Xh. Bu et al., SYNTHESIS, CRYSTAL-STRUCTURE AND PROPERTIES OF THE NICKEL(II) COMPLEXOF A NEW DIOXOCYCLAM BEARING 2-METHYLFURAN PENDANTS, Transition metal chemistry, 22(1), 1997, pp. 1-3
A new dioxocyclam ligand, bearing two 2-methylfuran pendants, has been
synthesized and its nickel(II) complex isolated as a single crystal.
The crystal structure of the complex has been determined by X-ray diff
raction analysis. The complex adopts an unusual cis-configuration. The
square-planar N-4 coordination of the four basal nitrogen atoms with
Ni-II is evident, with the dioxocyclam moiety composed of two tertiary
amine Ns and two deprotonated amide N(-)s; the latter nitrogens have
stronger coordination bonds than those in the tertiary amines. There i
s a hydrogen bond between O(1) and a water molecule [O(1) ... H2O = 2.
698 Angstrom]. The solution behaviour of NiL (1) has been further stud
ied by u.v.-vis. and cyclic voltammetric techniques. A remarkable red-
shift was observed for the maxima absorption band of the electronic sp
ectra of NiL (1) in comparison to that of NiL(0) (H(2)L(0), dioxocycla
m = 1,4,8,11-tetraazacyclo-tetradecane-5,7-dione).