Does a Sterically Bulky Group Occupy the Equatorial Site in Trigonal Bipyramidal Phosphorus?

10.1021/ol035990iOrganic Letters62145-14

Non-planarity at tri-coordinated aluminum and gallium ! Novel structures for X3Hnm (X=B, Al, Ga; n = 3, m =-2; n = 4, m = -1; n = 5, m = 0; n = 6, m = +1)

Structures and energies of