On heating [Mo(N₂)₂(PMe₂Ph)₄] and [ReCI(N₂) (PMe₂Ph)₄], the products formed are respectively

Concept:

EAN rule:

• In organometallic compounds Effective atomic number (EAN) rule predicts the stability of binary metal carbonyls in which the metal atom is in a zero or low oxidation state. 
• According to the EAN rule, thermodynamically stable transition metal organometallic complexes are formed when the sum of metal d electrons and electrons donated by the surrounding ligands are equaled to 18.
• Dinitrogen (N₂) is considered a two-electron donor species in organometallic complexes.    

Explanation:

• The complex [Mo(N₂)₂(PMe₂Ph)₄] follows the 18-electron rule (EAN rule). The number of valence electrons contributed by a metal atom to the total electron count in a zero-oxidation state is equal to the group number.
• In the complex [Mo(N2)2(PMe2Ph)₄], Mo has a zero oxidation state and it belongs to group 6. So, Mo contributes 6 electrons. The two Dinitrogen (N2) contributes a total of 4 electrons and four PMe2Ph contributes a total of 8 electrons.
• On heating the complex [Mo(N2)2(PMe2Ph)4] it results in removal of dinitrogen and forms the complex 

​[(η6-PhPMe2)Mo (PMe2Ph)3].

• The complex [(η6-PhPMe2)Mo (PMe2Ph)3] also obeys the EAN rule. One of the phenyl ring of the PMe2Ph ligand act as a 6-electron donor (\({\eta ^6}\)).
• The complex [ReCI(N2) (PMe2Ph)4], also follows the 18-electron rule (EAN rule). On heating the complex [ReCI(N2) (PMe2Ph)4], it also results in the removal of dinitrogen and forms the complex, [(PMe2Ph)4Re (μ-Cl)2Re (PMe2Ph)4]. 
• The product obeys the EAN rule as the two bridging Cl ligand contributes 3 electrons each to the metal centers.

Conclusion:

• On heating [Mo(N2)2(PMe2Ph)4] and [ReCI(N2) (PMe2Ph)4], the products formed are respectively, [(η6-PhPMe2)Mo (PMe2Ph)3] and [(PMe2Ph)4Re (μ-CI)2Re (PMe2Ph)4].