Development needs nomenclature

Since the early 1970s a panel convened by the International Union of Pure and Applied Chemistry and the International Union of Biochemistry and Molecular Biology has been working to formulate recommendations for carbohydrate nomenclature that meet developing needs of research and electronic data handling, while retaining links to the established literature base on carbohydrates. The realization of these endeavors is presented here in the final document Nomenclature of Carbohydrates, which provides a definitive reference for current researchers, both in the text version and in the version accessible on the World Wide Web (http //www.chem.qmw.ac.uk/iupac/2carb/), where amendments and revisions are maintained. 

This results in the need for a concomitant development of nomenclature to more accurately describe this type of bonding. 

General Items Involved in Coordination Nomenclature. In following the development of nomenclature practices for coordination compounds, one needs some frame of reference to compare the continuities and changes. This is perhaps most easily done by reference to a set of principles or rules which has been used by the author on other occasions (10, 11, 13). We shall follow the changes in the statement of a given rule while the specific field covered by the rule does not change. Prior to the time of Werner, there was no basis for a systematic nomenclature. The rules and practices established by Werner might be expressed as a number of simple rules (13). 

Finally some additional milestones in organization, research and development of RMs need to be mentioned. The large increase in the number of reference materials being produced led in 1975 to the formation of an ISO Council Committee on Reference Materials (ISO-REMCO) charged with the establishment of international guidelines on principles of certification, methods of use, needs, availability and nomenclature (Klich 1999), see also Sections 1.2 and 1.3. 

The nomenclature of nickel compounds should be further standardized (WHO 1991). Analytical methods must be developed and standardized in order to facilitate speciation of nickel compounds in atmospheric emissions, biological materials, and in other environmental samples (NAS 1975 WHO 1991). Studies are needed to elucidate the biogeochemical nickel cycle on a global scale and determine its potential for long-range transport (WHO 1991). 

We illustrate the nomenclature introduced above in an example taken from coordination chemistry. In fact, equilibrium species of interesting complexity are commonly encountered in coordination chemistry and to a large extent coordination chemists have developed the principles of equilibrium studies. Consider the interaction of a metal ion M (e.g. Cu2+) with a bidentate ligand L (e.g. ethylenediamine, en) in aqueous solution. For work in aqueous solution the pH also plays an important role and thus, the proton concentration H (=[ff+]), as well as several differently protonated species, need to be taken into account. Using the nomenclature commonly employed in coordination chemistry, there are three components, M, L, and H. In aqueous solution they interact to form the following species, HL, H2L, ML, Mia, ML3, MLH, MLH1 and OH. (In fact, more species are formed, e.g. ML2H 1, but the above selection will suffice now.) The water molecules are usually not defined as additional components. The concentration of water is constant and its value is taken into the equilibrium constants. 

Another characteristic point is the special attention that in intermetallic science, as in several fields of chemistry, needs to be dedicated to the structural aspects and to the description of the phases. The structure of intermetallic alloys in their different states, liquid, amorphous (glassy), quasi-crystalline and fully, three-dimensionally (3D) periodic crystalline are closely related to the different properties shown by these substances. Two chapters are therefore dedicated to selected aspects of intermetallic structural chemistry. Particular attention is dedicated to the solid state, in which a very large variety of properties and structures can be found. Solid intermetallic phases, generally non-molecular by nature, are characterized by their 3D crystal (or quasicrystal) structure. A great many crystal structures (often complex or very complex) have been elucidated, and intermetallic crystallochemistry is a fundamental topic of reference. A great number of papers have been published containing results obtained by powder and single crystal X-ray diffractometry and by neutron and electron diffraction methods. A characteristic nomenclature and several symbols and representations have been developed for the description, classification and identification of these phases. 

Before proceeding one needs to mention Chemical Abstracts (CA), a journal published by the American Chemical Society, that abstracts the world s chemical hterature and has developed its own nomenclature rules. The CA rules are generally very close to the IUPAC rules, but there are some differences. Most of the differences are not important at the level of the discussions in this book. One difference that needs to be mentioned is the placement of locants. CA does not place locants immediately before the part of the name to which they apply. Thus, the CA name for the first subunit in XV is 2,4-pyridinediyl instead of pyridine-... 

This chapter covers literature published since 1982 early materials are included here only where needed as a basis for describing further developments or where not previously mentioned in CHEC-1 <84CHEC-l(5)669>. The structural types surveyed here include 1,2,3-triazoles, benzotriazoles, their dihydro derivatives and carbocyclic fused compounds. Compounds with heterocyclic fused rings are not included. The nomenclature system was discussed in CHEC-T <84CHEC-I(5)670>. 

Although symbols are not a part of nomenclature, the two are closely related, and the former have played an extremely important role in chemistry. Because of the difficulty of establishing priority of discovery for most of the elements of atomic number above 100, and because of the need to refer to hypothetical elements with higher atomic numbers, IUPAC has developed interim systematic symbols and names for such elements. 

The saccharides have long and awkward names by the IUPAC system, consequently a highly specialized nomenclature system has been developed for carbohydrates. Because this system (and those like it for other natural products) is unlikely to be replaced by more systematic names, you will find it necessary to memorize some names and structures. It will help you to remember the meaning of names such as aldopentose and ketohexose, and to learn the names and details of the structures of glucose, fructose, and ribose. For the rest of the carbohydrates, the nonspecialist needs only to remember the kind of compounds that they are. 

Although (6) does not refer to a different constitution, as did (5), it is incompatible with the coding techniques that have been used so far The math model developed up to this point does not contain structures with two bonds together — without an intervening atom consequently, until this part of the nomenclature is developed at a later time, alternation of atoms and bonds is required. Furthermore, such a scheme is not needed. A simple cyclic repetition conveys the desired bonding pattern of the monomer namely ... 

Another use for the zero integer superscript occurs in the domain of catenanes and rotaxanes. Although the same examples as the ones cited in Schill s monograph [1] for the development of a suitable nomenclature have been selected for discussion, his organizational scheme — which is merely an extension of I.U.P.A.C. s organic chemistry nomenclature — has not been. Instead, the nomenclature developed earlier for more traditional compounds is easily expandable to include these "compounds". Toward this end, note that in the formulation described in Chapter 1, the semi-colon was selected as a co-ordinate separator and the colon as a sub-ordinate separator of strings of nomenclature code. One now needs only to introduce the use of the zero superscript to indicate that the choice of locant numbering is irrelevant. 

Nomenclature development is slow work the workers are usually busy men with much else to do. Sometimes there is need for early decisions. These facts have, to a degree, been stumbling blocks in the attaining of international agreement. Nomenclature work within a nation is much prolonged when put on an international basis. Usually, however, the effort is worth while. It is not practicable and, perhaps, not desirable for everything in the nomenclature field to be done on an international basis, as some more or less specific problems are largely local in interest. 

When atomic theory developed to the point where it was possible to write specific formulae for the various oxides and other binary compounds, names reflecting composition more or less accurately then became common no names reflecting the composition of the oxosalts were ever adopted, however. As the number of inorganic compounds rapidly grew, the essential pattern of nomenclature was little altered until near the end of the 19th century. As a need arose, a name was proposed and nomenclature grew by accretion rather than by systematization. 

This Chapter deals with some basic notation and nomenclature of solid-state chemistry. In some areas, such as amorphous systems and glasses, the nomenclature needs further development. The reader is also referred to the work of the International Union of Crystallography. 

---