Neither synthesis nor detection in matrix isolation experiments has been accomplished for the parent compounds of phosphanylalanes and -gallanes of type A. H₂ elimination reactions between [(CO)₅WPH₃] and H₃ENMe₃ (E=Al, Ga) have enabled the first synthesis of Lewis acid/base stabilized complexes of the type B. Comprehensive density functional theory (DFT) calculations on the aluminum systems verify the high stability of the complexes of type B.