Synthesis, electron paramagnetic resonance, and magnetic studies of binuclear bis(.eta.5-cyclopentadienyl)titanium(III) compounds with bridging pyrazolate, biimidazolate, and bibenzimidazolate anions

1978 ◽  
Vol 17 (8) ◽  
pp. 2078-2084 ◽  
Author(s):  
Benjamin F. Fieselmann ◽  
David N. Hendrickson ◽  
Galen D. Stucky
Crystals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 637
Author(s):  
Natalia Tereba ◽  
Tadeusz M. Muzioł ◽  
Robert Podgajny ◽  
Grzegorz Wrzeszcz

In this paper, three new heterometallic compounds were described and compared with the molecular formula [Cu(pn)2Zn(NCS)4] (1), [Cu(N,N-Me2-en)2Zn(NCS)4] (2), [Cu(N-Me-en)2Zn(NCS)4]∙½H2O (3) where pn = 1,2−diaminopropane, N,N-Me2-en = N,N‒dimethylethylenediamine and N-Me-en = N-methylethylenediamine, respectively. The compounds mentioned above were characterized by elemental analysis, infrared (IR), electronic, electron paramagnetic resonance (EPR) spectra, and magnetic studies. Crystal structures for 1 and 2 were determined by X-ray analysis. Copper(II) in these complexes adopts 4 + 2 coordination with two elongated (in 2 very long and considered as semi-coordination) Cu-S bonds. The Cu-N and Cu-S bond lengths depend on substituent position affecting steric hindrance and hence a topology of the chain. Both chains form different zigzag patterns characterized by one or two Cu-Zn distance values. Weak magnetic interaction is observed, ferromagnetic in the case of 1 and antiferromagnetic in the case of 2, due to diversity of the above structural features.


Optical absorption and fluorescence, magnetic susceptibility and electron magnetic resonance experiments have been made of Tb 3+ , 4f 8 , ions in lanthanide nicotinate dihydrate single crystals. Optical absorption spectroscopy in undiluted terbium nicotinate dihydrate (TbND) indicates that the ground state of Tb 3+ , 7 F 6 , is a singlet exhibiting a quadratic Zeeman effect, and this is confirmed by the observation of a temperature-independent Van Vleck paramagnetism below 4.2 K. This is what one would expect for a non-Kramers ion in a crystal field of no symmetry. In spite of this, electron paramagnetic resonance (epr) is observed from Tb 3+ ions both in dilute LaND containing 0.01 mole fraction of Tb and in TbND. In the dilute material, in spite of the absence of site symmetry, the results show a nearly degenerate non-Kramers doublet with a g value of 17.2(8), close to the maximum possible value of 12 g j ; the ground state must therefore be predominantly M j = ±6. The epr in TbND arises from some type of defect site involving two interacting dissimilar Tb 3+ ions. The spectrum of Tb 3+ ions observed by optical fluorescence is also attributed to defect sites.


1996 ◽  
Vol 35 (4) ◽  
pp. 1039-1044 ◽  
Author(s):  
Lawrence R. Gahan ◽  
Vincent A. Grillo ◽  
Trevor W. Hambley ◽  
Graeme R. Hanson ◽  
Clifford J. Hawkins ◽  
...  

Measurements have been made in lanthanide nicotinate dihydrate (LnND) single crystals, where Ln ═ Dy and Er, of optical absorption, including the Zeeman effect, of magnetic susceptibility between 1.4 and 4.2 K, of electron paramagnetic resonance between about 9 and 35 GHz, and of magnetic resonance at 22 MHz. As in the case of TmND (Baker et al . 1986 a ), the measurements are consistent with a ground state with a large amplitude of M j ═ ± J , an almost Ising-like g -matrix, and a purely magnetic dipole-dipole interaction between nearest-neighbour Ln 3+ ions. In this respect, the Kramers ions Dy 3+ and Er 3+ exhibit features similar to the non-Kramers ions Tb 3+ and Tm 3+ in the nicotinate dihydrates.


2017 ◽  
Vol 121 (17) ◽  
pp. 4333-4340 ◽  
Author(s):  
Elena Smolensky Koganov ◽  
Gregory Leitus ◽  
Rinat Rozin ◽  
Lev Weiner ◽  
Noga Friedman ◽  
...  

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