Ladder-like heteropolynuclear assemblies cyanido bridges and platinum(II)-thallium(I) bonds: structural and photophysical properties.

Dalton Trans

Departamento de Química, Instituto de Investigación en Química (IQUR), Complejo Científico Tecnológico, Universidad de La Rioja, 26006 Logroño, Spain.

Published: May 2024

We describe the mononuclear anionic cyanido-pentafluorophenyl complexes, (NBu)[Pt(C^N)(CF)(CN)] [C^N = 7,8-benzoquinolate (bzq) 1, 2-(2,4-difluorophenyl)pyridinate (dfppy) 2] and the heteropolynuclear derivatives [{Pt(C^N)(CF)(CN)}Tl] (C^N = bzq 3, dfppy 4). These complexes were synthesized a two-step modular synthesis by reaction of the corresponding potassium salts K[Pt(C^N)(CF)(CN)], prepared from [Pt(C^N)(CF)(DMSO)] and KCN in acetone/HO, with TlPF. The structures of {[Pt(bzq)(CF)(CN)Tl]·THF} (3·THF) and [{Pt(dfppy)(CF)(CN)}Tl]·dioxane [4]4·dioxane, determined by X-ray crystallography, confirm the presence of Pt(II)-Tl(I) bonds [2.9795(6)-3.0736(3) Å], but in the dfppy complex, the incorporation of dioxane, causes a significant structural change. Thus, whereas [3·THF] achieves a bent-ladder shape extended double chain Tl⋯[Pt⋯Tl]⋯Pt supported by lateral bridging [Pt](μ-CN)[Tl] ligands, [4]4·dioxane is formed by discrete PtTl rectangular aggregates stabilized by [Pt](μ-CN)[Tl] and Pt⋯Tl bonds, which are connected by dioxane bridging molecules through Tl⋯O(dioxane) additional contacts. Solid state emissions are redshifted compared with the mononuclear derivatives 1 and 2 and have been assigned, with the support of theoretical calculations on PtTl models, to metal-metal'-to-ligand charge transfer (MM'LCT [d/s σ*(Pt, Tl) → π*(C^N)]) for 3 and mixed MM'LCT/IL for 4. In fluid THF solution, the complexes are not emissive. At 77 K, 3 and 4 exhibit bright emissions attributed to the formation of bimetallic [{Pt(C^N)(CF)(CN)}Tl(THF)], and anionic [Pt(C^N)(CF)(CN)] fragments. Furthermore, both 3 and 4 exhibit a reversible mechanochromism with a red shift of the emissions upon crushing, suggesting some degree of shortening of metal-metal separation. Finally, complex 3 shows solvatochromic behavior with color/luminescence changes by treatment with a drop of MeOH, CHCl, THF or EtO, with shifts from 583 in 3-MeOH to 639 nm in 3-THF. However, 4 only demonstrates a bathochromic response to MeOH.

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http://dx.doi.org/10.1039/d4dt00674gDOI Listing

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Ladder-like heteropolynuclear assemblies cyanido bridges and platinum(II)-thallium(I) bonds: structural and photophysical properties.

Dalton Trans

May 2024

Departamento de Química, Instituto de Investigación en Química (IQUR), Complejo Científico Tecnológico, Universidad de La Rioja, 26006 Logroño, Spain.

We describe the mononuclear anionic cyanido-pentafluorophenyl complexes, (NBu)[Pt(C^N)(CF)(CN)] [C^N = 7,8-benzoquinolate (bzq) 1, 2-(2,4-difluorophenyl)pyridinate (dfppy) 2] and the heteropolynuclear derivatives [{Pt(C^N)(CF)(CN)}Tl] (C^N = bzq 3, dfppy 4). These complexes were synthesized a two-step modular synthesis by reaction of the corresponding potassium salts K[Pt(C^N)(CF)(CN)], prepared from [Pt(C^N)(CF)(DMSO)] and KCN in acetone/HO, with TlPF. The structures of {[Pt(bzq)(CF)(CN)Tl]·THF} (3·THF) and [{Pt(dfppy)(CF)(CN)}Tl]·dioxane [4]4·dioxane, determined by X-ray crystallography, confirm the presence of Pt(II)-Tl(I) bonds [2.

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