Preparations and Reactions of Coordination Compounds

Preparations and reactions of coordination compounds 4.6 Oxidation-redaction reactions... 

It is possible to improve the existing techniques of synthesis of PcCu and other metal phthalocyanines from phthalimide or urea and PA, applying electrosynthesis. These processes have many peculiarities. The solvent nature greatly affects the course of the majority of reactions of coordination compound formation [119,120]. The solvent used for PcCu preparation must be inert in order not to influence the desirable reaction course, and simultaneously must have electroconductivity to carry out electrolysis. It is recommended to use the derivatives of urea as such solvents and promoters at the same time. The use of a standard electrochemical procedure [9-14,20,121-124a] could be useful for the PcCu industry, since a typical industrial... 

In metal complexes, ligands may occupy different positions aroimd the central atom. Since the ligands in question are usually either next to one another cis) or opposite each other (trans), this type of isomerism is often also referred to as cis-trans isomerism. Such isomerism is not possible for complexes with coordination numbers of 2 or 3 or for tetrahedral complexes. In those systems, all coordination positions are adjacent to one another. However, cis-trans isomerism is very common for square planar and octahedral complexes, the only two types to be discussed here. Methods of preparation and reactions of some of these compounds are described in Chapter 4. 

Trialkyl- and triarylarsine sulfides have been prepared by several different methods. The reaction of sulfur with a tertiary arsine, with or without a solvent, gives the sulfides in almost quantitative yields. Another method involves the reaction of hydrogen sulfide with a tertiary arsine oxide, hydroxyhahde, or dihaloarsorane. X-ray diffraction studies of triphenylarsine sulfide [3937-40-4], C gH AsS, show the arsenic to be tetrahedral the arsenic—sulfur bond is a tme double bond (137). Triphenylarsine sulfide and trimethylarsine sulfide [38859-90-4], C H AsS, form a number of coordination compounds with salts of transition elements (138,139). Both trialkyl- and triarylarsine selenides have been reported. The trialkyl compounds have been prepared by refluxing trialkylarsines with selenium powder (140). The preparation of triphenylarsine selenide [65374-39-2], C gH AsSe, from dichlorotriphenylarsorane and hydrogen selenide has been reported (141), but other workers could not dupHcate this work (140). 

One of the more important recent developments in organometallic aluminum chemistry has been the formation and isolation of low-coordinate compounds, and, in particular, cations. These were first prepared in reactions of various aluminum reagents with crown ethers to form the inclusion compounds known as liquid clathrates. 71,72 Most of the evidence supports the presence of ion pairs as the basis of the solvent inclusion effect. Indeed, the compound [AlMe2-18-crown-6]+[AlMe2Cl2] was isolated from one such system (the cation is shown in Figure 6(a)).73 This was the first time the Me2Al+ unit had been structurally characterized. 

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