Metal the reactivity

For chalcogenide thin films it is possible to use elemental S, Se, Te as precursors provided that the other source is a volatile and reactive metal. ZnS deposition using elemental zinc and sulphur was the first ALD process developed [4]. Therefore for precursors other than metals, the reactivity of elemental chalcogens is not sufficient. For other precursor types, including halides, 6-diketonates and organometalHcs, simple hydrides, such as H2S, H2Se and H2Te, have typically been used as a second precursor. 

Tacticity is required for the synthesis of crystalline thin polysilane films used for optical and semiconductor devices. Modern synthetic routes allow control over the conformation and tacticity of polysilane molecules used as precursors for thin layers of photoresists, photoconductors and nonlinear optical phases in complex semiconductor and (opto)electronic devices. These properties can be exploited only if the synthesis method ensures a minimal level of contamination, especially with oxygen and metals, and special care is taken to limit electronic-grade polysilanes to a level of contamination on the order of a few ppm in the case of oxygen and in the ppb range for metals. The reactivity of polysilane toward oxygen has forced placing the devices in a helium environment during measurement procedures.36... 

In the reactions with organometallic complexes of f-metals, the reactivity of a pure Lewis base for the 1,3,2(A2)-diazasiloles was observed. Thus, silylene 85 reacts with (Cp)3Ln to give the complexes (Cp)3Ln(85) (Ln = Y, Yb)... 

The lanthanides exhibit a number of features in their chemistry that differentiate them from the d-block metals. The reactivity of the elements is greater than that of the transition metals, akin to the Group n metals ... 

While the differences in reactivities of the A,0-chelated complexes used for polymerization initiators is often influenced by the metal (e.g., yttrium is typically more active than group 4 metals), the reactivity trends for the A, 0-chelates show that the ligand has a profound effect on the polymerization. These examples show that... 

With Sn2+ and Pb + based catalysts, two ligands are coordinated and the methoxy group of the activated alcohol can be involved in the crystalline field (ether-metal bond) and be responsible for a donor-type effect on the metal. The reactivity sequence is now reversed (Table I) ... 

For group 10 metals, the reactivity is similar at low temperature, partially dealkylated surface tin species, [Ms(SnR4, j), ], are obtained (Table 21), whereas at higher temperatures, adatoms are obtained. 

For group 10 metals, the reactivity tends to decrease in the order [Ni > Pd Pt]. For example, cw-NiMe2(dppe) decomposes smoothly via path (b) without notable inhibitory effect of free phosphines [9], In contrast, cw-PdMe2(dppe) does not undergo path (h) hut path (a) the reaction is effectively suppressed by added phosphines [2,4], Platinum(II) dialkyls are inactive towards reductive elimination. 

Other loose ends which I might have discussed are the missing asymmetric stretching band for carboxy-lates on reduced metals ( ), the reactive surface carbon which is produced by self hydrogenation of acetylene on nickel (9), and simultaneous infrared and magnetic studies of chemisorption (] ). In some cases termination of projects was due to reaching the limit of what we could effectively accomplish. In other cases it was due to a shortage of time because of the numerous worthwhile projects which were open to us in 1952. 

This chapter summarized recent advances in the reduction chemistry of rare earth metals and described our own efforts in synthesizing inverse sandwiches of rare earth arene complexes using ferrocene-based diamide ligands. Unprecedented molecules were synthesized and their unusual electronic structures were studied. Highlights included the synthesis of the first scandium naphthalene complex and its reactivity toward P4 activation and the isolation and characterization of a 6-carbon, lOTi-electron aromatic system stabilized by coordination to rare earth metals. The reactivity of those complexes was also discussed. 

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