Wydział Chemii

Mirosław Karbowiak

Czesław Rudowicz

Takayuki Ishida

2013

Inorganic Chemistry

52

13199-13206

10.1021/ic4021542

Naukowa

Angielski

Artykuł

This study is the first in a series of experimental and theoretical investigations of the crystal-field (CF) energy levels obtained from optical electronic spectra for selected heterometallic 4f-3d compounds intensively studied for the development of novel single-molecule magnets (SMMs). An intriguing question is why the [{Dy^III(hfac)₃}₂Cu^II(dpk)₂] (abbreviated as [Dy₂Cu]; Hhfac = 1,1,1,5,5,5-hexafluoropentane-2,4-dione, Hdpk = di-2-pyridyl ketoxime) has antiferromagnetic coupling, whereas [Gd₂Cu] and heavy [Ln₂Cu] systems usually show ferromagnetic coupling. As the first step to explain this peculiarity, the recently synthesized complex, [Dy₂Pd], is investigated. This complex is isostructural with [Dy₂Cu] yet contains the diamagnetic Pd ion instead of the magnetic Cu(II) ion. Experimental energy levels of Dy³⁺ ions in the powder [Dy₂Pd] sample were determined from the 4.2 K absorption spectra. CF analysis was performed yielding the fitted free ion and CF parameters. The number of freely varied parameters was restricted using the superposition model. The fittings yield very satisfactory agreement between the experimental and the calculated energy levels (rms = 12.0 cm^–1). The energies and exact composition of the state vector for the ground multiplet ⁶H_15/2 of Dy³⁺ are determined. These results are used for the simulation of the temperature dependence of the magnetic susceptibility, which enables the theoretical interpretation of the experimentally measured magnetic susceptibility in the range 1.8–300 K for the [Dy₂Pd] complex. This study provides background for the subsequent investigation of the magnetic exchange interactions in the pertinent heterometallic complexes.

http://dx.doi.org/10.1021/ic4021542

https://www.acs.org/content/acs/en.html