Crystal and electronic structures of Ni(II) silanethiolates containing flexible diamine ligands

Pladzyk, Agnieszka; Ożarowski, Andrzej; Ponikiewski, Łukasz

doi:10.1016/j.ica.2015.10.034

Cited by 9 publications

(5 citation statements)

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“…In contrast, J 2 corresponds to angles around 96.5°, leading to stronger ferromagnetic interactions and to a stabilization of a S = 4 spin ground state for the cluster. Finally, the magnitude and sign of the obtained axial ZFS parameter for each Ni II ion lies within the range (from +0.9 cm –1 to +7.59 cm –1 ) typically observed for hexacoordinated Ni II with an elongated distortion. ,,− …”

Section: Resultssupporting

confidence: 71%

Synthesis, Magnetic and High-Field EPR Investigation of Two Tetranuclear Ni^II-Based Complexes

et al. 2019

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Two tetranuclear compounds with a cubanelike structure were synthesized from a one-pot reaction between Ni II and 2,2,6,6-tetramethyl-3,5-heptanedione (Hdpm) for 1 or 4,4,4-trifluoro-1-phenyl-1,3-butanedione (Hbta) for 2 in the presence of sodium methoxide. The crystal structures of both compounds have been determined by single-crystal X-ray diffraction, and their magnetic properties have been studied by SQUID magnetometry as well as by high-field electron paramagnetic resonance (HFEPR) spectroscopy. For 1, the temperature dependence of the magnetic susceptibility can be fitted by taking into account Ni•••Ni ferromagnetic interactions, which leads to an S = 4 ground-state spin. For 2, both antiferromagnetic and ferromagnetic interactions are present. However, the latter are dominant, which also leads to an S = 4 ground-state spin, in good agreement with the HFEPR study.

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Section: Resultssupporting

confidence: 71%

Synthesis, Magnetic and High-Field EPR Investigation of Two Tetranuclear Ni^II-Based Complexes

et al. 2019

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“…In contrast, Cr(DTBMS) 4 has substantial zfs (at X-band, | D | > h υ) and is thus a case where HFEPR can be fruitfully employed. HFEPR has been applied to a number of octahedral d 8 complexes (chiefly of Ni II ), − but not to the corresponding electron/hole system of tetrahedral d 2 , with the exception of an oxide material doped with Mn V ions (Ba 2 In 2– x Mn x O 5+ x ) . The present study is thus the first application of HFEPR to a tetrahedral d 2 ion in a molecular system.…”

Section: Resultsmentioning

confidence: 96%

High-Frequency and -Field EPR (HFEPR) Investigation of a Pseudotetrahedral Cr^IV Siloxide Complex and Computational Studies of Related Cr^IVL₄ Systems

et al. 2019

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Chromium species are the active sites in a variety of heterogeneous catalysts, such as the Phillips catalyst, which is composed of Cr ions supported by SiO2 and is used to produce polyethylene. Among the catalytically relevant oxidation states of chromium is CrIV. Families of neutral, homoleptic, four-coordinate complexes, CrL4, with a variety of monoanionic, monodentate ligands, such as L = alkyls, aryls, amides, ketimides (R2C = N–), alkoxides, and siloxides, are available and can provide information regarding Cr sites in heterogeneous materials. For example, the previously reported siloxide, Cr(DTBMS)4, where DTBMS = –OSiMe t Bu2 (di-tert-butylmethylsiloxide), may be considered a molecular analogue of CrIV supported by SiO2. Such CrL4 complexes can have either a singlet (S = 0) or triplet (S = 1) spin ground state, and the spin state preferences of such complexes are not fully understood. A truly tetrahedral d2 S = 1 complex would exhibit no zero-field splitting (zfs), and the zfs is indeed small and observable by X-band EPR for several CrR4 and Cr(OR)4 complexes. In contrast, Cr(DTBMS)4 has zfs beyond the range amenable to X-band EPR so that high-frequency and high-field EPR (HFEPR) is appropriate. HFEPR of Cr(DTBMS)4 in the solid state shows the presence of three very similar triplet species with the major component having D = +0.556 cm–1. Classical ligand-field theory (LFT) and quantum chemical theory (QCT), including ab initio methods, use EPR and electronic absorption spectra to give a complete picture of the electronic structure of Cr(DTBMS)4, and other complexes of formula Cr(ER n )4, E = C, n = 3; E = N, n = 2; E = O, n = 1; E = F, n = 0. Computations show the importance of ligand steric bulk and of π-bonding in controlling the subtleties of electronic structure of CrL4 species. These electronic structure results, including zfs, which is a measure of excited state accessibility, for both triplet and singlet excited states, might be related to the catalytic activity of paramagnetic Cr species.

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“…Negative D Ni from −3 to −5.8 cm −1 was found in both cis-40 and trans-41 N 4 O 2 environments. Contrary to this, positive D Ni = +7.596 cm −1 was found in trans-N 4 S 2 coordination, 42 which was attributed to strong delocalization of the nickel d z 2 orbital due to the presence of two sulfur ligands on the z axis, resulting in lowering of the orbital reduction factor k z .…”

Section: ■ Results and Discussionmentioning

confidence: 86%

Magnetic Properties of a Dinuclear Nickel(II) Complex with 2,6-Bis[(2-hydroxyethyl)methylaminomethyl]-4-methylphenolate

et al. 2016

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Magnetic properties of dinuclear nickel(II) complex [Ni(sym-hmp)](BPh)·3.5DMF·0.5(2-PrOH) (1), where (sym-hmp) is 2,6-bis[(2-hydroxyethyl)methylaminomethyl]-4-methylphenolate anion and DMF indicates dimethylformamide, were investigated using high-frequency and -field electron paramagnetic resonance (HFEPR). To magnetically characterize the mononuclear nickel(II) species forming the dimer, its two dinuclear zinc(II) analogues, [Zn(sym-hmp)](BPh)·3.5DMF·0.5(2-PrOH) (2) and [Zn(sym-hmp)](BPh)·2acetone·2HO (2'), were prepared. One of them (2') was structurally characterized by X-ray diffractometry and doped with 5% mol nickel(II) ions to prepare a mixed crystal 3. From the HFEPR results on complex 1 obtained at 40 K, the spin Hamiltonian parameters of the first excited spin state (S = 1) of the dimer were accurately determined as |D| = 9.99(2) cm, |E| = 1.62(1) cm, and g = [2.25(1), 2.19(2), 2.27(2)], and for the second excited spin state (S = 2) at 150 K estimated as |D| ≈ 3.5 cm. From these numbers, the single-ion zero-field splitting (ZFS) parameter of the Ni(II) ions forming the dimer was estimated as |D| ≈ 10-10.5 cm. The HFEPR spectra of 3 yielded directly the single-ion parameters for D = +10.1 cm, |E| = 3.1 cm, and g = 2.2. On the basis of the HFEPR results, the previously obtained magnetic data (Sakiyama, H.; Tone, K.; Yamasaki, M.; Mikuriya, M. Inorg. Chim. Acta 2011, 365, 183) were reanalyzed, and the isotropic interaction parameter between the Ni(II) ions was determined as J = -70 cm (H = -J S·S). Finally, density functional theory calculations yielded the J value of -90 cm in a qualitative agreement with the experiment.

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Crystal and electronic structures of Ni(II) silanethiolates containing flexible diamine ligands

Cited by 9 publications

References 58 publications

Synthesis, Magnetic and High-Field EPR Investigation of Two Tetranuclear Ni^II-Based Complexes

Synthesis, Magnetic and High-Field EPR Investigation of Two Tetranuclear Ni^II-Based Complexes

High-Frequency and -Field EPR (HFEPR) Investigation of a Pseudotetrahedral Cr^IV Siloxide Complex and Computational Studies of Related Cr^IVL₄ Systems

Magnetic Properties of a Dinuclear Nickel(II) Complex with 2,6-Bis[(2-hydroxyethyl)methylaminomethyl]-4-methylphenolate

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Crystal and electronic structures of Ni(II) silanethiolates containing flexible diamine ligands

Cited by 9 publications

References 58 publications

Synthesis, Magnetic and High-Field EPR Investigation of Two Tetranuclear NiII-Based Complexes

Synthesis, Magnetic and High-Field EPR Investigation of Two Tetranuclear NiII-Based Complexes

High-Frequency and -Field EPR (HFEPR) Investigation of a Pseudotetrahedral CrIV Siloxide Complex and Computational Studies of Related CrIVL4 Systems

Magnetic Properties of a Dinuclear Nickel(II) Complex with 2,6-Bis[(2-hydroxyethyl)methylaminomethyl]-4-methylphenolate

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Synthesis, Magnetic and High-Field EPR Investigation of Two Tetranuclear Ni^II-Based Complexes

Synthesis, Magnetic and High-Field EPR Investigation of Two Tetranuclear Ni^II-Based Complexes

High-Frequency and -Field EPR (HFEPR) Investigation of a Pseudotetrahedral Cr^IV Siloxide Complex and Computational Studies of Related Cr^IVL₄ Systems