Synthesis, crystal structure, magnetic properties, and cyclic voltammetry of the unsymmetric (mu-oxalato)-[N,N ',N '',N '''-tetrakis(2-pyridylmethyl)-1,4,8,11-tetraazacyclotetradecane]dicobalt(II) perchlorate trihydrate
Sp. Sovilj et al., Synthesis, crystal structure, magnetic properties, and cyclic voltammetry of the unsymmetric (mu-oxalato)-[N,N ',N '',N '''-tetrakis(2-pyridylmethyl)-1,4,8,11-tetraazacyclotetradecane]dicobalt(II) perchlorate trihydrate, SYN REAC IN, 29(5), 1999, pp. 785-803
Citations number
39
Categorie Soggetti
Inorganic & Nuclear Chemistry
Journal title
SYNTHESIS AND REACTIVITY IN INORGANIC AND METAL-ORGANIC CHEMISTRY
A new dinuclear cobalt(II) complex, [Co-2(ox)tpmc](ClO4)(2). 3H(2)O, (tpmc
= N,N',N ",N"'-tetrakis(2-pyridylmethyl)-1,4,8,11-tetraazacyclotetradecane,
ox(2-) = oxalate ion), has been synthesized and its crystal structure solv
ed by single crystal X-ray diffraction studies. It crystallizes in the mono
clinic system, space group P2(1),with a = 9.7858(8) Angstrom, b = 21.455(2)
Angstrom, c = 21.241(2) Angstrom, beta = 100.069(8)degrees, V = 4391.0(8)
Angstrom(3), Z = 4, R = 0.083, Rw = 0.086. Its Structure consists of two di
nuclear, crystallographically unique molecules in which the oxalate ion bri
dges two cobalt(II) ions unsymmetrically. Each cobalt is hexacoordinated wi
th four macrocyclic nitrogens and two oxygens in an octahedral arrangement
of an "exo" coordination of a macrocyclic ligand. The third oxygen is simul
taneously bonded to both cobalt ions and the last one remains uncoordinated
, which is the unique way of oxalato ion coordination. Intramolecular antif
erromagnetic coupling between the two cobalt(II) ions is observed and yield
ed J = -9.3 cm(-1), g(parallel to) = 5.64 and g(perpendicular to) =-1.21. T
he variable temperature (4.2 - 292 K) magnetic susceptibility measurements
are interpreted on the basis of the spin Hamiltonian H = 25/9JS(A)S(B) + go
beta Hz(S-AZ + S-BZ). Cyclic voltammetry suggests that the complex is elec
trochemically stable up to the potential of the cobalt reduction.