The Structure of Disiloxane Triflamide Derivatives and Their Hydrogen and Metal Complexes

Supramolecular structure of triflamidated disiloxanes consists of infinite chains of dimers with different noncovalent bonds. The NH∙∙∙O = S bonds moderate in strength, the NH∙∙∙F, СH∙∙∙F, CH∙∙∙O = S or CH∙∙∙OSi are weak. The complexes with proton and electron acceptors showe either cooperative or competitive effects.

Abstract

The supramolecular structure of the products of triflamidation of 1,1,3,3-tetramethyl-1,3-divinyldisiloxane – 6-iodo-3-(triflamidomethyl)-4-triflyl-1,4,2,7-oxazadisilepane 1 and 2,2,4,4-tetramethyl-6,8-bis(triflyl)-3-oxa-6,8- diaza-2,4-disilabicyclo[3.2.2]nonane 2 – is analyzed based on the x-ray analysis and theoretical calculations in gas phase and in a polar medium (DMSO). In the crystal, it consists of infinite chains of the dimers formed by noncovalent bonds of the NH and CH groups with the SO₂ or SiOSi oxygen and CF₃ fluorine atoms. The calculated maximum positive and negative molecular electrostatic potentials (MEPs) of the monomers are consistent with the lengths of intra and intermolecular bonds in the dimers formed thereof. The NH∙∙∙O═S bonds in the dimers of 1 and 2 are “moderate” in strength (∼4 kcal/mol), the NH∙∙∙F, СH∙∙∙F, CH∙∙∙O═S or CH∙∙∙OSi are weak (1–3 kcal/mol). The interactions in the complexes of molecules 1 and 2 with proton and electron acceptors such as acetonitrile, pyrrole, or zinc chloride can be both cooperative and anticooperative (competitive) depending on their nature.

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