Halides block metal

The hydride ion, H, can function as a ligand to tf-block metals. Compare the differences in bonding to metal ions that you would expect between H and the halide ions. 

Hydrides of variable composition are not only formed with pure metals as solvents. A large number of the binary metal hydrides are non-stoichiometric compounds. Non-stoichiometric compounds are in general common for d,f and some p block metals in combination with soft anions such as sulfur, selenium and hydrogen, and also for somewhat harder anions like oxygen. Hard anions such as the halides, sulfates and nitrides form few non-stoichiometric compounds. Two factors are important the crystal structures must allow changes in composition, and the transition metal must have accessible oxidation states. These factors are partly related. FeO,... 

Oxathiolane 2,2-dioxide undergoes metallation with n-butyllithium as expected at the 3-position (81JOC101). The anion may be alkylated with alkyl halides or carbonyl compounds. The isomeric 1,3-oxathiolane 3,3-dioxides also undergo metallation ortho to the sulfone and, when the 4-position is blocked, metallation at the 2-position may be used as an efficient conversion of alkyl halides into aldehydes as shown in Scheme 22 (79TL3375). 

Ionic liquids with anions containing transition metal complexes were among the earliest developed room temperature ionic liquids [60], Transition metal based ionic liquids have been synthesized either by reaction of phosphonium or imidazolium halides with the corresponding metal halides, or by metathesis with alkali salts of the metal-based anions. Among the metal containing ionic liquids, ionic liquid-crystals are excluded in this section as they were reviewed thoroughly in 2005 [61], Synthesis of metal based salts can be divided in to three groups (1) transition metal salts, (2) p-block metal salts and (3)/-block metal salts. 

Table 6.8 gives stability constants for the complexes [FeX] and [HgX] for different halide ions while the stabilities of the Fe complexes decrease in the order F > CP > Br, those of the Hg complexes increase in the order F < CP < Br < P. More generally, in examinations of stability constants by Ahrland, Chatt and Davies, and by Schwarzenbach, the same sequence as for Fe + was observed for the lighter s- and /i-block cations, other early J-block metal cations, and lanthanoid and actinoid metal cations. These cations were collectively termed class (a) cations. The same sequence as for Hg complexes was observed for halide complexes of the later J-block metal ions, tellurium, polonium and thallium. These ions were collectively called class (b) cations. Similar patterns were found for other donor atoms ligands with O- and iV-donors form more stable complexes with class (a) cations, while those with S- and F-donors form more stable complexes with class (b) cations. 

Phosphonium halides, PH4X, are formed by treating PH3 with HX but only the iodide is stable under ambient conditions. The chloride is unstable above 243 K and the bromide decomposes at 273 K. The [PH4] ion is decomposed by water (equation 14.29). Phosphine acts as a Lewis base and a range of adducts (including those with low oxidation state rf-block metal centres) are known. Examples include H3B-PH3, C13B-PH3, Ni(PH3)4 (decomposes above 243 K) and Ni(CO)2(PH3)2. Combustion of PH3 5delds H3PO4. 

M — M ) is approximately offset by the difference in lattice energies of the compounds, the two metal halides will be of about equal stability. This commonly happens with (i-block metal halides. 

Alfred Werner (working at the University of Zurich) was awarded the Nobel Prize for Chemistry in 1913 for his pioneering work that began to unravel the previous mysteries of the compounds formed between block metal ions and species such as H2O, NH3 and halide ions. A famous problem that led to Werner s theory of coordination concerns the fact that C0CI3 forms a series of complexes with NH3 ... 

For metals exhibiting variable oxidation states, the relative thermodynamic stabilities of two ionic halides that contain a common halide ion but differ in the oxidation state of the metal (e.g. AgF and AgF2) can be assessed using Bom Haber cycles. In such a reaction as 17.19, if the increase in ionization energies (e.g. M — M versus M— M +) is approximately offset by the difference in lattice energies of the compounds, the two metal halides will be of about equal stability. This commonly happens with block metal halides. 

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