Other Iodo Complexes

Salts of black [Til6]2-, white [Thl6]2, and red [UI6]2- also have been prepared in the same manner.2,3 The preparations of [Cul4]2- and [Cel6]2 were attempted, but salts of these ions are not sufficiently stable to be observed even at the freezing point of liquid HI. Salts of black [UI6] have been prepared from the chloro salts in this manner4 but are unstable and decompose rapidly above about — 30°. 

---

Other iodo complexes have been isolated containing 1,2-bis(dimethyl-arsino)benzene (181), bis(diphenylphosphino)methane and 1,2-bis-(diphenylphosphino)ethane (237), 2,9-dimethyl-1,10-phenanthroline... 

Picolylphenylketone S-benzyldithiocarbazate, 48, yielded paramagnetic [ Ni(48-H)A 2] (A = Cl, Br) and diamagnetic [Ni(48-H)I] [207]. All three compounds are non-electrolytes and the iodo complex is planar while the other two complexes involve sulfur bridging atoms and five-coordinate nickel(II) centers. All three complexes can be converted to monomeric, octahedral complexes by addition of pyridine, 2-picoline or quinoline. 

There are many fluorocomplexes of aluminum. The general formula for the fluoroaluminates is M I, I, a I- based upon A1F6 octohedra. which may share comers to give other ratios of A1 F than 1 6. Chloroaluminates of the type M lAlClj] are obtainable from fused melts. Aluminum ions form chloro-, bromo-, and iodo-complexes containing tetrahedral IALX41 ions. However, in sodium aluminum fluoride NaAlF4, the aluminum atoms are in the centers of octohedra of fluorine atoms in which the fluorine atoms are shared with neighboring aluminum atoms. 

Addition of excess iodide to the insoluble Hgl2 results in the formation of soluble mercury iodo complex [Hgl3] , with a trigonal planar structure. The ion is solvated in water and converts to a tetrahedral structure. Further, addition of H leads to tetrahedral [Hg ] ". Reaction of iodide salts with Hg can be used to produce mercury iodo complexes. Other halide and pseudohalides also form [HgXj] and [HgX4] . The tetrahalo anions see Anion) are usually tetrahedral, while the trihalo ions readily add solvent molecules to form distorted tetrahedral or Trigonal Bipyramidal structures. 

For example, complexes with very strong EPD ligands, such as Ng ", NCS ", CN, or F may exist even in solvents of high DN such as HMPA or DMSO. In solvents of weak or medium EPD properties, complex formation is essentially quantitative. On the other hand, bromo and iodo complexes usually exist only in weak EPD solvents, such as NM, PDC, or AN, and are completely ionized in solvents such as DMF, DMSO, or HMPA. The stabilities of chloro complexes are somewhat higher in the respective solvents. According to Table VII the chloride ion has an EPD strength similar to that of DMF or DMSO. Consequently chloro complexes in these solvents (compare Table IV) are ionized to some extent, sometimes with autocomplex formation. 

Methods for the synthesis of C-functionalised arylphosphines based on the direet introduetion of phosphino groups into aryl halides or tosylates, eatalysed by a variety of metals, have eontinued to develop. The reaetions of seeondary phosphines (and seeondary phosphine oxides) with bromo- or iodo-arenes, eatalysed by palladium aeetate or other palladium complexes, have been used... 

A real breakthrough came with the discovery of promoter molecules that could be added to the reaction mixture. One such promoter is Ru(CO)3I2. Its mode of action seems to be in part to act as an I abstractor from [MeIr(CO)2I3] (equation 9.37), which has the effect of accelerating steps c and d. Several other transition metal carbonyl-iodo complexes will work, as will simple iodides of Zn, Cd, and Hg. Studies have shown that the iodinated promoter product is recycled by contributing its extra I- to the process for producing CH3I. 

Complexes of relatively strongly oxidizing metal ions with the more reducing halide ions are not prepared easily because the halide ion is oxidized by the metal ion. The low-temperature (< 25°) method discussed here allows the preparation of bromo and iodo complexes of oxidizing metal ions which could not be prepared by other means. The complex is formed directly as a solid salt in which crystal-lattice energy gives stability. 

Although in theory it should be possible to prepare almost all anionic bromo and iodo complexes by this method, the real value of the method lies in the preparation of those complexes that cannot be made by other methods or can be made only with difficulty. The increased reactivity, due to the very fine crystal size of the products obtained by this method, probably makes it desirable that bromo and iodo complexes which are easily prepared from solutions be made in that manner. Typical examples of bromo and iodo complexes which can be prepared by this method are discussed here. 

The corresponding iodo complexes are readily prepared by metathesis reactions with sodium iodide. Other reactions have been reviewed and recently [M(> -CjMe5)Cl2]2 have proved to be valuable precursors to novel bridged carbene complexes of the type [ M(> -C5Me5)Y 2(/i-CH2)2]- In the presence of base, [Rh(> -C5Me5)Cl2]2 is an effective catalyst for the hydrogenation of olefins and for the hydrosilylation of olefins and the disproportionation of aldehydes. ... 

The dependence of the molar absorptivity on the composition of the dioxane-water solvent mixture indicates that in these mixtures both solvents are capable of coordinating to the cobalt(III) parent complex thus, the system may contain different solvates (and possibly mixed solvates), the absorbances of which are not identical. The concentrations of these solvates depend on the composition of the solvent mixture. In this way the composition of the solvent mixture influences the value of the absorbance. On the other hand, the stability of the iodo complex examined is governed by the stabiUties of those solvates from which the mixed solvate is formed in the given system by means of substitution of the coordinated solvent molecules by iodide. Hence, it is understandable that the correlation... 

Other reactions. Aqueous with [PtCle] precipitates K2[PtCl6], very similar to (NH4)2[PtCl6] (see NH/ under Reduced nitrogen above), usable to determine these alkalis quantitatively. The bromo- and iodo-complexes are less satisfactory. The salt Na2[PtCl6] is very soluble and is decomposed by light in alkaline solution, forming Pt02. 

---