Issue 45, 2010

Solid-state transformation of [Co(NCS)2(pyridine)4] into [Co(NCS)2(pyridine)2]n: from Curie–Weiss paramagnetism to single chain magnetic behaviour

Abstract

Reaction of Co(NCS)2 with pyridine (pyr) in aqueous solution at room temperature leads to the formation of the pyridine-rich 1 : 4 compound of composition [Co(NCS)2(pyridine)4] (1) reported recently. On heating, the pyridine-rich 1 : 4 compound transforms into its corresponding pyridine-deficient 1 : 2 compound of composition [Co(NCS)2(pyridine)2]n (2), which decomposes on further heating. In the crystal structure of compound 2 the metal cations are coordinated by four N-atoms of two pyridine ligands and two N-bonded thiocyanato anions, each in mutually trans orientation, and by two S-atoms of two adjacent thiocyanato anions in a slightly distorted octahedral geometry. The thiocyanato anions bridge the metal cations forming one-dimensional polymeric chains. IR spectroscopic investigations on the pyridine-deficient 1 : 2 compound prepared in thermal decomposition are in accordance with bridging thiocyanato anions. Magnetic measurements of the pyridine-rich 1 : 4 compound and pyridine-deficient 1 : 2 compound reveal different behaviour with Curie–Weiss paramagnetism for compound 1 and single chain magnetic behaviour for compound 2, with a Mydosh-parameter φ = 0.12 and an effective energy barrier (−Ueff/kB) of 62.5 K for the spin relaxation.

Graphical abstract: Solid-state transformation of [Co(NCS)2(pyridine)4] into [Co(NCS)2(pyridine)2]n: from Curie–Weiss paramagnetism to single chain magnetic behaviour

Supplementary files

Article information

Article type
Paper
Submitted
23 Jul 2010
Accepted
10 Sep 2010
First published
14 Oct 2010

Dalton Trans., 2010,39, 11019-11026

Solid-state transformation of [Co(NCS)2(pyridine)4] into [Co(NCS)2(pyridine)2]n: from Curie–Weiss paramagnetism to single chain magnetic behaviour

J. Boeckmann and C. Näther, Dalton Trans., 2010, 39, 11019 DOI: 10.1039/C0DT00904K

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