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

Abstract

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.

Improving the potential of paraCEST through magnetic-coupling induced line sharpening

“…The crossover angle between ferromagnetic and antiferromagnetic interaction is 97°, which closely resembles those of dinuclear Cu( ii ) systems (97.5°) due to the dominant role of the d x 2 − y 2 magnetic orbital over d z 2 in dictating magnetic interaction. 34–37 1 follows this criterion with a weak antiferromagnetic interaction indicated by the 97.2° bridge angle. Broken symmetry DFT calculations using the ORCA 5.0.3 software package correctly predict the antiferromagnetic coupling constant qualitatively but overestimate the J value (see the ESI†) due to systematic over-localization of electrons in the DFT approach.…”

Structures and magnetic studies of four new Ni(ii) coordination polymers built using symmetrical tetracarboxylate and N-donor linkers

“…The small but negative J value indicated a weak antiferromagnetic interaction. Although it is considered difficult to determine the zero-field splitting from the magnetic data, the D parameter can often be obtained, 24 because the parameters differ in the temperature range involved and the degree of decrease.…”

Sentezlenen Yeni Ni (II) Komplekslerinin Spektroskopik ve antifungal özelliklerinin İncelenmesi

“…Polidentat ligantlar arasındaki Schiff bazları, kataliz, ışık veren problar, analitik kimya, manyeto-yapısal kimya, tarımsal ilaç kimya, biyolojik alanlar gibi çeşitli alanlarda potansiyel uygulamaları nedeniyle özellikle ilgi çekicidir [1][2][3][4][5][6][7][8][9][10]. Çok sayıda binükleer kompleks yapı sentezlenmiş ve bu yapılar içinde çeşitli köprülerin aracılık ettiği Ni (II) iyonları arasındaki değişimden kaynaklanan etkileşimlerin niteliğini ve gücünü yöneten faktörlerin araştırılması için model olarak literatürlerde belirtilmiştir; fenoksido [11][12][13][14][15][16][17][18], azido [19,20], cyanato ve tiocyanato [19,21], karboksilat [22] vb. Schiff bazlı komplekslerin, yapılarında mevcut olan hetero ve metal atomları nedeniyle önemli biyoaktivite [23] gösterdiği bildirilmiştir.…”