(Isonitrile)platinum(II) Complexes of an Amido Bis(N-heterocyclic carbene) Pincer Ligand

Li, Mengdi; Liska, Tadeas; Swetz, Anna; Ayoub, Nicholas A.; Lai, Po−Ni; Zeller, Mat­thias; Gray, Thomas

doi:10.1021/acs.organomet.0c00065

Cited by 12 publications

(11 citation statements)

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“…Square planar d 8 platinum complexes have recently drawn considerable interest because of their intriguing light-emitting and assembly properties. − Platinum complexes often display phosphorescent emissions due to the strong spin–orbit coupling of the platinum atom. By tuning the ligand structure and coordination mode, full-color emissive platinum complexes have been synthesized and investigated. − The assembly properties of platinum complexes are mostly associated with their tendency to form π–π and Pt–Pt interactions upon aggregation. − In this context, a great number of platinum complexes have been reported to display appealing assembly behavior with tunable emission properties. − …”

Section: Introductionmentioning

confidence: 99%

A Carbazole-Bridged Biscyclometalated Diplatinum Complex: Synthesis, Characterization, and Dual-Mode Aggregation-Enhanced Phosphorescence

2021

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A cationic carbazole-bridged biscyclometalated diplatinum complex 4 has been synthesized and characterized. Single-crystal X-ray analysis demonstrates that complex 4 displays a dimeric structure with noncovalent π–π stacking and unique double Pt–Pt interactions. In aerated dilute CH3CN, complex 4 is characterized by a very weak monomeric yellow emission (λemi = 547 nm; Φ = 0.51%), which is attributed to the triplet intraligand (3LC) excited state mixing with some charge transfer characters. In contrast, under aerated conditions, the dispersion of 4 in a mixed solvent of CH3CN/Et2O (1/9, v/v) or CH3CN/H2O (1/9, v/v) displays intense yellow (λemi = 550 nm; Φ = 35.5%; τ = 11.10 μs) and red emission (λemi = 635 nm; Φ = 14.1%; τ = 7.00 μs), respectively. These aggregation-induced phosphorescent emission enhancements are considered being caused by the oxygen-shielding effect and the molecular rigidification-induced decrease of nonradiative decays in the aggregate state. The morphology and size of the aggregates under these two conditions are examined by scanning electron microscope and dynamic light scattering analysis. The absorption and emission properties of 4 are further rationalized by time-dependent density functional theory calculations on a model compound.

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Section: Introductionmentioning

confidence: 99%

A Carbazole-Bridged Biscyclometalated Diplatinum Complex: Synthesis, Characterization, and Dual-Mode Aggregation-Enhanced Phosphorescence

2021

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“…Carbene ligands, mostly the N-heterocyclic carbenes (NHCs), are among the important ligands that have attracted much attention in organometallic chemistry and homogeneous catalysis. − Many groups are interested in the preparation of new NHC ligands and their metal complexes to explore their reactivity in catalysis, photophysics, and medicinal chemistry. − Among these NHC ligands are bis-NHC ligands, which comprise pairs of NHC rings connected by a methylene linker. − …”

Section: Introductionmentioning

confidence: 99%

Selectivity in Competitive C_sp²–C_sp³ versus C_sp³–C_sp³ Reductive Eliminations at Pt(IV) Complexes: Experimental and Computational Approaches

et al. 2021

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Three classes of Pt(II) complexes of the types [PtMe 2 (NHC)] (NHC = 1,1′-dimethyl-3,3′-methylenediimidazolin-2,2′-diylidene), [PtMe 2 (N^N)] (N^N = 2,2′-bipyridine, 1,10phenanthroline), and [PtMe(C^N)(SMe 2 )] (C^N = 2-phenylpyridinate, benzo[h]quinolinate), with a systematic variation in the chelating ligand, were chosen to investigate the oxidative addition of Pt(II) complexes with acetyl halides and the ensuing C−C reductive elimination from the corresponding Pt(IV) complexes.In accordance with the nature of the chelating ligand, the following conclusions can be ascertained: (i) in the reaction of [PtMe 2 (NHC)] complex 1a with acetyl halides, the order of the energy barriers (kcal/mol) for C−X bond activation is computed as Cl (24.4) ≈ Br (23.7) ≈ I (23.6), which are in a narrow range, showing no significant halide effect; (ii) while the energy barriers for oxidative addition of acetyl halides to complex 1a are almost the same, the C sp 3 −C sp 2 (CH 3 −COMe) reductive elimination barriers from [PtMe 2 (NHC)(MeCO)X] for X = Cl, Br, I are 23.5, 16.3, and 10.3 kcal/mol, respectively (lower than the acetyl halide oxidative addition to [PtMe 2 (NHC)]), suggesting that, when X = I, the Pt(IV) complex is more prone to undergo reductive elimination in comparison to the related Cl and Br analogues; (iii) the NHC Pt(IV) complexes selectively form C sp 3 −C sp 2 bonds instead of C sp 3 −C sp 3 bonds in reductive elimination; (iv) while NHC Pt(IV) complexes undergo a C−C reductive elimination process, the C−C coupling reaction is quite difficult for [PtCl(COMe)Me 2 (N^N)] complexes because of the high energy barrier found for C−C bond formation versus C−Cl oxidative addition; (v) similarly to NHC Pt(IV) complexes, the cycloplatinated (IV) complexes [PtCl(COMe)Me(C^N)(SMe 2 )] readily undergo C−C bond formation with reductive elimination.

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“…Gray and co-workers constructed another family of N-heterocyclic carbene Pt(II) complexes 45 – 53 displaying a BIMCA pincer ligand (BIMCA = bis-imidazolylcarbazolate) and isonitrile or acetylides as ancillary ligand (Figure ). The BIMCA ligand contains an organic carbazole chromophore, to which are directly attached two NHC units, generating a rigid (ĈN̂C) pincer ligand around the Pt(II) center. , Owing to steric factors around the metal center, the X-ray structures of these complexes showed that the metal is tetra-coordinated displaying a distorted tetrahedral geometry instead of a square-planar structure.…”

Section: Luminescent Platinum(ii) Complexes With N-heterocyclic Carbe...mentioning

confidence: 99%

Luminescent Complexes of Platinum, Iridium, and Coinage Metals Containing N-Heterocyclic Carbene Ligands: Design, Structural Diversity, and Photophysical Properties

Amouri

2022

Chem. Rev.

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The employment of N-heterocyclic carbenes (NHCs) to design luminescent metal compounds has been the focus of recent intense investigations because of the strong σ-donor properties, which bring stability to the whole system and tend to push the d−d dark states so high in energy that they are rendered thermally inaccessible, thereby generating highly emissive complexes for useful applications such as organic light-emitting diodes (OLEDs), or featuring chiroptical properties, a field that is still in its infancy. Among the NHC complexes, those containing organic chromophores such as naphthalimide, pyrene, and carbazole exhibit rich emission behavior and thus have attracted extensive interest in the past five years, especially carbene coinage metal complexes with carbazolate ligands. In this review, the design strategies of NHC-based luminescent platinum and iridium complexes with large spin−orbit-coupling (SOC) are described first. Subsequent paragraphs illustrate the recent advances of luminescent coinage metal complexes with nucleophilic-and electrophilic-based carbenes based on silver, gold, and copper metal complexes that have the ability to display rich excited state emissions in particular via thermally activated delayed fluorescence (TADF). The luminescence mechanism and excited state dynamics are also described. We then summarize the advance of NHC−metal complexes in the aforementioned fields in recent years. Finally, we propose the development trend of this fast-growing field of luminescent NHC− metal complexes.

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(Isonitrile)platinum(II) Complexes of an Amido Bis(N-heterocyclic carbene) Pincer Ligand

Cited by 12 publications

References 46 publications

A Carbazole-Bridged Biscyclometalated Diplatinum Complex: Synthesis, Characterization, and Dual-Mode Aggregation-Enhanced Phosphorescence

A Carbazole-Bridged Biscyclometalated Diplatinum Complex: Synthesis, Characterization, and Dual-Mode Aggregation-Enhanced Phosphorescence

Selectivity in Competitive C_sp²–C_sp³ versus C_sp³–C_sp³ Reductive Eliminations at Pt(IV) Complexes: Experimental and Computational Approaches

Luminescent Complexes of Platinum, Iridium, and Coinage Metals Containing N-Heterocyclic Carbene Ligands: Design, Structural Diversity, and Photophysical Properties

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(Isonitrile)platinum(II) Complexes of an Amido Bis(N-heterocyclic carbene) Pincer Ligand

Cited by 12 publications

References 46 publications

A Carbazole-Bridged Biscyclometalated Diplatinum Complex: Synthesis, Characterization, and Dual-Mode Aggregation-Enhanced Phosphorescence

A Carbazole-Bridged Biscyclometalated Diplatinum Complex: Synthesis, Characterization, and Dual-Mode Aggregation-Enhanced Phosphorescence

Selectivity in Competitive Csp2–Csp3 versus Csp3–Csp3 Reductive Eliminations at Pt(IV) Complexes: Experimental and Computational Approaches

Luminescent Complexes of Platinum, Iridium, and Coinage Metals Containing N-Heterocyclic Carbene Ligands: Design, Structural Diversity, and Photophysical Properties

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Selectivity in Competitive C_sp²–C_sp³ versus C_sp³–C_sp³ Reductive Eliminations at Pt(IV) Complexes: Experimental and Computational Approaches