Self‐Assembly, Spectroscopic and Electrochemical Studies of Nickel(II)‐4,8‐Diazaundecanediamide Complex

The self‐assembly of NiCl 2 ·6H 2 O with a diaminodiamide ligand 4,8‐diazaundecanediamide (L‐2,3,2) gave a [Ni(C 9 H 20 N 4 O 2 )(Cl)(H 2 O)] Cl·2H 2 O ( 1 ). The structure of 1 was characterized by single‐crystal X‐ray diffraction analysis. Structural data for 1 indicate that the Ni(II) is coordinated to two tertiary N atoms, two O atoms, one water and one chloride in a distorted octahedral geometry. Crystal data for 1: orthorhombic, space group P 21 nb, a = 9.5796(3) Å, b = 12.3463(4) Å, c = 14.6305(5) Å, Z = 4. Through NH···Cl–Ni (H···Cl 2.42 Å, N···Cl 3.24 Å, NH···Cl 158°) and OH···Cl–Ni contacts (H···Cl 2.36 Å, O···Cl 3.08 Å, OH···Cl 143°), each cationic moiety [Ni(C 9 H 20 N 4 O 2 ) (Cl)(H 2 O)] + in 1 is linked to neighboring ones, producing a charged hydrogen‐bonded 1D chainlike structure. Thermogrametric analysis of compound 1 is consistent with the crystallographic observations. The electronic absorption spectrum of Ni(L‐2,3,2) 2+ in aqueous solution shows four absorption bands, which are assigned to the 3 A 2g → 3 T 2g , 3 T 2g → 1 Eg, 3 T 2g → 3 T 1g , and 3 A 2g → 3 T 1g transitions of triplet‐ground state, distorted octahedral nickel(II) complex. The cyclic volammetric measurement shows that Ni 2+ is more easily reduced than Ni(L‐2,3,2) 2+ in aqueous solution.