Cleavage of acyclic diaminocarbene ligands at an iridium(iii) center. Recognition of a new reactivity mode for carbene ligands.



Kinzhalov, Mikhail A, Eremina, Anzhelika A, Smirnov, Andrey S, Suslonov, Vitalii V, Kukushkin, Vadim Yu and Luzyanin, Konstantin V ORCID: 0000-0001-9312-7139
(2019) Cleavage of acyclic diaminocarbene ligands at an iridium(iii) center. Recognition of a new reactivity mode for carbene ligands. Dalton transactions (Cambridge, England : 2003).

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Abstract

Reaction of [Ir(μ-Cl)(ppy)2]2 (1) with 4 equivs of CNC6H4X (X = F 2a, Cl 2b, Br 2c, I 2d) in the presence of 2 equivs of AgOTf in dichloromethane at 20-25 °C furnished the bisisocyanide complexes [Ir(ppy)2(CNC6H4X)2](OTf) ([3a-d](OTf); 72-87%). Reaction of [3a-d](OTf) with an excess of gaseous ammonia at room temperature gave the bisdiaminocarbene species [Ir(ppy)2{C(NH2)NHC6H4X}2](OTf) [5a-d](OTf) (73-83%); the two-step addition proceeds through an intermediate formation of appropriate monocarbene complexes [4a-d](OTf). Further reaction of [5a-d](OTf) with an excess of gaseous ammonia at 50 °C led to the cleavage of one diaminocarbene ligand to the cyanide ligand in [Ir(ppy)2(CN){C(NH2)NHC6H4X}] (6a-d) and this transformation is accompanied with the elimination of a substituted aniline. Treatment of [5a-d](OTf) with N(CH2CH2OH)3 at 50 °C resulted in the cleavage of the diaminocarbene ligand to the isocyanide and uncomplexed NH3; isocyanide remains bound to the iridium(iii) center in [Ir(ppy)2{C(NH2)NHC6H4X}(CNC6H4X)](OTf) (4a-d). All isolated compounds were characterized by elemental analyses (C, H, N), molar conductivity measurements, TG/DTA, HRESI+/--MS, FTIR, 1D (1H, 13C{1H}, 19F{1H}) and 2D (1H,1H-COSY, 1H,13C-HMQC/1H,13C-HSQC, 1H,13C-HMBC) NMR, and also by X-ray diffraction (for the bisisocyanide 3, the diaminocarbene/isocyanide 4, the bisdiaminocarbene 5, and the diaminocarbene/cyanide 6 type complexes).

Item Type: Article
Depositing User: Symplectic Admin
Date Deposited: 13 May 2019 07:26
Last Modified: 25 Jun 2022 12:10
DOI: 10.1039/c9dt01138b
URI: https://livrepository.liverpool.ac.uk/id/eprint/3040776