▁on ▁the ▁tell ur ium ▁atom ▁and ▁counts ▁up ▁to ▁ 6 ▁counter - clock wise ▁on ▁the ▁carbon ▁atoms . ▁The ▁positions ▁adjacent ▁to ▁the ▁ch al c ogen , ▁number ed ▁ 2 ▁and ▁ 6 ▁can ▁also ▁be ▁called ▁α , ▁the ▁next ▁two ▁positions ▁ 3 ▁and ▁ 5 ▁can ▁be ▁term ed ▁" β " ▁and ▁the ▁opposite ▁carbon ▁at ▁position ▁ 4 ▁can ▁be ▁called ▁" γ ". ▁ ▁Occ urrence ▁Because ▁tell urop y ry li um ▁is ▁a ▁posit ively ▁charged ▁c ation , ▁it ▁takes ▁the ▁solid ▁form ▁as ▁a ▁salt ▁with ▁non - n uc le oph ill ic ▁an ions ▁like ▁per ch lor ate , ▁t etra flu or ob or ate , ▁or ▁hex a flu or oph osph ate . ▁ ▁Properties ▁The ▁positive ▁charge ▁is ▁not ▁conf ined ▁to ▁the ▁tell ur ium ▁atom ▁in ▁tell urop y ry li um , ▁but ▁dist ributes ▁on ▁the ▁ring ▁in ▁several ▁reson ance ▁structures , ▁so ▁that ▁the ▁α ▁and ▁ γ ▁positions ▁have ▁some ▁positive ▁charge . ▁A ▁nucle oph ill ic ▁attack ▁targets ▁these ▁carbon ▁atoms . ▁ ▁The ▁shape ▁of ▁the ▁tell urop y ry li um ▁mole c ule ▁is ▁not ▁a ▁pre fect ▁hex agon , ▁as ▁the ▁bond length s ▁to ▁the ▁tell ur ium ▁atom ▁at ▁about ▁ 2 . 0 6 8   Å ▁compared ▁to ▁about ▁ 1 . 4   Å ▁for ▁the ▁carbon - car bon ▁b onds