Iridium complexes featuring a tridentate SiPSi ligand: from dimeric to monomeric 14, 16 or 18-electron species

• Published in: Dalton transactions : an international journal of inorganic chemistry 2019-09, Vol.48 (37), p.141-1418
• Main Authors: Cuevas-Chávez, Cynthia A, Vendier, Laure, Sabo-Etienne, Sylviane, Montiel-Palma, Virginia
• Format: Article
• Language: English
• Subjects: Chemical Sciences; Coordination chemistry; Crystallography; Electrons; Hydrides; Hydrogen bonds; Iridium compounds; Ligands; NMR; Nuclear magnetic resonance
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c9dt03136g

In the solid state, the dinuclear iridium complex [μ-Cl-Ir(SiMe 2 CH 2 - o -C 6 H 4 ) 2 PPh] 2 , 1 , is shown by X-ray diffraction to bear dibenzylsilylphosphine ligands in SiPSi tridentate coordination modes as well as chloride bridges. In C 6 D 6 solution, 1 dissociates into the 14-electron species [IrCl(SiMe 2 CH 2 - o -C 6 H 4 ) 2 PPh] prone to coordinate one or two L-type ligands such as PR 3 (R = Cy, Ph, OEt), CO and CH 3 CN giving rise to the corresponding mononuclear 16- or 18-electron complexes [IrCl(SiMe 2 CH 2 - o -C 6 H 4 ) 2 PPh(L) x ] ( x = 1, 2) as evidenced by X-ray and NMR studies. The dinuclear structure is retained upon reaction with Et 3 SiH which results in the formation of [μ-Cl,μ-H-Ir 2 {(SiMe 2 CH 2 - o -C 6 H 4 ) 2 PPh} 2 ] with a bridging hydride. On the basis of NMR studies, the reaction of the triphenylphosphine complex [IrCl(SiMe 2 CH 2 - o -C 6 H 4 ) 2 PPh(PPh 3 )] with LiBHEt 3 leads to the hydride complex [IrH(SiMe 2 CH 2 - o -C 6 H 4 )(η 2 -H-SiMe 2 CH- o -C 6 H 4 )PPh(PPh 3 )] in which one SiPSi ligand has been transformed and is now bonded to iridium in a tetradentate mode via P, Si, an agostic Si-H bond, and C of a methine as a result of the activation of one methylene group. Dimer [Ir{P( o -C 6 H 4 CH 2 SiMe 2 ) 2 Ph}(μ-Cl)] 2 featuring tricoordinate phosphinodisilyl ligands dissociates in solution to the reactive 14 electron monomer [Ir(SiPSi)Cl].