Polynuclear complexes reactivity

The preparative potential of silyl- or stannyl-substituted polynuclear complexes is currently far from being exploited. Due to the reactivity of silyl ligands, selective cleavage of metal-silicon bonds is possible. In some cases this was observed during the reaction of an anionic silyl complex with metal... 

Nickel-metal bonds, binuclear and polynuclear complexes, homometallic clusters, 8, 111 Nickel nanoparticles, preparation, 12, 87 Nickel-nitriles, synthesis and reactivity, 8, 150 Nickelocenes... 

It is also likely that radical cation formation occurs in reactions of very reactive arenes with Pd(II) (see Section II.B.3.b), which would also lead to biaryl formation. That the reactions of arenes with Pd(II) compounds are far from simple is illustrated by the work of Arzoumanidis and Rauch.573,574 In the reaction of Pd(02CCF3)2 with benzene or naphthalene in TFA, a variety of polynuclear complexes, containing both Pd(I) and Pd(II) and arenes, were isolated574 in addition to the usual biaryls. 

Several mononuclear carbonyl complexes may be synthesized with iridium(I), but most intriguing of those are the binary carbonyls. [Ir(CO)4] (46) may be synthesized by the reduction of Ir4(CO)i2 (45) with sodium under an atmosphere of carbon monoxide. More vigorous reduction of (45) with sodium can also yield the very reactive trianion, [Ir(CO)3] (47) (equation 13). These anions may then be used for the synthesis of other mono and polynuclear (see Polynuclear Complexes) carbonyl compounds of iridium. 

The polynuclear complexes of aluminum can help answer exactly the questions many geochemists pose about reactions at mineral surfaces, including (1) How does the reactivity of a metal-oxygen bond relate to covalency and coordination geometry ... 

On the basis of their kinetic study, Gupta et al. 330) proposed the existence of a reactive complex [Tl(SCN)] " and two nonreactive complexes [Tl2(SCN)] " and [HT1(SCN)2] " and determined the rate and stability constants. Polynuclear complexes [Tl2(SCN) ] " as intermediates in reaction (26) have also been proposed by Treindl and Fico as a... 

Other anions with which Fe(III) forms complexes are the silicates Fe(II) is less reactive with these species. This is used to limit the separation of hydrated Fe2 03 from waters, e.g. in water mains (this also concerns hydrated Mn(III) and Mn(IV) oxides). In waters containing 15-20 mg 1 Si the Fe2 03 separates with difficulty. It is best stabilized in alkaline media at pH 7.5. The formation of cationic or anionic complexes is supposed, e.g. [FeSiO(OH)3] and [Fe(OH).O.Si(OH)3]. At higher concentrations of iron, polynuclear complexes can be formed. 

In the course of our research, which focused on the synthesis of pentachloro or pentafluorophenyl-containing Pd or Pt complexes, we developed synthetie procedures for the preparation of square-planar Pt(II) or Pd(II) anionic complexes i.e. palladate or platinate complexes) containing from one to four perhalophenyl groups per metal center. The study of the reactivity of these complexes revealed that because of their anionic nature, they have an excess of electron density around the metal center (probably located on the d orbital) and they can react with Lewis acids giving rise to neutral reaction products. When the Lewis acid is a metal complex or a metal salt, polynuclear derivatives with metal-metal bonds of a donor-acceptor nature are obtained. Most of the work presented in this account has been carried out by reacting the platinate substrates with silver derivatives, which afford polynuclear complexes containing Pt Ag bonds. Our first paper in this field ap-... 

Clusters with interstitial atoms are an interesting class of polynuclear complexes. Several examples of compounds with interstitial atoms (H, C, Ge, N, P, S, etc.) have been reported. These compounds exhibit special behavior because the presence of main-group atoms in the cluster cage influences the chemical reactivity and stability of the system and its geometric structure. In the following section we consider some of these peculiarities, related both to the stability and to the electronic properties of clusters with interstitial elements. 

C3.4 Synthesis, structure and reactivity of homo- and hetero- J. Fomies and E. Lalinde, J. Chem. Soc., Dalton Trans., 1996, 2587-polynuclear complexes of platinum bearing ChCR 2599 (43)... 

There is much current interest in the synthesis and reactivity of transition metal complexes containing P atoms or aggregates. In particular, (/i-t -P2) dinuclear and cyclo (t/ -Ps) mononuclear complexes have received special attention, on account of their ability to act as complex ligands in the formation of polynuclear complexes. Whereas reported syntheses of these... 

Mixed-valence polynuclear complexes are of current interest as they exhibit unusual structural, bonding, reactivity spectroscopic, and magnetic properties which can find applications in areas such as the study of electron transfer processes and the design of molecular electronics. ... 

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