Parent element hydrides

The nature of the binary hydride is related to the characteristics of the parent element (Fig. 14.8). Strongly electropositive metallic elements form ionic compounds with hydrogen in which the latter is present as a hydride ion, H, and has oxidation number —1. These ionic compounds are called saline hydrides (or saltlike hydrides ). They are formed by all members of the s block with the exception of beryllium and are made by heating the metal in hydrogen ... 

Substances are arranged in alphabetical order by the most common name, except that compounds such as hydrides, oxides, and acids are grouped with the parent element (the same ordering used in the table Physical Constants of Inorganic Compounds ). 

Hydrides are an exception as they display similar energy distributions as their parent elemental signals. 

Hunt s group (50, 51) have pioneered the application of the Cl source to organometallics such as the iron tricarbonyl complex of heptafulvene, whose electron impact spectrum shows (M—CO)+ as the heaviest ion, in contrast to the methane Cl spectrum with the ion as base peak. Boron hydrides (52) and borazine (53) have also been studied. The methane Cl spectrum of arenechromium and -molybdenum (54) show protonation at the metal giving a protonated parent or molecular ion. Risby et al. have studied the isobutane Cl mass spectra of lanthanide 2,2,6,6-tetramethylheptane-3,5-dionates[Ln(thd)3] (55) and 1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-oetanedione [H(fod)] lanthanide complexes (56). These latter complexes have been suggested as a means of analysis for the lanthanide elements. 

DERIVATIVES OF MAIN GROUP ELEMENTS Selection of parent hydrides and their names... 

It is generally an arbitrary matter to decide where to apply substitutive nomenclature in these cases. Table 5.1 shows the elements to which both CNIC and CNOC approve the application. Table 5.2 gives the names of the corresponding mononuclear parent hydrides. The only additional elements to which substitutive nomenclature may sometimes be applied are the halogens, particularly iodine. 

The modified element name sila indicates replacement in the carbon skeleton, and similar treatment can be applied to other element names. The parent hydride names of Table 5.2 may all be adapted in this way and used in the same fashion as in the oxa-aza nomenclature of organic chemistry. In inorganic chemistry, a major use is in names of cyclic derivatives that have heteroelement atoms replacing carbon atoms in structures. It may be possible to name such species by Hantzsch-Widman procedures (see p. 77), and these should always be used when applicable. 

Many organo-derivatives of the Group Vb elements have been prepared. The substituted phosphines, arsines, and stibines (for example, CH3PH2, (CH3)2AsH, and (CH3)sSb) are, like their parent hydrides (p. 253), easily flammable, toxic, and only weakly basic toward H4. However, the fully substituted arsines and phosphines form surprisingly stable adducts with salts of univalent gold, divalent platinum and palladium,... 

It is also used for naming compounds formally derived from the hydrides of certain elements in groups 13-17 of the periodic table. Like carbon, these elements form chains and rings which can have many derivatives, and the system avoids the necessity for specifying the location of the hydrogen atoms of the parent hydride. 

IR-2.15.3.1 Element ordering on the basis of the periodic table IR-2.15.3.2 Ordering of parent hydrides... 

Generally, nomenclature systems require a root on which to construct the name. This root can be an element name (e.g. cobalt or silicon ) for use in additive nomenclature, or can be derived from an element name (e.g. sil from silicon , plumb from plumbum for lead) and elaborated to yield a parent hydride name (e.g. silane or plumbane ) for use in substitutive nomenclature. 

Chemical nomenclature deals with names of elements and their combinations. Whereas writing the symbol or the name of an element is straightforward, a choice of which element to write first in the formula and in the name has to be made as soon as an element is associated with one or more other elements to form, for example, a binary compound. The order of citation of elements in formulae and names is based upon the methods outlined below. Furthermore, groups of atoms, such as ions, ligands in coordination compounds and substituent groups in derivatives of parent hydrides, are ordered according to specified rules. 

Where there is a choice of parent hydrides among those listed in Table IR-6.1 (or corresponding hydrides with non-standard bonding numbers, cf. Section IR-6.2.2.2), the name is based on the parent hydride of the element occurring first in the sequence ... 

This applies in particular to the naming of organometallic compounds of elements of groups 13-16 when a choice has to be made between several parent hydrides (Section IR-10.3.4). 

IR-6.2.2.2 Homonuclear acyclic parent hydrides with elements exhibiting non-standard bonding numbers... 

Substitutive nomenclature is recommended only for derivatives of the parent hydrides named in Table IR-6.1 (in Section IR-6.2.1), and derivatives of polynuclear hydrides containing only these elements (see Sections IR-6.2.2 to IR-6.2.4). The bonding numbers of the skeletal atoms are understood to be as in Table IR-6.1 (these bonding numbers, e.g. 4 for Si and 2 for Se, are termed standard bonding numbers). Other bonding numbers must be indicated by an appropriate designator (the X convention , see Section IR-6.2.2.2 and Section P-14.1 of Ref. 1). 

---