Compounds of Group IIB

A second, more indirect result of these studies is that for the first time large amounts, —10 g, of each of the bis(trifluoromethyl)Group IIB compounds became readily available. Bis(trifluoromethyl)mer-cury, for example, in addition to the syntheses indicated previously (1, 40), can also be conveniently prepared by any of a number of alternative methods, ranging from the direct fluorination of (CH3)2Hg to the reaction of mercury halides with CF3 radicals (99). The other disubsti-tuted compounds of Group IIB, (CF3)2Cd L2 and (CF3)2Zn L2, can be easily prepared from (CF3)2Hg as described below (100, 101). 

The compounds of groups IIB-IVB are often prepared in poiycrystaliine form as phosphors, catalysts (15.2.2.2) and infrared transmitting materials. Their use as semiconductors is almost exclusively for optoelectronic purposes (i.e., light emission and detection). Thus the phosphor preparation technology has relevance to preparation of these semiconductors in powder form. The most common reactions employed are... 

The interpretation and correlation of spectroscopic properties, in the context of structure and bonding, for compounds of group IB and group IIB metals, have been covered in a comprehensive review (1). It is hoped... 

Fig. 284. Addition compounds with thioethers of metal halides of Group IIB.

Table 2, Chemical Shifts of Group IIB Metal Compounds ...

The synthesis of compounds containing boron-group IIB bonds also occurs by two pathways. The most convenient method is using anionic borane or carboranc species, as in the group-IB case, to react with Zn, Cd, or Hg halides. Moreover, reactions between organometallic compounds (Zn, Cd) with unchanged boranes arc also realized, so Zn and Cd decaboranes, e.g., MB H 2 n solvent (M = Zn, Cd), result from reactions of decaborane(14) with MRj . 

Formation of the Group-IIA-Group-IIB Element Bond 7.3.4.1. Phase Diagrams, Intermetallic Phases and Compounds... 

The sole interest in the chemistry of species containing group-IIA-group-IIB element bonds is metallurgical. Tne available data on phase equilibria have been reviewed and a handbook of phase diagrams published . Furthermore, structural data for intermetallic phases and compounds have been critically assessed . ... 

Equilibrium conditions for the synthesis of intermetallic phases and compounds are concisely summarized as a function of temperature and composition in the form of phase diagrams. Consequently, in the following subsections, these relationships for group-IIA-group-IIB metal systems are reviewed. The phase diagrams in ref. 1 arc used as a baseline work published before this compilation is not specifically referred to, but that reported subsequently is used, as appropriate, to modify or replace these phase diagrams. 

As a result of their reactivity, particular attention must be given to preparation and purification of the metals, the conditions under which the metals, alloys and compounds are handled and the choice of material for the containment vessel. Ultrapure group-IIB metals may be used without further purification, but it is advisable to purify the group-IIA metals by a multidistillation process, the final distillation preferably being carried out in situ. The reactants and products are best handled in an atmosphere of a purified inert gas, usually He or Ar (N2 cannot be used because of the ready formation of group-IIA metal nitrides) alternatively, they can be handled under vacuum or, in rare cases, under halide fluxes. The containment vessel is normally fabricated from a refractory. 

Formation of the Group-IB or -IIB-Group-IB or -MB Metal Bonds 8.2.3. In Univalent Compounds of Zinc and Cadmium... 

Although reaction of carbonyl anions with group-IIB salts is seldom used to prepare derivatives of Zn and Cd, it works when used. Compounds containing Mo—Cd and W—Cd bonds can be synthesized by reacting aq Cd(CN)2 with dry Na[M(CO)3Cp-tj5] (M = Mo, W) ... 

The first published examples of hydrosilation, which appeared about 30 years ago, noted that they were observed to proceed by free-radical mechanisms initiated thermally (about 300°C) (J), by acyl peroxides (4), by azonitriles (5), by ultraviolet light (6), or by y radiation (7). The first hint that catalysts known to be effective for hydrogenation might also be effective for hydrosilation was found in a French patent (8) (1949) which stated that catalysts may be chosen from compounds and salts of the elements of Groups IIA, IVA, IB, and IIB of the periodic table and metals of Group VIII and certain of their salts. No example to demonstrate this was included in the patent. 

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