Molecular orbital, increased valence, valence bond and non-pairing spatial orbital formulae for three-centre bonding

Abstract

The simple valence-bond and molecular orbital formulae for three-centre bonding involving four electrons and three atoms Y, A, and B are

Y 4-B - Y-A 'P, and Y---A---B

Increased-valence formulae that have been developed recently are

Y-A . B and Y . A-B

If Y and B are the same type of atom, and bond-orbitals are used as wave functions for Y-A and A-B bonds, then the near-equivalence of the molecular orbital and increased-valence wave functions is demonstrated.

Bond-orders (or numbers) for these and Linnett's5s6 non-pairing spatial orbital formula

Y . A . B

are calculated.