Roman numeral

The Stock Oxidation-Number System. Stock sought to correct many nomenclature difficulties by introducing Roman numerals in parentheses to indicate the state(s) of oxidation, eg, titanium(II) chloride for TiCl2, iron(II) oxide for FeO, titanium(III) chloride for TiCl, iron(III) oxide for Fe203, titanium(IV) chloride for TiCl, and iron(II,III) oxide for Fe O. In this system, only the termination -ate is used for anions, followed by Roman numerals in parentheses. Examples are potassium manganate(IV) for K2Mn02, potassium tetrachloroplatinate(II) for K PtCl, and sodium hexacyanoferrate(III) for Na3Fe(CN)3. Thus a set of prefixes and terminations becomes uimecessary. 

Other methods for indicating or implying the presence of an atom in a nonstandard valence state have been used, especially the use of the prefix hydro e.g. 108). Such methods are sometimes convenient for simple molecules, but they are difficult to apply generally. A more general method that has seen extensive use utilizes the italicized symbol for the element with a superscript Roman numeral to indicate the valence (e.g. 109). This method has been objected to, however, because of ambiguity the superscript Roman number is also used to indicate oxidation number in inorganic compounds, and italicized atomic symbols are customarily used as locants for substituents. The A convention is a modification of the principle of this method, and avoids the objection. It was made a Provisional Recommendation of lUPAC in 1981. 

As found in commerce, the cinchona alkaloids are not necessarily pure quinidine, for example, may contain up to 30 per cent, of dihydroquinidine. Working with carefully pmdfied specimens of the four chief cinchona alkaloids and their dihydro-derivatives, Buttle, Henry and Trevan found the results recorded in the table (p. 471) in tests with malaria in canaries. The figures in brackets represent the dose of quinine necessary to produce the same degree of protection as unit dose of the alkaloid named. To the results are also added the data found later by the same authors, with Solomon and Gibbs, for some of the transformation products (p. 449) of quinine and quinidine. The Roman numeral at the head of each column refers to the type formula on p. 470. 

The last two chapters in this volume are of a series of four, the remaining two to appear in the next volume. Cross references to these articles include, for ea identification, the roman numeral given in the title of chapters. 

The vertical columns are known as groups. Historically, many different systems have been used to designate the different groups. Both Arabic and Roman numerals have been used in combination with the letters A and B. The system used in this text is the one recommended by the International Union of Pure and Applied Chemistry (IUPAC) in 1985. The groups are numbered from 1 to 18, starting at the left. 

There is one complication. As mentioned earlier, certain metals in the transition and post-transition series form more than one cation, for example, Fe2+ and Fe3+. To distinguish between these cations, the charge must be indicated in the name. This is done by putting the charge as a Roman numeral in parentheses after the name of the metal ... 

In naming the compounds of transition or post-transition metals, we ordinarily indicate the charge of the metal cation by a Roman numeral ... 

In contrast, we never use Roman numerals with compounds of the Group 1 or Group 2 metals they always form cations with charges of +1 or +2, respectively. 

As you can deduce from the preceding examples, the oxidation number of the central metal ion is indicated by a Roman numeral written at the end of the name. 

The existence of groups of lines and of energy levels within states within a series may schematically be taken account of by introducing Roman-numeral subscripts, thus ... 

Fig. 4-15. A schematic view of the losses in an x-ray spectrograph. The Roman numerals refer to the steps in Table 4-4.

In naming the derivatives of pentazenes, the numeration of the nitrogens of the open chain is in Roman numerals, I, II, III, IV and V the numeration of any substituent attached to the nitrogens is in Arabic numerals... 

The apothecaries system uses whole numbers and fractions. Decimals are not used in this system. The whole numbers are written as lowercase Roman numerals, for example, x instead of 10, or v instead of 5. 

When setting up tiie proportion, the apothecaries system was written in Arabic numbers instead of Roman numerals, and their order was reversed (1 gr instead of gr i) so that all numbers and abbreviations are uniform in presentation. 

The name of a monatomic cation is the same as the name of the element forming it, with the addition of the word ion, as in sodium ion for Na+. When an element can form more than one kind of cation, such as Cu+ and Cu2+ from copper, we use the oxidation number, the charge of the cation, written as a Roman numeral in parentheses following the name of the element. Thus, Cu+ is a copper(I) ion and Cu2+ is a copper(II) ion. Similarly, Fe2+ is an iron(II) ion and Fe3" is an iron(III) ion. As shown in Fig. C.6, most transition metals form more than one kind of ion so unless we are given other information we need to include the oxidation number in the names of their compounds. 

The name of a monatomic cation is the name of the element plus the word ion for elements that can form more than one type of cation, the oxidation number, a Roman numeral indicating the charge, is included. 

Step 1 Identify the cation and the anion (see Table D.l or Appendix 3A, if necessary). To determine the oxidation number of the cation, decide what cation charge is required to cancel the total negative charge of the anions. Step 2 Name the cation. If the metal can have more than one oxidation number (most transition metals and some metals in Groups 12 through 15/V), give its charge as a Roman numeral. 

A Roman numeral denotes the oxidation number of the central metal ion ... 

If the complex has an overall negative charge (an anionic complex), the suffix -ate is added to the stem of the metal s name. If the symbol of the metal originates from a Latin name (as listed in Appendix 2D), then the Latin stem is used. For example, the symbol for iron is Fe, from the Latin ferrum. Therefore, any anionic complex of iron ends with -ferrate followed by the oxidation number of the metal in Roman numerals ... 

As already described in part 2.3.2 for a set of pairs (R, a) (Fig. 3 a) the remaining geometric variables were optimized in keeping with a symmetry restriction (Fig. 3 b). The energy function E = f(R, a) obtained here in the gas phase is presented in Fig. 4 as a graphic representation of isoenergetic lines above the R-a-plane. Tire points marked by Roman numerals are minimas (educts I products III, IV, V) and the saddle... 

Derivatives with different substitution patterns on the various residues can be named by the method of 2-Carb-37.2, assigning a roman numeral to each residue. 

Structures in which the linking glycosidic oxygen is replaced by -CH2- may be named by use of the replacement prefix carba- (c/. 2-Carb-34.2) for emphasis of homomorphic relationships. The oxygen replaced is given the locant of the carbon atom to which it is attached in the residue with the lower roman numeral (cited as superscript) (cf 2-Carb-37.2), with suffix a1. 

Oxidation state is a frequently used (and indeed misused) concept which apportions charges and electrons within complex molecules and ions. We stress that oxidation state is a formal concept, rather than an accurate statement of the charge distributions within compounds. The oxidation state of a metal is defined as the formal charge which would be placed upon that metal in a purely ionic description. For example, the metals in the gas phase ions Mn + and Cu are assigned oxidation states of +3 and +1 respectively. These are usually denoted by placing the formal oxidation state in Roman numerals in parentheses after the element name the ions Mn- " and Cu+ are examples of manganese(iii) and copper(i). 

Figure 1. An unrooted phylogenetic tree of the myosins based on the amino acid sequence comparison of their head domains demonstrating the division of the myosin superfamily into nine classes. The lengths of the branches are proportional to the percent of amino acid sequence divergence and a calibration bar for 5% sequence divergence is shovk n. The different classes of myosins have been numbered using Roman numerals in rough order of their discovery and hypothetical models of the different myosin structures are shown. Question marks indicate either hypothetical or unknown structural features, and only a fraction of the known myosins are shown. (Taken, in modified form, from Cheney et al., 1993).

Further subdivision of a five-digit slice utilizes lower-case Roman numerals in parentheses (i), (ii), (iii), etc. It is often found that as a consequence of the organization, cognate material is located in different chapters but in similarly numbered pieces, i.e., in parallel sections. Section numbers, rather than page numbers, are the key by which the material is accessed through the various indexes. 

Note that the Roman numeral subscripts refer to numbered reactions and have nothing to do with iodine. All these examples have involved elementary reactions. Multiple reactions and apparently single but nonelementary reactions are called complex. Complex reactions, even when apparently single, consist of a number of elementary steps. These steps, some of which may be quite fast, constitute the mechanism of the observed, complex reaction. As an example, suppose that... 

The two error types mentioned in the title are also designated with the Roman numerals I and II the associated error probabilities are termed alpha (a) and beta ( 8). 

Restriction enzymes are named after the bacterium from which they are isolated. For example, EcoRI is from Escherichia coli, and BamEII is from Bacillus amyloliquefaciens (Table 40-2). The first three letters in the restriction enzyme name consist of the first letter of the genus (E) and the first two letters of the species (co). These may be followed by a strain designation (R) and a roman numeral (I) to indicate the order of discov-ery (eg, EcoRI, EcoRIE). Each enzyme recognizes and cleaves a specific double-stranded DNA sequence that is 4—7 bp long. These DNA cuts result in blunt ends (eg,... 

Figure 41-9. Diagrammatic representation of the structures of two ion channels. The Roman numerals indicate the four subunits of each channel and the Arabic numerals the a-helical transmembrane domains of each subunit. The actual pores through which the ions pass are not shown but are formed by apposition of the various subunits. The specific areas of the subunits involved in the opening and closing of the channels are also not indicated. (After WKCatterall. Modified and reproduced from Hall ZW An Introduction to Molecular Neurobiology. Sinauer, 1992.)...

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