Homework Help
Homework Help
View Details
Assignment Help
Assignment Help
View Details
Online Tutoring
Online Tutoring
View Details
Home » Chemistry Homework Help » Organic Chemistsry » Magnetic Properties
Magnetic Properties
The transition metal complexes are known to be paramagnetic in character. CFT helps us to understand the magnetic properties in terms of magnetic susceptibility measurements. The magnetic property of a substance depends upon the oxidation state, electronic configuration, co-ordination number of central metal and the nature of ligand field. An unpaired electron because of its spin is equivalent to an electric current flowing in a circular conductor. Hence, it behaves as a magnet. The magnetic moment will thus be expressed as
                                                                             


Here, e = charge of an electron,

m = mass of electron, h = planck’s constant

and c = velocity of light.

The value of obtained from the above expression is 9.274 × 10-21 ergs gauss-1. This is taken as a unit of magnetic moment called Bohr magneton (B.M.)

A substance containing one or more unpaired electrons has a definite value of magnetic moment and is attracted in external magnetic field. Such substances are called paramagnetic substances. On the other hand those substances having paired electrons will have zero magnetic moment and hence do not possess magnetic properties. These are known as diamagnetic substances.

The magnetic moment of a substance depends upon the number of unpaired electrons i.e. greater is the number of unpaired electrons more is the magnetic moment. It has been shown that the magnetic moment of a substance containing ‘n’ unpaired electrons is approximately given by the expression below:

Magnetic moment, Bohr magnetons.

Magnetic moment is also given mathematically as,
                                      
(here S = sum of spins of electrons)
                       
Or (∵ value of gyromagnetic ratio = 2.0)

This relationship is used to calculate the number of unpaired electrons in an ion.

From the knowledge of a number of unpaired electrons and the value of magnetic moment () it is possible to find
   
Valence state of the metal ion is a given complex.
   
Natures of bonding in the complex i.e. spin free or spin-paired type.

The values of n calculated by this expression for different magnetic moments are given in the table below:

Magnetic moment (Bohr magneton) Number of unpaired electrons (n)
0 0
1.73 1
2.83 2
3.87 3
4.90 4
5.92 5

A critical study of the magnetic data of co-ordination compounds of metals of the first transition series reveals some complications. For metal ions with upto three electrons in the d-orbitals, like Ti3+ (d1); V3+ (d2); Cr3+ (d3); two vacant d-orbitals are available for octahedral hybridization with 4s- and 4p- orbitals. The magnetic behaviour of these free ions and their co-ordination entities is similar. When more than three 3d electrons are present, the required pair of 3d-orbitals for octahedral hybridization is not directly available (as a consequence of Hund’s rule). Thus for (Cr2+, Mn3+), d5 (Mn2+, Fe3+), d6 (Fe2+, Co3+) cases, a vacant pair of d orbitals results only by pairing of 3d electrons which leaves two, one and zero unpaired electrons respectively.

The magnetic data agree with maximum spin pairing in many cases, especially with co-ordination compounds containing d6 ions. However, with species containing d4 and d5 ions there are complications.
   
[Mn(CN)6]3- has magnetic moment of two unpaired electrons while [MnCl6]3- has a paramagnetic moment of four unpaired electrons.
   
[Fe(CN)6]3- has magnetic moment of a single unpaired electron while [FeF6]3- has a paramagnetic moment of five unpaired electrons.
   
[CoF6]-3 is paramagnetic with four unpaired electrons while [Co(C2O4)3]3- is diamagnetic.

This apparent anomaly is explained by valence bond theory in terms of formation of inner orbital and outer orbital co-ordination entities. [Mn(CN)6]3- [Fe(CN)6]3- and [Co(C2O4)3]3- are inner orbital complexes are paramagnetic and the latter diamagnetic. On the other hand, [MnCl6]3-, [FeF6]3- and [CoF6]3- are outer orbital complexes involving sp3d2-hybridisation and are paramagnetic corresponding to four, five and four unpaired electrons.

Services:- Magnetic Properties Homework | Magnetic Properties Homework Help | Magnetic Properties Homework Help Services | Live Magnetic Properties Homework Help | Magnetic Properties Homework Tutors | Online Magnetic Properties Homework Help | Magnetic Properties Tutors | Online Magnetic Properties Tutors | Magnetic Properties Homework Services | Magnetic Properties
Submit Your Query ???
Topics
Activation Energy Average Rate Determination Rate Equation Value Reactions Collision Theory Reactions Temperature Effect Half Life Of Reaction Integrated Rate Equation Rate Equation Expression Reaction Mechanism Pseudo First Order Reaction Rate Equation Law Chemical Reaction Rate Additional Compounds Co-ordination Compounds Coordination Compounds Bonding Coordination Compounds Colors Octahedral Complex Splitting Tetrahedral Complex Splitting Stabilization Energy Crystal Field Theory Stability Affecting Factors Isomerism In Compounds Magnetic Properties Metal Carbonyls D-orbitals Orientation Mononuclear Compounds Naming Coordination Compounds Stability Terminology Compounds Werner Theory First Row Transition Elements Elements Electric Configuration F-block Elements Halides And Sulphides Metals-Oxides, Oxoanions Potassium Dichromate Potassium Permanganate The Actinoids The Lanthanoids Cell Potential Concentration Cells Electrolytic Solution Conductance Corrosion Gibbs Energy Electrochemical Series Rusting Electrochemical Theory Electrode Potential Electrolytic Cells Fuel Cells Galvanic Cells Electrode Potential Measurement Nerst Equation Corrosion Prevention Primary Cells Redox Reactions Salt Bridge Secondary Cells Standard Hydrogen Electrode Electrodes Types Steel Production Process Metals Extraction Metallurgy Principles Conduction In Insulators Conduction In Metals Density Of Unit Cell Solids-Electrical Properties Solids-Magnetic Properties Non Stoichiometric Defects Stoichiometric Defects Azeotropes Solutions-Colligative Properties Degree Of Association Degree Of Dissociation Depression In Freezing Point Elevation In Boiling Point Henry Law Constant Ideal Solutions Isotonic, Hypotonic Solutions Osmotic Pressure-Molar Mass Non Ideal Solutions Osmosis Solid In Liquid Solution Vapour Pressure Lowering Solubility Of Gases Solids In Liquids Solubility Types Of Solutions Liquid Solutions Pressure Adsorption Adsorption-Gases On Solids Adsorption From Solution Adsorption Applications Catalysis Chemical Adsorption Colloidal Solutions Coagulation Colloidal State Adsorption, Absorption Difference Emulsions Enzyme Catalysis Gels Heterogeneous Catalysis Homogeneous Catalysis Physical Adsorption Colloidal Solution Purification Group 15 Elements Group 16 Elements Dioxygen Chemical Reactions Dinitrogen Dioxygen The Oxygen Family Halides And Oxides Hydrogen Chloride Interhalogen Compounds Halogens Oxoacids Phosphorus Trichloride Nitric Acid Properties The Noble Gases Alcohols And Phenols C-O Bond Cleavage Phenol Preparation Ethers Alcohols General Preparation Alcohols Industrial Preparation Nomenclature Alcohols Physical Properties Phenols Preparation Phenolic Group Reactions Alkyl Group Reactions Some Commercial Alcohols Chemicals In Food Cleansing Action Of Soaps Drug Target Interaction Drugs And Medicines Non-Soapy Detergents Soaps Types Of Drugs Haloalkanes Chemical Properties Halides, Aryl Halides Haloalkanes And Halorenes Nucleophilic Substitution Halides Nomenclature Haloalkanes Physical Properties Haloarenes Physical Properties Polyhalogen Compounds Haloalkanes From Alcohols Haloalkanes From Hydrocarbons Cannizzaro Reaction Carboxylic Acid Preparation Of Acids Oxidation In Aldehydes Aldehydes, Ketones Properties Carboxylic Acid Properties Aldehydes, Ketones Preparation -COOH Group Reactions -OH Group Replacement Aldehydes, Ketones Reduction Carbonyl Oxygen Atom Commercial Carbonyl Compounds Commercial Carboxylic Acids Amines Amines Character Amines Chemical Properties Cyanides, Isocyanides Diazonium Salts Amines Types Aliphatic Amines Nomenclature Ortho Effect Amines Physical Properties Preparation Of Amines Diazonium Salts Properties Amines With Nitrous Acid Amines With Aldehydes Amines-Structure Basicity Biodegradable Polymers Polymerization Mode Polymers-Molecular Forces Polymers-Molecular Mass Natural, Synthetic Polymers Natural Rubber Polymers Condensation Polymers Polydienes Preparation Polyhallolefins Preparation Structure Based Polymers Synthetic Rubber