Theoretical study of hydrogen and halogen bond interactions of methylphosphines with hypohalous acids

Ab initio calculations were used to analyze the interactions between hypohalous acids (HOX; X = F, Cl, Br, I) and methylphosphine derivatives (PHnMe3-n, n = 0-3) at the MP2/6-311++G(2d,2p) level of theory. Interaction of HOX with PHnMe3-n lead to both hydrogen bond (HOXPHnMe3-n-HB) as well as halogen bond (HOXPHnMe3-n-XB) complexes. Stabilities of both HB and XB complexes increase with basicity of the phosphines that is larger for XB complexes. However HB complexes of a phosphine molecule with different HOX are in the same order of stabilities, but XB complexes of heavier hypohalous acids are more stable. Except for HOCl-PH3, HOCl-PH2Me and HOCl-PHMe2 systems, XB complexes have greater stabilities than their HB counterparts in other cases. Electron densities of complexes were characterized with the atoms-in-molecules (AIMs) methodology. The charge transfer within dimers was analyzed by means of natural bond orbitals (NBOS). (C) 2013 Elsevier B.V. All rights reserved.