Crystal structures of optically active diastereomeric telluronium and selenonium salts anion—cation interactions in the crystalline state

Selenirenium and Tellurirenium Ions

“…The latter value is similar to those in telluronium ions such as PhMeEtTe + (211.7 pm). [18] The C = C bond length (128.8 pm) is as was found in the selenium compounds, but the C-Te-C angle (34.18) is even smaller. Ring strain, and the TeÀC bond, which is weaker than a SeÀC bond, and in this case even more elongated, explain the low stability of these compounds.…”

“…The latter are similar to those in normal selenonium ions, such as PhMeEtSe + (SeÀPh 193.0 pm, SeÀMe 192.6 pm). [18] The bond angles at the selenium atom are small (388) and are thus even smaller than in the thiirenium ion (40.858). [4] The C = C bond lengths (127.9 and 128.5 pm, sulfur analogues 127.8 pm [4] ) are remarkable short, and are intermediate between a double bond ((Z)-tBuCH=CHtBu 134.3 pm) and a triple bond (tBuC CtBu 120.2 pm).…”

Selenirenium‐ und Tellurireniumionen

“…Letztere entsprechen denjenigen in normalen Selenoniumionen wie PhMeEtSe + (Se-Ph 193.0 pm, Se-Me 192.6 pm). [18] Die Winkel am Heteroatom betragen knapp 388 und sind damit noch kleiner als im Thiireniumion (40.858). [4] Die C = C-Bindungen sind mit 127.9 und 128.5 pm (S-Analogon 127.8 pm [4] ) bemerkenswert kurz; die Werte liegen zwischen denen für Doppelbindungen ((Z)-tBuCH=CHtBu 134.3 pm) und Dreifachbindungen (tBuC CtBu 120.2 pm).…”

“…Letztere ähnelt derjenigen in einfachen Telluroniumionen wie PhMe-EtTe + (211.7 pm). [18] Die C = C-Bindung (128.8 pm) entspricht jener der Selenanaloga, der C-Te-C-Winkel ist mit 34.18 noch kleiner als der entsprechende Winkel in den Selenverbindungen. Die Ringspannung und die, verglichen mit der Se-C-Bindung, ohnehin schwächere Te-C-Bindung, die zudem im Tellurireniumion noch aufgeweitet ist, bestimmen die geringe Stabilität dieser Verbindungen.…”

Isolation and Racemization Mechanism of Optically Active Benzylmethylphenyltelluronium Salts

“…Previously, we isolated optically active dialkylaryltelluronium salts but observed no racemization even in solution. [7][8][9] Koizumi and co-workers also isolated stable optically active dialkyl-or alkylaryl(2-exo-hydroxy-10-bornyl)telluronium salts. [10] Recently, we synthesized benzylmethylphenyltelluronium salts and isolated their optically active isomers with several counteranions.…”