Gallium Ligand Coordinated Group 15 Compounds (LGa−ECp', L=(CHNMe)2CH, E=N − Bi, Cp'=η1‐C5H5): Changeover from Electron‐Sharing to Donor‐Acceptor σ‐Interaction

Abstract

AbstractWe have analyzed the electronic structure and bonding situation in monomeric compounds of gallium with group 15 elements (LGa−ECp', L=(CHNMe)2CH, E=N (1), P (2), As (3), Sb (4) and Bi (5)) at the M06/def2‐TZVPP//BP86/def2‐SVP level of theory. The compounds 1–5 have a singlet ground state with a polarized Ga−E double bond. The molecular orbital analysis indicates that the Ga−E π‐MO and the lone pair on E are susceptible to nucleophilic reactivity. The nucleophilic reactivity of Ga−E π‐MO increases, and that of lone pair on E reduces when the compound changes from 1 to 5. The EDA‐NOCV analysis indicates that the nitrogen and phosphorous form charge‐separated electron‐sharing σ‐bond with Ga. The apparent switchover between the electron‐sharing σ‐interaction and donor‐acceptor σ‐interaction occurs when the group 15 element is arsenic. On the other hand, antimony and bismuth exhibit donor‐acceptor interaction with the LGa fragment in compounds 4 and 5. The π‐bond in 1–5 is similar and is formed by the donation of the p‐type lone pair on E‐atom (pz) to the empty pz‐orbital of Ga. The bonding analysis also shows that the strength of π‐bonding is reduced on moving towards the heavier elements. A very high first and second proton affinity indicates that group 15 elements in compounds 1–5 act as double Lewis bases.