Borderline metals complexation transfer

The reductive decomposition of thiocyanato complexes should be applicable to the electrodeposition of other metal sulfides. We have tried this with Pd2, Co2+, Ni2+, Zn2+ and In3+.I8 While thin films of PdS, CoS and NiS could be successfully electrodeposited, other metal sulfides such as ZnS and In2S3 could not be obtained. This is an interesting series of results when we think of the softness (hardness) of these metals as acid. TC coordinates with its sof basic S atom to soft acidic Cd2+ and Pd2+, while hard acidic In3+ only permits coordination with hard basic N atom to form an isothiocyanato-complex. Other metals are at the borderline accepting coordination of both S and N. Because reduction of TC is catalyzed by a central metal,75,76) such ligand reduction may result in the formation of metal sulfides only for thiocyanato-complexes. The difference in bahavior among Co2+, Ni2+ and Zn2+ could be reasoned as the consequence of efficient catalysis of the electron transfer reaction by the transition metals. Such trends fit nicely with the previous findings by electrochemical analyses. 7) It is therefore understood that the chemical structure of the active species is decisive to the film formation. Thus, designing such molecular precursors which are chemically stable but can be electrochemically decomposed to metal sulfides should broaden the possibilities of electrochemical thin film synthesis. 

These ligands, with the recently established HjO, have a very close relation with solvent water. Therefore throughout this section chemistry in solution and in the solid state will be juxtaposed and related in a way not possible for other ligands. Indeed the pH dependence of species present in solution has an important bearing on solid complexes, in that the latter are often prepared from solution. The parent complexes, aquo ions [M(OH2)i]" , are important both in salt hydrates and in solution, and have even been studied to a limited extent in the gas phase. Other complexes containing water, hydroxide and oxide in various proportions are all related to these aquo cations by simple and rapidly established proton transfer equilibria. Eventually deprotonation leads to 0x0 anions. Some of these, such as chromate or permanganate, can be considered as complexes others, such as PbOj" and GeOj, are on the borderline with mixed metal oxides. Most such species have... 

Although hydrogen bonding, charge-transfer complexes, and the role of metals and metal surfaces can be correlated by the principle, the role of the solvent can moderate its effects, some nuclei and groups must be considered borderline, and the volume of data has proved daunting for its routine application. Nonetheless, the correlation has proved useful, and Table 5.18 contains some of the material that will allow predictions to be made. 

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