| Summary: | The family of practically requested “common” silatrane derivatives of triethanolamine X-Si(OCH<sub>2</sub>CH<sub>2</sub>)<sub>3</sub>N, <b>1</b>, was enlarged with the first representatives of 3,4,6,7,10,11-tribenzo-2,8,9trioxa-5-aza-1-silatricyclo(3.3.3.0^1,5^)undecanes X-Si(O-<i>para</i>-R-C<sub>6</sub>H<sub>3</sub>)<sub>3</sub>N, tribenzsilatranes <b>2</b> (R = H (<b>a</b>), Me (<b>b</b>), F (<b>c</b>)), carrying the substituent R in the side aromatic rings. These compounds were prepared via the transesterification of phenyl trimethoxysilane with the corresponding triphenol amines and studied using XRD and DFT calculations. These derivatives of 1-X-(4-R-2,2′,2′′-nitrilotriphenoxy)silane are expected to have, as their parent “common” silatranes <b>1,</b> diverse biological and pharma activities. A common characteristic feature of the molecular structures of both <b>1</b> and <b>2</b> is the presence of an intramolecular dative bond N→Si whose existence is evidenced by geometric and quantum topological (AIM) criteria. In the crystals, the length of this bond (<i>d</i><sub>SiN</sub>) is noticeably longer in tribenzsilatranes than in <b>1</b>. The results of DFT B3PW91/6-311++G(d,p) calculations suggest the reason for this to be the more rigid nature of the potential functions of the N→Si bond deformation in <b>2</b> compared to <b>1</b>. The relative degree of “softness”/”hardness” of the potential functions can be assessed from the difference in the calculated values of <i>d</i><sub>SiN</sub> in isolated molecules <b>1</b> and <b>2a–c</b> and in their crystals.
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