Bonds bismuth-selenium

The 8-N rule states that the number of bonds (or local coordination, x) equals 8 minus the number of the periodic group. This rule is illustrated in Fig. 1.2 where we see that for N — 7 the halogens take dimeric structure types with x = 1, for N = 6 the chalcogenides selenium and tellurium take helical chain structures with x = 2, for N = 5 the pnictides arsenic, antimony, and bismuth take a puckered layer structure with x = 3, and for N = 4 the semiconductors... 

Selenium-bismuth bonds are formed in the mutual cleavages of dibismuthines and diselenides (equation 69).218 This particular compound is stable at -30 °C, unlike the tellurium analogue. At room temperature the compound disproportionates to give the diseleno derivative (equation 70). Similar behaviour was noted in the analogous sulfur compounds (Section 28.17.2.1). 

In this chapter the topic of colour phenomena that are related to secondary bonding is extended beyond the thermochromic distibanes and comprises also cyclostibanes and organometallic derivatives with bonds of antimony or bismuth with selenium, tellurium or iodine. 

Bonds to Sulphur or Selenium.— Arsenic, antimony, and bismuth trichlorides react with bis(2-mercaptoethyl) sulphide, liberating hydrogen chloride and forming the cyclic compounds (99).686 Complete spectroscopic data... 

In the first section of this chapter some of the properties of the elements hydrogen, carbon, nitrogen, phosphorus, arsenic, antimony, bismuth, oxygen, sulfur, selenium, tellurium, fluorine, chlorine, bromine, and iodine are described. The following sections are devoted to some of their compounds with one another, especially the single-bonded normal-valence compounds. Compounds of nonmetals with oxygen are discussed in the following chapter. 

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