TY - JOUR
T1 - (NBu4)Ni(mnt)2
T2 - A novel bistable high temperature spin-Peierls-like system
AU - Willett, Roger D.
AU - Gómez-García, Carlos J.
AU - Ramakrishna, B. L.
AU - Twamley, Brendan
N1 - Funding Information:
Work supported in part by ACS-PRF 34779-CA and by the Spanish project MAT2001-3507. R.D.W. thanks the University of Valencia for a visitors grant.
PY - 2005/11/17
Y1 - 2005/11/17
N2 - The title compound, tetrabutylammonium bis(1,2-dimercaptoethene-1,2- dicarbonirtilato-S,S′)-nickel (III) [henceforth (NBu4)Ni(mnt) 2] undergoes a hysteretic phase transition that occurs at 172 K upon cooling. Crystallographic studies show that the phase transition is an order-disorder type involving one arm of the NBu4+ cation. Both phases are monoclinic, space group C2/c with a = 30.860(3), b = 13.804(2), c = 15.678(2) Å and β = 115.642(3)° with V = 6020.8(11) Å3 at room temperature and with a = 31.073(3), b = 13.928(1), c = 14.414(1) Å and β = 115.073(2)° and V = 5652.1(9) Å3 at 84 K. In both phases, the anions form non-uniform stacks parallel to the crystallographic c direction. In the high temperature phase, the Ni-S distances between anions are accidentally equal, and the stacks behave as nearly uniform antiferromagnetic chains with nearly equal exchange constants. At the phase transition, a non-uniform compression of the stacks occurs and the magnetic moment drops rapidly, indicating a magnetic dimerization of the stacks. Susceptibility and Cp measurements show an approximate 7°C thermal hysteresis.
AB - The title compound, tetrabutylammonium bis(1,2-dimercaptoethene-1,2- dicarbonirtilato-S,S′)-nickel (III) [henceforth (NBu4)Ni(mnt) 2] undergoes a hysteretic phase transition that occurs at 172 K upon cooling. Crystallographic studies show that the phase transition is an order-disorder type involving one arm of the NBu4+ cation. Both phases are monoclinic, space group C2/c with a = 30.860(3), b = 13.804(2), c = 15.678(2) Å and β = 115.642(3)° with V = 6020.8(11) Å3 at room temperature and with a = 31.073(3), b = 13.928(1), c = 14.414(1) Å and β = 115.073(2)° and V = 5652.1(9) Å3 at 84 K. In both phases, the anions form non-uniform stacks parallel to the crystallographic c direction. In the high temperature phase, the Ni-S distances between anions are accidentally equal, and the stacks behave as nearly uniform antiferromagnetic chains with nearly equal exchange constants. At the phase transition, a non-uniform compression of the stacks occurs and the magnetic moment drops rapidly, indicating a magnetic dimerization of the stacks. Susceptibility and Cp measurements show an approximate 7°C thermal hysteresis.
KW - Antiferromagnetic chain
KW - Bistable behavior
KW - Crystal structure
KW - Dimerization
KW - Nickel dithiolate complex
KW - Phase transition
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U2 - 10.1016/j.poly.2005.03.088
DO - 10.1016/j.poly.2005.03.088
M3 - Article
AN - SCOPUS:27744584908
VL - 24
SP - 2232
EP - 2237
JO - Polyhedron
JF - Polyhedron
SN - 0277-5387
IS - 16-17
ER -