Anion ligands

When there are several types of ligands, anionic ligands are cited before the neutral ligands. 

Pu(IV) forms polyatomic complexes with inorganic and organic ligands. As the number of anionic ligands increases, cationic, neutral, and anionic complexes form and the sequential stabiUty constants, typically decrease. For the following reaction, where M is Pu + and L is a ligand,... 

The reaction of toluene-3,4-dithiol(3,4-dimercaptotoluene) and antimony trichloride ia acetone yields a yeUow soHd Sb2(tdt)2, where tdt is the toluene-3,4-dithiolate anionic ligand (51). With the disodium salt of maleonitnledithiol ((Z)-dimercapto-2-butenedinitrile), antimony trichloride gives the complex ion [Sb(mnt)2] , where mat is the maleonitnledithiolate anionic ligand. This complex has been isolated as a yeUow, crystalline, tetraethyl ammonium salt. The stmctures of these antimony dithiolate complexes have apparendy not been unambiguously determiaed. 

The unknown selenium-nitrogen anions [ScsN], [ScaNa] and [ScaNaH] have also been stabilized by coordination to platinum.A few examples of complexes involving anionic ligands with two different chalcogens, e.g., [ESNa] and [ESNaH] (E = Se, Te), are known. 

Ligands L, L can be drawn from virtually the full range of inorganic and organic neutral and anionic ligands and, indeed, the reaction severely limits the range of donor solvents in which B10H14 can be dissolved. The approximate sequence of stability is ... 

A11R2X (much the most stable) X = anionic ligand especially Br ... 

The lithium salt of 2-(di-wo-propylamino)-l,2-thiaborolide with [( -Cp ) RuC1]4 or [(i -Cp )ZrCl3] yields sandwiches similar to 39 (M = Ru, ZrCl2) (OOOM4935). The same anionic ligand enters a sequence of reactions with dimethylchlorosilane, lithium cyclopentadienyl, lithium di-wo-propylamide, and zirconium(IV) chloride to give sandwich 41. 

The names of anionic ligands are obtained by substituting the suffix -o for the normal ending. Examples include... 

Ruthenium probably forms more nitrosyl complexes [115] than any other metal. Many are octahedral Ru(NO)Xs systems, where X5 can represent a combination of neutral and anionic ligands these contain a linear (or very nearly) Ru-NO grouping and are regarded as complexes of ruthenium(II). They are often referred to as (Ru(NO) 6 systems. 

As with rhodium (and cobalt), introduction of five ammonia molecules is relatively straightforward, but the sixth substitution is difficult, requiring more forcing conditions. One versatile route involves the formation of the pentammine triflate complex ion [Ir(NH3)5(03SCF3)]2+, where the labile triflate group is readily replaced by water, then by a range of anionic ligands [148]. 

Sulfurdiimine, Triazenido, Azabutadiene and Triatomic Hetero Anion Ligands... 

Anionic ligands end in -o for anions that end in -ide (such as chloride), -ate (such as sulfate), and -ite (such as nitrite), change the endings as follows ... 

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. 

The majority of ligands are either neutral or anionic. Those which coordinate to a metal ion through a single atom are described as monodentate or unidentate. Examples of such ligands which we have encountered thus far include water, ammonia and chloride. A more extensive listing of common ligands is found in Table 1-3. We stress at this point that there is no difference in kind between the interactions of a metal centre with either neutral or anionic ligands. 

A number of general features in Table 1-3 is apparent. Complexes may be cationic, neutral or anionic. Ligands may be simple monatomic ions, or larger molecules or ions. Many ligands are found as related neutral and anionic species (for example, water, hydroxide and oxide). Complexes may contain all of the same type of ligand, in which case they are termed homoleptic, or they may contain a variety of ligand types, whereby they are described as heteroleptic. Some ligands such as nitrite or thiocyanate can coordinate to a metal ion in more than one way. This is described as ambidentate behaviour. In such cases, we commonly indicate... 

---