Everything about Iupac Nomenclature Of Inorganic Chemistry 2005 totally explained

The IUPAC Recommendations 2005, Nomenclature of Inorganic Chemistry replaces their previous recommendations "Nomenclature of Inorganic Chemistry, IUPAC Recommendations 1990 (Red Book I)", and "where appropriate" (sic) "Nomenclature of Inorganic Chemistry II, IUPAC Recommendations 2000 (Red Book II)". The recommendations take up over 300 pages and the full text can be downloaded from IUPAC. (External Link

) Corrections have been issued. (External Link

)

Apart from a reorganisation of the content, there's a new section on organometallics and a formal element list to be used in place of electronegativity lists in sequencing elements in formulae and names. The concept of a preferred IUPAC name (PIN), a part of the revised blue book for organic compound naming, hasn't yet been adopted for inorganic compounds. There are however guidelines as to which naming method should be adopted.

Naming methods

The recommendations describe a number of different ways in which compounds can be named. These are:

compositional naming (for example sodium chloride)
substitutive naming based on parent hydrides (GeCl₂Me₂ dichlorodimethylgermane)
additive naming ([MnFO₃] fluoridotrioxidomanganese) Additionally there are recommendations for the following:
naming of cluster compounds
allowed names for inorganic acids and derivatives
naming of solid phases for example non-stoichiometric phases For a simple compound such as AlCl₃ the different naming conventions yield the following:
compositional: aluminium trichloride (stoichiometrically) or dialuminium hexachloride (dimer)
substitutional: trichloralumane
additive: trichloridoaluminium; hexachloridoaluminium (dimer without structural information); di-μ-chlorido-tetrachlorido-1κ²Cl,2κ²Cl-dialuminium (dimer with structural information)

Sequencing elements - the "electronegativity" list

Throughout the recommendations the use of the electronegativity of elements for sequencing has been replaced by a formal list which is loosely based on electronegativity. The recommendations still use the terms electropositive and electronegative to refer to an elements relative position in this list.
A simple rule of thumb ignoring lanthanides and actinides is:

for two elements in different groups - then the element in the higher numbered group has higher "electronegativity"

for two elements within the same group the element with the lower the atomic number has the higher "electronegativity"

Hydrogen is fitted in to be less electronegative than polonium and more electronegative than nitrogen. Hence the formulae of water and ammonia can be written NH₃ and H₂O respectively. The full list, from highest to lowest "electronegativity":-

Group 17 in atomic number sequence for example F-At followed by

Group 16 in atomic number sequence for example O-Po followed by

H, hydrogen followed by

Group 15 in atomic number sequence for example N-Bi followed by

Group 14 in atomic number sequence for example C-Pb followed by

Group 13 in atomic number sequence for example B-Tl followed by

Group 12 in atomic number sequence for example Zn-Hg followed by

Group 11 in atomic number sequence for example Cu-Rg followed by

Group 10 in atomic number sequence for example Ni-Ds followed by

Group 9 in atomic number sequence for example Co-Mt followed by

Group 8 in atomic number sequence for example Fe-Hs followed by

Group 7 in atomic number sequence for example Mn-Bh followed by

Group 6 in atomic number sequence for example Cr-Sg followed by

Group 5 in atomic number sequence for example V-Db followed by

Group 4 in atomic number sequence for example Ti-Rf followed by

Group 3 in atomic number sequence for example Sc-La followed by

the lanthanides in atomic number sequence for example La-Lu followed by

the actinides in atomic number sequence for example Ac-Lr followed by

Group 2 in atomic number sequence for example Be-Sg followed by

Group 1 (excl H) in atomic number sequence for example Li-Fr followed by

Group 18 in atomic number sequence for example He-Rn

Determining the nomenclature to use

Action	Addition compound?	efinite stoichiometry?	ono-atomic?	olecular?	etal present?	ond to carbon?	rans metal group3-12?	ain groupmetal groups 1,2,3-6?
Treat each component separately use compositional	Y
use solids naming	N	N
Element or monoatomic cation/anion/radical naming	N	Y	Y
Divide components into "electropositive"/"electronegative" treat each component separately use generalised stoichiometric naming	N	Y	N	N
Use Blue book (Organic compound)	' N	Y	N	Y	N	Y
Use additive naming for group 3- 12 organometallics	N	Y	N	Y	Y	Y	Y
Use substitutive naming for group 3- 6 organometallics Use compositional for groups 1-2 organometallics	N	Y	N	Y	Y	Y	N	Y
Use additive naming for coordtn. complexes	N	Y	N	Y	Y	N	Y
Choose either substitutive or additive	N	Y	N	Y	N	N

Note "treat separately" means to use the decision table on each component

Compositional nomenclature

Element names

Sample of indeterminate structure

An indeterminate sample simply takes the element name.For example a sample of carbon (which could be diamond, graphite etc or a mixture) would be named carbon.

Specific allotrope

Molecular

O₂ dioxygen (acceptable name oxygen)

O₃ trioxygen (acceptable name ozone)

P₄ tetraphosphorus (acceptable name white phosphorus)

S₆ hexasulfur (acceptable name ε-sulfur)

S₈ cyclo-octasulfur (acceptable names for the polymorphic forms are α-sulfur, β-sulfur, γ-sulfur)

Crystalline form

This is specified by the element symbol followed by the Pearson symbol for the crystal form.(Note that the recomendations specifically italicise the second character.

C_n carbon(cF8) (acceptable name diamond)

Sn_n tin(tI4) (acceptable name β- or white tin )

Mn_n manganese(cI58) (acceptable name α-manganese)

Amorphous recognised allotropes

Examples include P_n,. red phosphorus ; As_n, amorphous arsenic.

Compounds

Compositional names impart little structural information and are recommended for use when structural information isn't available or doesn't need to be conveyed. Stoichiometric names are the simplest and reflect either the empirical formula or the molecular formula. The ordering of the elements follows the formal electronegativity list for binary compounds and electronegativity list to group the elements into two classes which are then alphabetcally sequenced. The proportions are specified by di-, tri-, etc. Where there are known to be complex cations or anions these are named in their own right and then these names used as part of the compound name.

Binary compounds

In binary compounds the more electropositive element is placed first in the formula. The formal list is used. The name of the most electronegative element is modified to end in -ide and the more electropositive elements name is left unchanged.
Taking the binary compound of sodium and chlorine: chlorine is found first in the list so therefore comes last in the name. Other examples are

PCl₅ phosphorus pentachloride

Ca₂P₃ dicalcium triphosphide

NiSn nickel stannide

Cr₂₃C₆ tricosachromium hexacarbide

Ternary compounds and beyond

The following illustrate the principles.
The 1:1:1:1 quaternary compound between bromine chlorine iodine and phosphorus :

PBrClI phosphorus bromide chloride iodide (phosphorus is the most electropositive, the others are all designated as electronegative and are sequenced alphabetically) The ternary 2:1:5 compound of antimony, copper and potassium can be named in two ways depending on which element(s) are designated as electronegative.

CuK₅Sb₂ copper pentapotassium diantimonide,(both copper and potassium are designated as electropositive and are sequenced alphabetically)

K₅CuSb₂ pentapotassium diantimonide cupride (only potassium is designated as electropositive and the two electronegative elements are sequenced alphabetically) (Note the red book shows this example incorrectly)

Naming of ions and radicals

Cations

Monoatomic cations are named by taking the element name and following it with the charge in brackets e.g

Na⁺sodium(1+)

Cr³⁺ chromium(3+) Sometimes an abbreviated from of the element name has to be taken, for example germide for germanium as germanide refers to GeH₃⁻.
Polyatomic cations of the same element are named as the element name preceded by di-, tri-, etc., for example:

Hg₂²⁺ dimercury(2+) Polyatomic cations made up of different elements are named either substitutively or additively, for example :

PH₄⁺ phosphanium

SbF₄⁺ tetrafluorostibanium (substitutive) or tetrafluoridoantimony(1+)

Note that ammonium and oxonium are acceptable names for NH₄⁺ and OH₃⁺ respectively. (Hydronium isn't an acceptable name for OH₃⁺ )

Anions

Monatomic anions are named as the element modified with an -ide ending. The charge follows in brackets, (optional for 1−) for example:

Cl⁻ chloride(1−) or chloride

S²⁻ sulfide(2−) Some elements take their Latin name as the root e.g

silver, Ag, argentide

copper, Cu, cupride

iron, Fe, ferride

tin, Sn, stannide Polyatomic anions of the same elemnt are named as the element name preceded by di-, tri-, etc., for example:

O₂²⁻ dioxide(2−) (or peroxide as an acceptable name)

C₂²⁻ dicarbide(2−) (or acetylide as an acceptable name)

S₂²⁻ disulfide(2−) or sometimes as an alternative derived from a substitutive name for example

S₂²⁻ disulfanediide Polyatomic anions made up of different elements are named either substitutively or additively, the name endings are -ide and -ate respectively for example :

GeH₃⁻ germanide (substitutive), or trihydridogermanate(1−) (additive)

TeH₃⁻ tellanuide substitutive where -uide specifies anion composed of additional hydride attached to parent hydride

[PF₆]⁻ hexafluoro-λ⁵-phosphanuide (substitutive), or hexafluoridophosphate(1−) (additive)

SO₃²⁻ trioxidosulfate(2−) (additive), or sulfite (acceptable non-systematic name) A full list of the alternative acceptable non-systematic names for cations and anions is in the recommendations. Many anions have names derived from inorganic acids and these are dealt with later.

Radicals

The presence of unpaired electrons can be indicated by a "·". For example:

He^·+ helium(·+)

N₂^(2·)2+ dinitrogen(2·2+)

Naming of hydrates and similar lattice compounds

The use of the term hydrate is still acceptable for example Na₂SO₄·10H₂O, sodium sulfate decahydrate. The recommended method would be to name it sodium sulfate—water(1/10). Similarly other examples of lattice compounds are:

CaCl₂·8NH₃, calcium chloride— ammonia (1/8)

2Na₂CO₃·3H₂O₂, sodium carbonate—hydrogen peroxide (2/3)

AlCl₃·4EtOH, aluminium chloride—ethanol (1/4)

Specifying proportions using charge or oxidation state

As an alternative to di-, tri- prefixes either charge or oxidation state can be used. Charge is recommended as oxidation state may be ambiguous and open to debate.

Substitutive nomenclature

This naming method generally generally follows established IUPAC organic nomenclature. Hydrides of the main group elements (groups 13-17) are given -ane base names, for example borane, BH₃. Acceptable alternative names for some of the parent hydrides are water rather than oxidane and ammonia rather than azane. In these cases the base name is intended to be used for substituted derivatives.
This section of the recommendations covers the naming of compounds containing rings and chains.

Base hydrides

BH₃	borane	CH₄	methane	NH₃	azane (ammonia)	H₂O	oxidane (water)	HF	fluorane (hydrogen fluoride)
AlH₃	alumane	SiH₄	silane	PH₃	phosphane	H₂S	sulfane (hydrogen sulfide or dihydrogen sulfide)	HCl	chlorane (hydrochloric acid)
GaH₃	gallane	GeH₄	germane	AsH₃	arsane	H₂Se	selane	HBr	bromane (hydrobromic acid)
InH₃	indigane	SnH₄	stannane	SbH₃	stibane	H₂Te	tellane (hydrogen telluride or dihydrogen telluride)	HI	iodane (hydroiodic acid)
TlH₃	thallane	PbH₄	plumbane	BiH₃	bismuthane	H₂Po	polane (hydrogen polonide or dihydrogen polonide)	HAt	astatane

Hydrides with non-standard bonding - lambda convention

Where a compound has non standard bonding as compared to the parent hydride for example PCl₅ the lambda convention is used. For example:

PCl₅ pentachloro-λ⁵-phosphane

SF₆ hexafluoro-λ⁵-sulfane

Polynuclear hydrides

A prefix di-, tri- etc is added to the parent hydride name. Examples are:-

HOOH, dioxidane (hydrogen peroxide is an acceptable name)

H₂PPH₂, diphosphane

H₃SiSiH₂SiH₂SiH₃, tetrasilane

Rings and Chains

The recommendations describe three ways of assigning "parent" names to homonuclear monocyclic hydrides (i.e single rings consisting of one element):

the Hantzsch–Widman name (the method preferred for rings of size 3-10)

"skeletal replacement nomenclature" - specifying the replacement of carbon atoms in the corresponding carbon compound with atoms of another element (for example silicon becomes sila, germanium, germa) and a multiplicative prefix tri, tetra, penta etc)(the method preferred for rings greater than 10)

by adding the prefix ‘cyclo’ to the name of the corresponding unbranched, unsubstituted chain

Boron hydrides

The stoichiometric name is followed by the number of hydrogen atoms in brackets. For example B₂H₆, diborane(6). More structural information can be conveyed by adding the "structural descriptor" closo-, nido-, arachno-, hypho-, klado- prefixes.
There is a fully systematic method of numbering the atoms in the boron hydride clusters, and a method of describing the position of bridging hydrogen atoms using the μ symbol.

Main group organometallic compounds

Use of substitutive nomenclature is recommended for group 13-16 main group organometallic compounds. Examples are :

AlH₂Me named methylalumane

BiI₂Ph named diiodo(phenyl)bismuthane For organometallic compounds of groups 1-2 can use additive (indicating a molecular aggregate) or compositional naming. Examples are:

[BeEtH] named ethylhydridoberyllium or ethanidohydridoberyllium

[Mg(η⁵-C₅H₅)₂] named bis(η⁵-cyclopentadienyl)magnesium, or bis(η⁵-cyclopentadienido)magnesium

Na(CHCH₂) sodium ethenide (compositional name) However the recommendation notes that future nomenclature projects will be addressing these compounds.

Additive nomenclature

This naming has been developed principally for coordination compounds although it can be more widely applied. Examples are:

Si(OH)₄ tetrahydroxidosilicon (additive),or silanetetrol (substitutive) (note silicic acid is an acceptable name - orthosilicic has been dropped).

[CoCl(NH₃)₅]Cl₂ pentaamminechloridocobalt(2+) chloride

Recommended procedure for naming mononuclear compounds

The recommendations include a flow chart which can be summarised very briefly:

identify the central atom,

identify and name the ligands,

specify coordination mode of ligands for example using kappa and/or eta conventions

sequence the ligands

specify coordination geometry i.e polyhedral symbol,configuration index (using CIP rules and absolute configuration for optically active compounds.

Ligand names

Anionic ligands

If the anion name ends in -ide then as a ligand its name is changed to end in -o. For example the chloride anion, Cl⁻ becomes chlorido. This is a difference from organic compound naming and substitutive naming where chlorine is treated as neutral and it becomes chloro, as in PCl₃, which can be named as either substitutively or additively as trichlorophosphane or trichloridophosphorus respectively.
Similarly if the anion names end in -ite, -ate then the ligand names are -ito, -ato.

Neutral ligands

Neutral ligands don't change name with the exception of the following:

water, "aqua"

ammonia, "ammine"

carbon monoxide bonded via carbon, "carbonyl"

nitrogen monoxide bonded via nitrogen, "nitrosyl"

Examples of ligand names

Formula	ame
Cl⁻	chlorido
CN⁻	cyanido
H⁻	hydrido
D⁻or ²H⁻	deuterido or [²H]hydrido
PhCH₂CH₂Se⁻	2-phenylethane-1-selenolato
MeCOO⁻	acetato or ethanoato
Me₂As⁻	dimethylarsanido
MePH⁻	methylphosphanido
MeCONH₂	acetamide (not acetamido)
MeCONH⁻	acetylazanido or acetylamido (not acetamido)
MeNH₂	methanamine
MeNH⁻	methylazanido, or methylamido, or methanaminido
MePH₂	methylphosphane
CO	carbonyl

Sequence and position of ligands and central atoms

Ligands are ordered alphabetically by name and precede the central atom name. The number of ligands coordinating is indicated by the prefixes di-, tri-, tetra- penta- etc for simple ligands or bis-, tris-, tetrakis-,etc for complex ligands. For example:

[CoCl(NH₃)₅]Cl₂ pentaamminechloridocobalt(2þ) chloride where ammine (NH3)precedes chloride. The central atom name(s) come after the ligands. Where there's more than one central atom it's preceded by di- tr-, tetra- etc.

Os₃(CO)₁₂, decacarbonyldihydridotriosmium Where there are different central atoms they're sequenced using the electronegativity list.

[ReCo(CO)₉] nonacarbonylrheniumcobalt

Bridging ligands- use of μ symbol

Ligands may bridge two or more centres. The prefix μ is used to specify a bridging ligand in both the formula and the name. For example the dimeric form of aluminium trichloride: � Al₂Cl₄(μ-Cl)₂

� di-μ-chlorido-tetrachlorido-1κ²Cl,2κ²Cl-dialuminium

This example illustrates the ordering of bridging and non bridging ligands of the same type. In the formula the bridging ligands follow the non bridging whereas in the name the bridging ligands precede the non bridging. Note the use of the kappa convention to specify that there are two terminal chlorides on each aluminium.

Bridging index

Where there are more than two centres that are bridged a bridging index is added as a subscript. For example in basic beryllium acetate which can be visualised as a tetrahedral arrangement of Be atoms linked by 6 acetate ions forming a cage with a central oxide anion, the formula and name are as follows:
� [Be₄(μ₄-O)(μ-O₂CMe)₆]

� hexakis(μ-acetato-κO:kO′)-μ₄-oxido-tetrahedro-tetraberyllium

The μ₄ describing the bridging of the central oxide ion. (Note the use of the kappa convention to describe the bridging of the acetate ion where both oxygen atoms are involved.) In the name where there a ligand is involved in different modes of bridging, the multiple bridging is listed in decreasing order of complexity, for example μ₃ bridging before μ₂ bridging.

Kappa,κ, convention

The kappa convention is used to specify which ligand atoms are bonding to the central atom and in polynuclear species which atoms, both bridged and unbridged link to which central atom. For monodentate ligands there's no ambiguity as to which atom is forming the bond to the central atom. However when a ligand has more than one atom that can link to a central atom the kappa convention is used to specify which atoms in a ligand are forming a bond. The element atomic symbol is italicised and preceded by kappa,κ. These symbols are placed after the portion of the ligand name that represents the ring, chain etc where the ligand is located. For example:

pentaamminenitrito-κO-cobalt(III) specifies that the nitrite ligand is linking via the oxygen atom Where there's more than one bond formed from a ligand by a particular elemnt aq numerical superscript gives the count. For example:

aqua[(ethane-1,2-diyldinitrilo-κ²N,N’)tris(acetato-κO)acetato]cobaltate(1-), the cobalt anion formed with water and pentadentate edta, which links via two nitrogen atoms and three oxygen atoms. There are two bonds from nitrogen atoms in edta which is specified by -κ²N,N’. The three bonds from oxygen are specified by tris(acetato-κO), where there's one ligation per acetate. In polynuclear complexes the use of the kappa symbol is extended in two related ways. Firstly to specify which ligating atoms bind to which central atom and secondly to specify for a bridging ligand which central atoms are involved. The central atoms must be identified, for example by assigning numbers to them. (This is formally dealt with in the recommendations). To specify which ligating atoms in a ligand link to which central atom, the central atom numbers precede the kappa symbol, and numerical superscript specifies the number of ligations and this is followed by the atomic symbol. Multiple occurrences are separated by commas.
   Examples: � di-μ-chlorido-tetrachlorido-1κ²Cl,2κ²Cl-dialuminium, (aluminium trichloride).

   : tetrachlorido-1κ²Cl,2κ²Cl specifies that there are two chloride ligands on each aluminium atom. � decacarbonyl-1κ³C,2κ³C,3κ⁴C-di-μ-hydrido-1:2κ²H;1:2κ²H-triangulo-(3 Os—Os), (Decacarbonyldihydridotriosmium).

   :decacarbonyl-1κ³C,2κ³C,3κ⁴C shows that there are three carbonyl groups on two osmium atoms and four on the third. � :di-μ-hydrido-1:2κ²H;1:2κ²H specifies that the two hydride bridge between the osmium atom 1 and osmium atom 2.

Eta, η, convention

The use of η to denote hapticity is systematised. The use of η¹ isn't recommended. When the specification of the atoms involved is ambiguous the position of the atoms must be specified. This is illustrated by the examples:

Cr(η⁶-C₆H₆)₂, named as bis(η⁶-benzene)chromium as all of the (contiguous) atoms in the benzene ligands are involved there position doesn't have to be specified

[(1,2,5,6-η)-cycloocta-1,3,5,7-tetraene](η⁵-cyclopentadienyl)cobalt in this only two (at positions 1 and 5) of the four double bonds are linked to the central atom.

Coordination geometry

For any coordination number above 2 more than one coordination geometry is possible. For example four coordinate coordination compounds can be tetrahedral, square planar, square pyramidal or see-saw shaped. The polyhedral symbol is used to describe the geometry. A configuration index is determined from the positions of the ligands and together with the polyhedral symbol is placed at the beginning of the name. For example in the complex (SP-4-3)-(acetonitrile)dichlorido(pyridine)platinum(II) the (SP-4-3) at the beginning of the name describes a square planar geometry, 4 coordinate with a configuration index of 3 indicating the position of the ligands around the central atom. For more detail see polyhedral symbol.

Organometallic groups 3-12

Additive nomenclature is generally recommended for organometallic compounds of groups 3-12 (transition metals and zinc, cadmium and mercury).

Metallocenes

Following on from ferrocene the first sandwich compound with a central Fe atom coordinated to two parallel cyclopentadienyl rings, names for compounds with similar structures such as osmocene and vanadocene are in common usage. The recommendation is that the name-ending ‘ocene’ should be restricted to compounds where there are discrete molecules of bis(η⁵-cyclopentadienyl)metal (and ring-substituted analogues), where the cyclopentadienyl rings are essentially parallel, and the metal is in the d-block. The terminology does NOT apply to compounds of the s- or p-block elements such as Ba(C₅H₅)2 or Sn(C₅H₅)2].
Examples of compounds that meet the criteria are :

vanadocene, [V(η⁵-C₅H₅)₂]

chromocene, [Cr(η⁵-C₅H₅)₂]

cobaltocene, [Co(η⁵-C₅H₅)₂]

nickelocene, [Ni((η⁵-C₅H₅)₂]

ruthenocene, [Ru(η⁵-C₅H₅)₂]

osmocene, [Os(η⁵-C₅H₅)₂]

decamethylmanganocene, [Mn(η⁵-C₅H₅)₂]

[Re(η⁵-C₅H₅)₂]. Examples of compounds that shouldn't be named as metallocenes are:

C₁₀H₁₀Ti

[Ti(η⁵-C₅H₅)₂Cl₂] is named dichloridobis(η⁵-cyclopentadienyl)titanium NOT titanocene dichloride

Polynuclear cluster compounds

Metal-metal bonds

In polynuclear compounds with metal- metal bonds these are shown after the element name as follows:
(3 Os—Os) in Decacarbonyldihydridotriosmium A pair of brackets contain a count of the bonds formed (if greater than 1), followed by the the italicised element atomic symbols separated by an "em-dash".

Polynuclear cluster geometry

The geometries of polynuclear clusters can range in complexity. A descriptor for example tetrahedro or the CEP descriptor for example Td-(13)-Δ⁴-closo] can be used. this is determined by the complexity of the cluster. Some examples are shown below of descriptors and CEP equivalents. (The CEP descriptors are named for Casey, Evans and Powell who described the system.

number of atoms	descriptor	EP descriptor
3	triangulo
4	quadro
4	tetrahedro	[Td-(13)-Δ⁴-closo]
5		[D_3h-(131)-Δ⁶-closo]
6	octahedro	[O_h-(141)-Δ⁸-closo]
6	triprismo
8	antiprismo
8	dodecahedro	[D_2d-(2222)-Δ⁶-closo]
12	icosahedro	[I_h-(1551)-Δ²⁰-closo]

Examples:
decacarbonyldimanganese bis(pentacarbonylmanganese)(Mn—Mn)
dodecacarbonyltetrairidium tri-μ-carbonyl-1:2κ²C;1:3κ²C;2:3κ²C-nonacarbonyl- 1κ²C,2κ²C,3κ²C,4κ³C-[T_d-(13)-Δ⁴-closo]-tetrarhodium(6 Rh—Rh)
or tri-μ-carbonyl-1:2κ²C;1:3κ²C;2:3κ²C-nonacarbonyl- 1κ²C,2κ²C,3κ²C,4κ³C-tetrahedro-tetrarhodium(6 Rh—Rh)

Inorganic acids

Hydrogen names

The recommendations include a description of hydrogen names for acids. The following examples illustrate the method:

HNO₃ hydrogen(nitrate)

H₂SO₄ dihydrogen(sulfate)

HSO₄⁻ hydrogen(sulfate)(2−)

H₂S dihydrogen(sulfide) Note that the difference from the compositional naming method (hydrogen sulfide) as in hydrogen naming there's NO space between the electropositive and electronegative components.
This method gives no structural information regarding the position of the hydrons (hydrogen atoms). If this information is tio be conveyed then the additive name should be used, (see the list below for examples).

List of acceptable names

The recommendations give a full list of acceptable names for common acids and related anions. A selection from this list is shown below.

acid acceptable name	related anions- acceptable names and additive names
boric acid, [B(OH)₃]
carbonic acid, [CO(OH)₂]
chloric acid, [ClO₂(OH)] hydroxidodioxidochlorine
chlorous acid, [ClO(OH)] hydroxidooxidochlorine
nitric acid, [NO₂(OH)] hydroxidodioxidonitrogen
nitrous acid,[NO(OH)] hydroxidooxidonitrogen
perchloric acid, [ClO₃(OH)] hydroxidotrioxidochlorine
phosphoric acid, [PO(OH)₃] trihydroxidooxidophosphorus
phosphonic acid, [PHO(OH)₂] hydridodihydroxidooxidophosphorus
phosphorous acid, H₃PO₃ trihydroxidophosphorus
sulfuric acid, [SO₂(OH)₂] dihydroxidodioxidosulfur

Solids

Stoichiometric phases are named compositionally. Non-stoichiometric phases are more difficult. Where possible formulae should be used but where necessary naming such as the following may be used:

iron(II) sulfide (iron deficient)

molybdenum dicarbide (carbon excess)

Mineral names

Generally mineral names shouldn't be used to specify chemical composition. However a mineral name can be used to specify the structure type in a formula for example

BaTiO₃ (perovskite type)

Approximate formulae &variable composition

A simple notation may be used where little information on the mechanism for variability is either available or isn't required to be conveyed:

~FeS (circa or approximately) Where there's a continuous range of composition this can be written for example, K(Br,Cl) for a mixture of KBr and KCl and (Li₂,Mg)Cl₂ for a mixture of LiCl and MgCl₂. The recommendation is to use trhe following generalised method for example

Cu_xNi_1-x for (Cu,Ni)

KBr_xCl_1-x for K(Br,Cl) Note that cation vacancies in CoO could be described by CoO_1-x

Point defects(Kröger-Vink) notation

Point defects, site symmetry and site occupancy can all be described using Kröger-Vink Notation, note that the IUPAC preference is for vacancies to be specified by V rather than V (the element vanadium).

Phase nomenclature

To specify the crystal form of a compound or element the Pearson symbol may be used. The use of "Strukturbericht" (for example A1 etc) or Greek letters isn't acceptable. The Pearson symbol may be followed by the space group and the prototype formula. Examples are:

carbon(cF 8), diamond

RuAl(CP22, Pm3m )(CsCl type)

Polymorphism

It is recommended that polymorphs are identified, (for example for ZnS where the two forms zincblende (cubic) and wurtzite (hexagonal))as ZnS(c) and ZnS(h) respectively.

Further Information

Get more info on 'Iupac Nomenclature Of Inorganic Chemistry 2005'.

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