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 endings change as follows:
"ide" becomes "-ido"
"ate" becomes "-ato"
"ite" becomes "-ito"
so for example chloride becomes chlorido, bromide becomes bromido, fluoride becomes fluorido, hydroxide becomes hydroxido, cyanide CN- becomes cyanido and C2O42- oxalato
"ate" becomes "-ato"
"ite" becomes "-ito"
so for example chloride becomes chlorido, bromide becomes bromido, fluoride becomes fluorido, hydroxide becomes hydroxido, cyanide CN- becomes cyanido and C2O42- oxalato
For neutral ligands, the name of the molecule is used.
Watch out for tricky ones like H2NCH2CH2NH2 1,2 diammino ethane).
Important exceptions: water is called
‘aqua’, ammonia is called ‘ammine’, carbon monoxide is "carbonyl" and nitrogen monoxide "nitrosyl".
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-, tetra-, penta-, hexa- and hepta-.
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(OH2)3]3+
Question 2 [Pt(NH3)5Cl]3+
Question 3 [Fe(CN)6]4-
Question 4 [NiCl4]2-
Answers at bottom of the page.....
Question - Write the Formula of the complex ion from
the Name
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:
The symbol of the metal is written first, then negatively charged ligands, followed by the neutral ligands:
Question 1 hexaammineiron(III)
Question 2 tetrachloridocuprate(II)
Question 3 hexafluoridocobaltate(III)
Question 4 tetraaquadihydroxidoiron(III)
Question 5 tetraamminediaquacopper(II) ion.
Question 4 tetraaquadihydroxidoiron(III)
Question 5 tetraamminediaquacopper(II) ion.
Answers below ....
Answers to "Get the name from the Formula"
Answer 1 triamminetriaquachromium(III)
Answer 2 pentaamminechloridoplatinum(IV)
Answer 3 hexacyanidoferrate(II)
Answer 4 tetrachloridonickelate(II)
Answers to "Write the Formula of the complex ion from the Name"
Answer 1 [Fe(NH3)6]3+
Answer 2 [CuCl4]2-
Answer 3 [CoF6]3-
Answer 4 [Fe(OH2)4(OH)2]+
Answer 5 [Cu(NH3)4(OH2)2]2+
Answer 4 [Fe(OH2)4(OH)2]+
Answer 5 [Cu(NH3)4(OH2)2]2+
