1. Coordination Chemistry:
IUPAC Nomenclature
Dr. C. Haldar & Dr. RP John)
Department of Applied Chemistry

2. Recommended Books
D. J. Shriver, P. W. Atkins and C. H. Langford, Inorganic Chemistry, ELBS, 2nd Ed, 1994.
J. E. Huheey, E. A. Keiter and R. L. Keiter, Inorganic Chemistry: Principle, structure and reactivity, Harper Collins, 4th Ed, 1993.

3. What is a Transition Metal?

4. Ligands Ligand Formula Name Fluoride F- Fluorido Nitrate NO3- Nitrato
A ligand has only one donor atom is a “monodentate”; with two donor atoms will be “bidentate”; “tridentate” for three; “tetradentate” for four…..etc.
Ligand
Formula
Name
Fluoride F-
Fluorido
Nitrate
NO3-
Nitrato
Nitrite
NO2-
Nitrito
Carbonate
CO32-
Carbonato
Cyanide
CN-
Cyanido
Thiocyante
SCN-
Thiocyanto
NCS-
Isothiocyanato
Hydride H-
Hydrido
Hydroxide
OH-
Hydroxido
Water
H2O
Aqua
Ammonia
NH3
Ammine
Carbon monoxide CO
Carbonyl
Nitric oxide NO
Nitrosyl

5. Ligands
A ligand that has more than one donor atom is of “multi-dentate/poly-dentate”.
Some common bi-dentate ligands

6. Ligands
Common tri-dentate ligands
Common tetra-dentate ligands

7. Bridging ligands:

8. Polydentate Ligands
The association mode of a multi-dentate is called “chelation”.
Ethylenediaminetetraacetate, mercifully abbreviated EDTA, has six donor atoms
Multi-dentate “chelating” ligand

9. Nomenclature of Coordination Complexes
Rule 1: The names of neutral coordination complexes are given without spaces. For coordination compounds that are ionic the cation is named first and separated by a space from the anion, as is the case for all ionic compounds.
Na [PtCl3(NH3)]: Sodium amminetrichloridoplatinate (II)
K2 [CuBr4]: Potassium tetrabromidocuprate(II)
Rule 2: The name of the coordination compound (neutral, cationic or anionic) begins with the names of the ligands. The metal is listed next, following in parentheses by the oxidation state of the metal.
Rule 3: When more than one of a given ligand is bound to the same metal atom or ion, the number of such ligands is designated by the following prefixes:
2 di 6 hexa deca
3 tri 7 hepta undeca
4 tetra 8 octa dodeca
5 penta 9 nona

10. Nomenclature of Coordination Complexes
Rule 4: Neutral ligands are given the same name as the uncoordinated molecule, but with spaces omitted. Some examples are:
(CH3)2SO dimethylsulfoxide (DMSO)
(NH2)3CO urea
C5H5N pyridine
terpy terpyridine
bpy ,2’-bipyridine
en ethylenediamine
PCl trichlorophosphine
PPh triphenylphopshine
EXCEPTIONS: Some neutral molecules, when serving as ligands are given special
names. These are:
NH3 ammine
H2O aqua
NO nitrosyl
CO carbonyl
CS thiocarbonyl

11. Nomenclature of Coordination Complexes
Rule 5: Anionic ligands are given names that end in the letter “o”. When the name of the free, uncoordinated anion ends in “ate”, the ligand name is changed to end in “ato”.
Some examples are :
CH3CO2- (acetate) acetato
SO42- (sulfate) sulfato
CO32- (carbonate) carbonato
acac acetylacetonato
When the name of the free, uncoordinated anion ends in “ide”, the ligand name is changed to end in “ido”. Some examples are:

12. Nomenclature of Coordination Complexes
Certain anionic ligands are given special names, all ending in “o”:
CN- cyanido
F- fluorido
Cl- chlorido
O2- oxido
O2- superoxido
OH- hydroxido
H- hydrido
CH3O- methoxido
Rule 6: The ligands are named alphabetically, ignoring the prefixes bis, tris, etc…
Rule 7: When the coordination entity is an anion, the name of the metal is altered to end in “ate”. This is done for some metals by simply changing the ending “ium” to “ate”:
Scandium scandate
Titanium titanate
Chromium chromate
Zirconium zirconate

13. Nomenclature of Coordination Complexes
For other metals, the name is given the ending “ate”:
Manganese manganate
Cobalt cobaltate
Nickel nickelate
Tantalum tantalate
Tungsten tungstate
Finally, the names of some metals are based on the Latin name of the element:
Iron ferrate
Copper cuprate
Silver argentate
Gold aurate
Rule 8: Geometrical isomers are designated by cis- or trans- and mer- or fac-, the latter two standing for meridional or facial, respectively.

14. Nomenclature of Coordination Complexes
Rule 9: In case of ligands that are capable of binding via different donor atoms, the atom involved in the attachment is denoted with an italized element symbol preceded by a ‘’ separated by ‘–’ at the end of the ligand name.
-SCN- thiocyanato (thiocyanato-S)
-NCS- isothiocyanto (thiocyanto-N)
-NO2- nitrito-N
-ONO- nitrito-O
Examples:
[Co(NH3)5CO3]Cl Pentaamminecarbonatocobalt(III) chloride
[Cr(H2O)4Cl2]Cl Tetraaquadichloridochromium(III) chloride
K2[OsCl5N] Potassium pentachloridonitridoosmate(VI)
K3[Fe(CN)5NO] Potassium pentacyanidonitrosylferrate(II)
[Mn(H2O)5I3]Cl hexaaquatriiodidomanganese(II) chloride
[fac-Co(NH3)3(I)3] fac-triamminetris(iodido)cobalt(III)
[cis-Co(NH3)4(N3)2]Br cis-tetraamminediazidocobalt(III) bromide

15. Nomenclature: additional rules
To avoid confusion about the identity of poly halide ions the are prefixed by di, tri etc, while their monodentate counter parts are prefixed by bis, tris etc.
Example: I3- is triiodido (I-)3 is termed tris(iodido)
In case of ligands that are compounds having multiple substituents they are prefixed with bis, tris, tetrakis etc. to avoid repetition of di, tri, tetra etc.
Example: bis(ethylenediammine)
In case multiple atoms of the same ligand is bound to the same central metal ion, the atom that is bound is identified by ‘’ followed by element symbol perfixed by ‘-’ separated by ‘:’ or ‘,’ at the end of the ligand name
Example: Slide no. 18, example 1, i.e. glycinato-N:O
If multiple identical atoms of the same ligand is linked to the same central metal ion the number is indicated by the Arabic numeral exponent to .
Example: see slide no.19, example 2

16. Nomenclature: additional rules
If two atoms of the same ligand that are bound to the central metal ion is bound to each other, then ‘’ symbol is prefixed followed by’-’ before the name of the ligand. The number of such atoms that is bound to the central metal is denoted by the arabic numeral exponent on ‘’.
Example: see slide no.19, example 2
If a ligand is linked to multiple metal ions then, then the ligand name is prefixed by ‘µ’ followed by ’-’, and the number of such metal ions linked is indicated by the arabic numeral subscript to ‘µ’
Example: See slide no 19
If a ligand is linked to multiple metal ions via same donor atoms elements and if the donor atoms identity is different, then the atoms are identified by arabic numeral superscript to the atom symbol, and the metal ions to which they are attached are identified by using arabic numeral labels prefixes to the symbol ‘’.
Example: See slide no. 18, example 3

17. Simple Problem
Write the names of the following coordination compounds:
[Co(NH3)4Cl2]Cl
K3[Fe(CN)6]
[Pt(NH3)4)][Pt(Cl)4]
[CoCl(ONO)(NH3)4]Cl
Tetraamminedichloridocobalt(III) chloride
Potassium hexacyanidoferrate(III)
Tetraammineplatinum(II) tetrachloridoplatinate(II)
Tetraamminechloridonitrito-Ocobalt(III) chloride
Write formulas for the following compounds:
Pentaamminechloridocobalt(III) chloride
Dichloridobis(ethylenediamine)platinum(IV) nitrate
Amminetetraaquasulfatochromium(II)
Solution
[Co(NH3)5Cl]Cl2
[Pt(en)2Cl2](NO3)2
[Cr(H2O)4(NH3)(SO4)]

18. Nomenclature contd…… Cis-bis(glycinato-N:O)platinum(II)
(PdCl2)n catena-poly-di-µ-chloridopalladium(II)
[Cu2(CH3COO)4(H2O)2] tetrakis(µ-acetato-1O1:2O2)-diaquadicopper(II)
[Mn2(CO)10] bis(pentacarbonylmanganese)(Mn—Mn)
Os3(CO) Cyclo-tris(tetracarbonylosmimum)(3Os-Os)
W2Me bis(trimethyltungsten)(W-W)
trans-[Co(en)2I(H2O)](NO3)2
trans-aquabis(ethylenediamine)iodidocobalt(III) nitrate
mer-[Ru(PPh3)3Cl3] mer-trichloridotris(triphenylphosphine)ruthenium(III)

19. Name the compounds Pentaammineaquacobalt(III) chloride
Bis(ethane-1,2-diamine-2N)2-peroxidocobalt(III)
Dichloridobis(triphenylphosphane- P)platinum(II)
Dicarbonyl(5-cyclopentadienyl)(cyclopenta-2,4-dien-1-yl- C1)iron

20. Problem:

21. Exercise: Identify name or formula
µ-amido-µ-peroxidobis[pentaamminecobalt(III)] chloride

22. Exercise: Answers