Tetrel bonds

The bottom-up synthesis of well-defined (semi)metal and intermetalloid clusters that can reach the nanometer scale represents a major challenge. Deltahedral structures reach a limit in size unless more capable templates are found. However, Zintl ions themselves can serve as building units for the formation of larger structures, including classical and nonclassical tetrel-tetrel bonds. Two further examples justify the plan to use such tetrel dusters as precursors for nanoscale dusters ... 

Grabowski, S. J. (2014). Tetrel bond-a-hole bond as a preliminary stage of the SN2 reaction. Physical Chemistry Chemical Physics, 16(5), 1824—1834. 

Bauza A, Mooibroek TJ, Frontera A (2013) Tetrel-bonding interaction rediscovered supramolecular force Angew Chem Int Ed Engl 52 12317-12321... 

Grabowski SJ (2014) Tetrel bond—o-hole bond as a preliminary stage of the Sfj2 reaction. Phys Chem Chem Phys 16 1824-1834... 

Li QZ, Guo X, Yang X, Li WZ, Cheng JB, Li HB (2014) A sigma-hole interaction with radical species as electron donors does single-electron tetrel bonding exist Phys Chem Chem Phys 16(23) 11617-11625. doi 10.1039/c4cp01209g... 

Soluble heptapnicanortricyclane anions [Pny] (Fig. 3a) and trishomocubane-shaped (ufosane-like) anions [Pnn] (Fig. 3d) are very common and known as in the binary solids for Pn = P, As, Sb (Table 2). Oxidative coupling of these monomers leads to the dimers [Pny-Pny]" and [Pnn-Pnn]" for Pn = P and As (Fig. 3b, e), which - as observed for the tetrel element clusters - have an external homoatomic bond, but in this case the structures of the monomeric units are fully retained upon dimerization. A trimeric oxidative coupling product of [Py] is the... 

C. Other Systems with Multiple Bonds between Heavier Tetrel Atoms. . 334... 

In this chapter the focus is laid on species comprising two E—C bonds, including however those rare examples where two different organyl groups are bonded to the two-coordinate tetrel atom (Table 1) and which are not homoleptic within a stricter definition. 

TABLE 1. Parameters (bond length in pm, angle in deg) of germylenesR1R2Ge with two-coordinate tetrel atom... 

Apart from the unique adduct 5150, in which two plumbylene moieties are bridged by a MgBr2(thf)4 molecule viaBr —> Pb interactions [Pb—Br 296.4(2) pm], and few cyclopen-tadienyl derivatives where chelating amines interact with the two-valent tetrel atom62, unsupported adducts of Lewis bases with tetrylenes have been restricted to carbene-type bases so far. However, only donor carbenes, such as Arduengo carbenes, isonitriles or ylids, form simple adducts with dative C —> E interactions (Table 8). Carbenes or analogous species which also exhibit a substantial acceptor ability form multiple bonds instead (see Section III). 

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