Question

Select correct statement(s) regarding $[Ni{(DMG)_2}]$ complex compound
A. It acts as oxidizing agent because $N{i^{2 + }}$ cation is having EAN 34
B. It is extra-stabilized by hydrogen bonding
C. Its IUPAC name in bis(dimethylglyoximato)nickel(II)
D. It’s ligand contains two different donor sites.

Answer 1

the ligand in the complex compound is dimethylglyoximate it is a bidentate ligand based upon its denticity. Denticity is defined by the number of donations accepted by a central atom from a particular ligand. Hence DMG accepts two donations from the ligand.

Complete step by step answer:
physically EAN signifies the number of electrons available around a central atom within a complex,including the electrons accepted from the ligands.
EAN is an effective atomic number, the stable EAN number is 36, Hydrogen bonding is the electrostatic force of attraction between hydrogen and a highly electronegative atom. Ligands form coordinate bonds with central metal atoms by donating electrons.
Mathematically EAN=Z−X+Y,
EAN = Effective Atomic number
Z=Atomic number of the metal
X=Number of electrons lost during the formation of the metal ion from its atom(oxidation number of central atom with sign)
Y=Number of electrons collected from the ligands
In $N{i^{2 + }}$
EAN=Z−X+Y
EAN=28−2+8=3
Since $[Ni{(DMG)_2}]$ is neutral complex the oxidation state of Ni in the complex is 34 and to achieve stable EAN of 36, $[Ni{(DMG)_2}]$ needs two electrons but due to the exception in EAN it does not act as an oxidizing agent. hence, $[Ni{(DMG)_2}]$ does not act as an oxidizing agent. Thus option A is incorrect.
This complex has extra stability due to the formation of metal chelate. A compound composed of a metal ion and a chelating agent. Chelating ligand is a ligand that can form ring structure with the central atom. Thus option B is incorrect as the complex is stable but not due to hydrogen bonding.

The IUPAC name of the compound $[Ni{(DMG)_2}]$ is Bis(dimethylglyoximato)nickel(II) according to the IUPAC rules the prefix Bis indicates two. Since the ligand is a bidentate ligand we are using the workd bis. Since the name of the negative ligand ends with –O, the ligand is named as dimethylglyoximato.
The oxidation state is written in roman numerals in parenthesis. To calculate the oxidation number the formula using is oxidation number = charge on the complex – charge due to ligand,
Since it is a neutral complex the charge on the complex is zero, since it is a bidentate ligand therefore charge due to ligand is 2.
Oxidation number = 0-2=2
Since the molecule is neutral, the name of the metal is written as nickel and not as nickelate.
Rule of IUPAC says that the name of the central metal atom remains the same in cationic and neutral complexes and in case of anionic complex the name of the central metal atom ends with suffix –ate.
The ligand DMG is a bidentate ligand and not ambidentate ligand. Hence, it contains only one donor site which is an oxygen atom. Thus option D is incorrect.

So, the correct answer is “Option C”.

Note:
While calculating EAN number be cautious of the Atomic number of element mentioned and the oxidation state of the complex, and while calculate the oxidation state of the complex using formula. It should be written in brackets in roman numerical. If there are two donor atoms then it is a bi dentate ligand and if the ligand can ligate through different atoms then it is an ambidentate ligand.