METALS Database

Eiichi Nakata, Materials Database Metals and Alloys, Nikkan Kogyo Shimbun, Tokyo, 1989. 

Metal-MACiE database [http //www.ebi.ac.uk/thornton-srv/databases/Metal MACiE/home.html] webcite... 

Ab-initio calculations are particularly usefiil for the prediction of chemical shifts of unusual species". In this context unusual species" means chemical entities that are not frequently found in the available large databases of chemical shifts, e.g., charged intermediates of reactions, radicals, and structures containing elements other than H, C, O, N, S, P, halogens, and a few common metals. 

For applied work, an optical characterization technique should be as simple, rapid, and informative as possible. Other valuable aspects are the ability to perform measurements in a contactless manner at (or even above) room temperature. Modulation Spectroscopy is one of the most usehil techniques for studying the optical proponents of the bulk (semiconductors or metals) and surface (semiconductors) of technologically important materials. It is relatively simple, inexpensive, compact, and easy to use. Although photoluminescence is the most widely used technique for characterizing bulk and thin-film semiconductors. Modulation Spectroscopy is gainii in popularity as new applications are found and the database is increased. There are about 100 laboratories (university, industry, and government) around the world that use Modulation Spectroscopy for semiconductor characterization. 

Of course, densities of pure metals do not change over time, though the available precision may improve a little over the decades. However, many more complex data do change significantly as new experiments are done, and new materials or material systems come along constantly and so entirely new data flood the literature. Materials scientists, like chemists, physicists and engineers, need means of finding these. Those means are called databases. This brief chapter surveys how databases are assembled and used, with special attention to materials. 

Another recent database, still in evolution, is the Linus Pauling File (covering both metals and other inorganics) and, like the Cambridge Crystallographic Database, it has a "smart software part which allows derivative information, such as the statistical distribution of structures between symmetry types, to be obtained. Such uses are described in an article about the file (Villars et al. 1998). The Linus Pauling File incorporates other data besides crystal structures, such as melting temperature, and this feature allows numerous correlations to be displayed. 

Offers direct access to virtually all of the world s scientific and data bases for toxicology and related information. Covers chemicals, pesticides, food additives, industrial chemicals, heavy metals, environmental pollutants, and pharmaceuticals. The Center is online to more than 400 computerized databases, including DIALOG, MEDLARS, STN International, ITIS, and DROLS. It performs searches for outside users for a fee. 

L. G. SiLLfiN and A. E. Martell, Stability Constants of Metal-ion Complexes, The Chemical Society, London, Special Publications No. 17, 1964, 754 pp., and No. 25, 1971, 865 pp. Stability Constants of Metal-lon Complexes, Part A. Inorganic Ligands (E. Hcigfeldt, ed.), 1982, pp. 310, Part B. Organic Ligands (D. Perrin, ed.), 1979, pp. 1263. Pergamon Press, Oxford. A continually updated database is now provided by L. D. Pettit and K. J. Powell (eds.), IVPAC Stability Constants Database, lUPAC and Academic Software. 

NIST Database 46 Gritically Selected Stability Gonstants of Metal Gomplex-es Database, U.S. Department of Gommerce, Gaithersburg, MD, 1998, ver. 5.0. 

In the Cambridge Structural Database [39] only two macrocyclic molecules with transition metals, in which the metal ions are joined only by imidazolyl units, have been reported. One structure is trimetallic and contains plati-num(II) [40a] and the second one is tetrametallic with copper(II) ions [40b]. 

Some similar bimetallic acylamino complexes are also known with transition metal ions, e.g., with vanadium(II) [67], palladium(II) [68], and especially platinum(II) [69]. In the Cambridge Structural Database [39] only one trimetallic structure is found in which three iron(II) ions are bridged by a total number of six acylamino ligands [70]. 

As an example, Baitz et al7 focused on different technologies and peripheral system conditions to reduce dust and heavy metal emissions from a refinery. They stressed that the knowledge of the sensitive life cycle parameters and a suitable database, and thus the possibility to quantify impacts, enables a sustainable decision-making in process design and process optimisation. 

Obviously, use of such databases often fails in case of interaction between additives. As an example we mention additive/antistat interaction in PP, as observed by Dieckmann et al. [166], In this case analysis and performance data demonstrate chemical interaction between glycerol esters and acid neutralisers. This phenomenon is pronounced when the additive is a strong base, like synthetic hydrotalcite, or a metal carboxylate. Similar problems may arise after ageing of a polymer. A common request in a technical support analytical laboratory is to analyse the additives in a sample that has prematurely failed in an exposure test, when at best an unexposed control sample is available. Under some circumstances, heat or light exposure may have transformed the additive into other products. Reaction product identification then usually requires a general library of their spectroscopic or mass spectrometric profiles. For example, Bell et al. [167] have focused attention on the degradation of light stabilisers and antioxidants... 

Wavelength database libraries of >32000 analytical lines can be used for fast screening of the echellogram. Such databases allow the analyst to choose the best line(s) for minimum interferences, maximum sensitivity and best dynamic range. Further extension of the wavelength range (from 120 to 785 nm) is desirable for alkali metals, Cl, Br, Ga, Ge, In, B, Bi, Pb and Sn, and would allow measurement of several emission lines in a multivariate approach to spectral interpretation [185]. 

Metals Crystallographic Data File (CRYSTMET). Toth Information Systems Inc., Ottawa, Canada. Electronic database of crystal structures of metals, intermetallic compounds and minerals. WWW.Tothcanada.com. 

G. P. Shields, P.R. Raithby, F. H. Allen, W. D. S. Motherwell, The assignment and validation of metal oxidation states in the Cambridge Structural Database. Acta Crystallogr. B46 (2000) 244. 

Smith, R. M. Martell, A. E. Motekaitis, R. J, NIST Critically Selected Stability Constants of Metal Complexes Database, Version 5, NIST Standards Reference Database 46, U. S. Dept. Commerce, Gaithersburg, MD, 1998. 

Data on additive production are mostly absent in LCI databases. Some data are available for metals production and for bisphenol-A, but even for widely used additives such as phthalates and brominated flame retardants, production data are not available. 

Information on structure and bonding in alkali metal species with group 14, 15, and 16 ligands has been mainly focused on lithium derivatives the heavier analogs have been dealt with to a much-reduced extent. As mentioned in a 2004 review article,11 a search in the Cambridge Structural Database (CSD) revealed 778 structures with an Li-C bond, but only 197 with an Na-C, 235 with a K-C, 57 with an Rb-C, and just 31 with a Cs-C bond. 

Overall, the alkali metal alkoxide and aryloxide systems are excellent examples in demonstrating the effects of steric influences on both molecular aggregation and also on the nature of any extended network architecture adopted. The large database of O-M complexes that have now been identified has led to a good deal of predictability regarding the coordination chemistry of these species. 

---