SYNTHESIS, STRUCTURAL CHARACTERIZATION AND MAGNETIC-BEHAVIOR OF 2 NEW(MU(1,3)-N-3)(2) DINUCLEAR NICKEL COMPOUNDS - STUDY OF THE MAGNETIC TRANSITION AT 235 K FOR THE CIS-(MU(1,3)-N-3)(2)[NI(DL-CTH)](2)(CLO4)(2) COMPOUND
A. Escuer et al., SYNTHESIS, STRUCTURAL CHARACTERIZATION AND MAGNETIC-BEHAVIOR OF 2 NEW(MU(1,3)-N-3)(2) DINUCLEAR NICKEL COMPOUNDS - STUDY OF THE MAGNETIC TRANSITION AT 235 K FOR THE CIS-(MU(1,3)-N-3)(2)[NI(DL-CTH)](2)(CLO4)(2) COMPOUND, Inorganica Chimica Acta, 278(1), 1998, pp. 43-50
The dinuclear compounds cis-(mu(1,3)-N-3)(2)[Ni(dl-cth)](2)(ClO4)(2) (
1a) and cis-(mu(1,3)-N-3)(2)[Ni(dl-cth)](2)(PF6)(2) . (CH3)(2)NCHO (2)
, in which dl-cth is the dl isomer of 5,5,7,12,12,14-hexamethyltetraaz
acyclotetradecane, were synthesized by reaction of the [Ni(dl-cth)](2) cation with azido ligand in aqueous medium. Compound 1a crystallizes
in the orthorhombic system, group Pbca, a = 14.784(2), b = 15.371(2),
c = 19.954(3) Angstrom, V = 4534.4(1) Angstrom(3), Z = 4, R = 0.039 a
nd shows a magnetic and structural transition centred at 235 K, giving
an amorphous compound 1b. Complex 2 crystallizes in the monoclinic sy
stem, group P21/c, a = 12.215(4), b = 9.675(2), c = 24.221(4) Angstrom
, beta = 99.46(2)degrees, V = 2823.5(1) Angstrom(3), Z = 4, R = 0.054,
Magnetic measurements show very strong antiferromagnetic coupling for
1a (J = -113 cm(-1)) and moderate coupling for 1b and 2 (J = -64.5 an
d -75.1 cm(-1)). The magnetic data are discussed on the basis of the s
tructural parameters, which suggest a distortion from a planar, eight-
membered Ni-2(mu(1,3)-N-3)(2) ring for 1a to a chair conformation for
1b. (C) 1998 Elsevier Science S.A. All rights reserved.