Given below are two statements:
Statement I: N(CH₃)₃ and P(CH₃)₃ can act as ligands to form transition metal complexes.
Statement II: As N and P are from same group, the nature of bonding of N(CH₃)₃ and P(CH₃)₃ is always same with transition metals.
In the light of the above statements, choose the most appropriate answer from the options given below:

Solution

Chemistry ma’am · 3 steps

Both have a lone pair to donate, but only phosphorus can also take electrons back from the metal.

1. Statement I. A ligand only needs a lone pair to donate to the metal. N in N(CH₃)₃ and P in P(CH₃)₃ each carry one lone pair, so both can form a σ bond with a transition metal. Statement I is correct.
2. Statement II. Being in the same group does not make the bonding identical. Phosphorus is in period 3 and has vacant low-lying orbitals that can accept electron density from filled metal d orbitals. This is called back bonding. Nitrogen, in period 2, has no such orbitals.

   Ligand	σ donation (lone pair)	π back bonding from metal	Nature of bonding
   N(CH₃)₃	yes	no, no vacant orbitals on N	pure σ donor
   P(CH₃)₃	yes	yes, vacant orbitals on P	σ donor and π acceptor

3. So. The two ligands bond to metals in different ways, so Statement II is incorrect. Statement I is correct and Statement II is incorrect, which is option (d).

The idea to keep. Any species with a lone pair can be a ligand. Whether it also accepts back bonding depends on vacant orbitals: P, CO and alkenes can; NH₃ and amines cannot.

Answer from the NTA final answer key. Solution by PrepWiser.