A computational study of hydrogen-, halogen-, lithium- and beryllium-bonded interactions in model H3P center dot center dot center dot YZ (YZ = HF, CIF, LiF, BeH2) complexes involving the Lewis base phosphine (H3P) was undertaken. A subsequent investigation of the interplay between the F-/Cl-center dot center dot center dot H P and P center dot center dot center dot YZ interactions in model F-/Cl-center dot center dot center dot H3P center dot center dot center dot YZ complexes revealed strong cooperative effects, leading to bond breakage of the H-P and/or Cl-F bonds in some cases. These results were rationalized using natural bond orbital (NBQ) and quantum atoms in molecules (QTAIM) analyses of the electron density, as well as a consideration of the relative electronegativities of the P and Y atoms. (C) 2016 Elsevier B.V. All rights reserved.