Download Nomenclature

2015
NOMENCLATURE
Nomenclature
Ligands are frequently named using older trivial names rather than the International Union
of Pure and Applied Chemistry (IUPAC) names. Table 1 list common ligands. Those with two
or more points of attachment to metal atoms are called chelating ligands, and their
compounds are called chelates (pronounced key-lates), a name derived from the Greek
khele, the claw of a crab. Ligands such as ammonia are monodentate, with one point of
attachment (literally, “one tooth”).
Ligands are described as bidentate if they have two points of attachment, as in
ethylenediamine (NH2CH2CH2NH2), which can bond to metals through the two nitrogen
atoms. The prefixes tri-, tetra-, penta-, and hexa- are used for three through six bonding
positions (Table 2).
Chelate rings may have any number of atoms; the most common contain five or six atoms,
including the metal. Smaller rings have angles and distances that lead to strain; larger rings
frequently result in crowding, both within the ring and between adjoining ligands. Some
ligands form more than one ring; ethylenediaminetetraacetate (EDTA) can form five via its
carboxylate groups and two amine nitrogen atoms.
Table 1
Common Name
hydrido
fluoro
chloro
bromo
IUPAC Name
hydrido
fluoro
chloro
bromo
Formula
H
F
Cl
Br
iodo
nitrido
azido
oxo
iodo
nitrido
azido
oxido
cyano
thiocyanato-S(S-bonded)
I
N3
N 3
O2
CN
SCN
cyano
thiocyano
Inorganic Chemistry B
1
2015
NOMENCLATURE
isothiocyano
hydroxo
isothiocyanato-N(N-bonded)
hydroxo
aqua
carbonyl
thiocarbonyl
nitrosyl
nitro
nitrito
aqua
carbonyl
thiocarbonyl
nitrosyl
nitrito -N (N-bonded)
nitrito- O (O-bonded)
methylisocyanide
phosphine
methylisocyanide
phosphane
pyridine
ammine
methylamine
amido
imido
pyridine (abbrev. py)
ammine
methylamine
azanido
azanediido
Inorganic Chemistry B
NCS
OH
H2O
CO
CS
NO+
NO2
ONO
CH3NC
PR3
C5H5N
NH3
MeNH2
NH2
NH2
2
2015
NOMENCLATURE
Table 2
Inorganic Chemistry B
3
2015
NOMENCLATURE
Inorganic Chemistry B
4
2015
NOMENCLATURE
Nomenclature Rules
1. The cation comes first, followed by the anion.
Examples: diamminesilver(I) chloride, [Ag(NH3)2]Cl
potassium hexacyanoferrate(III), K3[Fe(CN)6]
2. The inner coordination sphere is enclosed in square brackets. Although the metal is
provided first within the brackets, the ligands within the coordination sphere are written
before the metal in the formula name.
Examples: tetraamminecopper(II) sulfate, [Cu(NH3)4]SO4
hexaamminecobalt(III) chloride, [Co(NH3)6]Cl3
3. The number of ligands of each kind is indicated by prefixes (Table 3). In simple cases, the
prefixes in the second column are used. If the ligand name already includes these prefixes or
is complicated, it is set off in parentheses, and prefixes in the third column (ending in –kis)
are used.
Examples: dichlorobis(ethylenediamine)cobalt(III), [Co(NH2CH2CH2NH2)2Cl2]+
tris(2,2-bipyridine)iron(II), [Fe(C10H8N2)3]2+
Table 3
2
di
bis
3
4
5
6
7
8
9
10
tri
tetra
penta
hexa
hepta
octa
nona
deca
tris
tetrakis
pentakis
hexakis
heptakis
octakis
nonakis
decakis
Inorganic Chemistry B
5
2015
NOMENCLATURE
4. Ligands are generally written in alphabetical order according to the ligand name, not the
prefix.
Examples: tetraamminedichlorocobalt(III), [Co(NH3)4Cl2]+
(tetraammine is alphabetized by a and dichloro by c , not by the prefixes)
amminebromochloromethylamineplatinum(II), Pt(NH3)BrCl(CH3NH2)
5. Anionic ligands are given an o suffix. Neutral ligands retain their usual name. Coordinated
water is called aqua and coordinated ammonia is called ammine . Examples are in Table 1.
6. Two systems exist for designating charge or oxidation number:
a. The Stock system puts the calculated oxidation number of the metal as a Roman numeral in
parentheses after the metal name. Although this is the most commonly employed method, its
drawback is that the oxidation state of a metal within a complex can be ambiguous, and
difficult to specify.
b. The Ewing-Bassett system puts the charge on the coordination sphere in parentheses after
the name of the metal. This convention offers an unambiguous identification of the species.
In either case, if the charge is negative, the suffix -ate is added to the name.
Examples:
tetraammineplatinum(II) or tetraammineplatinum(2+), [Pt(NH3)4]2+
tetrachloroplatinate(II) or tetrachloroplatinate(2–), [PtCl4]2
hexachloroplatinate(IV) or hexachloroplatinate(2–), [PtCl6]2
7. Prefixes designate adjacent (cis -) and opposite (trans -) geometric locations. Other
prefixes will be introduced as needed.
Examples:
cis - and trans -diamminedichloroplatinum(II), [PtCl2(NH3)2]
cis - and trans -tetraamminedichlorocobalt(III), [CoCl2(NH3)4]+
Inorganic Chemistry B
6
NOMENCLATURE
2015
8. Bridging ligands between two metal ions (Figures 1) have the prefix -.
Examples :
tris(tetrammine--dihydroxocobalt)cobalt(6+), [Co(Co(NH3)4(OH)2)3]6+
-amido--hydroxobis(tetramminecobalt)(4+), [(NH3)4Co(OH)(NH2)Co(NH3)4]4+
Fig. Bridging Amide and Hydroxide Ligands in
Fig. cis and trans Isomers of
-amido--hydroxobis(tetraamminecobalt)(4+),
Diamminedichloroplatinum(II), [PtCl2(NH3)2].
[(NH3)4Co(OH)(NH2)Co(NH3)4]4+.
The cis isomer, also known as cisplatin, is used
in cancer treatment.
9. When the complex is negatively charged, the names for these metals are derived from the
sources of their symbols:
iron (Fe) ferrate
lead (Pb) plumbate
silver (Ag) argentate
tin(Sn) stannate
gold (Au) aurate
copper (Cu) cuprate
Examples:
tetrachloroferrate(III) or tetrachloroferrate(1–), [FeCl4]
dicyanoaurate(I) or dicyanoaurate(1–), [Au(CN)2]
Name these coordination complexes:
a. Cr(NH3)3Cl3
b. Pt(en)Cl2
c. [Pt(ox)2]2
d. [Cr(H2O)5Br]2+
e. [Cu(NH2CH2CH2NH2)Cl4]2
f. [Fe(OH)4]
Inorganic Chemistry B
7
2015
NOMENCLATURE
Give the structures of these coordination complexes:
a. Tris(acetylacetonato)iron(III)
b. Hexabromoplatinate(2–)
c. Potassium diamminetetrabromocobaltate(III)
d. Tris(ethylenediamine)copper(II) sulfate
e. Hexacarbonylmanganese(I) perchlorate
f. Ammonium tetrachlororuthenate(1–)
Inorganic Chemistry B
8