Torsional distortions in trimesitylsilanes and trimesitylgermanes

Syntheses and structural analysis of the sterically encumbered germanes (o-ButC6H4)3GeX (X=Br, H, Cl, OH), (o-ButC6H4)2GeBr2, and Mes2GeH2: distortions arising from the presence of an ortho-tert-butyl substituent

“…With the exception of the C 3 -symmetric 1, these angles each occur three times in each molecule, and the values shown in Table 3 are the average of these three values for each molecule. This type of distortion is also observed in substituted aryl germanes where the ortho-substituents all point in the same direction, or in compounds that have two ortho-substituents, and so is also observed in Mes 3-GeH (12) [17] and Mes 3 GeOH (17) [23]. The value of 4 can then be used to describe the rotation of the rings in these species, where…”

“…The hydrogen bound to germanium was refined, and the GeeH bond distance is 1.37(2) A. The structure of 2 can be compared to the arylgermanium hydride species Ph 3 GeH (10) [9], (o-CH 3 C 6 H 4 ) 3 GeH (11) [16], and Mes 3 GeH (12) ( Table 2) [17]. The average GeeC bond distance in 2 is elongated relative to the average GeeC bonds in both 10 [9], and 11 [16] but are shorter than that in 12 [17].…”

“…The structure of 2 can be compared to the arylgermanium hydride species Ph 3 GeH (10) [9], (o-CH 3 C 6 H 4 ) 3 GeH (11) [16], and Mes 3 GeH (12) ( Table 2) [17]. The average GeeC bond distance in 2 is elongated relative to the average GeeC bonds in both 10 [9], and 11 [16] but are shorter than that in 12 [17]. The GeeH bond distance in 2 is similar to that in 10 (1.48(3) A) [9] but shorter than the corresponding distance in 11 (1.712(1) A) [16].…”

“…In order to accommodate the three ortho-tert-butyl groups, the aryl rings are rotated such that one angle becomes more acute than 30 (a) and one becomes more obtuse than 30 (b) as shown in Fig. 6 [17,23]. With the exception of the C 3 -symmetric 1, these angles each occur three times in each molecule, and the values shown in Table 3 are the average of these three values for each molecule.…”

Propeller rotation of aryl groups in triarylsilanes and triarylstannanes

“…The mesityl systems (1-3) were available from a previous study. 4 Durylsodium was reacted with trichlorosilane to produce tridurylsilane (4), which was converted to chlorotridurylsilane (5) by the action of phosphorus pentachloride. Reaction of allyllithium with 5 produced allyltridurylsilane (6).…”