Coordination Chemistry Bonding in transition-metal complexes

Slides:

Advertisements

Similar presentations

Crystal Field Theory The relationship between colors and complex metal ions.

Advertisements

Metal Complexes -- Chapter 24

Mysteries of polarized light Enantiomers have identical properties except in one respect: the rotation of the plane of polarization of light Enantiomers.

Inorganic Chemistry Laboratory

Ch 10 Lecture 3 Angular Overlap

Which colours are exhibited? colour wheel This colour wheel demonstrates which colour a compound will appear if it only has.

2-1 Orbitals and energetics Bonding and structure Ligand field theory Charge Transfer Molecular orbital theory Provide fundamental understanding of chemistry.

Coordination Chemistry II

Lecture 22 Electronic structure of Coordination Compounds 1) Crystal Field Theory Considers only electrostatic interactions between the ligands and the.

Coordination Chemistry Bonding in transition-metal complexes.

Prentice-Hall © 2002 Complex Ions and Coordination Compounds.

Placing electrons in d orbitals (strong vs weak field)

6  ligands x 2e each 12  bonding e “ligand character” “d 0 -d 10 electrons” non bonding anti bonding “metal character” ML 6  -only bonding The bonding.

Coordination Chemistry Bonding in transition-metal complexes.

Metal-ligand  interactions in an octahedral environment Six ligand orbitals of  symmetry approaching the metal ion along the x,y,z axes We can build.

Big-picture perspective: The interactions of the d orbitals with their surrounding chemical environment (ligands) influences their energy levels, and this.

Transition Metal Complexes. Transition metal complexes consist of a central Transition metal ion surrounded by a number of ligands. As a result of their.

Transition Metal Chemistry The Chemistry of the d-block elements.

Transition Metals Occupy the d-block of periodic table Have d-electrons in valence shell Some characteristics of Transition Metals and their compounds.

CHAPTER 5: CRYSTAL FIELD THEORY

Crystal Field Theory The relationship between colors and complex metal ions.

Coordination Chemistry:

Chap 24 Part 2 Color and Magnetism  The color of the complex is the sum of the light not absorbed (reflected) by the complex.Color Color of a complex.

Bonding in coordination compounds

Coordination Chemistry II: Bonding

Coordination Chemistry II

Crystal Field Theory i) Separate metal and ligands have high energy ii) Coordinated Metal - ligand get stabilized iii) Metal and Ligands act as point charges.

Transition Metal Chemistry and Coordination Compounds

Coordination Complexes Chapter 20. Copyright © Houghton Mifflin Company. All rights reserved.20 | 2 What we learn from Chap 20 We begin the chapter with.

COORDINATION COMPOUNDS

Crystal Field Theory, Electronic Spectra and MO of Coordination Complexes Or why I decided to become an inorganic chemist or Ohhh!!! The Colors!!!

CHEM 522 Chapter 01 Introduction. Transition Metal Organometallic Chemistry Organic versus inorganic chemistry Transition metals –Oxidation state –d orbitals.

Crystal Field Theory Molecular Orbital Theory: Donor- Acceptor Interactions.

Unit 3 Summary. Crystal Field Theory x z y M n Which d-orbitals are effected the most?

NATURE OF THE LIGAND- SMALL LIGANDS APPROACH THE LIGANDS EASILY, SO THEY CAN CAUSE GREAT CRYSTAL FIELD SPLITTING. LIGANDS CONTAINING EASILY POLARISABLE.

Co-ordination Chemistry Theories of Bonding in Co-ordination compound. 1. Valence Bond Theory 2. Crystal Field Theory 3. Molecular Orbital Theory.

Ligand field theory considers the effect of different ligand environments (ligand fields) on the energies of the d- orbitals. The energies of the d orbitals.

Ch 10 Lecture 1 Bonding Basics I.Evidence of Electronic Structure A.What is Electronic Structure? 1)Electronic Structure = what orbitals electrons reside.

The Chemistry of Coordination Compounds Chapter 20 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Transition-Metal Complexes are extremely colorful!

Figure 23.2 Radii of transition metals as a function of group number.

Coordination Chemistry: Bonding Theories

COORDINATION COMPOUNDS

Coordination complexes

metal ion in a spherical

Chemistry of Coordination Compounds

Chemistry of Coordination Compounds

Applications of Crystal Field Theory: Ionic Radii

Chapter 9 Coordination Chemistry I

and to what degree they may be forbidden depends on selection rules:

Metal-Ligand bonding in transition metal complexes

Ligand Field Theory: σ Bonding

Chapter 9 Coordination Chemistry I

Dear Students of Inorganic Chemistry 2,

TRANSITION ELEMENTS.

Metal-Ligand bonding in transition metal complexes

Dr. Pandit Khakre Asst. Prof Mrs. K.S.K. College, Beed.

Metal Complexes -- Chapter 24

Crystal Field Theory The relationship between colors and complex metal ions.

Transition Metal Chemistry: Crystal Field Theory

Transition Metals and Coordination Chemistry

Chapter 9 – Molecular Geometry and Bond Theory

Magnetic Properties of Coordination Compounds

Physical Chemistry Chapter V Polyatomic Molecular Structure 2019/4/10

semester 2 Lecture note 1 Crystal Field Theory

Invisible Ink 2[Co(H2O)6]Cl2(s) Co[CoCl4](s) + 12 H2O

Transition Metals and Color

Mr.Halavath Ramesh 16-MCH-001 Dept. of Chemistry Loyola College University of Madras-Chennai.

Presentation transcript:

Coordination Chemistry Bonding in transition-metal complexes

with the negatively charged ligands Crystal field theory: an electrostatic model The metal ion will be positive and therefore attract the negatively charged ligands But there are electrons in the metal orbitals, which will experience repulsions with the negatively charged ligands

Ligand/d orbital interactions Orbitals point at ligands (maximum repulsion) Orbitals point between ligands (less pronounced repulsion)

The two effects of the crystal field

Splitting of d orbitals in an octahedral field eg 3/5 Do Do 2/5 Do t2g Do is the crystal field splitting E(t2g) = -0.4Do x 3 = -1.2Do E(eg) = +0.6Do x 2 = +1.2Do

The magnitude of the splitting (ligand effect) Weak field Strong field The spectrochemical series CO, CN- > phen > NO2- > en > NH3 > NCS- > H2O > F- > RCO2- > OH- > Cl- > Br- > I-

The magnitude of the splitting (metal ion effect) Weak field Strong field increases with increasing formal charge on the metal ion increases on going down the periodic table

Placing electrons in d orbitals Strong field Weak field Strong field Weak field d1 d2 d3 d4

When the 4th electron is assigned it will either go into the higher energy eg orbital at an energy cost of D0 or be paired at an energy cost of P, the pairing energy. d4 Strong field = Low spin (2 unpaired) Weak field = High spin (4 unpaired) P < Do P > Do Notes: the pairing energy, P, is made up of two parts. 1) Coulombic repulsion energy caused by having two electrons in same orbital

P = sum of all Pc and Pe interactions Pairing Energy, P The pairing energy, P, is made up of two parts. Coulombic repulsion energy caused by having two electrons in same orbital. Destabilizing energy contribution of Pc for each doubly occupied orbital. Exchange stabilizing energy for each pair of electrons having the same spin and same energy. Stabilizing contribution of Pe for each pair having same spin and same energy P = sum of all Pc and Pe interactions

Placing electrons in d orbitals 1 u.e. 5 u.e. d5 0 u.e. 4 u.e. d6 1 u.e. 3 u.e. d7 2 u.e. d8 1 u.e. d9 0 u.e. d10

Positive favors high spin. Neg favors low spin.

Spectrochemical Series Purely s ligands: D: en > NH3 (order of proton basicity) donating which decreases splitting and causes high spin: D: H2O > F > RCO2 > OH > Cl > Br > I (also proton basicity) Adding in water, hydroxide and carboxylate D: H2O > F > RCO2 > OH > Cl > Br > I p accepting ligands increase splitting and may be low spin D: CO, CN-, > phenanthroline > NO2- > NCS-

Splitting of d orbitals in a tetrahedral field Dt e Dt = 4/9Do Always weak field (high spin)

A crystal-field aproach: from octahedral to tetrahedral Less repulsions along the axes where ligands are missing

Magnetic properties of metal complexes Diamagnetic complexes very small repulsive interaction with external magnetic field no unpaired electrons Paramagnetic complexes attractive interaction with external magnetic field some unpaired electrons

Measured magnetic moments include contributions from both spin and orbital spin. In the first transition series complexes the orbital contribution is small and usually ignored.