K 8 [B 12 (BSe 3 ) 6 ]: A Novel Selenoborato‐ closo ‐dodecaborate with Different Anion Substitution Patterns

Systematic studies on selenoborates containing a B 12 cluster entity and alkali metal cations led to the new crystalline phase K 8 [B 12 (BSe 3 ) 6 ] which consists of a icosahedral B 12 cluster completely saturated with trigonal‐planar BSe 3 units and potassium counter‐ions. For the first time three different anion substitution patterns are observed in one crystal structure. The new chalcogenoborate was prepared in a solid state reaction from potassium selenide, amorphous boron and selenium in evacuated carbon coated silica tubes at a temperature of 850 °C. K 8 [B 12 (BSe 3 ) 6 ] crystallizes in the monoclinic space group Cm (no. 8) with a = 16.288(2)Å, b = 41.617(4)Å, c = 9.788(1)Å, β = 109.59(1)°, and Z = 6.