Atomic pnictides

So far little work has been performed on the UPD of pnictides N, P, As, Sb. It would appear that UPD of N, or even electrodeposition of N from an aqueous solution, is not a likely event. P has been known to deposit with ferrous metals, such as Ni, to form NiP alloys [257-261], This induced co-deposition of P with Ni suggests that it can be electrodeposited, although it does not appear that bulk P would be stable in an aqueous solution. It may be that P can be induced to form an atomic layer on the right metal, possibly Ga or In. 

Hitherto no monometalated molecular pnictide exists without solvation of the main group metal atom. Therefore, the monomeric species L (Fig. 2) can only be stabilized if the Li ion has its coordination sphere enlarged through donor solvation. More importantly, the lithium phosphanides of the type K undergo oligomerization processes to form dimer, tetramer, hexamer, or polymeric assemblies M—Q (Fig. 2), which dissociate in solution more easily than related amides (2, 11, 12). 

At present, it appears that one of the criteria for construction of an ECALE cycle for a compound is whether atomic layers of one of the compound s elements can be formed using an equilibrium analogous to Eq. (5) oxidative UPD. As indicated above, the elements that can be deposited using oxidative UPD are mostly nonmetals such as the halides, chalcogen-ides, and pnictides. 

The impact on actinide solid state physics of Zachariasen s ideas has been great. It has triggered a very fruitful effort in structure determination. In the meantime, it has underlined the importance, in the theory of actinides, of knowing exactly atomic volumes as an indicator of the complexities of the metallic bond. The same picture of the variation of atomic radii appears for compounds having partial metallic character. In Fig. 5, for instance, the variation vs. Z of the lattice parameter ao of actinide pnictides is compared with the atomic radii of metals. Actinide pnictides have an NaCl type structure. Their... 

The general shape of these curves at least for pnictides up to AnAs indicates clearly that the metallie bond is dominated by the electronic structure of the actinide atom. In the further discussion of this chapter (and in Chaps. C-F) it will be made clear that the shape is explained, contrarily to Zachariasen s hypothesis, by means of the f participation in the bond. 

In the cellular multiple scattering model , finite clusters of atoms are subjected to condensed matter boundary conditions in such a manner that a continuous spectrum is allowed. They are therefore not molecular calculations. An X type of exchange was used to create a local potential and different potentials for up and down spin-states could be constructed. For uranium pnictides and chalcogenides compounds the clusters were of 8 atoms (4 metal, 4 non-metal). The local density of states was calculated directly from the imaginary part of the Green function. The major features of the results are ... 

A large variety of ligands form bonds with transition metals via one or more pnictide atoms. These range from simple ER3 (E = P, As, Sb, Bi R = alkyl, aryl, alkoxy, aryloxy, halogen and their combinations/permutations) molecules to ligands of elaborate architecture such as the macrocycles described in Section 14.2.1.7. 

Pnictides with group IV cations only are found with this structure (102, 103). Half the metal atoms have the same coordination as the cations in PbCl2. The coordination polyhedra of the remaining metal atoms, on the... 

Consider that atoms have a size range of about 1-2 A. Most inorganic solids, with the exception of halides, sulfides (and other pnictides), are based upon the oxygen atom, i.e.- oxide = O", whose atomic radius does not change even when sulfates, phosphates and silicates are formed. Oxide has an atomic diameter of 1.5 A or 0.15 nm. = 0.00015 (om. Nanoparticles are clumps of 1000 to 10,000 atoms. The latter would be a particle of 0.15 (om. in diameter. They can be metal oxides, semiconductors, or metals with novel properties useful for electronic, optical, magnetic and/or catalytic uses. 

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