Steric Control at the Wingtip of a Bis-N-Heterocyclic Carbene (NHC) Ligand: Coordination Behaviour and Catalytic Responses of its Ruthenium Compounds - Université de Rennes Accéder directement au contenu
Article Dans Une Revue Organometallics Année : 2012

Steric Control at the Wingtip of a Bis-N-Heterocyclic Carbene (NHC) Ligand: Coordination Behaviour and Catalytic Responses of its Ruthenium Compounds

Résumé

Changing the N-substituents of a methylene-linked bis-NHC ligand from n-butyl to bulky mesityl shifts ligand coordination from normal/normal to normal/abnormal mode. The mesityl wingtip groups afford [RuII(MesNHC(CH2)NHCMes)(MesNHC(CH2)aNHCMes)(CH3CN)2][PF6]2 (1), in which one of the ligands exhibits mixed C2/C4 binding to the same metal, while the second ligand utilizes C2/C2 carbons for metal coordination. On the contrary, the n-butyl analogue leads to metal oxidation, affording a RuIII complex [Ru(nBuNHC(CH2)NHCnBu)2Cl2][PF6] (2) upon crystallization in air, where both ligands show normal C2/C2 coordination. Thus, the resulting complexes exhibit different structural and electronic characteristics, which are further reflected in their catalytic responses. The catalytic utilities of both compounds toward carboxylic acid addition onto terminal alkyne are evaluated in this work. The abnormally bound 1 shows higher activity and better selectivity compared to all-normal counterpart 2.

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Chimie
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Dates et versions

hal-00870674 , version 1 (07-10-2013)

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Sayantani Saha, Tapas Ghatak, Biswajit Saha, Henri Doucet, Jitendra K. Bera. Steric Control at the Wingtip of a Bis-N-Heterocyclic Carbene (NHC) Ligand: Coordination Behaviour and Catalytic Responses of its Ruthenium Compounds. Organometallics, 2012, 31 (15), pp.5500-5505. ⟨10.1021/om300469n⟩. ⟨hal-00870674⟩
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