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Ladder-like heteropolynuclear assemblies cyanido bridges and platinum()-thallium() bonds: structural and photophysical properties
We describe the mononuclear anionic cyanido-pentafluorophenyl complexes, (NBu 4 )[Pt(C^N)(C 6 F 5 )(CN)] [C^N = 7,8-benzoquinolate (bzq) 1 , 2-(2,4-difluorophenyl)pyridinate (dfppy) 2 ] and the heteropolynuclear derivatives [{Pt(C^N)(C 6 F 5 )(CN)}Tl] (C^N = bzq 3 , dfppy 4 ). These complexes were s...
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| Published in: | Dalton transactions : an international journal of inorganic chemistry 2024-05, Vol.53 (18), p.7788-78 |
|---|---|
| Main Authors: | , , , , , |
| Format: | Article |
| Language: | |
| Online Access: | Get full text |
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| Summary: | We describe the mononuclear anionic cyanido-pentafluorophenyl complexes, (NBu
4
)[Pt(C^N)(C
6
F
5
)(CN)] [C^N = 7,8-benzoquinolate (bzq)
1
, 2-(2,4-difluorophenyl)pyridinate (dfppy)
2
] and the heteropolynuclear derivatives [{Pt(C^N)(C
6
F
5
)(CN)}Tl] (C^N = bzq
3
, dfppy
4
). These complexes were synthesized
via
a two-step modular synthesis by reaction of the corresponding potassium salts K[Pt(C^N)(C
6
F
5
)(CN)], prepared
in situ
from [Pt(C^N)(C
6
F
5
)(DMSO)] and KCN in acetone/H
2
O, with TlPF
6
. The structures of {[Pt(bzq)(C
6
F
5
)(CN)Tl]·THF}
n
(
3·THF
)
n
and [{Pt(dfppy)(C
6
F
5
)(CN)}Tl]
4
·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
]
n
achieves a bent-ladder shape extended double chain Tl [Pt Tl]
n
Pt supported by lateral bridging [Pt](μ-CN)[Tl] ligands,
[4]
4
·dioxane
is formed by discrete Pt
4
Tl
4
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 Pt
4
Tl
4
models, to metal-metal′-to-ligand charge transfer (
3
MM′LCT [d/s σ*(Pt, Tl) → π*(C^N)]) for
3
and mixed
3
MM′LCT/
3
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)(C
6
F
5
)(CN)}Tl(THF)
x
], and anionic [Pt(C^N)(C
6
F
5
)(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, CH
2
Cl
2
, THF or Et
2
O, with shifts from 583 in
3-MeOH
to 639 nm in
3-THF
. However,
4
only demonstrates a bathochromic response to MeOH.
We report here the synthesis, structures, optical properties and computational studies of new neutral heterometallic systems based on Pt(
ii
)-Tl(
i
) bonded [{Pt(C^N)(C
6
F
5
)(CN)}Tl]
n
units (C^N = bzq, dfppy), distinctly connected by Pt(μ-CN)Tl bonds. |
|---|---|
| ISSN: | 1477-9226 1477-9234 |
| DOI: | 10.1039/d4dt00674g |