Formulas of Mononuclear RULES Coordination Entities The formula of a compound is
ID: 699773 • Letter: F
Question
Formulas of
Mononuclear RULES
Coordination
Entities
The formula of a compound is a shorthand tool used to provide basic
information about the constitution of the compound in a concise and
convenient manner. Mononuclear coordination entities contain a single
central metal atom. The following rules are applied while writing the formulas:
(i) The central atom is listed first.
(ii) The ligands are then listed in alphabetical order. The placement of
a ligand in the list does not depend on its charge.
(iii) Polydentate ligands are also listed alphabetically. In case of
abbreviated ligand, the first letter of the abbreviation is used to
determine the position of the ligand in the alphabetical order.
(iv) The formula for the entire coordination entity, whether charged or
not, is enclosed in square brackets. When ligands are polyatomic,
their formulas are enclosed in parentheses. Ligand abbreviations
are also enclosed in parentheses.
(v) There should be no space between the ligands and the metal
within a coordination sphere.
(vi) When the formula of a charged coordination entity is to be written
without that of the counter ion, the charge is indicated outside the
square brackets as a right superscript with the number before the
sign. For example, [Co(CN)6]3–, [Cr(H2O)6]3+, etc.
(vii) The charge of the cation(s) is balanced by the charge of the anion(s).
Naming of
Mononuclear
Coordination
Compounds
The names of coordination compounds are derived by following the
principles of additive nomenclature. Thus, the groups that surround the
central atom must be identified in the name. They are listed as prefixes
to the name of the central atom along with any appropriate multipliers.
The following rules are used when naming coordination compounds:
(i) The cation is named first in both positively and negatively charged
coordination entities.
(ii) The ligands are named in an alphabetical order before the name of the
central atom/ion. (This procedure is reversed from writing formula).
(iii) Names of the anionic ligands end in –o, those of neutral and cationic
ligands are the same except aqua for H2O, ammine for NH3, carbonyl
for CO and nitrosyl for NO. These are placed within enclosing marks
( ) when written in the formula of coordination entity.
(iv) Prefixes mono, di, tri, etc., are used to indicate the number of the
individual ligands in the coordination entity. When the names of
the ligands include a numerical prefix, then the terms, bis, tris,
tetrakis are used, the ligand to which they refer being placed in
parentheses. For example, [NiCl2(PPh3)2] is named as
dichloridobis(triphenylphosphine)nickel(II).
(v) Oxidation state of the metal in cation, anion or neutral coordination
entity is indicated by Roman numeral in parenthesis.
(vi) If the complex ion is a cation, the metal is named same as the
element. For example, Co in a complex cation is called cobalt and
Pt is called platinum. If the complex ion is an anion, the name of
the metal ends with the suffix – ate.
Ans 2) Aquachlorosilver(II) chloride
Ans 3) Na4[PtCl4(OH)2]
Explanation / Answer
Individual homework Ne1 (Topic «Oxidation-reduction reaction. Coordination compounds») V-8 I. Balance the following oxidation-reduction equation ASH, + HNO H,Aso, + NO + H2O 2. Name the compound: [Ag(H,O)CI]CI 3. Write the formula of the following compound: sodium dihydroxotetrachloroplatinate (IV) 4. Given the ions and molecules: Zn". CN., NH,, H20, K··The coordination number is 4, Write the formulas of the coordination compounds. Name the compounds.