AN ATTEMPT TO PREPARE CIS-DIANIONOBIS(DIAMINE)NICKEL(II) COMPLEXES - CIS-TRANS-ISOMERISM AMONG THE DIANIONOBIS(DIAMINE)NICKEL(II) COMPLEXESOBTAINED BY THERMAL-REACTIONS OF THE CORRESPONDING TRIS(DIAMINE) COMPLEXES

Twenty-seven tris(diamine)nickel(II) complexes ([Ni(diamine)3]X2) were prepared and their thermal reactions were investigated in the solid p hase, where the diamine is ethylenediamine(en), N-methylethylenediamin e (N-men), N-ethylethylenediamine (N-een), 1,2-propanediamine (1,2-pn) , 1,3-propanediamine (1,3-pn), 1,2-butanediamine (1,2-bn), D,L-2,3-but anediamine (D,L-bn), iso-butanediamine (i-bn), or D,L-1,2-cyclohexaned iamine (D,L-chxn); and X is Cl-, Br-, or NO3-. Of these, twelve tris(d iamine) complexes lost their one mole of coordinated diamine upon heat ing, resulting in the stable, uniform bis(diamine) complexes, [NiX2(di amine)2]. The configurations of the bis complexes were determined by m eans of electronic spectroscopy. Almost all the bis complexes have tra ns configurations; the formation of a cis-dianiono complex was observe d only in the thermal reactions of [Ni(en)3]Cl2, [Ni(en)3]Br2, and [Ni (i-bn)3]Cl2.