Ligands in formulae

Abbreviations. These may be used to represent ligands in formulae, and they are cited in the same place as the formulae they stand for. The abbreviations should be lower case, and enclosed in parentheses. Some commonly used abbreviations are in [Tabic 1-3 ]... 

Coordination entity. A coordination entity is composed of a central atom, usually that of a metal, to which is attached a surrounding array of other atoms or groups of atoms, each of which is called a ligand. In formulae, (he coordination entity is enclosed in square brackets whether it is charged or uncharged. 

IR-2.15.3.3 Ordering characteristic groups for substitutive nomenclature IR-2.15.3.4 Ordering ligands in formulae and names IR-2.15.3.5 Ordering components in salt formulae and names IR-2.15.3.6 Isotopic modification IR-2.15.3.7 Stereochemical priorities IR-2.15.3.8 Hierarchical ordering of punctuation marks IR-2.16 Final remarks IR-2.17 References... 

Abbreviations can be used to represent complicated organic ligands in formulae (although they should not normally be used in names). When used in formulae they are usually enclosed in parentheses. 

Abbreviations for Ligand Names. Except for certain hydrocarbon radicals, for ligand (L) and metal (M), and a few with H, all abbreviations are in lowercase letters and do not involve hyphens. In formulas, the ligand abbreviation is set off with parentheses. Some common abbrevia-... 

The chemical symbols of anionic ligands precede those of neutral ligands in the chemical formula of the complex (but not necessarily in its name). Thus, Cl precedes H20 and NH3. 

In solution, most simple sugars and many of their derivatives occur as equilibrium mixtures of tautomers. The presence of a mixture of two anomers of the same ring size may be indicated in the name by the notation a,P-, e.g. a,P-D-gIucose. In formulae, the same situation can be expressed by separating the representation of the ligands at the anomeric centre from the a and P bonds [see examples (a) and (c)], or by use of a wavy line [(b) and (d)] (particularly if hydrogen atoms are omitted). 

The following letters are used in formulas and equations to denote different types of ligands ... 

Usually the value of the /asym//sym ratio is used for estimating the angle between geminal ligands in the M(XY)2 " complexes, based on the approximate formula of Cotton [21] ... 

If an octahedral complex has the formula MX3Y3, there are two possible isomers. In an octahedron, the positions are assigned numbers so the locations of ligands in the structure can be identified. The usual numbering system for ligands in an octahedral complex is... 

Since the early work dealing with Zeise s salt, many complexes have been prepared with the formula [PtL(C2H4)X2], where L = quinoline, pyridine, or ammonia and X=C1 , Br , I, or N()2. Similar compounds have been prepared that contain other alkenes than C2H4. Many of the complexes containing dienes, trienes, and tetraenes as ligands also contain carbonyl ligands. In fact, metal carbonyls are frequently starting complexes from which alkene complexes are obtained by substitution reactions. 

Although diphosphine disulfides of formula R2P(S)P(S)R2 take up a trans conformation in the solid state (see Section 5.2.3), upon coordination to a metal centre they can rearrange to adopt a cis conformation, hence facilitating bidentate chelation of the metal (e.g., Equation 78).117 In addition, a cis-bridging mode has also been proposed for these ligands in bi-metallic complexes.117... 

Some of the zwitterionic A557-silicates described in this chapter were studied for their chemical properties. As shown for 32,44, and 45 in Scheme 7, compounds of this particular formula type undergo an intermolecular exchange of their benzene-1,2-diolato(2-) ligands in solution at room temperature.38 Solution-state NMR studies ([D6]DMSO XH, 13C, 29Si) and FD MS experiments provided evidence for the equilibrium 32 + 44 2 45. 

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