Fluorboryl- und Fluorborandiyl-Cyclosilazane

Abstract

<jats:title>Abstract</jats:title><jats:p> Hexamethylcyclotrisilazanes and their lithium salts react with F<jats:sub>2</jats:sub>BN(SiMe<jats:sub>3</jats:sub>)<jats:sub>2</jats:sub> to give the corresponding mono-, bis-, and tris(fluoroboryl)cyclotrisilazanes. Di-fluoroboryl-substituted rings are obtained in the reaction of 1,3-bis(silyl)- and 1-boryl-cyclotrisilazanes with BF<jats:sub>3</jats:sub>-etherate. A compound consisting of two cyclodisilazanes connected by a (SiNBNSi)-bridge is formed in the reaction of lithiated bis(silyl)cyclotrisilazane with BF<jats:sub>3</jats:sub>-etherate. Ring coupling of two six membered rings occurs in the reaction of lithiated cyclotrisilazane with 1-difluoroboryl-cyclotrisilazane and in the reaction of lithiated bis(fluoroboryl)cyclotrisilazane with BF<jats:sub>3</jats:sub>-etherate in a molar ratio 2:1. Ring expansion takes place in the reaction of the lithium salt of a four membered SiN-ring with F<jats:sub>2</jats:sub>BN(SiMe<jats:sub>3</jats:sub>)<jats:sub>2</jats:sub>. Substitution occurs in the same reaction with F<jats:sub>3</jats:sub>SiN(SiMe<jats:sub>3</jats:sub>)<jats:sub>2</jats:sub>.</jats:p>

Darstellung und Kopplung von Cyclosilazanen und Borazinen - Precursoren für Si-B-N- und Si-B-C-N-Keramiken

“…2. Elektronische Effekte: Erstsubstituenten, die die Basizität des Ringes erhöhen, d. h. Substituenten mit +I-und/oder +M-Effekt, fördern die Tendenz zur Ringkontraktion, Substituenten mit elektronenziehendem Effekt begünstigen die Retention des Ringsystems [32,35].…”

“…Eigenschaften des angreifenden Liganden: Ist der angreifende Ligand Lewis-sauer, so wird der basische Charakter des Ringes erniedrigt, wodurch die Retention des sechsgliedrigen Ringes bzw. die Expansion des viergliedrigen Ringes begünstigt wird [32,35].…”

Cyclosilazanes and borazines: polymer precursors to silicon- and boron-containing ceramics

“…14,15,32 The six-membered N 3 Si 3 ring adopts a distorted boat conformation with normal Si-N distances and planar-coordinated boron atoms 14,15 (Eqn [16]). …”

Fluorsilyl‐ und Fluorboryl‐substituierte Cyclotetrasilazane Synthese und Kristallstrukturen

“…Difluorphenylsilpl-2,2,4,4,6,6,8,8-octamethylcyclotetrasilazan, 4. IH-NMR: 0,08 SiMe,, 0,27 SiMe, (5J,F = 1 , l Hz), 7,36 Sic,,4,81 SIC,(4J,,7 = 1,9 Hz),128,21,130,60 (2Jc,= 28,3 Hz),131,39,134,27 3,7g (10%). 226g (7%).…”