Ni, Pd, and Pt complexes of a tetradentate dianionic thiosemicarbazone-based O^N^N^S ligand

Haseloer, Alexander; Denkler, Luca Mareen; Jordan, Rose; Reimer, Max; Olthof, Selina; Schmidt, Ines; Meerholz, Klaus; Hörner, Gerald; Klein, Axel

doi:10.1039/d1dt00272d

Cited by 7 publications

(16 citation statements)

References 63 publications

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“…The O-H symmetric and asymmetric stretching modes in the calculated IR spectra of [Ni(Hdmg) 2 ] are far lower (2174 and 2240 cm -1 ) than those of [Pd(Hdmg) 2 ] (2939 and 2964 cm -1 ) and [Pt(Hdmg) 2 ] (2857 and 2934 cm -1 ) (Figure 2, Tables 1-3). The calculated values are perfectly in keeping with our calculated structural data and in line with increasing ionic radii for the metals (Pd 2+ > Pt 2+ >> Ni 2+ ) [63][64][65]67] weakening the H bond. For the asymmetric O-H .…”

Section: Infrared (Ir) Spectroscopysupporting

confidence: 87%

“…The calculated HOMO-LUMO energy gaps are 6.302 and 6.413 eV for the Ni and Pd complexes, respectively and reduced to 6.062 eV for the Pt complex, which is caused by a marked stabilisation of the LUMO (Figure 3). This series Pd > Ni > Pt agrees quite well with the experimental binding energies and electrochemical or optical HOMO-LUMO gaps of comparable series of Pt, Pd, and Ni complexes [63][64][65]67,77].…”

Section: Energies and Compositions Of The Frontier Orbitalssupporting

confidence: 85%

“…A shorter The calculated M-N bond lengths increase from 1.912 to 2.015 Å along the series Ni << Pt < Pd which reflects the size of the central atom (Tables S2-S4, Supplementary). In many experimental and theoretical studies, Pd II has been found slightly larger than Pt II [63][64][65][66][77][78][79][80][81], in keeping with the effects of the lanthanide contraction [82]. While for the Ni complex (Table S2) the two calculated M-N bonds show identical length, for Pd the M-N6(oximate) bond is slightly shorter than M-N3(oxime) (Table S3).…”

Section: Dft-optimised Molecular Geometriesmentioning

confidence: 64%

“…Recently reported DFT and TD-DFT calculations on the molecular and electronic structures of planar d 8 configured Ni II , Pd II , and Pt II complexes have shown that the reliability of calculated data with experimental data [58][59][60][61][62][63][64][65][66] is very much dependent on functionals and basis sets. Furthermore, comparative DFT and experimental studies for these three metals were recently reported [62][63][64][65][66][67] allowing to gauge for the differences of these three metals.…”

Section: Introductionmentioning

confidence: 99%

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DFT Investigation of the Molecular Properties of the Dimethylglyoximato Complexes [M(Hdmg)2] (M = Ni, Pd, Pt)

Niazi

Klein

2021

Inorganics

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Important applications of the NiII, PdII and PtII complexes [M(Hdmg)2] (H2dmg = dimethylglyoxime) stem from their metal...metal stacked virtually insoluble aggregates. Given the virtual insolubility of the materials, we postulated that the rare reports on dissolved species in solution do not represent monomolecular species but oligomers. We thus studied the structural and spectral properties of the monomolecular entities of these compounds using density functional theory (DFT) and time-dependent DFT computations in dimethyl sulfoxide (DMSO) as a solvent. The molecular geometries, IR and UV-vis spectra, and frontier orbitals properties were computed using LANL2DZ ecp and def2TZVP as basis sets and M06-2X as the functional. The results are compared with the available experimental and other calculated data. The optimised molecular geometries proved the asymmetric character of the two formed O–H…O bonds which connect the two Hdmg‒ ligands in the completely planar molecules. Calculated UV-vis spectra revealed the presence of three absorptions in the range 180 to 350 nm that are red-shifted along the series Ni–Pd–Pt. They were assigned to essentially ligand-centred π−π* transitions in part with metal(d) to ligand(π*) charge transfer (MLCT) contributions. The notorious d‒p transitions dominating the colour and electronics of the compounds in the solid-state and oligomeric stacks are negligible in our monomolecular models strongly supporting the idea that the previously reported spectroscopic observations or biological effects in solutions are not due to monomolecular complexes but rather to oligomeric dissolved species.

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Section: Infrared (Ir) Spectroscopysupporting

confidence: 87%

Section: Energies and Compositions Of The Frontier Orbitalssupporting

confidence: 85%

Section: Dft-optimised Molecular Geometriesmentioning

confidence: 64%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

DFT Investigation of the Molecular Properties of the Dimethylglyoximato Complexes [M(Hdmg)2] (M = Ni, Pd, Pt)

Niazi

Klein

2021

Inorganics

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“…Being interested in comparative studies of isoleptic Pt(II), Pd(II), and Ni(II) complexes [ 30 , 32 , 45 , 46 ], we started to explore the three complexes bearing the dpb ligand. Very recently, we found an elegant way to cyclonickelate the dpb ligand forming [Ni(dpb)Cl] [ 47 ].…”

Section: Introductionmentioning

confidence: 99%

Photoluminescence of Ni(II), Pd(II), and Pt(II) Complexes [M(Me2dpb)Cl] Obtained from C‒H Activation of 1,5-Di(2-pyridyl)-2,4-dimethylbenzene (Me2dpbH)

et al. 2021

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The three complexes [M(Me2dpb)Cl] (M = Ni, Pd, Pt) containing the tridentate N,C,N-cyclometalating 3,5-dimethyl-1,5-dipyridyl-phenide ligand (Me2dpb−) were synthesised using a base-assisted C‒H activation method. Oxidation potentials from cyclic voltammetry increased along the series Pt < Ni < Pd from 0.15 to 0.74 V. DFT calculations confirmed the essentially ligand-centred π*-type character of the lowest unoccupied molecular orbital (LUMO) for all three complexes in agreement with the invariant reduction processes. For the highest occupied molecular orbitals (HOMO), contributions from metal dyz, phenyl C4, C2, C1, and C6, and Cl pz orbitals were found. As expected, the dz2 (HOMO-1 for Ni) is stabilised for the Pd and Pt derivatives, while the antibonding dx2−y2 orbital is de-stabilised for Pt and Pd compared with Ni. The long-wavelength UV-vis absorption band energies increase along the series Ni < Pt < Pd. The lowest-energy TD-DFT-calculated state for the Ni complex has a pronounced dz2-type contribution to the overall metal-to-ligand charge transfer (MLCT) character. For Pt and Pd, the dz2 orbital is energetically not available and a strongly mixed Cl-to-π*/phenyl-to-π*/M(dyz)-to-π* (XLCT/ILCT/MLCT) character is found. The complex [Pd(Me2dpb)Cl] showed a structured emission band in a frozen glassy matrix at 77 K, peaking at 468 nm with a quantum yield of almost unity as observed for the previously reported Pt derivative. No emission was observed from the Ni complex at 77 or 298 K. The TD-DFT-calculated states using the TPSSh functional were in excellent agreement with the observed absorption energies and also clearly assessed the nature of the so-called “dark”, i.e., d‒d*, excited configurations to lie low for the Ni complex (≥3.18 eV), promoting rapid radiationless relaxation. For the Pd(II) and Pt(II) derivatives, the “dark” states are markedly higher in energy with ≥4.41 eV (Pd) and ≥4.86 eV (Pt), which is in perfect agreement with the similar photophysical behaviour of the two complexes at low temperatures.

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Luminescent Pd(II) Complexes with Tridentate ⁻ Aryl‐pyridine‐(benzo)thiazole Ligands

Stück

Krause

Brünink

et al. 2021

Zeitschrift anorg allge chemie

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Cyclometalated Pd(II) complexes generally show inferior luminescence properties compared with their Pt(II) analogues. The established approach employing tridentate C∧N∧N cyclometalating ligands has allowed us to create a series of square planar Pd(II) complexes [Pd(C∧N∧N )X] from their protoligands HC∧N∧N (2‐(6‐phenylpyridin‐2‐yl)thiazoles and ‐benzothiazoles; coligands X=Cl, Br, I) with extensive variations at the Carene group (phenyl, naphthyl, fluorenyl), the central Npyridine (pyridine, 4‐phenylpyridine, 3,5‐di‐tert‐butyl‐4‐phenylpyridine), and the peripheral Nthiazole (thiazole, benzothiazole) to probe for structural factors that might enhance efficient luminescence. Long‐wavelength bands at 400–500 nm were assigned to transitions into mixed ligand‐centred/metal‐to‐ligand charge transfer (MLCT) states based on time‐dependent (TD)DFT calculations. The MLCT contributions are rather low, in agreement with relatively long lifetimes and high photoluminescence quantum yields of up to 0.79 recorded in frozen glassy solvent matrices at 77 K along with emission bands showing pronounced vibrational progressions and peaking at about 520 nm. No photoluminescence was observed at 298 K in solution. Variation of the C∧N∧N ligand allowed to shift the experimental absorption energies from about 2.4 to 2.7 eV, in good agreement with the electrochemical band gaps (2.58 to 2.81 eV). The theoretical absorption and emission spectra excellently reproduced the experimental trends.

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Ni, Pd, and Pt complexes of a tetradentate dianionic thiosemicarbazone-based O^N^N^S ligand

Abstract: New tetradentate phenolate O^N^N^S thiosemicarbazone (TSC) ligands and their Ni(II), Pd(II) and Pt(II) complexes were studied. The diamagnetic and square planar configured orange or red complexes show reversible reductive electrochemistry...

Cited by 7 publications

References 63 publications

DFT Investigation of the Molecular Properties of the Dimethylglyoximato Complexes [M(Hdmg)2] (M = Ni, Pd, Pt)

DFT Investigation of the Molecular Properties of the Dimethylglyoximato Complexes [M(Hdmg)2] (M = Ni, Pd, Pt)

Photoluminescence of Ni(II), Pd(II), and Pt(II) Complexes [M(Me2dpb)Cl] Obtained from C‒H Activation of 1,5-Di(2-pyridyl)-2,4-dimethylbenzene (Me2dpbH)

Luminescent Pd(II) Complexes with Tridentate ⁻ Aryl‐pyridine‐(benzo)thiazole Ligands

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Ni, Pd, and Pt complexes of a tetradentate dianionic thiosemicarbazone-based O^N^N^S ligand

Abstract: New tetradentate phenolate O^N^N^S thiosemicarbazone (TSC) ligands and their Ni(II), Pd(II) and Pt(II) complexes were studied. The diamagnetic and square planar configured orange or red complexes show reversible reductive electrochemistry...

Cited by 7 publications

References 63 publications

DFT Investigation of the Molecular Properties of the Dimethylglyoximato Complexes [M(Hdmg)2] (M = Ni, Pd, Pt)

DFT Investigation of the Molecular Properties of the Dimethylglyoximato Complexes [M(Hdmg)2] (M = Ni, Pd, Pt)

Photoluminescence of Ni(II), Pd(II), and Pt(II) Complexes [M(Me2dpb)Cl] Obtained from C‒H Activation of 1,5-Di(2-pyridyl)-2,4-dimethylbenzene (Me2dpbH)

Luminescent Pd(II) Complexes with Tridentate − Aryl‐pyridine‐(benzo)thiazole Ligands

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Luminescent Pd(II) Complexes with Tridentate ⁻ Aryl‐pyridine‐(benzo)thiazole Ligands