An asymmetric Pt diimine acetylide complex providing unique luminescent multinuclear sandwich complexes with Cu salts

Horiuchi, Shigeo; Hiroiwa, Hirotaka; Sakuda, Eri; Arikawa, Yasuhiro; Umakoshi, Keisuke

doi:10.1039/d1cc07108d

Cited by 4 publications

(1 citation statement)

References 34 publications

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“…However, for the 3d 6 and 3d 8 valence electron configurations, the presence of low-lying distorted MC states represents a major challenge . In second- and third-row transition metal complexes with the d 6 and d 8 configurations, the respective MC states are often at higher energies than emissive MLCT or other charge-transfer (CT) states, , making nonradiative relaxation less prevalent and leading to favorable photophysical and photochemical behavior of complexes made from Ru II , Ir III , − Pt II , − or Au III . , Among 3d metals, Fe II has received the most attention concerning the relaxation of MLCT into MC states, − complemented recently by studies of isoelectronic Co III , Mn I , and Cr 0 compounds. − Thus, there is now a substantial body of literature on the photophysics of 3d 6 compounds, whereas 3d 8 complexes have remained underexplored in comparison …”

Section: Introductionmentioning

confidence: 99%

Molecular Design Principles to Elongate the Metal-to-Ligand Charge Transfer Excited-State Lifetimes of Square-Planar Nickel(II) Complexes

et al. 2022

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Square-planar NiII complexes and their electronically excited states play key roles in cross-coupling catalysis and could offer new opportunities to complement well-known isoelectronic PtII luminophores. Metal-to-ligand charge transfer (MLCT) excited states and their deactivation pathways are particularly relevant in these contexts. We sought to extend the lifetimes of 3MLCT states in square-planar NiII complexes by creating coordination environments that seemed particularly well adapted to the 3d8 valence electron configuration. Using a rigid tridentate chelate ligand, in which a central cyclometalated phenyl unit is flanked by two coordinating N-heterocyclic carbenes, along with a monodentate isocyanide ligand, a very strong ligand field is created. Bulky substituents at the isocyanide backbone furthermore protect the NiII center from nucleophilic attack in the axial directions. UV–Vis transient absorption spectroscopies reveal that upon excitation into 1MLCT absorption bands and ultrafast intersystem crossing to the 3MLCT excited state, the latter relaxes onward into a metal-centered triplet state (3MC). A torsional motion of the tridentate ligand and a NiII-carbon bond elongation facilitate 3MLCT relaxation to the 3MC state. The 3MLCT lifetime gets longer with increasing ligand field strength and improved steric protection, thereby revealing clear design guidelines for square-planar NiII complexes with enhanced photophysical properties. The longest 3MLCT lifetime reached in solution at room temperature is 48 ps, which is longer by a factor of 5–10 compared to previously investigated square-planar NiII complexes. Our study contributes to making first-row transition metal complexes with partially filled d-orbitals more amenable to applications in photophysics and photochemistry.

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Section: Introductionmentioning

confidence: 99%

Molecular Design Principles to Elongate the Metal-to-Ligand Charge Transfer Excited-State Lifetimes of Square-Planar Nickel(II) Complexes

et al. 2022

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Rational Synthesis of an Unsymmetric Pt Complex Unit Having Two Kinds of Pyrazolate Ligands: Elucidating Steric and Electronic Effects of Pyrazolate Ligands in Pt‐Ag Sandwich Complexes

et al. 2022

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Herein we report the rational synthesis of an unsymmetric Pt complex containing two different pyrazole ligands and a selective formation of Z‐shaped Pt2Ag2 complex using the unsymmetric Pt complex unit, whose structures were undoubtedly revealed by X‐ray crystallographic analysis in the solid state and NMR analysis in the solution state. The selective formation of the unsymmetric Pt and Pt2Ag2 complexes enable us to reveal that the steric effect from the pyrazole ligands determine the orientation of the Pt complex units but hardly influence on the photophysical properties of the complexes. The TD‐DFT calculations of the Pt and Pt2Ag2 complexes supported the small electronic contributions of pyrazole moieties. This synthetic route will build up a new strategy to obtain new types of precious metal sandwich complexes.

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Regioselective ligand substitution in square-planar Pt(II) complexes bearing N^C and C^C chelating ligands with pyrazole derivatives

Yang,

Moon,

Horiuchi

et al. 2024

Inorganica Chimica Acta

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An asymmetric Pt diimine acetylide complex providing unique luminescent multinuclear sandwich complexes with Cu salts

Abstract: Formation and photophysical properties of two types of sandwich complexes supported by asymmetric Pt complex units having two different acetylide moieties are reported. The asymmetric Pt complex unit was obtained...

Cited by 4 publications

References 34 publications

Molecular Design Principles to Elongate the Metal-to-Ligand Charge Transfer Excited-State Lifetimes of Square-Planar Nickel(II) Complexes

Molecular Design Principles to Elongate the Metal-to-Ligand Charge Transfer Excited-State Lifetimes of Square-Planar Nickel(II) Complexes

Rational Synthesis of an Unsymmetric Pt Complex Unit Having Two Kinds of Pyrazolate Ligands: Elucidating Steric and Electronic Effects of Pyrazolate Ligands in Pt‐Ag Sandwich Complexes

Regioselective ligand substitution in square-planar Pt(II) complexes bearing N^C and C^C chelating ligands with pyrazole derivatives

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