Tripodal Triamidometallates of the Heavy Group 14 Elements: Inorganic Cages with Remarkable “Ligand Properties”

Abstract

Anionic main group metal donors with potentially interesting ligand properties are obtained if ate complexes of the heavy p-block metals are formed by coordination between tripodal amides and divalent group 14 metal centres. The limitations of this approach, due to the potential oxidation by the central transition metal atom, may in part be suppressed by the presence of electronegative substituents at the M II centre, which makes the metallates less reducing. The considerable stability of the triamidostannates(II) towards Ag I or Au I−III is testimony to the practical significance of this. The most char-

Synthesis and Complexation of a Free Germanide Bearing a Tridentate N-Heterocyclic Substituent

“…The substituent (tmim)­H 3 was synthesized and deprotonated according to published procedures. , Subsequently, the germanide 1 was synthesized by nucleophilic substitution of chloride for the tmim 3– trianion on GeCl 2 ·dioxane (Scheme ), which is a common approach to synthesize germanides. − ,, The germanide was obtained either as its sodium salt 1 -Na or as its potassium salt 1 -K. The synthesis of 1 -Na requires an excess of GeCl 2 ·dioxane to reach completion, which is tentatively attributed to formation of insoluble NaGeCl 3 . In contrast, a stoichiometric amount of GeCl 2 ·dioxane was sufficient for the synthesis of 1 -K. Therefore, the potassium salt 1 -K was used for complexation studies.…”

“…All-nitrogen substituted germanides similar to 1 have received some attention, examples including triazidogermanide A , bicyclo triamido­germanide B , and the zwitterionic tripyrazolyl germanide C (Chart ). − Their coordination chemistry is scarce, and structurally characterized complexes are limited to a tungsten­(II) complex derived from structure A , a gold­(I) complex derived from structure B , and iron­(II) complexes of a tetradentate triphosphinogermyl ligand. − In the current work, the synthesis of compound 1 and its complexation to soft Lewis-acidic metal fragments (CuCl, Cu­(NCMe) 3 , and Fe­(CO) 4 ) is reported. In contrast to the silanide, coordination to the harder Lewis acid FeCl 2 results in at most a weak interaction with a small association constant in solution.…”