The First Hexa‐coordinated Tetranuclear Nickel Complex {[Ni(en) 2 ] 4 [H 4 L]}(ClO 4 ) 4 ·7H 2 O with Tetrakis‐bidentate Oxamato Bridge

The first tetranuclear nickel complex with the oxamato ligand, {[Ni(en) 2 ] 4 [H 4 L]}(ClO 4 ) 4 ·7H 2 O ( 1 ) (L = N , N ′, N ″, N ‴‐methanetetrayltetrakismethylenetetrakis (oxamato)), has been prepared and determined by single‐crystal X‐ray analysis. 1 crystallizes in the tetragonal space group I 4 1 /a, with a = 15.2744(9), c = 31.3748(2) Å and Z = 4. Each nickel (II) ion is in a distorted octahedral donor atom environment, which comprises four nitrogen atoms of two en molecules and two oxygen atoms of oxamato bridge. The shape of the entity looks like a propeller. The temperature‐dependent magnetic susceptibilities were analyzed by the Curie‐Weiss law; the following values were found C = 4.36 cm 3 K mol ‐1 , θ = ‐24.7 K, respectively.