The nonastannide(4-) anion Sn94-, a novel capped antiprismatic configuration (C4.upsilon.)

On the Structure of Nonastannide Clusters in Liquid and Solid State

“…[19,20] Many of the early theoretical results for nonastannide clusters are based on extended Hückel calculations and they all report that the C 4v geometry is more stable than D 3h . [21,22] This is in good agreement with both earlier and more recent results, [5,20] but the opposite result can also be obtained, indicating that the difference in energy is very small. [23] Since the description of the behaviour of nonastannide clusters in solution and solid state is so inconsistent, we believe that one of them can not be entirely correct.…”

“…[4][5][6][7][8][9][10][11][12][13][14][15] Several of these have been classified as having a C 4v geometry, as expected according to Wade's rules for a nido cluster such as Sn 9 4-. [16] However, some appear to adopt a D 3h geometry, which is typical for a closo geometry and expected for Sn 9 2-, but it is most certainly not the correct geometry for a nido cluster such as Sn 9 4-.…”

“…[5,17] However, the energy barrier for the fluctional behavior of the cluster was never determined, despite the low temperatures used during the experiments. This fluctional behaviour can even be retained when incorporating Pt 2 (PPh 3 ) into the cluster, [18] while other additions are more questionable with regards to the fluctional behaviour.…”

Easy Access to Soluble Polyanions—Stabilization of the One-Dimensional Chain1∞[K4Sn9] by [18]Crown-6 in [K4Sn9([18]crown-6)3]⋅ethylenediamine

“…The noncapped face in B possesses two diagonals of same length d. As predicted from Wades rules [24] all previously structurally well characterized Sn 4À 9 anions exhibit nearly undistorted clusters of type B. [21,25] More electron deficient, paramagnetic Sn 3À 9 ions have structures which lie between the two boundary structures A and B.…”

“…A more precise structural investigation of a C 4v -symmetrical anion was carried out later with [Na([2.2.2]crypt)] 4 Sn 9 . [25] [10] a) T. Intramolecular metallo ± ene reactions are efficient methods for the construction of substituted ring systems. [1] As the Type 1 metallo ± ene reaction illustrates, 2,(w À 1)-alkadienylmetal compounds A cyclize via the cyclic conjugated transition state B to form a (2-vinylcycloalkyl)methylmetal intermediate C, which is then protonated to give cycloalkanes D (Scheme 1).…”