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Complexation of selenium to ( R )‐Rh 2 (MTPA) 4 : thermodynamics and stoichiometry
Author(s) -
Duddeck Helmut,
Malik Shahid,
Gáti Tamás,
Tóth Gábor,
Choudhary Muhammad Iqbal
Publication year - 2002
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.990
Subject(s) - chemistry , selenide , adduct , rhodium , stoichiometry , molecule , selenium , nuclear magnetic resonance spectroscopy , stereochemistry , medicinal chemistry , catalysis , organic chemistry
Abstract Variable‐temperature 1 H and 77 Se NMR data for 3‐phenylselenenyl‐1‐phenyl‐1‐propene (1) in the presence of Rh 2 (MTPA) 4 (Rh*) prove that the equilibria are strongly shifted towards the adduct Rh*···1; free selenide molecules cannot be detected as long as uncomplexed rhodium atoms are available. In the case of excess Rh*, both 1 : 2 and 1 : 1 adducts (Rh* vs 1) are formed, and the latter is slightly favoured. With excess selenide, the system strongly favours the complexation of two selenide molecules (1 : 2 adduct), i.e. one at each rhodium atom. In this situation, intermolecular selenide exchange can be monitored by variable‐temperature 1 H NMR spectroscopy and the energy barrier is estimated to be 54–55 kJ mol −1 . Copyright © 2001 John Wiley & Sons, Ltd.