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Influence of Isotope Substitution on Lattice and Spin-Peierls-Type Transition Features in One-Dimensional Nickel Bis-dithiolene Spin Systems.
- Source :
- Chemistry - An Asian Journal; Mar2013, Vol. 8 Issue 3, p611-622, 12p
- Publication Year :
- 2013
-
Abstract
- Four new 1D spin-Peierls-type compounds, [D<subscript>5</subscript>]1-(4′- R-benzyl)pyridinium bis(maleonitriledithiolato)nickelate ([D<subscript>5</subscript>]R-Py; R=F, I, CH<subscript>3</subscript>, and NO<subscript>2</subscript>), were synthesized and characterized structurally and magnetically. These 1D compounds are isostructural with the corresponding non-deuterated compounds, 1-(4′- R-benzyl)pyridinium bis(maleonitriledithiolato)nickelate (R-Py; R=F, I, CH<subscript>3</subscript>, and NO<subscript>2</subscript>). Compounds [D<subscript>5</subscript>]R-Py and R-Py (R=F, I, CH<subscript>3</subscript>, and NO<subscript>2</subscript>) crystallize in the monoclinic space group P2<subscript>1</subscript>/ c with uniform stacks of anions and cations in the high-temperature phase and triclinic space group P $\bar 1$ with dimerized stacks of anions and cations in the low-temperature phase. Similar to the non-deuterated R-Py compounds, a spin-Peierls-type transition occurs at a critical temperature for each [D<subscript>5</subscript>]R-Py compound; the magnetic character of the 1D S=1/2 ferromagnetic chain for [D<subscript>5</subscript>]F-Py and the 1D S=1/2 Heisenberg antiferromagnetic chain for others appear above the transition temperature. Spin-gap magnetic behavior was observed for all of these compounds below the transition temperature. In comparison to the corresponding R-Py compound, the cell volume is almost unchanged for [D<subscript>5</subscript>]F-Py and shows slight expansion for [D<subscript>5</subscript>]R-Py (R=I, CH<subscript>3</subscript>, and NO<subscript>2</subscript>) as well as an increase in the spin-Peierls-type transition temperature for all of these 1D compounds in the order of F>I≈CH<subscript>3</subscript>≈NO<subscript>2</subscript>. The large isotopic effect of nonmagnetic countercations on the spin-Peierls-type transition critical temperature, T<subscript>C</subscript>, can be attributed to the change in ω<subscript>0</subscript> with isotope substitution. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 18614728
- Volume :
- 8
- Issue :
- 3
- Database :
- Complementary Index
- Journal :
- Chemistry - An Asian Journal
- Publication Type :
- Academic Journal
- Accession number :
- 85674818
- Full Text :
- https://doi.org/10.1002/asia.201200956