Nam

ing Coordination C

ompounds

(nomenclature)

•T

he cation is written before the anion

•T

he charge of the cation(s) is balanced by thecharge of the anion(s)

•In the com

plex ion, neutral ligands are written

before anionic ligands, and the whole ion is

placed in brackets

Rules for w

riting coordination compounds:

Nam

es of some com

mon ligands

Neutral L

igands:H

2 O

Aqua

NH

3A

mm

ineC

OC

arbonylN

ON

itrosyl

Anionic L

igands:F

-Fluoro

Cl -

Chloro

Br -

Brom

oI -

IodoO

H-

Hydroxo

CN

-C

yano

Latin nam

es used for some m

etal anions:

IronFerrate

Copper

Cuprate

Lead

Plumbate

Tin

StannateG

old A

urateSilver

Argentate

Exam

ple: K2 [C

o(NH

3 )2 Cl4 ]

Cations:2xK

+A

nion:

[Co(N

H3 )2 C

l4 ] 2-

NH

3 is neutralC

l - is negativeT

he metal m

ust be Co

2+

Check:

Charge of com

plex = charge of cations +

charge of anions0

+2

-2

See Summ

ary on page 926R

ules for naming coordination com

pounds

Nam

ing coordination compounds

Exam

ple: What is the nam

e for [Co(N

H3 )5 C

l]Cl2 ?

Charge of m

etal ion = charge of

- total charge of

complex ion

all ligands =

2+

- [(5x0) +

(1-)] =

3+i.e. C

o3+, or C

obalt(III)5 N

H3 ligands

pentaam

mine

1 Cl - ligand

chloro

Com

plex ion = pentaam

minechlorocobalt(III)

Counter ion =

chloride

[Co(N

H3 )5 C

l]Cl2 =

pentaamm

inechlorocobalt(III) chloride

Exam

ple: What is the nam

e for K3 F

e(CN

)6 ?

Charge of m

etal ion = charge of

- total charge of

complex ion

all ligands =

3+

- 6x(1-)

= 3+

i.e. Fe

3+, or Iron(III)6 C

N ligands

hexacyano

Com

plex ion = hexacyanoferrate(III)

Counter ion =

potassium

K3 F

e(CN

)6 = potassium

hexacyanoferrate(III)

Exam

ple: What is the nam

e for [Fe(en)2 (N

O2 )2 ]2 SO

4 ?

Exam

ple: What is the form

ula fortriam

minebrom

oplatinum(II) chloride?

[Pt(N

H3 )3 B

r] + and

Cl -

[Pt(N

H3 )3 B

r]Cl

Exam

ple: What is the form

ula for potassiumhexafluorocolbaltate(III)?

Isomers

2 or more chem

ical species with identical

composition but different properties

Figure 20.9

Exam

ple:[C

r(NH

3 )5 SO4 ]B

rand

[Cr(N

H3 )5 B

r]SO4

Exam

ple:[C

o(NH

3 )4 (NO

2 )Cl]C

l(binds through N

- nitro)

and

Co(N

H3 )4 (O

NO

)Cl]C

l(binds through O

- nitrito)

Figure 20.10

Linkage Isom

ers

Pt

NH

3

NH

3

Cl

Cl

Pt

NH

3

NH

3

Cl

Cl

Geom

etric isomers:

cis-Pt(N

H3 )2 C

l2trans-P

t(NH

3 )2 Cl2

These w

ere the isomers W

erner studied

Figure 20.12

cis- and trans-dichloro Isomers

Stefan Bernhard’s son drew

a picture:

Mirror Plane

mb

md

Non-chiral:

Chiral:

Optical isom

ers:isom

ers that have nonsuperimposable m

irror images

= enantiom

ersd- enantiom

er

Rotates plane polarized

light to the right-dextrorotatory (+

θ)

l- enantiomer

Rotates plane polarized

light to the left-levorotatory (-θ)

Figure 20.14

Rotation of plane polarized light by

chiral compounds

Figure 20.16

Figure 20.17