SYNTHESIS, SPECTROSCOPIC CHARACTERIZATION AND ELECTROCHEMICAL-BEHAVIOR OF NICKEL(II) COMPLEXES WITH C-MESO-5,5,7,12,12,14-HEXAMETHYLCYCLOTETRADECANE (ME6[14]ANEN4) - CRYSTAL-STRUCTURE OF (NI(ME6[14]ANEN4))I2
R. Ruiz et al., SYNTHESIS, SPECTROSCOPIC CHARACTERIZATION AND ELECTROCHEMICAL-BEHAVIOR OF NICKEL(II) COMPLEXES WITH C-MESO-5,5,7,12,12,14-HEXAMETHYLCYCLOTETRADECANE (ME6[14]ANEN4) - CRYSTAL-STRUCTURE OF (NI(ME6[14]ANEN4))I2, Transition metal chemistry, 18(5), 1993, pp. 523-527
A series of complexes of formula {Ni(Me6[14]aneN4)X2} (Me6[14]aneN4 =
12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane and X = N3 (1), NCO
(2), NCS (3), AcO (4) or I (5) has been synthesized. The crystal stru
cture of (5) has been determined by X-ray diffraction methods. The nic
kel atom is surrounded by a square-planar array of nitrogen atoms, giv
ing a low-spin complex. The macrocyclic ligand shows the most stable c
onformation, the six-membered rings exhibiting the chair form while th
e gauche conformation is adopted by the five-membered rings. Spectrosc
opic and magnetic data for (1)-(4) are consistent with octahedral coor
dination around the nickel atom, which is achieved by four N atoms of
the macrocyclic ligand in a single plane and by two azido-N (1), cyana
to-N (2), thiocyanato-N (3) and carboxylato-O (4) groups occupying the
axial positions. An electrochemical study of the oxidation of (1)-(5)
has been carried out in nonaqueous solvents and the prospects of synt
hesis of the corresponding nickel(III) species are discussed in the li
ght of the electrochemical data.