Formulae donor atom symbols

The order of citation of central atoms is based on electronegativity as described in Section IR-4.4.2.1. Ligands are cited alphabetically (Section IR-4.4.2.2) according to the first symbol of the ligand formula or ligand abbreviation (see Section IR-4.4.4) as written. Where possible, the ligand formula should be written in such a way that a/the donor atom symbol is closest to the symbol of the central atom to which it is attached. 

These systems may be used in names, but they are not always suitable for use in formulae. The use of donor atom symbols is possible in the formulae of simple systems (see Section IR-9.2.3.4), but care must be taken to avoid ambiguity. The kappa convention is not generally compatible with the use of ligand abbreviations. 

The second formula means merely that the HC1 molecule is a resonance hybrid between the ionic molecule H+Cl" and the molecule with the purely covalent bond, the direction of the arrow giving the direction in which the electrons have, on the average, been displaced (66). As, however, such an arrow is used by others (57), for indicating a coordinate link (semipolar double bond) caused by a lone electron pair of the donor atom, which likewise produces a dipole with its positive end on the donor side and its negative one on the acceptor side, the author suggests that the symbol — be used for the normal covalent bond, which, by resonance with an ionic structure, possesses a dipole. The point of this half arrow also indicates the direction of the negative end of the dipole. The full arrow — will then be reserved for the coordinate link. Both links play their roles in chemisorption, and it may be useful for the purposes of this article to introduce relatively simple symbols. According to this principle HC1 should be formulated as H—1-Cl. 

Chemical symbols and formulae have been frequently used in place of names to save space and often to secure clarity. Where an arrow (->) from the donor atom appears, it does not imply that the bond is different from the rest. 

IR-9.2.3.1 Sequence of symbols within the coordination formula IR-9.2.3.2 Use of enclosing marks IR-9.2.3.3 Ionic charges and oxidation numbers IR-9.2.3.4 Use of abbreviations IR-9.2.4 Specifying donor atoms IR-9.2.4.1 General IR-9.2.4.2 The kappa convention... 

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