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Esteruelas MA, Moreno-Blázquez S, Oliván M, Oñate E. N,C,N-Pincers in Platinum Bimetallic Complexes: Influence of the Pincer and Bridging Ligands on the Metal-Metal Bond and the Photophysical Properties. Inorg Chem 2024; 63:14482-14494. [PMID: 39028899 DOI: 10.1021/acs.inorgchem.4c01712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/21/2024]
Abstract
Precursors PtCl{κ3-N,C,N-[py-C6HMe2-py]} (1), PtCl{κ3-N,C,N-[py-O-C6H3-O-py]} (2), Pt(OH){κ3-N,C,N-[py-C6HMe2-py]} (3), and Pt(OH){κ3-N,C,N-[py-O-C6H3-O-py]} (4) were used to prepare d8-platinum bimetallic complexes. Precursors 1 and 2 react with AgBF4 and 7-azaindole (Haz) to give [Pt{κ3-N,C,N-[py-C6HMe2-py]}{κ1-N-[Haz]}]BF4 (5) and [Pt{κ3-N,C,N-[py-O-C6H3-O-py]}{κ1-N-[Haz]}]BF4 (6) and 3 and 4 with indolo[2,3-b]indole (H2ii) to generate Pt{κ1-N-[Hii]}{κ3-N,C,N-[py-C6HMe2-py]} (7) and Pt{κ1-N-[Hii]}{κ3-N,C,N-[py-O-C6H3-O-py]} (8). Subsequent addition of 3 and 4 to 5-7 affords bimetallic derivatives [{Pt[κ3-N,C,N-(py-C6HMe2-py)]}2{μ-N,N-[az]}]BF4 (9), [{Pt[κ3-N,C,N-(py-O-C6H3-O-py)]}2{μ-N,N-[az]}]BF4 (10), and {Pt[κ3-N,C,N-(py-C6HMe2-py)]}2{μ-N,N-[ii]} (11). X-ray structures of 9-11 reveal separations between the metals in sequence 9 (3.0515(4) Å) < 10 (3.2689(9) Å) < 11 (3.2949(2) Å). DFT calculations support σ overlap of the dz2 orbitals of platinum atoms, for 9 and 10. Accordingly, their absorption spectra show a MMLCT transition. Complex 9 is a red emitter. The excited state has 3MMLCT characteristics and a Pt-Pt separation of 2.763 Å. Complex 11 is a dual emitter in the red and NIR regions, in solid. Both excited states have a 3LC/LMCT characteristic and platinum-platinum separations of 3.290 and 3.202 Å. Intermediate 5 is a green emitter that achieves quantum yields close to unity, when diluted in PMMA and 1,2-dichloroethane at low concentrations.
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Affiliation(s)
- Miguel A Esteruelas
- Departamento de Química Inorgánica - Instituto de Síntesis Química y Catálisis Homogénea (ISQCH) - Centro de Innovación en Química Avanzada (ORFEO-CINQA), Universidad de Zaragoza - CSIC, Zaragoza 50009, Spain
| | - Sonia Moreno-Blázquez
- Departamento de Química Inorgánica - Instituto de Síntesis Química y Catálisis Homogénea (ISQCH) - Centro de Innovación en Química Avanzada (ORFEO-CINQA), Universidad de Zaragoza - CSIC, Zaragoza 50009, Spain
| | - Montserrat Oliván
- Departamento de Química Inorgánica - Instituto de Síntesis Química y Catálisis Homogénea (ISQCH) - Centro de Innovación en Química Avanzada (ORFEO-CINQA), Universidad de Zaragoza - CSIC, Zaragoza 50009, Spain
| | - Enrique Oñate
- Departamento de Química Inorgánica - Instituto de Síntesis Química y Catálisis Homogénea (ISQCH) - Centro de Innovación en Química Avanzada (ORFEO-CINQA), Universidad de Zaragoza - CSIC, Zaragoza 50009, Spain
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Aseman MD, Kiyavash S. High Selectivity in Csp 2-Csp 2 versus Csp 3-O Reductive Elimination from Cycloplatinated(IV) Complexes. Inorg Chem 2024; 63:12475-12484. [PMID: 38907728 DOI: 10.1021/acs.inorgchem.4c01096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/24/2024]
Abstract
The cycloplatinated(IV) complexes trans-[Pt(p-MeC6H4)(C∧N)(OAc)2(H2O)] (C∧N = benzo[h]quinolate, bhq, 2a, and 2-phenylpyridinate, ppy, 2b) were prepared by reacting the corresponding [Pt(p-MeC6H4)(C∧N)(SMe2)] precursors with PhI(OAc)2 through an oxidative addition (OA) reaction. Thermolysis of 2a at 65 °C generates cis-[Pt(κ1N-10-(p-MeC6H4)-bhq)(OAc)2(H2O)], 3a, which is the product of a Csp2Ar-Csp2bhq reductive elimination (RE). The observed coupling reaction is significantly different from the previously reported analogous thermolysis of trans-[PtMe(C∧N)(OAc)2(H2O)] (C∧N = bhq, 2c, and ppy, 2d) that selectively releases Me-OAc (C-O RE). The density functional theory (DFT) calculations and experimental observations reveal that the Csp2Ar-Csp2bhq coupling reaction occurs through the dissociation of a coordinated water ligand. This in turn is followed by the concomitant bond forming and bond breaking process via a three-center ring transition state, in contrast to the Csp3Me-OAc coupling, which had taken place by an outer sphere SN2 type RE reaction in methyl complexes.
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Affiliation(s)
- Marzieh Dadkhah Aseman
- Department of Chemistry, Faculty of Sciences, Tarbiat Modares University, P.O. Box, Tehran 14115-175, Iran
| | - Susan Kiyavash
- Department of Chemistry, Faculty of Sciences, Tarbiat Modares University, P.O. Box, Tehran 14115-175, Iran
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Thakur V, Thomas JM, Adnan M, Sivasankar C, Vijaya Prakash G, Thirupathi N. Syntheses, structural, photophysical and theoretical studies of heteroleptic cycloplatinated guanidinate(1-) complexes bearing acetylacetonate and picolinate ancillary ligands. RSC Adv 2024; 14:13291-13305. [PMID: 38655486 PMCID: PMC11037393 DOI: 10.1039/d4ra00828f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Accepted: 04/14/2024] [Indexed: 04/26/2024] Open
Abstract
Cycloplatination of symmetrical N,N',N''-triarylguanidines, (ArNH)2C[double bond, length as m-dash]NAr with cis-[Pt(TFA)2(S(O)Me2)2] in toluene afforded cis-[Pt(TAG)(TFA)(S(O)Me2)] (TAG = triarylguanidinate(1-)-κC,κN; TFA = OC(O)CF3; 6-9) in 75-82% yields. The reactions of 6-9 and the previously known cis-[Pt(TAG)X(S(O)Me2)] (X = Cl (1) and TFA (2-5)) with acetylacetone (acacH) or 2-picolinic acid (picH) in the presence of a base afforded [Pt(TAG)(acac)] (acac = acetylacetonate-κ2O,O'; 10-18) and [Pt(TAG)(pic)] (pic = 2-picolinate-κN,κO; 19) in high yields. The new complexes were characterised by analytical, IR and multinuclear NMR spectroscopies. Further, molecular structures of 11, 12, 13·0.5 toluene and 14-19 were determined by single crystal X-ray diffraction. Absorption spectra of 10-19 in solution and their emission spectra in crystalline form were measured. Platinacycles 10-19 are bluish green light emitter in the crystalline form, and emit in the λPL = 488-529 nm range (11 and 13-19) while 12 emits at λPL = 570 nm. Unlike other platinacycles, the emission band of 12 is broad, red shifted, and this pattern is ascribed to the presence of an intermolecular N-H⋯Pt interaction involving the endocyclic amino unit of the six-membered [Pt(TAG)] ring and the Pt(ii) atom in the adjacent molecule in an asymmetric unit of the crystal lattice. Lifetime measurements were carried out for all platinacycles in crystalline form, which revealed lifetime in the order of nanoseconds. The origin of absorption and emission properties of 11, 15, 18 and 19 were studied by TD-DFT calculations.
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Affiliation(s)
- Vasudha Thakur
- Department of Chemistry, University of Delhi Delhi 110 007 India
| | - Jisha Mary Thomas
- Department of Chemistry, Catalysis and Energy Laboratory, Pondicherry University Puducherry 605 014 India
| | - Mohammad Adnan
- Department of Physics, Nanophotonics Laboratory, Indian Institute of Technology-Delhi New Delhi 110 016 India
| | - Chinnappan Sivasankar
- Department of Chemistry, Catalysis and Energy Laboratory, Pondicherry University Puducherry 605 014 India
| | - G Vijaya Prakash
- Department of Physics, Nanophotonics Laboratory, Indian Institute of Technology-Delhi New Delhi 110 016 India
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Poveda D, Vivancos Á, Bautista D, González-Herrero P. Luminescent Platinum(II) Complexes with Terdentate N∧C∧C Ligands. Inorg Chem 2023; 62:20987-21002. [PMID: 38051299 PMCID: PMC10751801 DOI: 10.1021/acs.inorgchem.3c02399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Revised: 11/17/2023] [Accepted: 11/22/2023] [Indexed: 12/07/2023]
Abstract
The synthesis, structure, and luminescence of Pt(II) complexes of the type [Pt(N∧C∧C)(L)] are reported, where N∧C∧C is a terdentate ligand resulting from the cycloplatination of 2-(3,5-diphenoxyphenyl)pyridine or 2-(4,4″-dimethyl-[1,1':3',1″-terphenyl]-5'-yl)pyridine, and L represents a monodentate ancillary ligand, which can be γ-picoline, 4-pyridinecarboxaldehyde, PPh3, n-butyl or 2,6-dimethylphenyl isocyanide, CO, or the N-heterocyclic carbenes 1-butyl-3-methylimidazol-2-ylidene or 4-butyl-3-methyl-1-phenyl-1H-1,2,3-triazol-5-ylidene. Derivatives bearing CO, isocyanides, or carbenes showed the highest stabilities in solution, whereas the pyridine and PPh3 derivatives establish ligand-exchange equilibria in acetonitrile. Different supramolecular structures are observed in the solid state, which largely depend on the nature of the ancillary ligand. Isocyanides and CO favor π interactions between the aromatic rings, metallophilic Pt···Pt contacts, or a combination of both. In contrast, pyridine ligands may lead to bimolecular assemblies driven by C-H···O, C-H···Pt, or C-H/π hydrogen bonds. Luminescence was examined in fluid solution, poly(methyl methacrylate) matrices, and the solid state at 298 K, and in 2-methyltetrahydrofuran glasses at 77 K. The majority of derivatives show highly efficient emissions from 3ILCT/MLCT or 3ILCT/MLCT/LLCT excited states of monomeric species. The formation of excimers and different types of emissive aggregates are demonstrated, which lead to red-shifted emissions of different origins and characteristics depending on the involved noncovalent interactions.
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Affiliation(s)
- Dionisio Poveda
- Departamento
de Química Inorgánica, Facultad de Química, Universidad de Murcia, Campus de Espinardo, 19, 30100 Murcia, Spain
| | - Ángela Vivancos
- Departamento
de Química Inorgánica, Facultad de Química, Universidad de Murcia, Campus de Espinardo, 19, 30100 Murcia, Spain
| | - Delia Bautista
- Área
Científica y Técnica de Investigación, Universidad de Murcia, Campus de Espinardo, 21, 30100 Murcia, Spain
| | - Pablo González-Herrero
- Departamento
de Química Inorgánica, Facultad de Química, Universidad de Murcia, Campus de Espinardo, 19, 30100 Murcia, Spain
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Höhn V, Feuerstein W, Rehak FR, Kehry M, Lebedkin S, Kappes MM, Klopper W, Breher F. Non-Palindromic C∧C∧P Platinum and Palladium Pincer Complexes Showing Intense Phosphorescence via Direct Spin-Forbidden S 0 → T 1 Excitation. Inorg Chem 2023; 62:15627-15640. [PMID: 37682719 DOI: 10.1021/acs.inorgchem.3c02339] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/10/2023]
Abstract
The synthesis of C∧C∧P pre-ligands based on a dicyclohexylphosphine-substituted biphenyl framework is reported. The pre-ligands form the respective non-palindromic pincer complexes of PtII and PdII via double oxidative addition and subsequent comproportionation or C-H activation. The complexes of PtII as well as PdII emit similar green phosphorescence efficiently in the solid state, the former also in solution albeit with less intensity. The most fascinating photophysical feature, however, is a direct singlet-triplet (S0 → T1) excitation of this phosphorescence in the spectral window between the emission and the major singlet-singlet UV absorption. The S0 → T1 excitation spectra show a rich vibronic pattern, which is especially pronounced for the solid samples at cryogenic temperatures. The molar extinction of the lowest-energy singlet-triplet absorption band of the homologous Pt and Pd complexes as well as that of the Pt complex with a different (NHC) ancillary ligand were determined in tetrahydrofuran solutions. Quantum efficiencies of triplet formation (by intersystem crossing) via the "standard" excitation pathway S0 → Sn → T1 were determined for the Pt complexes and found to be different in dependence of the ancillary ligand.
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Affiliation(s)
- Verena Höhn
- Karlsruhe Institute of Technology (KIT), Institute of Inorganic Chemistry, Engesserstraße 15, 76131 Karlsruhe, Germany
| | - Wolfram Feuerstein
- Karlsruhe Institute of Technology (KIT), Institute of Inorganic Chemistry, Engesserstraße 15, 76131 Karlsruhe, Germany
| | - Florian R Rehak
- Karlsruhe Institute of Technology (KIT), Institute of Physical Chemistry, Fritz-Haber-Weg 2, 76131 Karlsruhe, Germany
| | - Max Kehry
- Karlsruhe Institute of Technology (KIT), Institute of Physical Chemistry, Fritz-Haber-Weg 2, 76131 Karlsruhe, Germany
| | - Sergei Lebedkin
- Karlsruhe Institute of Technology (KIT), Institute of Nanotechnology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Manfred M Kappes
- Karlsruhe Institute of Technology (KIT), Institute of Nanotechnology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Wim Klopper
- Karlsruhe Institute of Technology (KIT), Institute of Physical Chemistry, Fritz-Haber-Weg 2, 76131 Karlsruhe, Germany
| | - Frank Breher
- Karlsruhe Institute of Technology (KIT), Institute of Inorganic Chemistry, Engesserstraße 15, 76131 Karlsruhe, Germany
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