With Group VIB Elements

Formation of the Group-1 IIB-Group-IIIB Element Bond 6.2.3. in Combination with Group-VIB Elements... 

Thianthrenes have not been dealt with previously in Advances in Heterocyclic Chemistry. This chapter covers the chemistry of thianthrenes from 1960 to the end of Chemical Abstracts 1988 coverage. Earlier references are included only where they are of particular significance or serve to place later work in context. The family of linear tri-6-membered-cyclic heterocycles with group VIb elements located 1,4- in the central ring, of which thianthrene is a member, have been referred to as dibenzodi-chalcogenins, chalcogenanthrenes, and chalcanthrenes. This review will not attempt to draw comparisons between the chemistry of thianthrene and that of the other chalcanthrenes. 

Fig. 4. Mono(tricarbonyl) complexes of ansa-phanes with group VIb-elements [28b, 29-31]...

Fig. 5. Mon< triiari)onyl) complexes of [2.2]cyclophanes with group VIb-elements [31- 36]...

Complexes of group VIB elements with sulfur or selenium donor atoms are mainly concerned with complexes of selenium(II), tellurium(II) and tellurium(IV). The structural chemistry of complexes of selenium and tellurium with sulfur- and selenium-containing ligands has been well reviewed in the recent past.11... 

Although the results obtained can be considered as approximate rather than accurate, they give some information about the relative strength of oxocompounds of the Group VIb elements. Nevertheless, these results were used as initial data for the development of the processes of reduction of these oxocompounds in chloride melts [150-152]. Theoretical bases and principles for monitoring the electrochemical processes of deposition of the free refractory metals and their compounds with some non-metals (carbides, borides, silicides, etc.) from molten ionic media [153] were developed. 

Several hexachloro, hexabromo and hexaiodo complexes of the group VIB elements have been reported. For example, solutions of selenium tetrachloride in concentrated hydrochloric acid contain the hexachloro anion SeCli from which the ammonium and alkai metal salts can be readily obtained with the cesium salts being the least soluble. The... 

Group VIb elements provide by far the most representatives of carbonyl complexes of cyclophanes. Their preparation is achieved by heating the metal hexacarbonyl M(CO)g (M = Cr, Mo, W) with the respecting cyclophane in a high boiling point solvent, such as ligroin or di-n-butylether, for several hours... 

The chalcogenides are binary compounds of a chalcogen (i.e., the elements of Group Ilb zinc, cadmium, mercury) with a less electropositive element, such as those of Group VIb (oxygen, sulfur, selenium, and tellurium). This section covers the sulfides, selenides, andtellurides. Oxides are reviewed above in Ch. 11. Most of the chalcogenides have useful optical characteristics and their applications are usually found in optics. 

The group VIB cyanides, thiocyanates and selenocyanates and their complexes with species such as thiourea have been described.1,45 For example, the tellurium dithiocyanate complex has been prepared45 by treatment of tellurium dichloride or tellurium dibromide with ammonium thiocyanate. It seems that little information exists on the preparation of tellurocyanates and there is a sparsity of data on polonium derivatives. Indeed, the only known cyanide of polonium is probably a salt of the quadrivalent element.1... 

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