notes on nomenclature pecially in formulas. A list of common abbreviations is given in (9) below. Unfortunately, divergent practices have developed with consequent confusion. The following simple rules should govern the use of abbreviations
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How Should Abbreviations Be Used? When we know a person well we are prone to abandon formal titles and address him by a familiar name or nickname. Chemists are inclined to follmr the same procedure with familiar compounds particularly if the systematic name is a long one. The advantages of a short name or an abbreviation based on the systematic name are obvious. However, when we introduce a friend to another person, we usually use the formal title. Chemists in thcir oral and written prcsentations are not always careful to formally introduce others to the compounds which are familiar to them but not necessarily familiar to others. The Council of the American Chemical Society has requested that once in every article in a publication of the Society a complete systematic name for the subject compound be given. Not all chemical publications receive this careful scrutiny and not all reviewers are as sensitive to this matter as might be desired. Consequently, chemists are frequently confronted with entirely unfamiliar abbreviations and even names which are not elucidated in the text at hand. Areas in which the use of abbreviations are especially prevalent are biochemistry, commercial products, and coordination compounds. As yet there are no standard procedures for formulating abbreviations although Chemical Abstracts has adopted a list of acceptable abbreviations for its own use. In order to call attention to the situation and to bring some semblance of order to the confusion, the IUPAC Commission on tho Nomenclature of Inorganic Chemistry has included in its revised rules the section quoted below. I t is obvious that this is only a beginning. 7.35-Use
of Abbreviations
In the literature of coordination compounds, abbreviations for ligand names are used extensively, es488
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(1) It should be assumed that the reader will not be familiar with any but the most common abbreviations. Consequently, each paper should explain the abbreviations used in it. (2) Abbreviations should be short-generally not in excess of four letters. (3) Abbreviations should not be snch as to cause coniusion with the commonly accepted abbreviat,ions used for organic radicals: ?&,methyl; El,, ethyl; Ph, phenyl, etc. (4) All abbreviations for ligands, except L the general abbreviation for ligand and those shown with initial capital letters under 6shall be inlower case 1et.ters: en, pn, tren, bpy, etc.; M shall he the~general abbreviation ~ ~ I for metal.~ ~ ( 5 ) Abbreviations should not involve hyphens: e.g., phen not o-phen for o-phenanthroline (or 1,lO-phenanbhroline). (6) The neutral compound and the ligand ion derived from it should be clearly differentiated. Hacac, acetylacetone; acac, acetylacetonilto Hldmg, dimethylglyoxime (la-butanedione dioxime) 'Idrng, dimethylglyoximato(1-) d m ~dimethylglyoximato(2-) , B'edta, ethylenediaminetetraaeetic acid Hedt.a or edta, coordinated ions derived from H4edta. (7) In using abbreviations, care should be taken to be sure there is no confusion with symbols. The abbreviations should he separated from symbols or enclosed in parentheses.
[Co(en)rlJ+or [Co em]" not [CoenrlaC (8) Abbreviations for molecules or ions combined with the commonlv used svmbols for oreanic eroum sneh as Eten for A ei hvfptbv1ene"diamme: hfeaeac for 3-methvl-2.4-oentanedi-
organic groups are preferable. CHsCOCH(C*Hs)COCHa HCEtAc2
(9) Commonly used abbreviations are Anionic groups (parent acids given) Hncac acetvlacetone.. 2,4oentanedione, CHCOCH2. . COCH~ Hhe hienanide., H*NC(NH)NHC(NH)NH? -~ , , . . H.dmg dimethylglyoxime, 2,3-butanedione dioxime, CHaC(=NOH)C(=NOH)CHs Hledt.a et,hylenediaminetetraaceric acid, (HOOCCH>)r NCH2CH9N(CH2COOH)a Hlox oxalic acid. HOOC .COOH Neutral groups bpy 2,2'-bipyridine or Cut No 94399 2,2'-bipyridyl, o-phenylenebis(dimethylarsine), (CH8)nAsCaH4Asdiam ~
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dim diethylonetriamine, HvNCH2CH1NHCHCH3NHn diphos ethylenebis(diphenylphosphme), Ph2PCH2CH2DPI. L A > .
en
ethylenediamine, H2NCH2CHxNHq
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1,lO-phenanthroline,
pn py tren trien ur
propylenediamine, H2NCH(CHa)CHsNHa pyridine 2,2',2"-triaminotriethfimine, (H.NCHCH2)sN triethvlenetetraamine, (H2NCH2CH1NHCHt)2 urea, ~ H ~ N ) & o
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The Second Edition of the "Red Book" Those interested in the subject of chemical nomenclature should he aware of the appearance of a significant contribution to this subject issued by the Commission on the Nomenclature of Inorganic Chemistry of the International Union of Pure and Applied Chemistry. This report is entitled "Nomenclature of Inorganic Chemistry, Definitive Rules 1970" (1). Although the report is published in Pure and Applied Chemistry, the official organ of IUPAC, it is also available in book form (Butterworths). This report replaces the Definitive Rules 1957 (2) which because of the color of the binding became known as the "Red Book" to distinguish it from the corresponding "Blue Books" released by the Commission on the Nomenclature of Organic Chemistry (3'). The new edition of the "Red Book" embodies a number of significant clarifications, extensions, and additions to and a few changes from the earlier edition. These deserve comment. Language. The previous edition of the Rules was in hoth English and French. Because of the expansion of the rules, economics dictated that there be separate publication in each language. Nevertheless, the present hook is 110 pages whereas the dual language first edition had 93 pages. Preamble. The basic principles underlying inorganic nomenclature are different in many respects from those underlying organic nomenclature. These principles for inorganic nomenclature are less well understood than those for organic nomenclature. Consequently, a preamble has been added which presents the concepts of oxidation number and coordination number and describes fully the use of multiplying affixes, enclosing marks, numbers, and letters. Many of these have been treated in previous installments of these Notes (4). A and B Subgroups. The Commission has taken a stand for adhering to the A and B designations of the original Mendeleev periodic table rather than the modification introduced by Deming (6). This decision will not find favor in this country where the Deming table is on the wall of most lecture rooms and in nearly every textbook of introductory chemistry. Alphabetical Order of Listing Related Cmstituats. In double salts, oxide salts, and hydroxide salts, hoth the electropositive (except hydrogen) and electronegative constitutents are listed in alphabetical order KMgFa NaNH,HPO,
magnesium potassium fluoride ammonium sodium hydrogen phosphate (see below) NaaC1F(S0,)9 hexasodium chloride fluoridebis(sulfat,e) MgCI(0H) magnesium chloride hydroxide VO(S0d vanadium(1V)oxide sulfate
Strictly alphabetical order without regard to charge is used for ligands in coordination compounds. In formulas, the constituents of intermetallic compounds are placed in alphabetical order of their symbols rather than in the complicated order previously recommended. Ewens-Bassett System. The practice of indicating the charge on a complex ion by an Arabic number is accepted as an alternate to indicating the oxidation state of a central ion by a Roman number: iron(2+) or iron(I1) chloride.
Hydrides. The -ane ending is favored even more than previously: germane (GeHp), diphosphane (PzHa). Radicals. In names for polyatomic radicals, the use of di- is preferred to pyro-: PzOi4-, diphosphate. Iso- and Hetero-polyanions, These important classes of compounds constitute Chapter 4 of the Second Edition. In the previous edition these compounds were covered in Sections 7.5 and 7.6. The treatment has been greatly expanded (6) to include rings and substitution products. 0 x 0 Acids. The following changes in the names of acids (Chap. 5) have been made H2PHOa HPHIOl
phosphonic instead of phosphorous acid phosphinie instead of hypophosphorous acid H~P~OS diphosphonie instead of diphasphorous acid (HO)IOP-PO(OH)* hypophosphoric or diphosphoric (IV) acid
The last name is probably constructed after the pattern previously used for (H0)tP-0-PO(OH),, diphosphoric(111, V) acid. Double Salts Including Acid and Hydroxide-Oxide Salts. When more than one cation or anion are present they are cited in alphabetical order (see above) rather than in an order based on magnitude of charge, atomic number, and electronegativity. Many in this country will disagree with the Commission's decision to retain hydrogencarbonate (HC03-), etc. as one word. The Commission takes the position that they wish a name for the ion HC03- and hence write hydrogencarbonate as one word. Almost all nomenclature students in this country note that hydrogen is never used as a prefix and therefore two words are required. Coordinatim Compounds. Previously this section was seven pages long hut now comprises 47 pages. Several simplifications as well as new material have been introduced. Two of the simplifications are especially notexorthy. First, the order of citation of ligands, regardless of charge, composition, or type, is now strictly alphabetical. Second, the EwensBassett system is permitted not only for indicating the charge on a complex ion, [Co(en)(Cz04)~]-, (ethylenediamine)dioxalatocobaltate(l-) ion, but also that on a ligand when desired [Co{C2H4[N(CHr C00)2j2}NCS]a-, [ethylenediaminetetraacetate(4-)]thiocyanatocobaltate(3-). These modifications to coordination nomenclature practice render the system more useable and applicable to a wide range of chemical situations. Much progress has been made in using acceptable organic names for ligands instead of the rather old-fashioned and trivial names which have persisted in this field. A section on the use of abbreviations is included. An entirely new and rather extensive section on the naming of complexes with unsaturated molecules or groups is included. (This is modified from a preliminary publication (7).) Another new section is on the designation of isomers. This includes complexes with multidentate ions and a variety of configurations. A pattern for assigning locants to ligand positions in the coordination sphere has been adopted for nomenclature purposes. Further, it has been extended to di- and polynuclear compounds with bridging groups. The treatment of extended Volume 49, Number 7, July 1972
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structures is expanded. A completely new section on di- and polynuclear compounds with metal-metal bonds (with or without bridging groups) has been added. A treatment of absolute configurations has been added (8). An unofficial summary of many of the above changes appeared in 1966 (9). Several aspects of coordination nomenclature will be discussed later in these Notes. Addition Compounds. Formerly Section 7.7, the material on addition compounds now constitutes Chapter 8. The only significant change is the use of the diagonal or solidus instead of the colon for indicating the number of molecules. 3CdSO4.8H20 Cadmium sulfate-water (3/8) 8CHCb. 16HL3.136H20 Chloroform-hydrogen sulfide-water (8/16/136) Recent action by the ACS Committee on Nomenclature approves the use of the diagonal not only with numbers but also in place of dashes in the name. Crystalline Phases of Variable Composition. This chapter has bccn revised and expanded considerably. Previously Chapter 4, it now compriscs Chapter 9. Devices have bccn introduced for rcpreseuting sitcs in the structure of thc ideal composition and also interstitial sites, for distinguishing bctwccn tetrahedral and octahodral sitcs, for representing vacant sitcs, for designating a sitc on a surface, and for designating electron and positive holes (10). Boron Compounds. Chapter 11 on Boron Com-
490
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Journal o f Chemical Education
pounds (6 pages) has been added (11). The Chapter is essentially an abbreviated form of the rules adopted by the American Chemical Society (13). Names jor Ions and Raclicals. The table of names for ions and radicals has been expanded. Index. The usefulness of the second edition is greatly enhanced by an index. Literature Cited ( 1 ) "Nomenclature of Inorganic Chemistry" (2nd ed.). Pure Appl. Cham. 28 ( 1 ) . 1-110 (1971); issued as a hound book by Butterwonha, London; U S . agent: Crane, Russak, and Co. ( 2 ) "Nomenelature of Inorganic Chemistry." Butterworths. London. 1959. ( 3 ) "Nomenclature oi Organic Chemistry." Seotions A & B (2nd ed.), Butterwortha, London. 1966; Seotion C. Butterwonha. London, 1965: Seotions A , B, and C Combined (3rd ed.) Butterworths,
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