Polymetalated compounds

A common structural feature of compounds 81-89 is their distorted tetrahedral coordination geometry at zinc. A trend that can be observed in Table 5 is that with increasing Zn—O distances, the C—Zn—C angle also increases and consequently the O—Zn—O angle decreases. From a structural point of view 83 has interesting structural features. In this complex two 1,2-phenylene dianionic units are C, C-bridge bonded between two zinc atoms (Figure 45) and it represents one of the few examples of polymetallated compounds for which the structure has been established by an X-ray crystal structure determination . 

Insertion of GeX2 into M—X bonds to form M—GeX3 species is also explored, but less extensively than for Sn. The use of such MGeX3 species to form polymetallic compounds has been surprisingly neglected to date. 

The hexacyanometalate anions [BCCNlg]" have long been known to be flexible building blocks for obtaining polymetallic compounds. These... 

U ecent work has led to the synthesis of a variety of compounds in which metal atoms or ions are held in close proximity by chemical linkages. These polymetallic compounds represent a new class of materials that have distinctive chemical and physical properties, and in some systems the properties can be varied systematically by chemical synthesis. The compounds are of interest because of possible cooperative chemical and electronic interactions between the chemically linked metal centers. In the future it may prove possible (a) to create solid state materials that have controllable, and perhaps unusual, electrical conductivity properties (b) to prepare polymeric complexes which in solution have properties that are intermediate between those of solid state materials and those of simple monomeric complexes and (c) to devise chemical systems in which cooperative chemical interactions lead to net, multiple-electron redox processes, or to simultaneous, two- or more site reactions. 

Recent investigations outline the involvement of this class of polymetallic compounds in reactions of fundamental importance to catalysis, such as inner-sphere oxidation or transmetalation. Given the widespread use of copper(l) and silver(l) salts - and, to a lesser extent, thallium(l) - as additives in palladium- and platinum-based catalytic systems, a systematic study of these reactions is warranted. Additionally, gathering further knowledge on the properties and reactivity of metal-metal-bound species is a critical step toward the rational design of truly bimetallic catalytic cycles. 

Work on thallium derivatives of C2B10H12 includes the reaction of [l,7-C2BioHn-9-TICI2] with Na[M(CO)s] (M = Mn or Re) to give stable polymetallic compounds of unit formula... 

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