Pnictide ligands

Purex process, 6, 946 oxidation state reduction, 6, 947 Pnictide ligands double bonds, 2, 1045 triple bonds, 2, 1046 Podandocoronands classification, 2, 919 Podands... 

The interplay between a and n bonding between pnictide ligand and metal has subtle structural consequences. In the trigonal bipyramidal series of complexes M(CO)4(ER3) (M = Fe, Ru, Os E = P, As, Sb R = alkyl, aryl), in which the ER3 ligand may occupy an axial or an equatorial site,... 

The preparation of similar precursors suitable for the deposition of metal nitrides is analogous to the preparations of phosphorus and arsenic compounds. The initial reaction of metal trialkyls MR3 (M = A1, Ga, In) with amines (NHR 2) results in the formation of oligomeric amido compounds [R2MNR 2] (n = 2 or 3) which eliminate alkanes on thermolysis. The incorporation of a proton as a substituent on the pnictide bridging ligand has been examined, and many compounds of the type [R2MNHR ]2 have been synthesized. The presence of this proton may facilitate /3-elimination, allowing lower deposition temperatures to be used. 

There were significantly fewer reports on organozinc compounds bearing ligands with heavier group 15 donors than those on organozinc amides. This is mainly due to the weakness of the zinc-pnictide bonds, which rules out the use of... 

In actinide binary compounds an equation of state can also be developed on the same lines. The difference in electronegativity of the actinide and the non-actinide element plays an important role, determining the degree of mixing between the actinide orbitals (5 f and 6 d) and the orbitals of the ligand. A mixture of metallic, ionic and covalent bond is then encountered. In the chapter, two classes of actinide compounds are reviewed NaCl-structure pnictides or chalcogenides, and oxides. 

The cone angles refer to each coordinating pnictide of the ligand. 

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. 

Pnictide-transition metal bonds are essentially covalent coordinate, in which the pnictide provides the electrons. However, this simple picture does not account for all the structural data now available. The consensus view is that three factors are involved in the ligand contribution to the M—E bond (a) a bonding (Section 14.4.2), (b) n bonding (Section 14.4.3), and (c) steric factors (Section 14.3). The effect of the metal will not be discussed here, except insofar as individual complexes are used as examples. 

Alkene-like E=E ligands occur via a number of synthetic routes in pnictide chemistry those arising, for example, from P4 are dealt with later. The E==E ligands are useful in synthesizing clusters. A list of E—E bond lengths from the review by Schere284 is given in Tables 18 and 19. Huttner et a/.293 synthesized the star-shaped cluster (51 equation 77). 

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