Homoleptic low-valent polyazides of group 14 elements

Abstract

First examples of coordinatively unsaturated, homoleptic azido complexes of low-valent group 14 elements are reported. A simple strategy uses low-valent precursors, ionic azide transfer reagents and bulky cations to obtain salt-like compounds containing E(N3)3(-) of Ge(II)/Sn(II) which are fully characterised, including XRD. Remarkably, these compounds are kinetically stable at r.t. and isolable in sub-gram quantities.

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.…”

“…Angles close to 90° are commonly found in germanides, also in the absence of a cage structure enforcing them, as for example in compound A (Chart ). ,,− This is a consequence of the generally low propensity of heavier elements to undergo orbital hybridization, i.e., the inert pair effect. − …”

“…23,32 Subsequently, the germanide 1 was synthesized by nucleophilic substitution of chloride for the tmim 3− trianion on GeCl 2 •dioxane (Scheme 2), which is a common approach to synthesize germanides. [24][25][26][27][28][29]33,34 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 .…”

“…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.…”

Labile Low-Valent Tin Azides: Syntheses, Structural Characterization, and Thermal Properties

“…The crystals of compound 2 and 3 consist of tin complexes ( 25 Complexes with low-valent main group centres ( Table 1) often have a lone pair that affects their reactivity and coordination geometry. The unsupported Ag-Sn bond of the adduct HB{3,5-(CF 3 ) 2 pz} 3 Ag-Sn(N 3 )( n Pr 2 ATI) (vide supra), for instance, involves the lone pair on Sn rather than azido ligands bridging Ag with Sn centres.…”