Heteropolynuclear

Many heteropolynuclear Au(III)/Ag derivatives have been described in the previous Section 3.2. 

Although the Ag- -Ag interactions are not very strong, there are many examples of complexes, which contain Ag-,M contacts. Silver forms very stable heteropolynuclear complexes with different structural motifs, among them it is worth mentioning the species where silver interacts with platinum, gold, iron, mercury, etc. 

Other heteropolynuclear gold(II) complex that can be obtained by replacement of halide groups in bis(ylide)gold(II) species by other anionic nucleophilic metal complex is the tin derivative [Au2 Sn[N(p-Tol)SiMe2]3SiMe 2 M-(CH2)2PPh2 2] (350).2041... 

The possibility of coordinating functionalized TTFs onto polynuclear core is a very stimulating issue because it is now well established that polynuclear cores, with some restrictions of course, can act as SMMs. We started a systematic investigation of polynuclear paramagnetic complexes with TTF CH=CH—py ligands to scan the possibility to access to bifunctional molecules which can act at the same time as SMM and single component metal. We succeeded in coordinating our modified TTFs to several homo- or heteropolynuclear complexes. This opens new perspectives in the field of multifunctional materials. The size of these molecules, which is of the order of 4 nm, is another important aspect in the field of molecular scale electronic. 

Within each chapter the submissions are ordered, as far as possible, according to the columns of the periodic table. In Chapter 5, homopolynu-clear complexes are presented first, followed by heteropolynuclear compounds. Many submissions, however, contain several parts. As a consequence, the location of some of the procedures can not adhere to this general sequence. 

A final example concerns the formation of heteropolynuclear hydroxide complexes.116 The complexes [(OH)Fe(OH)2Cr]3+, [(OH)Fe(OH)2Cr(OH)]2+ and [(OH)2Fe(OH)2Cr(OH)]+, or polymers such as Fe(OH)2M "+ (M = V, Cr, Mn, Co, Ni, Cu n = 2-4) have been studied with a view to an understanding of the inclusion of transition metals in iron ores as mixed oxides rather than their occurrence as discrete mineral phases. Many other examples might have been chosen in this section. Reference should be made to the general reviews given above. However it should be clear that simple inorganic coordination complexes play a major role in the chemistry of natural aqueous systems at low temperatures. 

It is clear from the previous sections that the capacity of mesityl groups to act as bridges fosters the isolation of homo- or heteropolynuclear complexes. Thus, tetranuclear dicationic derivatives [ (Ph3As)Au(p-mes)Ag 2(p-dpam)](C104)2110 (dpam = Ph2 AsCH2AsPh2) and [(Ph3P)Au(p-mes)Ag(tht)]2(TfO)227 have been prepared by reaction... 

The kinetic inertness of [Fe(CN)6]4 is typified by the extremely slow thermal displacement of CN by a,a -diimines. Such reactions are however catalyzed270 by a variety of metal ions such as Hg2+ and the stability constants for some of the intermediate heteropolynuclear complexes have been determined.271... 

The formation of a dimerized extracted species was first reported for the extraction of copper(II) with propanoic acid (40, 41). Later, nickel and cobalt were found to be extracted as dimers (22), and a mixed copper(II) carboxylate dimer involving acetate and decanoate was reported (147). More recently, attention has been drawn to the extraction of heteropolynuclear metal carboxylates (90, 91). 

The formation of heteropolynuclear carboxylates is a common phenomenon, which must be taken into account particularly in the separation of metal ions. 

Balzani et al. (70) employed a strategy focusing on complexes as metals and as ligands (71,72), for developing a number of interesting supramolecular systems. Ditopic polypyridyl ligands, for example, 2,3- and 2,5-dipyridylpyrazine (2,3-dpp and 2,5-dpp), 2,2 -biquinoline (biq), tetrapyrido[3,2-fl 2, 3 -c 3",2"-/z 2", 3 "-/]-phenazine (73,74) (tppz), and 2,3,5,6-tetrakis(2-pyridyl)pyrazine (75-77) (tpypz), in combination with monotopic ligands (e.g., bpy and phen) were utilized in the preparation of a number of homo- and heteropolynuclear complexes of well-defined structures (Fig. 2). 

Chen, Z.N., Fan, Y., and Ni, J. (2008) Lrrminescent heteropolynuclear or multicomponent complexes with polypyridyl-functionalized alkynyl Ugands. Dalton Transactions, 573-581. 

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