ic0619153_si_002.pdf (522.71 kB)
Series of Trinuclear NiIILnIIINiII Complexes Derived from 2,6-Di(acetoacetyl)pyridine: Synthesis, Structure, and Magnetism
journal contribution
posted on 2007-04-30, 00:00 authored by Takuya Shiga, Nobuhiro Ito, Akiko Hidaka, Hisashi Ōkawa, Susumu Kitagawa, Masaaki OhbaEighteen trinuclear NiII2LnIII complexes of 2,6-di(acetoacetyl)pyridine (H2L) (Ln = La−Lu except for Pm) were prepared
by a “one-pot reaction” of H2L, Ni(NO3)2·6H2O, and Ln(NO3)3·nH2O in methanol. X-ray crystallographic studies
indicate that two L2- ligands sandwich two NiII ions with the terminal 1,3-diketonate sites and one LnIII ion with the
central 2,6-diacylpyridine site, forming the trinuclear [Ni2Ln(L)2] core of a linear NiLnNi structure. The terminal Ni
assumes a six-coordinate geometry together with methanol or water molecules, and the central Ln assumes a
10-coordinate geometry together with two or three nitrate ions. The [Ni2Ln(L)2] core is essentially coplanar for large
Ln ions (La, Ce, Pr, Nd) but shows a distortion with respect to the two L2- ligands for smaller Ln ions. Magnetic
studies for the Ni2Ln complexes of diamagnetic LaIII and LuIII indicate an antiferromagnetic interaction between the
terminal NiII ions. A magnetic analysis of the Ni2Gd complex based on the isotropic Heisenberg model indicates a
ferromagnetic interaction between the adjacent NiII and GdIII ions and an antiferromagnetic interaction between the
terminal NiII ions. The magnetic properties of other Ni2Ln complexes were studied on the basis of a numerical
approach with the Ni2La complex and analogous Zn2Ln complexes, and they indicated that the NiII−LnIII interaction
is weakly antiferromagnetic for Ln = Ce, Pr, and Nd and ferromagnetic for Ln = Gd, Tb, Dy, Ho, and Er.