that two oxalato groups would be named as a bis(oxalato) rather than a dioxalato complex. Here again, however, the textbooks are not consistent. I soon began to realize that there was little chance for the students to get i t right given the present state of their confused lecturers and textbooks and that there was a definite need for a rigorous set of rules to put, a t last, some order into the chaos. I would greatly appreciate hearing comments from your readers on this matter.
Textbook Survey Publisher Title
Year
Author(s) Page
System
F. A. Conon and G. Wilkinson Wiley Advanced Inorganic Chemistry, 4th hd. 1980 not given anionic then neutral used in text F. A. Conon and G. Wilkinson Wiley Basic inorganic Chemisfry 1977 p 137 neutral then anionic
Robert J. Lancashlre
B. Douglas, D. H. McDaniel, and J. J. Alexander Wiley Concepts snd Mcdels of Inorganic Chemistry 1983 Appendix B alphabetical p 768 T. Mmller Wiley inorganic Chemistr-A Modern lnwoduction 1982 p370 anionic, neutral, then cationic: ligands "often named in this order" but alphabetical used in examples
Edlter'o Note: Conard Fernelius, a well-known expert on nomenclb ture and participant in many IUPAC decisions, was asked to comment on the above lener. Before his death last summer he sent this d r m of an article giving an overview of the problems that produced the ambiguities commented on by Lancashire. We are publishing this version posthumously as a "lener reply" since it gives our readers a participantls view of the development of nomenclature.
Wiley B. Segal Chemishy--Experiment and Theory 1985 p 769 anionic, neubal, men cationic J. E. Brady and G. E. Humiston Wiley General Chemistry-Principles and Structure Sf, 3rd ad. 1982 p678 alphabetical R. H. Petrucci Collier Macmillan GeneralChemisw-Principles and Mcdem Applications, 41h ed. 1985 p 745 alphabetical
Harper and Row J. E. Huheey inorganic Chemisvy, 33rd ed. 1983 Appendix J alphabetical, but said ''anionic first" p A102 more common so will use that in examples
"Correct" Methods for Namlna lnoraanlc ComDounds To the Editor: "Practice does not make perfect; perfect practice makes perfect." Vince Lombardi
W. W. Porterfield Addisan-Wesley Inorganic Chemistry-A Unified Approach AppendixA alphabetical 1984 p 673 Saunders College inorganic Chemistry p519 1977
University of the West lndies Mona, Kingston 7, Jamaica
K. E. Purcell and J. C. Kotz alphabetical
N. N. Greenwood and A. Earnshaw Pergamon Chemistry of the Elements 1984 not given international Textbook Co. K. M. McKay and R. A. McKay inorganic Chemistry, 3rd ed. 1981 not given
With regard to the second problem, most texts give only limited advice. Usually a statement of the type: di-, tri-, tetra-, and so on, are used with simple ligand names and the prefixes bis-, tris-, tetrakis-, and so on, with more complicated ligand names. The preamble to the 1970 IUPAC publication on Inorganic Nomenclature (p 0.32) says "Chemists are not agreed on the use of the multiplicative affixes his, tris, etc. Some limit their use as far as possible and others follow the practice of 'when in doubt use them'." My own understanding of their use was that, if the ligand itself had amultiplier in itsname, then the alternate prefixes were used to eliminate any ambiguity. For example, dimethylamine might refer to two methylamines or one dimethylamine ligand, but bis(methy1amine) is unambiguous. A colleague once suggested to me that his working rule was to count the number of syllables in the name of the ligand. If it were more than three. then he used the alternate prefixes and enclosed the ligand in brackets. Thiv approach c&tainly makes it easv todrtermine which lirands are "rumdicatrd". and I have suggested to my studenis that this see& to be reasonable system to adopt. As an example, this would mean
a
Chemists have need to communicate as do the members of any other group or professionals. A general language like English is continually undergoing modification; so also is the language of chemistry. There are, however, some significant differences in the way this modification takes place. Not only are themeanings of existing words being broadened and new words introduced to denote new combinations, reactions, characteristics, etc., but also morphological practices are being sharpened to avoid confusion and misunderstanding. For a practicing chemist to be aware completely of the changes and to shift his own usage in harmony with the "best" practice, he needs help. What does he do when the sources do not always agree? First, how did the present situation arise? Systematic inorganic chemical nomenclature originated with Guyton de Morveau (I) was extended by him and his colleagues (2) and popularized by Lavoisier (3).This semisystematic inorganic nomenclature was an integral part of La Revolution Chimioue. It was based on comnosition and wa3 remarkable for irstime. In fact, it survives in significant part to the present dav because with relatively minor modification i t was able to krvive the impact of expanding knowledge and changing concepts. Hence, while organic chemists were busy developing sy&ematic' nomenclature for carbon compounds, inorganic chemists got along reasonably well with the nomenclature of Guyton de Morveau somewhat expanded. I t is said that the International Union of Chemistrv (forerunner of the oresent International Union of Pure a n d ~ p p l i e dChemistry (IUPAC)) found little enthusiasm among inorganic chemists when commissions on the "reform of chemical nomenclature" were appointed in 1920. Eventually, an inorganic commission became active and issued a
'
A systematic name reproduces the composition (and often the structure as well).
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Number 10 October 1987
901
,eport in 1940 (4). This was reprinted in a number of lanmaces and became the accented standard. The Commission in ;he Nomenclature of 1n;rganic Chemistry (CNIC) was ,eactivated in 1946 and produced an extensive report in 1957 5). This was reprinted in the standard handbooks and con.inued in subsequent editions almost to the present day. I t ,emains the authority most commonly referred to in compiations and textbooks. Why is this so when a revised edition ,f the Rules was published in 1971 (6) and another revision is n progress? IUPAC is not an organization with unlimited funds. In 'act, it barely remains solvent and is always looking for new rources of revenue. Between the publishing of the 1940 and ;he 1957,Rules, IUPAC signed a contract with an official ~ublisherin the hooe that orofits from nuhlications would provide some income. Although the Committee on Publications of the Union oermitted translation of the Rules and publication of the translation by an adhering society, they iid not permit republication in English by such a society. Hence, when the ACS soughtto publish an Americanversion ~fthe 1957 Rules, this could be done only upon the payment sf a significant royalty to the IUPAC publisher. The American version appeared (7) only because Chemical Abstracts, always the key organization for nomenclature activities in this country, paid the hill. (The IUPAC policy has recently been altered but the volume of the Rules has also heen increased and hence the cost of repuhlication.) There was no American version of the 1970 Rules and manv inoreanic chemist* do not even know of their existence. One w d d think that the release of the Rules as an IUPAC nul)lication and their appearance in Pure and Applied Chemistry would be sufficient for every practicing chemist and every chemical librarian to know abbut the ~ u i e sSuch . hasn't proven to be the case. Even the handbooks did not change. The high cost of the official IUPAC publication placed the hook beyond the financial reach of most individual chemists. So in all sincerity a knowledgeable chemist can feel he is up to date (1957 Rules) when, in reality, his practice has beensuperceded (1970 Rules). I once waited in the office of a distinguished chemist while he was answering a student's question. His answer was comoletelv wrone (bv 1970 Rules) althoueh. had I said anything, he could usetheiatest edition of hanib:bboks, etc., to justify his statement. Efforts have been made to call attention to some of these oddities in inorganic nomenclature, hut the reader interest simply isn't there. The situation is all the more ironic because everyone can obtain at reasonable cost, reliable information on chemical nomenclature from Chemical Abstracts (7). Even the search for the "official" or "approved" name does not result in absolute certainty. The IUPAC has no way of enforcing its decisions. The reports of its commissions must be adooted hv the national oreanizations that are consistent parts' of IUPAC. whateverenforcement there is of the IUPAC "recommendations" (the term that has currently replaced "rules") isleft to the individual countries. In general, IUPAC reports are accepted in this country by the ACS Committee on Nomenclature acting for the Society and the National Research Council (adhering body to NPAC). There are a few places where, for good reason, practice in this country does not agree with IUPAC (spelling of aluminum and ceiium, separation of hydrogen and carbonate for the HC03- ion, etc.) (8). Although the United States and the United Kingdom have a long record of agreement in chemical nomenclature (9, lo), there are a few differences. The Royal Chemical Society has an editorial committee for its publications that does not hesitate to alter an author's nomenclature. In this country, nomenclature matters are left to the editor of each journal with the result that policies are not com~letelvuniform. Anvone desirine a comoletelv acceptablLname would be weli advised to fhow the indexing practice of Chemical Abstracts. In doine so, however, one should be aware that the requirements for-indexing aremore 902
Journal of Chemical Education
restrictive than just locating a systematic name. In indexing, economy dictates that there be one, and only one, name for a given compound, whereas there may be more than one systematic name (11). 11is logical toassume that the principal task of nomenclature rommitt~es/commissionsis the develo~mentof superior nomenclature. Actually, the most impo;tant task i; the rudifieation oirxisting practirps and of rerognizing inronsisrencies and shortcomines. Finallv.. the results of their evaluations and proposals g u s t he made known t o users of nomenclature. The last orohablv is that which should -~~~ receive more attention. Lancashire in his letter (12) . . .ooints out two of the nlaces where considerable confusion exists. An examination of them will he illustrative of how progress in nomenclature comes about. The 1940 Inorganic Rules containno mention of bis-, tris-, etc. The 1957 Rules (5) (2.251) calls them multiplicative2 numerical prefixes and states that they are used when there are "a number of complexgroups of atoms particularly when the name indicates a numerical prefix with a different significance". There is the further statement that the "whole group may he placed in parentheses". The only example aiven is CalPCL19. calcium bis(bexafluoronhosohateL The 195j 0 r G k c Rules (13) state ( ~ 2 . g ) "The : presence of identical radicals each suhstituted in the same way may be indicated by the appropriate multiplying prefix his-, tris-, tetrakis-, pentakis-, etc. The c o m ~ l e t expression e denotine a side chain may be enclosed in parenthkses or the carbin atoms in side chains may be indicated by prime numbers". Note the use of may rather than are or should be. The 1965 Organic Rules (14) repeat the statement about "identical radicals each suhstituted in the same way" but adds "or to avoid ambiguity". Nothing is said about parentheses althoueh thev are used in the examoles. In the American versi& of the 1957 Rules (13G) the comment is inserted that Chemical Abstracts extends the use of bis-. tris-. etc. to "all complex expressions" and always uses parentheses with these prefixes. In i960 The Chemical Society (now Royal Chemical Society) published a Handbook for Chemical Societv Authors ( 1 5 ) . h it, there is a long fodtnote on the use of h a y in the 1957 Rules that includes the following:
.
~
~
A
The Chemical Society's practice is (i) to Use the simplest form which is clear in a particular case, (ii) to adopt the more usual di, tri, etc. in place of the less usual his-, tris-, etc., unless a definite advantage accrues with the latter, and (iii) to prime a single subsidiary numeral and thus avoid parentheses,but to use parentheses without primes when mare than one subsidiary numeral is required . . . . Bis, tris, etc. are most useful when immediately preceding another numerical prefix, as in 14-hisdimethylamin. . ..In eom~lex onaphthalene or his-2.4-dinitrophenvlhvdrazone . . rarecases, and then only, the useofparentheseswith bis, tris, &., may appear justified. By 1970, the direction of inorganic chemical research had moved in such a direction as to require extensive use of his-, tris-, tetrakis-, etc., with or without the use of parentheses. On balance. the desire for soecific directions (with the anticipated outcome of a lack ofconcensus) against a portrayal of the divided practice and leaving the decision to the user, led the Commission to opt for the latter. Since IUPAC straddles the fence, the Endish-s~eakinachemist either follows the practice of the ~ o i a~l h k m i c a l ~ ~ o c ior e tthat y of Chemical Abstracts. The order of listing ligands in names for coordination compounds is part of the general problem of the order of
Not a good term because "multiplying" and "multiplicative" are used for both sets of numerical prefixes.
listing constitutents in a name. First, however, a few comments on the development of the nomenclature for coordination compounds. Although Werner (16) stated the general principles of such nomenclature and others added to them, what had become general practice was not codified into a set of rules. Even the 1940 Inorganic Rules (4) were not explicit. Real codification was not made until 1948 (17). There followed a oeriod of develo~mentorior (18) . . to the 1957 Inorganic ~ i l e (5). s What are the orocedures for order of citation? For binarv compounds, inoiganic chemists have long placed the name of the electropositive constitutent before that of the more electronegative and extended the practice to placing cations before anions. When more than one kind of cation andlor anion is present, the 1957 Rules (5)state Cations shall be arranged in order of increasing valeney [6.321]; cations of each valeney group shall he arranged in order of decreasing atomic number, with the palyatomic radical ions (e.g., NH4+)at the end of their appropriate group [6.322] . . . anions are to be cited in the order ofthe followinggroups:(1) H-; (2) O Z a n d OH-; (3) simple (one element) inorganic anions other than Hand 02-; (5)inorganicanions containing two or more elements; (5) anions of organic acids [6.33]. Then followed specific ordering for groups (3). (4), and (5), the last being alphabetical. For coordination compounds the order of citing ligands was (1) anionic ligands and (2) neutral and cationic ligands. The order within (1) was the same as that for anions in mixed salts, and within (2) the following: (a) H1O. NH?: (b) other inoreanic lieands in the order of incr&ng elr~~'tn~neyativity of t h r co&linatingelement; ( c ) organic ligands i n alphahetical order. I n prustice, these complicated r111esproved i~nuurkable. Oraiinic rhemists had wrestled with thenrdrrinp ofsubstituencs in names. The debate between order or complexity and alphabetical was settled in favor of alphabetical, So for the 1970 Inorganic Rules CNIC decided to cite all ligands, regardless of charge, in alphabetical order3 (7.311) with the single exception that, when the same ligand is present in the same coordination entity as a hridging group and as a simple ligand, the bridging group(s) is (are) given before the simple ligands. In the 15 years since the publication of these Rules no one suggested a superior ordering. Literature Cited
I. CuytmdeMorvoau,L. B. J P h y s 1782,19.310,382:Ann.Cl~im.eLPhys. 1789,[1]25, 9ns 2. Guyton de Mmveau. L. 8.;1.avoisier. A. I..; Berthollet, C. L.; de Foureroy. A. F. Method? ds Nomencloture Chim4ue; Paris, 1787. 3. Lauoiaier. A. L. Trnild E l h e n l n i r e ds Chimi*. 3rd ed.:Detpruille: Parii. 1801: Val. I. Part 1. pp 70-81; all (of Part 11. 4. Jarisson, W. P.: Basset& H : Dsmiens, A.; Fichte.. F ; Remy, H. '"Rules for Naming l n o ~ a n i eCompaundr", Commitbe for the Reform of Inorganic Nomenclature, Union internationale de chimie, Soparate, 64 pp, 1938; Berichfe 1940. 73A. 53; J. Them. Soe 1940, 140% J. Am. Chem. Soe. 1941, 63, 889-97: cf. Barefoot, R.: MeHryde, W. A. E. Chem. Canada 1951. 31-34 cf. Patterson, A. M. Chsm. Emg. Neal8 1954.32(271.27Ll. 5, IllPAC Commhion on the Namenelaturo of Inorganic Chemistry."Nomenclature af Inorpanic Chemistry". Comples Renduea. 17th Con/erenc% Stockholm 1953; I957 Report. Rutterwolih'r: London. 1959: Chrm. Ber. 1959.7.47-85; J . Am. Chrm. Sor.
7. (alScolt,.l. D.,Chem.Abslr.194S,39,5869-5871.(blChem.Abslr 1962,56,1N"%N. (cl Chsm. Abstr. 1967.66, 1 1-56 1. Id1 Chsm. Absfr. 1972. 76, 21 1-140 1; Chsm. Abafroclslnder G u t d ~1978,9S. 1-2201. (el Cham.AbsLi.Index Guide L982,IOi.I-
291 1:rcisue 1984.101.I-231 1. 8. Forneliua, W. C.;Loening, K.; Adama,R. M. J. Chsm. Educ 1976.53.495, 9. J. Chom.Snc. IR79.36.276: IR82.41.217-252. 1 0 Am. Chsm. J. 1883,4,%11:J. Am. Cham. .Sot. 1884.7.55, 112: 1886.8, 116125:Pror. Am. C h e m Soc. 1921,43,81-82: l922,44,5fi,77. 11.
Fernelius.W.C.:Luenine.K.:Adsms.R.M.J. Chsm. Educ. 1976.51.495.
15. Handbook for Chsmicol S o c i ~ r y Authora,Spec. Public. No. 14, TheChemical Society: 16.
(a1 Werner,A.Z.Annrg. Chem. l897,14.23. (bl Werner,A.:Klein,A.Z. Anorg. Chem.
1897,14,28. (cl Werner. A.NeuereAnschaugenou/den Gebietederonorganischrn Chemie, 3rd. ed.: Vieweg: Braunsehweig. 1913; pp 92-95: New idear on Inorganic C h m i a r r v Hedlev. E. P..Trans. from 2nd German ed.:. Lonmans Green: London. . 1911;ppi5.1~4. i70.255. 17. Ferneliur. W.C.:I.arscn.E.M.;Marchi,L.E.:Rollinron,C.L. Chem.Ena.Nelvs1948, 26, 520. 18. (a1 Ewens, R. V. G.;Basset,, H. C h < m Ind. i h n d o n l , 1949, 131. (b) Ferncliua, W. C. Adunnces iin Chemistry SerksNo. 8; American Chemical Suciety: WashingLon. DC. 195:i; pp 9-37. 19. Fernaiiur, W. C. J . Cham. Dor. l964.4.70-81: (19651.5,2W-204:Aduenres in Chemis. try brisr 1967.62.147-60.
W. Conard Fernellus
Kent State University Y a n t . OH 44242
Permlsslon To the Editor: -
How many of you have had the experience of going beyond the text in vour lectures and havinevour students r e s ~ o n das if something awful were being do& to them? You had hroken some contract by actually teaching them more than that for which they had contracted. When this happens I use the analogy of what they would do in a supermarket if the checkout clerk gave them free extra groceries. They would undoubtedly accept the extra groceries as a gift, hut the extra knowledge that is proffered is regarded as something to he avoided at all costs. After talking about this idea briefly I then give them permission to learn something extra. It is almost as if they would not he willing to accept this extra information without the permission. This attitude is not confined to general chemistry classes, hut i t seems to hold a t all levels. I first hecarne forcefully aware of this attitude when I began using the skits I have written for general chemistry.' If I didn't give my students explicit permission to enjoy the skits, then they did not know how to react. Would there be a test on them? Did they have to take notes? Could they laugh? So, I structure the situation. I tell them to put away their notebooks, lean back, and enjoy themselves, that it is okay to laugh and react, and that it is also okay to throw things a t the performers as long as the ohjects are soft and nonstaining. Our renditions of the skits are much more fun for evervone once the audience has been eiven ~ermission to . enjoy and instructions on what behavior is acceptable. You mav think that this is an obvious ooint. I t is not. This is the waybeople behave, and, unless there is an expectation and permission, they frequently do not know how to respond. Once you have this awareness as a teacher, you can use it to he a more effective teacher. How many of your students actually read the material for a given lecture beforehand even though they have been told that this enhances their learning and even though they know that they will get more out of a lecture following this procedure? Students attend lectures for (among other things) the purpose of finding out what to study. What you cover in your lecture, what you write on the blackboard, gives them clues as to what is important. So, your entire lecture may he considered to he an exercise in ~ermissioneivine. .. .. Students have bren trninrd to study only those things that are wrirren down. Mere ucrbol transmission of informarim is freuuentlv ignored. If you think it is important enough to ~ r i t ~ d o w d , then so do they. Knowledge of the power of permission can make your lectures more effective if you consciously use that knowledge. Rubin Battino
14. Commission on
Wright State University Dayton, OH 45435
the Nomenclature of Organic Chemistry. Nomencloture o/ Orgonie
Chrmirfr.~.Ser. C: Buttenvarths: London. 1957. p 4.
At the same time, alphabetical ordering of cations and anions in mixed salts was adopted.
A new edition is available from the author for $2.00.
Volume 64 Number 10
October 1967
903
