Ab initio MP2/aug'-cc-pVTZ calculations were performed to investigate the pnicogen-bonded complexes F4-nHnP+:N-base, for n = 0-3, each with a linear or nearly linear F-P center dot center dot center dot N alignment. The nitrogen bases include the sp(3) bases NH3, NClH2, NFH2, NCl2H, NCl3, NFCl2, NF2H, NF2Cl, and NF3 and the sp bases NCNH2, NCCH3, NP, NCOH, NCCl, NCH, NCF, NCCN, and N-2. The binding energies vary between -20 and -180 kJ.mol(-1), while the P-N distances vary from 1.89 to 3.01 angstrom. In each series of complexes, binding energies decrease exponentially as the P-N distance increases, provided that complexes with sp(3) and sp hybridized bases are treated separately. Different patterns are observed for the change in the binding energies of complexes with a particular base as the number of F atoms in the acid changes. Thus, the particular acid-base pair is a factor in determining the binding energies of these complexes. Three different charge-transfer interactions stabilize these complexes. These arise from the nitrogen lone pair to the sigma*P-F-ax, sigma*P-F-eq, and sigma*P-H-eq orbitals. The dominant single charge-transfer energy in all complexes is N-1p --> sigma*P-F-ax. However, since there are three N-1p --> sigma*P-F-eq charge-transfer interactions in complexes with F4P+ and two in complexes with F3HP+, the sum of the N-1p--> sigma*P-F-eq charge-transfer energies is greater than the N-1p --> sigma*P-F-ax charge-transfer energies in the former complexes, and similar to the N-1p --> sigma*P-F-ax energies in the latter. The total charge-transfer energies of all complexes decrease exponentially as the P-N distance increases. Coupling constants (1p)J(P-N) across the pnicogen bond vary with the P-N distance, but different patterns are observed for complexes with F4P+ and complexes of the sp(3) bases with F3HP+. These initially increase as the P-N distance decreases, reach a maximum, and then decrease with decreasing P-N distance as the P center dot center dot center dot N bond acquires increased covalent character. For the remaining complexes, (1p)J(P-N) increases with decreasing P-N distance. Complexation increases the P-F-ax distance and (1)J(P-F-ax) relative to the corresponding isolated ion. (1)J(P-F-ax) correlates quadratically with the P-N distance.