Zur Bildung einer Zinn‐Zinn‐Bindung in Bis(hexamethyldisilazyl)‐Zinn(II) unter C‐H Bindungsbruch

Abstract

Bis(hexamethyldisilazyl)tin(II) in excess reacts with the molecular alumosiloxane (Ph 2 SiO) 8 (AlO(OH)) 4 to yield the well known tin(II) derivative (Ph 2 SiO) 8 (AlO 2 ) 4 Sn 2 and the novel bicyclic [(Me 3 Si) 2 N]Sn[N(SiMe 3 )SiMe 2 CH 2 ] 2 Sn[N(SiMe 3 ) 2 ] containing a tin-tin bond, which is formally related to the starting molecule by a missing hydrogen atom. From X-ray diffraction studies on single crystals it follows that the new compound has almost C 2 point symmetry (the twofold axis intersecting the tin-tin bond) and that this tin-tin bond is the fusion edge of anellated fivefold

Deprotonation of Group 14 Metal Amide Complexes Bearing Ditopic Carbanionic N-Heterocyclic Carbene Ligands. Constitutional Isomerism and Dynamic Behavior

“…This is presumably due to the increased electrophilicity of Sn1, which is a four-coordinate tin center (although still formally tin­(II)) involved in a formal dative covalent bond with Sn2. The Sn–Sn bond length is measured to be 2.870(1) Å, which is slightly longer than that expected based on the covalent radius of tin ( r cov = 1.39 Å; ∑ r cov = 2.78 Å) , and is slightly longer than the distances observed in hexaphenylditin and a similar heterocyclic compound which resulted from loss of hydrogen from the trimethylsilylamide ligand, [Sn­{N­(SiMe 3 ) 2 }­{N­(SiMe 3 )­(SiMe 2 CH 2 )}] 2 , , for which the Sn–Sn bond lengths are 2.770(4) and 2.737(2) Å, respectively. That being said, a search of the Cambridge Structural Database reveals a wide range in Sn–Sn bond lengths, which easily extend beyond 3 Å, indicating the elasticity of the bond, whose length may be significantly influenced by the steric influence of the ligands as much as the electronic properties of the bonding interaction.…”

“…[6a] Interestingly, contrasting reactivity is observed for the lithium salt of same ditopic carbanionic N-heterocyclic carbene, There are a handful of reported examples of the bis(trimethylsilyl)amide ligand being deprotonated in basic reaction media to afford metallacycles. [10][11][12][13][14] The basicity of the amide by-product is likely to also be increased due to the presence of IPr in solution. IPr has been shown to readily coordinate to lithium cations, hence, any amide aggregates which may form in solution are likely to be more basic, much as the reactivity of n BuLi is enhanced by the addition of a chelating ligand such as TMEDA (tetramethylethylenediamine).…”

The role of the bis-trimethylsilylamido ligand, [N{SiMe3}2]−, in main group chemistry. Part 2: Structural chemistry of the metallic p-block elements

“…An unusual reaction between Sn(N{SiMe 3 } 2 ) 2 105 and the molecular alumosiloxane (Ph 2 SiO) 8 (AlO{OH}) 4 afforded, in addition to the known tin derivative (Ph 2 SiO) 8 (AlO 2 ) 4 Sn 2 , the bicyclic compound 153 containing a Sn Sn bond [121]. In a similar reaction, metallation of the diphosphanylsilane Si(i-Pr) 2 (PHMe) 2 with stannylene 105 generated a polycyclic compound consisting of a Sn 3 P 4 Si 2 core unit which contains an Sn Sn bond (154, Fig.…”