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What else can I help you with?
What is the covalent name for SeBr6?
Selenium hexabromide.
Why are electrons active?
For most cmpds of the main group elements the lone pairs are of equal importance as bond pairs in determining structure hence the basis of VSEPR theory. The lone pairs are said to be stereochemically active. But for some higher-coordination main-group cmpds the lone pair becomes stereochemically inactive. For example, the [SeCl6]2-, [SeBr6]2-, [TeCl6]2-, and [TeBr6]2- ions all have regular octahedral structures in the solid state. But According to VSEPR these AX6E ions should not have a regular octahedral structure. For transition metal cmplxs and organometallic cmpds the d e-s are completely stereochemically inactive: d AOs point between the ligands (e.g., oct [M(H2O)6]^n+ ions) or are involved in π bonding. Cr(CO)6 (octahedral), Fe(CO)5 (trigonal bipyramidal), Ni(CO)4 (tetrahedral), but all have 18 e-s: geometry dictated by ligands. ;)
