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Early/Late Heterobimetallic Tantalum/Rhodium Species Assembled Through a Novel Bifunctional NHC‐OH Ligand
Author(s) -
Srivastava Ravi,
Moneuse Raphaël,
Petit Julien,
Pavard PaulAlexis,
Dardun Vincent,
Rivat Madleen,
Schiltz Pauline,
Solari Marius,
Jeanneau Erwann,
Veyre Laurent,
Thieuleux Chloé,
Quadrelli Elsje Alessandra,
Camp Clément
Publication year - 2018
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.201705507
Subject(s) - carbene , protonolysis , chemistry , ligand (biochemistry) , bifunctional , rhodium , medicinal chemistry , alkyl , tantalum , stereochemistry , alkoxy group , organic chemistry , catalysis , biochemistry , receptor
The straightforward synthesis of a new unsymmetrical hydroxy‐tethered N‐heterocyclic carbene (NHC) ligand, HL, is presented. The free ligand exhibits an unusual OH–carbene hydrogen‐bonding interaction. This OH–carbene motif was used to yield 1) the first tantalum complex displaying both a Fischer‐ and Schrock‐type carbene ligand and 2) a unique NHC‐based early/late heterobimetallic complex. More specifically, the protonolysis chemistry between the ligand's hydroxy group and imido‐alkyl or alkylidene‐alkyl tantalum precursor complexes yielded the rare monometallic tantalum–NHC complexes [Ta(X t Bu)(L)(CH 2 t Bu) 2 ] (X=N, CH), in which the alkoxy‐carbene ligand acts as a chelate. In contrast, HL only binds to rhodium through the NHC unit in [Rh(HL)(cod)Cl] (cod=cycloocta‐1,5‐diene), the hydroxy pendant arm remaining unbound. This bifunctional ligand scaffold successfully promoted the assembly of rhodium/tantalum heterobimetallic complexes upon either 1) the insertion of [Rh(cod)Cl] 2 into the Ta–NHC bond in [Ta(N t Bu)(L)(CH 2 t Bu) 2 ] or 2) protonolysis between the free hydroxy group in [Rh(HL)(cod)Cl] and one alkyl group in [Ta(N t Bu)(CH 2 t Bu) 3 ].