Rules for naming the complex ion when given the formula in square brackets eg: [Fe(CN)6]4-
Rules :
1.
Name the ligands first, in alphabetical order, then the
metal atom or ion. Note: The metal atom or ion is written before the ligands in
the chemical formula.
2.
For negatively charged ligands the name ends in
"-o"; so for example chloride
becomes chloro, bromide becomes bromo, fluoride becomes fluoro, hydroxide
becomes hydroxo, cyanide CN- becomes cyanido and C2O42-
oxalato
For neutral ligands, the common name of the molecule is used
e.g. H2NCH2CH2NH2 ethylenediamine).
Important exceptions: water is called
‘aqua’, ammonia is called ‘ammine’.
3. If there are more than one of each type of ligand then Greek prefixes are used to designate the number of each
type of ligand in the complex ion, e.g. di-, tri- and tetra-.
Numerical Prefixes
di, tri, tetra, penta, hexa, hepta and octa
4. After naming the ligands, name the central metal. If the
complex ion is a positively charged ion overall, the metal is named the same as
the element. For example, Co is called
cobalt and Pt is called platinum, copper is called copper. However, if the
complex ion is a negative ion overall then the name of the metal should end
with the –ate. For example, Co in a negative ion complex is
called cobaltate and Pt is called platinate. For some metals, the Latin names
are used in e.g. Fe is called ferrate and Cu becomes cuprate
5 The oxidation state of the metal is then added in Roman
Numerals.
Test
yourself – get the name from the formula :
Question 1 [Cr(NH3)3(H2O)3]3+
Question 2 [Pt(NH3)5Cl]3+
Question 3 [Fe(CN)6]4-
Question 4 [NiCl4]2-
Answers
to get the name from the Formula
Answer
1 triamminetriaquachromium(III)
Answer 2 pentaamminechloroplatinum(IV)
Answer
3 hexacyanoferrate(II)
Answer 4 tetrachloronickelate(II)
When writing the formula of a complex ion when given the name, a different set of rules applies :
The symbol of the metal is written first, then negatively charged ligands, followed by the neutral ligands:
Question - Get the Formula of the complex ion from
the Name
Question 1 hexaammineiron(III)
Question 2 tetrachlorocuprate(II)
Question 3 hexafluorocobaltate(III)
Question 4 tetraaquadihydroxoiron(III)
Question 5 tetraamminediaquacopper(II) ion.
Question 4 tetraaquadihydroxoiron(III)
Question 5 tetraamminediaquacopper(II) ion.
Answers - Get the Formula from the Name
Answer 1 [Fe(NH3)6]3+
Answer 2 [CuCl4]2-
Answer 3 [CoF6]3-
Answer 4 [Fe(OH)2(H2O)4]+
Answer 5 [Cu(NH3)4(H2O)2]2+
Answer 4 [Fe(OH)2(H2O)4]+
Answer 5 [Cu(NH3)4(H2O)2]2+