bonds.
Coordination number formula: Coordination number = Density x Number of ligands.
Calculation of oxidation number of central metal, using K4Fe(CN)6 as an example.
Central metal's oxidation state is calculated as +2.
Determining the charge the central atom should carry if all ligands and shared electron pairs are removed.
Two types of complexes: homoleptic (same ligands) and heteroleptic (different ligands).
Nomenclature rules for naming ligands: Anionic ligands use "-o" suffix, halogens use "halido," and others have specific suffixes.
Naming of ligands in alphabetical order, followed by metal name and oxidation state.
Example of naming a compound with di- and tri- ligands, considering alphabetical order.
Naming compounds with cationic and anionic parts, distinguishing between ligands and anions in nomenclature.

53:05

Naming Coordination Compounds: Rules and Guidelines

The rules for naming coordination compounds involve first writing the cationic part name followed by the anionic part.
Generally, there is no need to write the number of cations or anions during ionization.
When naming the coordination sphere, start with the ligands' names, then the metal, and its oxidation state in alphabetical order.
If a ligand's name includes a numerical prefix, like "di" or "tri," it should be used accordingly.
Organic ligands' names dictate using "bis," "tris," etc., instead of numerical prefixes.
The central metal's name varies based on whether the coordination sphere is cationic or anionic.
The oxidation number of the central atom is indicated in Roman numerals.
Ligands are listed alphabetically regardless of charge, including polydentate ligands.
Abbreviated ligands are placed in alphabetical order based on the first letter of the abbreviation.
The formula of the coordination entity, with or without a charge, is enclosed in square brackets without spaces between ligands and the metal.

01:10:33

Naming and Properties of Coordination Complexes

The cationic part is named first, with ligands given in the cationic part, indicating a cardinic secant.
The complex is named as "carbonyl co tetra nickel," with nickel having a charge of zero.
To calculate the total charge on the complex, the charge on nickel (0) plus 4 times the charge for carbonyl (0) results in a total charge of zero.
In the third part, potassium tetra cyano nickelate is named as "K4[Fe(CN)4]," with a charge of -4.
The IUPAC nomenclature for the complex "sodium amine bromo or chloro nitrite" is determined by alphabetical order and the oxidation state of the metal.
The correct name for the complex ion is "sodium amine bromo or bromido chloro or chloride nitrite nitro nitro n or nitrite n platinate two."
Werner's theory distinguishes between primary valency (ionizable) and secondary valency (non-ionizable) in coordination compounds.
The coordination number of a central metal in a complex is determined by the number of monodentate ligands bonded by sigma bonds.
Primary valency is non-directional, while secondary valency is directional in nature.
Reacting different ions like CoCl3 and NH3 with AgNO3 in excess results in the formation of complex compounds, with specific ligand arrangements leading to the precipitation of certain ions.

01:28:36

"Formation and Analysis of Coordination Complexes"

The text discusses the formation of coordination complexes with Co and NH3 ligands.
It explains the process of forming coordination numbers and the role of ligands in creating coordination spheres.
The text emphasizes the importance of understanding secondary and primary valency in coordination complexes.
A question is posed regarding the number of ions produced by a complex of ammonia and chlorine, leading to a discussion on dissociation and ion calculation.
Different scenarios are presented to determine the complex that produces four ions, with option A being the correct answer.
A question is given as homework regarding the coordination number of a cation.
The text transitions to discussing the Valence Bond Theory, explaining the interactions between metal ions and ligands.
It introduces the concept of weak and strong field ligands, detailing their impact on electron pairing and magnetic properties of complexes.
The text provides steps to analyze a complex, starting with calculating the oxidation state of the central metal and writing its electronic configuration.
An example is given to illustrate the process of determining the electronic configuration and electron pairing in a cobalt complex with strong field ligands.

01:46:10

Hybridization in Coordination Chemistry: d2sp3 and sp3d2

The process of hybridization involves the intermixing of vacant orbitals to form equal energy orbitals, known as hybridized orbitals.
Hybridization occurs when different energy orbitals intermix to create equal energy levels, resulting in degenerate orbitals.
The specific hybridization process discussed is d2sp3, where two d orbitals, one s orbital, and three p orbitals intermix.
The resulting hybridization, d2sp3, leads to an inner orbital complex with an octahedral geometry.
The complex formed is diamagnetic due to all electrons being paired, resulting in a dipole moment of zero.
The calculation of dipole moment is based on the formula root n * (n + 2), with n representing the number of unpaired electrons.
The text further discusses the intermixing of orbitals in a complex involving cobalt, determining the hybridization as sp3d2.
The resulting complex is an outer orbital complex with an octahedral geometry, leading to paramagnetic properties due to the presence of unpaired electrons.
The coordination number and geometry of a complex determine whether it is an inner or outer orbital complex.
The text concludes with practical exercises for students to apply the concepts of hybridization and complex formation in solving questions related to coordination chemistry.

02:03:22

Transition Metal Complexes and Crystal Field Theory

The elements discussed are nickel, gangnam, titanium, vanadium, chromium, manganese, iron, cobalt, and nickel, with an atomic number of 28.
The oxidation state of the elements is calculated to be +2, resulting in 3d8 configuration.
Due to the strong ligand CN, pairing of electrons occurs, leading to a hybrid orbital configuration of dsp2.
The complex formed is an inner orbital complex, resulting in a diamagnetic complex with no unpaired electrons.
The most stable complex is determined based on chelation effects, with option C being the correct answer.
Diamagnetic complexes are identified by paired electrons, serving as homework for further practice.
Limitations of the valence bond theory are discussed, including assumptions, lack of qualitative interpretation of magnetic data, color explanation, and quantitative interpretation of stability.
Crystal field theory (CFT) is introduced, emphasizing electrostatic interactions between metal and ligands.
Energy splitting of d orbitals in octahedral complexes due to ligand approach along the x-axis is explained.
Electron filling in d orbitals is detailed, with the calculation of crystal field stabilization energy (CFSE) for determining stability.

02:20:45

"Field Ligands Determine Orbital Pairing Order"

Pairing occurs with strong field ligands, not with weak field ligands.
Electronic configurations determine pairing in orbitals.
Strong field ligands lead to specific electron filling order.
Calculation of CFSC involves specific formulas based on electron numbers in different orbitals.
Factors affecting CFSC include the nature of the ligand, metal cation type, and chelation effect.
Tetrahedral complexes have different orbital energy due to ligand approach.
Pairing always occurs in tetrahedral complexes regardless of field strength.
D orbital splitting in tetrahedral complexes is smaller than in octahedral complexes.
Color in coordination compounds arises from dd transitions due to unpaired electrons.
Limitations of crystal field theory include the inability to explain bond strength and certain properties.

02:37:15

Isomerism in Coordination Complexes: A Summary

Coordination isomerism occurs when ligands interchange between cationic and ionic entities in different metal ions in a complex.
Ionization isomerism arises when the anion outside the complex changes upon ionization in a solution.
Solvate isomerism, similar to ionization isomerism, occurs when water is involved as a solvent in the interchange of ligands.
Geometrical isomerism is present in heterolyptic complexes like square planar and octahedral geometries, but not in tetrahedral complexes due to angles.
Tetrahedral complexes lack geometrical isomerism due to the uniform angles between ligands.
Square planar and octahedral geometries can exhibit geometrical isomerism based on ligand arrangements.
Optical isomerism involves mirror images that are non-superimposable, known as enantiomers.
Optically inactive compounds have symmetry elements like a plane or center of symmetry, while optically active compounds lack these elements.
In square planar complexes, geometrical isomerism is possible when ligands are different, allowing for cis and trans forms.
Octahedral complexes show geometrical isomerism in certain arrangements of ligands, such as when all ligands are not in the same plane, leading to facial and meridonial isomerism.

02:54:50

"Geometrical Isomerism in Complexes: Understanding Forms"

Geometrical isomerism is shown in a complex with a facial and meridional form, where all three ligands are in the same plane except for one.
A complex with ligands A and B, where A is a bidentate ligand and B is a monodentate ligand, can exhibit geometrical isomerism with trans and cis forms.
Octahedral and square planar complexes can show geometrical isomerism, with examples provided for both trans and cis forms.
The complex in question exhibits geometrical isomerism due to its octahedral coordination number of six, with trans and cis forms possible.
Analyzing statements about isomerism in a complex reveals that only one statement is incorrect, identifying the wrong statement as the task.
Determining the stoichiometries of AgCl formed when AgNO3 is in excess and reacts with different complexes yields varying amounts of AgCl, with the correct order being three, two, and one moles.
Encouragement is given to engage with the material, assess understanding through questions, and revisit concepts for clarity and success in the chapter.

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