Question

\[[NiC{{l}_{2}}{{\{P{{({{C}_{2}}{{H}_{5}})}_{2}}({{C}_{6}}{{H}_{5}})\}}_{2}}]\] exhibits temperature dependent magnetic behavior (paramagnetic/diamagnetic). The coordination geometries of \[N{{i}^{2+}}\] in the paramagnetic and diamagnetic states are respectively:
A. Tetrahedral and tetrahedral
B. Square planar and square planar
C. Tetrahedral and square planar
D. Square planar and tetrahedral

Answer 1

Hint: Paramagnetic substances are those substances in which unpaired electrons are present while in diamagnetic substances all the electrons are paired. Diamagnetic materials are repelled by magnetic field and paramagnetic attracted by magnetic field.

Complete step by step solution:
 In inorganic coordination complexes the geometrical pattern formed by the atoms in the ligands are bonded to the central atom in a molecule or a coordination complex. The geometrical arrangement will vary according to the type and number of ligands bonded to the metal atom known as coordination. The number of σ-bonds between the central atom and ligands is known by coordination number.
\[[NiC{{l}_{2}}{{\{P{{({{C}_{2}}{{H}_{5}})}_{2}}({{C}_{6}}{{H}_{5}})\}}_{2}}]\] showing paramagnetic and diamagnetic effects due to temperature dependency.

The electronic configuration of Ni is \[[Ar]3{{d}^{8}}4{{s}^{2}}\], but in this complex Ni is present with +2 oxidation state so,
\[N{{i}^{2+}}\] = \[[Ar]3{{d}^{8}}4{{s}^{0}}\]
- In paramagnetic case \[N{{i}^{2+}}\]\[s{{p}^{3}}\] hybridized molecule which is tetrahedral in nature as no pairing of electrons occurs.
- In case of diamagnetic substance \[N{{i}^{2+}}\] form \[ds{{p}^{2}}\] complex as pairing of electrons occurs in this case so complex formed is square planar in shape.
So, the correct answer is “Option C”.

Note: Many coordination compounds have different geometric structures. Two common forms are the square planar in which four ligands are arranged at the corners of a hypothetical square around the central metal atom, and the octahedral in which six ligands are arranged four in a plane and one each above and below the plane. Altering the position of the ligands relative to one another can produce different compounds with the same chemical formula.