The Bis(cyclopentadienyl)thallate(I) Anion Isoelectronic with Stannocene

A bent thallocene anion is found in complexes 1 and 2 , which are prepared by the reaction of [CpTl] and [Cp 2 Mg] (for 1 ) or [CpLi] (for 2 ) and N,N,N ′, N ′, N ″‐pentamethyldiethylenediamine (PMDETA). The [(η 5 ‐Cp) 2 Tl] − anion is isoelectronic and isostructural with stannocene. Ab initio calculations show that the bent structure with C S symmetry is only marginally more stable than the linear conformer with D 5h symmetry. equation image