On bonding in bis(dimethylglyoximato)nickel(II)

Publication date: 15 August 2017 Source:Computational and Theoretical Chemistry, Volume 1114 Author(s): Shanti G. Patra, Nilangshu Mandal, Ayan Datta, Dipankar Datta The Ni(II) complex of dimethylglyoxime (dmgH where H is dissociable oxime proton) occurs as an infinite chain of the discrete molecule Ni(dmgH)2 with a NiNi distance of 3.24Å. Density Functional Theoretical calculations, using LanL2DZ and 6-31+G(2d,p) as two sets of basis functions and M06-2X as the functional, show that the dimeric unit [Ni(dmgH)2]2 has a cohesive energy more than 20kcalmol−1. This energy is almost same in the corresponding hypothetical zinc analogue. Since there cannot be any metal-metal bond in [Zn(dmgH)2]2, possibility of a NiNi bond in [Ni(dmgH)2]2 is precluded. This is supported by qualitative m.o. analyses also. Further the NiNi bond distance is almost same as the sum of the van der Waals radii of the two Ni atoms as designated by Bondi which is 3.26Å. It is found that the binding energy in [Ni(dmgH)2]2 arises from aromatic-aromatic interactions and that in [Zn(dmgH)2]2 due to π-π interactions between the ligand frameworks. An energy decomposition analysis show that electrostatic and dispersion effects govern the cohesive energy in [Ni(dmgH)2]2 and [Zn(dmgH)2]2. Their numerical values are comparable. The orbital interactions in them are relatively less. [Zn(dmgH)2]n is not stable for n>2. There are two types of chelate rings in Ni(dmgH)2 monomer – a five membered one w...

Source: Computational and Theoretical Chemistry - May 27, 2017 Category: Chemistry Source Type: research