Question

The geometries of the ammonia,complexes of $N{i^{2 + }},P{t^{2 + }}\,and\,Z{n^{2 + }}$ respectively are:
A. Octahedral,square planar and tetrahedral.
B. square planar, Octahedral, and tetrahedral
C. tetrahedral, square planar and Octahedral
D. Octahedral, tetrahedral, square planar

Answer 1

Hint: The geometrical pattern formed by the atoms in the ligands that are bonded to the central atom in a molecule or a coordination complex. The geometrical pattern is described as a number of atoms bonded, to the central atom or on the coordination number of a complex.

Complete answer:
A coordination complex consists of a central atom or ion, which is usually metallic and is called the coordination centre, and a surrounding array of bound molecules or ions, that are in turn known as ligands or complexing agents. The geometrical arrangement will vary according to the number and type of ligands bonded to the metal centre, and to the coordination preference of the central atom, a metal in a coordination complex. the most common coordination geometries is octahedral, where six ligands are coordinated to the metal in a symmetrical distribution, leading to the formation of an octahedron. Other common coordination geometries are tetrahedral and square planar in which four ligands are coordinated to the central atom.
In $N{i^{2 + }}$ central atom when formed complex with ammonia $N{H_3}$ the complex formed is ${[Ni{(N{H_3})_6}]^{2 + }}$ in which the coordination number is six giving it an octahedral shape.
In $P{t_{}}^{2 + }$ central atom when formed complex with ammonia $N{H_3}$ the complex formed is ${[Pt{(N{H_3})_4}]^{2 + }}$ in which the electronic configuration is 5d with coordination number four giving it a square planar shape
Similarly in $Z{n^{2 + }}$ central atom when formed complex with ammonia $N{H_3}$ the complex formed is $[Zn{(N{H_3})_4}]$ in which the electronic configuration is $3{d^{10}}$ with coordination number four giving it a tetrahedral shape.
Therefore the correct sequences for the complex are Octahedral,square planar and tetrahedral.

Hence the correct option is (A).

Note:
The coordination number of a complex is influenced by the relative sizes of the metal ion and the ligands and by electronic factors, such as charge which is dependent on the electronic configuration of the metal ion.