Question

Select the correct statements for[Pt(NH3)2Cl2][Pt(NH3)2Cl2]:

(a): Geometrical Isomerism
(b): Optical Isomerism
(c): All bond length are equal.
(d): Chelation effect is effect.
(e): Hydrogen bonding is present.
Pt is in +2 oxidation state in this compound. I know that that for 4d and 5d series transition metals, most ligands behave as Strong field ligands for them. Therefore the structure of this would a low spin, inner orbital complex or we can say a square planar structure is formed. Since it is of the type[MA2B2][MA2B2]. It will show cis trans geometrical isomerism. Hence option (a) turns out to be correct. Since it is square planar, it will show no optical isomerism. No chelation effect is present as there are no chelating ligands. Both amine and chlorido are monodentate. No hydrogen bonding is also present. The option I am struggling with is option (c). I know that bond lengths in square planar are equal only when the ligands are same. Here the ligands are not same and hence the bond lengths are not equal. I want to know exactly which bonds are shorter and which longer and why. I have tried to search for it but could not find it. I need help here. The bond lengths in cisplatin are:
Pt-Cl: 2.298 Å to 2.325 Å Pt-NH3: 2.04 Å so clearly Pt-Cl bonds are longer
This maybe due to small size of Ammonia molecule which enables it to come closer to the central metal atom.

Answer 1

In [Pt(NH3)2Cl2], the Pt-NH3 bonds are shorter than Pt-Cl bonds due to the smaller size of ammonia. This explains geometric differences resulting in varying bond lengths within the square planar structure of the complex.

Step-by-step explanation:

In the [Pt(NH3)2Cl2] coordination compound, which exhibits a square planar geometry, different bond lengths arise due to the differences in ligand sizes and their bonding interactions with the central platinum atom.

The bond lengths observed in cisplatin, a form of this compound, show that Pt-NH3 bonds are shorter (about 2.04 Å) compared to Pt-Cl bonds (ranging from 2.298 Å to 2.325 Å) due to the smaller size of the ammonia molecule allowing for a closer approach to platinum.

Due to this dissimilarity in ligand size and electronic properties, Pt-NH3 and Pt-Cl bonds have different bond lengths within the complex. Consequently, option (c), stating that all bond lengths are equal, is incorrect since the [Pt(NH3)2Cl2] complex has non-equivalent ligands leading to varying Pt-ligand distances.