Issue 29, 2019

Mesityl(amidinato)tetrylenes as ligands in iridium(i) and iridium(iii) complexes: silicon versus germanium and simple κ1-coordination versus cyclometallation

Abstract

Reactions of the mesityl(amidinato)tetrylenes E(tBu2bzam)Mes (tBu2bzam = N,N′-bis(tert-butyl)benzamidinate; Mes = mesityl; E = Ge (1Ge), Si (1Si)) with the iridium precursors [Ir2(μ-Cl)24-cod)2] (cod = 1,5-cyclooctadiene) and [Ir2Cl2(μ-Cl)25-Cp*)2] (Cp* = 1,2,3,4,5-pentamethylcyclopentadienyl) at room temperature led to simple coordination of the tetrylene in the case of the germylenes ([IrCl(η4-cod){κ1Ge-Ge(tBu2bzam)Mes}] (2Ge) and [IrCl25-Cp*){κ1Ge-Ge(tBu2bzam)Mes}] (3Ge), respectively, but to cyclometallated products in the case of the silylenes ([IrHCl(η4-cod){κ2C,Si-Si(tBu2bzam)CH2C6H2Me2}] (4Si) and [IrCl(η5-Cp*){κ2C,Si-Si(tBu2bzam)CH2C6H2Me2}] (5Si), respectively. While the cyclometallation of the germylene ligand of the iridium(I) complex 2Ge could not be achieved by heating this complex in toluene at 90 °C, a similar treatment of the iridium(III) complex 3Ge led to [IrCl(η5-Cp*){κ2C,Ge-Ge(tBu2bzam)CH2C6H2Me2}] (5Ge), which is the germanium analogue of 5Si. DFT calculations have shown that the mononuclear κ1E-tetrylene iridium(I) complexes [IrCl(η4-cod){κ1E-E(tBu2bzam)Mes}] (E = Si, Ge; isolated only for E = Ge, 2Ge) should not participate as intermediates in the synthesis of the cyclometallated iridium(III) derivatives [IrHCl(η4-cod){κ2C,E-E(tBu2bzam)(CH2C6H2Me2)}] (E = Ge, Si; isolated only for E = Si, 4Si).

Graphical abstract: Mesityl(amidinato)tetrylenes as ligands in iridium(i) and iridium(iii) complexes: silicon versus germanium and simple κ1-coordination versus cyclometallation

Supplementary files

Article information

Article type
Paper
Submitted
02 Mud 2019
Accepted
06 Kho 2019
First published
07 Kho 2019

Dalton Trans., 2019,48, 10996-11003

Mesityl(amidinato)tetrylenes as ligands in iridium(I) and iridium(III) complexes: silicon versus germanium and simple κ1-coordination versus cyclometallation

J. A. Cabeza, J. M. Fernández-Colinas, P. García-Álvarez, L. González-Álvarez and E. Pérez-Carreño, Dalton Trans., 2019, 48, 10996 DOI: 10.1039/C9DT01853K

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