3, 5‐Dimethylpyrazolyl‐Substituted Di‐ and Trisiloxanes. Issue 26 (16th August 2016)

• Record Type: Journal Article
• Authors: Bitto, Florian; Brendler, Erica; Böhme, Uwe; Wagler, Jörg; Kroke, Edwin
• Is Part Of: European journal of inorganic chemistry. Issue 26(2016)
• Page Start: 4207
• Page End: 4215
• Publication Date: 2016-08-16
• Subjects: Silicon -- Siloxanes -- Nitrogen heterocycles -- Coordination modes -- Density functional calculations; Chemistry, Inorganic -- Periodicals; Organometallic chemistry -- Periodicals; Bioinorganic chemistry -- Periodicals; Solid state chemistry -- Periodicals; 546
• DOI: 10.1002/ejic.201600591
• Languages: English
• ISSNs: 1434-1948

Abstract

Abstract : The synthesis and characterization of di‐ and trisiloxanes with 3, 5‐dimethylpyrazolyl (pz*) moieties are presented. Disiloxanes of the type O(SiMe3– n pz* n )2 ( n = 1, 2, and 3 in2, 3, and4, respectively) are easily accessible through a trans ‐silylation approach. Crystal structure analyses of compound4 and the two side products5 and6 illustrate different coordination motifs of pz* (terminal vs. bridging) in the disiloxane system. The reaction of O2 Si3 Cl8 with Me3 Sipz* led to the unsymmetrically substituted trisiloxane pz*3 SiO‐Sipz*2 O‐SiCl2 pz* (7 ) with bridging pz* units and tetra‐ and pentacoordinate silicon atoms and the fully pyrazolyl‐substituted trisiloxane O2 Si3 pz*8 (8 ), depending on the choice of the reaction conditions. The 29 Si NMR properties of7 were investigated by 29 Si CP/MAS NMR spectroscopy and supporting quantum chemical calculations analyzing the principal components of the chemical‐shift tensor for all three silicon atoms in this molecule. Abstract : The reaction of 3, 5‐dimethypyrazolyltrimethylsilane with chloro‐substituted disiloxanes and octachlorotrisiloxane afforded fully substituted disiloxanes and trisiloxanes. The properties of a special asymmetric trisiloxane (see picture) were investigated with respect to its formation and 29 Si NMR shielding‐tensor components.