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Cation‐Mediated Conversion of the State of Charge in Uranium Arene Inverted‐Sandwich Complexes
Author(s) -
Camp Clément,
Mougel Victor,
Pécaut Jacques,
Maron Laurent,
Mazzanti Marinella
Publication year - 2013
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201302752
Subject(s) - trifluoromethanesulfonate , disproportionation , chemistry , stoichiometry , toluene , medicinal chemistry , crystallography , yield (engineering) , stereochemistry , catalysis , organic chemistry , materials science , metallurgy
Two new arene inverted‐sandwich complexes of uranium supported by siloxide ancillary ligands [K{U(OSi(O t Bu) 3 ) 3 } 2 (μ‐η 6 :η 6 ‐C 7 H 8 )] ( 3 ) and [K 2 {U(OSi(O t Bu) 3 ) 3 } 2 (μ‐η 6 :η 6 ‐C 7 H 8 )] ( 4 ) were synthesized by the reduction of the parent arene‐bridged complex [{U(OSi(O t Bu) 3 ) 3 } 2 (μ‐η 6 :η 6 ‐C 7 H 8 )] ( 2 ) with stoichiometric amounts of KC 8 yielding a rare family of inverted‐sandwich complexes in three states of charge. The structural data and computational studies of the electronic structure are in agreement with the presence of high‐valent uranium centers bridged by a reduced tetra‐anionic toluene with the best formulation being U V –(arene 4− )–U V , KU IV –(arene 4− )–U V , and K 2 U IV –(arene 4− )–U IV for complexes 2 , 3 , and 4 respectively. The potassium cations in complexes 3 and 4 are coordinated to the siloxide ligands both in the solid state and in solution. The addition of KOTf (OTf=triflate) to the neutral compound 2 promotes its disproportionation to yield complexes 3 and 4 (depending on the stoichiometry) and the U IV mononuclear complex [U(OSi(O t Bu) 3 ) 3 (OTf)(thf) 2 ] ( 5 ). This unprecedented reactivity demonstrates the key role of potassium for the stability of these complexes.