9380673.ppt

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

What is a transition metal?
Transition metals have incompletely filled d subshells or
produce ions with incompletely filled d subshells.
This is responsible for many of the properties of
transition metals including color, catalytic activity,
formation of paramagnetic compounds, and the
tendency to form complex ions.

Is zinc a transition metal?
Explain your answer.
Write out the electronic
structure of Zn and of Zn2+

20.1
Electron Configurations and Other Properties of the First-Row Transition Metals

20.1
Physical Properties of Elements K to Zn

Oxidation States of the 1st Row Transition Metals
20.1

20.1
Ionization Energies for the 1st Row Transition Metals

General Properties of Transition Metals
Small atomic radii and close packing—strong
metallic bonds
Transition metals have…
• Higher ________________________
• Higher ________________________
• Higher ________________________
• Higher ________________________
• Higher ________________________
…than _________________________
p.650

A ________________________ typically consists of a complex
ion and a counter ion.
A ________________________ contains a central metal cation
bonded to one or more molecules or ions.
The molecules or ions that surround the
metal in a complex ion are called _______.
A ligand has ______________ unshared
pair of valence electrons
H
O
H
••
H
N
H
H
••
•
•
Cl
••
•
•
-
•
•
C O
•
•
20.3
pp.653ff

20.3
The atom in a ligand that is bound directly to the metal atom is
the _________________________.
H
O
H
••
H
N
H
H
The number of donor atoms surrounding the central metal atom
in a complex ion is the _______________________.
Ligands with:
one donor atom _____________
two donor atoms
three or more donor atoms
H2O, NH3, Cl-
ethylenediamine
EDTA
_____________
_____________

20.3
H2N CH2 CH2 NH2
•• ••
____________ ligand ____________ ligand
(EDTA)
Bidentate and polydentate ligands are called ______________

What are the oxidation numbers of the metals in
K[Au(OH)4] and of [Cr(NH3)6](NO3)3 ?
OH- has charge of ___
K+ has charge of ___
? Au + __ + (__x-__) = 0
Au = +___
NO3
- has charge of __
NH3 has no charge
? Cr + (__x__) + (__x-__) = 0
Cr = ___
20.3
Ex. 20.1, p.655

Naming Coordination Compounds
20.3
• The cation is named before the anion.
• Within a complex ion, the ligands are named first in
________________ order and the metal atom is named last.
• The names of anionic ligands end with the letter o. Neutral
ligands are usually called by the name of the molecule. The
exceptions are H2O (aquo), CO (carbonyl), and NH3 (amine).
• When several ligands of a particular kind are present, the
Greek prefixes di-, tri-, tetra-, penta-, and hexa- are used to
indicate the number. If the ligand contains a Greek prefix,
use the prefixes bis, tris, and tetras to indicate the number.
• The oxidation number of the metal is written in Roman
numerals following the name of the metal.
• If the complex is an ion, its name ends in –ate.

20.3
Names of Common Ligands in Coordination Compounds

20.3
What is the systematic name of
[Cr(H2O)4Cl2]Cl ?
________________________________
Write the formula of
tris(ethylenediamine)cobalt(II) sulfate
Names of Anions
Containing Metal Atoms
________________________________

Structure of Coordination Compounds
20.4
Coordination number Structure
2
4
6
Linear
Tetrahedral or Square planar
Octahedral

20.4
___________________ are compounds that are made up of
the same types and numbers of atoms bonded together in the
same sequence but with different spatial arrangements.
___________________ are stereoisomers that cannot be
interconverted without breaking a chemical bond.
cis-[Pt(NH3)2Cl2] trans-[Pt(NH3)2Cl2]

20.4
cis-[Co(NH3)4Cl2] trans-[Co(NH3)4Cl2]
Are these
additional
geometric
isomers of
[Co(NH3)4Cl2]?

20.4
_________________ are non-superimposable mirror images.
cis-[Co(en)2Cl2] trans-[Co(en)2Cl2]
_________________
____________
_________________
____________

20.4
_______________________
are optically active.

_________________________
– rotates plane polarized light to the right
_________________________
– rotates plane polarized light to the left
_________________________
rotate plane polarized light by the same
amount, but in opposite directions
_________________________
– an equimolar mixture of enantiomers

Coordination compounds are used in:
___________ – extracting gold and silver, purifying nickel
___________ – treating lead poisoning and cancer
___________ – identification of certain chemicals
___________ – largely banned from modern detergents
because the phosphates caused
eutrophication of lakes

_________ _________ _________ explains
the bonding of complex ions in terms of two
electrostatic forces
1. _________ between the positive metal ion
and the negatively charged ligand or the
negatively charged end of a polar ligand
2. _________ between the electron lone pairs
on the ligands and the d orbitals of the metals
pp.659ff

Bonding in Coordination Compounds
20.5
All equal in energy in the absence of _____________ !

20.5
Isolated
transition metal
atom Bonded transition
metal atom
As a result of these two metal-ligand electrostatic interactions,
the 5 d orbitals in an octahedral complex are split between two
sets of energy levels: a higher level with two orbitals and a lower
level with three levels. Crystal field splitting (D) . p.659

20.5
Isolated
transition metal
atom Bonded
transition metal
atom
____________ ____________ ____________ (D) is the
energy difference between two sets of d orbitals in a metal
atom when ligands are present. And…

20.5
D = hn

The absorption maximum for the complex ion [Co(NH3)6]3+
occurs at 470 nm. What is the color of the complex and
what is the crystal field splitting in kJ/mol?
Absorbs blue, will appear orange.
D = hn
hc
l
=
(6.63 x 10-34 J s) x (3 x 108 m s-1)
470 x 10-9 m
= = __________ J
D (kJ/mol) = 4.23 x 10-19 J/atom x 6.022 x 1023 atoms/mol
= ___________ kJ/mol
20.5

20.5
I- < Br- < Cl- < OH- < F- < H2O < NH3 < en < CN- < CO
Spectrochemical Series
Strong field ligands
_____________ D
Weak field ligands
_____________ D

20.5

Reactions of coordination compounds
Coordination compounds typically
undergo ligand exchange
(a/k/a ligand substitution) in solution

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