Monometalated compounds

Some other sp3 organogembismetallic compounds were reported as the synthesis of 1,3 dizinc derivatives using the boron-zinc exchange24 (Protocol 11), or the synthesis of l,n-heterobimetallic reagents.25 In the latter case, the reactivity of these derivatives is mainly the same as that of the monometallic compound. 

Cool the monometallic compound solution to -50°C, then add dropwise a solution of iodine (1.06 g, 4.2 mmol) in Et20 (20 mL). Let the mixture warm to room temperature over 1 h. 

Nanoscale materials such as multimetallic nanoparticles, particularly when alloyed, are of great importance due to their diverse range of electrical, optical, and catalytic properties. Bimetallic nanoparticles often exhibit enhanced catalytic reaction rates and better selectivity compared to the monometallic compounds. Such mixed nanoparticles were successfully synthesized by irradiating a solution containing a mixture of two (and even more) metal ions and precursors. Different bimetallic systems were studied, such as Ag/Pd, Au/Pd and Ag/Au nanoparticles. However, depending on the experimental conditions, both situations of alloyed or, more often, core-shell nanoparticles can be obtained. 

On the basis of the isolation of the intermediate compound 4 a reaction pathway was proposed (Scheme 1). Initially there is coordination of one phosphine with the formation of adduct III. This phosphine rearranges from axial to equatorial coordination with partial displacement of one acetate group. Proton transfer in this species IV yields the monometalated compound V, which further reacts with one additional phosphine to form the bimetalated compound. 

There is spectroscopic evidence for the formation of two adducts, ll.Pa and 11.Pb, of structural types Via and VIb (Scheme 2) in the reaction of the mono-metalated compound (11) with a stoichiometric amount of triphenylphosphine. Low-temperature NMR spectra confirmed that these two adducts are in equilibrium and that the [ll.Pa]/[ll.Pb] ratio increases as the temperature increases from -60 to -1-25 °C. If excess phosphine is used the bis adduct, II.P2, is also detected. Similar equilibria occur with other monometalated compounds. ... 

Formation by cocomplexation approach. The cocomplexation approach is an alternative way to bimetallic combinations using the corresponding monometallic compounds [12]. It is helpful for the synthesis of mixed-ligand bases. Examples are given in Table 27.2. 

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