STRUCTURE AND PROPERTIES OF AN OXALATO-BRIDGED DINICKEL(II) COMPLEX WITH A TETRAAZAMACROCYCLE BEARING AN AMINOMETHYL PENDANT ARM, 5-AMINOMETHYL-5fi(5)42fi(S)-DIMETHYL-1,4,8,11-TETRAAZACYCLOTETRADECANE

摘要

The oxalato-bridged dinickel(II) complex with the title ligand, [Ni_2(L~a H)_2(mu-ox)](ClO_4)_2 centre dot 2H_2O (1), was prepared and its structure was determined by X-ray crystallography, as well as that of the monomeric nickel(II) complex, [Ni(L~aH)ox]ClO_4 centre dot 3H_2O (2). In Complexes 1 and 2, the ligand, L~a, is folded along the N(4)-Ni(1)-N(11) axis. The antiferromagnetic coupling between the two nickel(II) centers in 1 was revealed and the coupling constant, J = -17.4cm~(-1), and g = 2.11 were estimated. It was found that the oxalato-bridged dimer 1 was readily converted to the mononuclear cis-nickel(II) complex [NiL~a0 (OH_2)](ClO_4)_2 (3a), in basic aqueous solution. In [NiL~a (CH_3CN)]I_2 (3b), which was derived from 3a, the aminomethyl pendant arm is coordinated to the Ni(II) ion and L" is folded along the N(1)-Ni(1)-N(8) axis.