title: Carbenes as Electron-Pair Donors for P⋅⋅⋅C Pnicogen Bonds.
abstract: Ab initio MP2/aug'-cc-pVTZ calculations were performed on the P⋅⋅⋅C pnicogen-bonded complexes of the singlet carbene molecules C(NH2)2, C(OH)2, and cyclic C(OCH)2[OHC] with H2XP molecules, with X=F, Cl, NC, OH, CH3, CN, CCH, and H. The H2XP:C(NH2)2and H2XP:C(OH)2complexes have Cssymmetry and two different structures: one in which the symmetry plane of the complex and the local symmetry plane of the carbene are non-coplanar, and the other in which they are coplanar. The non-coplanar H2XP:C(NH2)2and H2XP:C(OH)2complexes arise only when X is one of the more electronegative substituents. Coplanar H2XP:C(NH2)2complexes form when X is one of the more electropositive substituents, whereas coplanar H2XP:C(OH)2complexes exist for all X. H2XP:C(NH2)2and H2XP:C(OH)2are stabilized by covalent P-C bonds or P⋅⋅⋅C pnicogen bonds, but co-planar H2(CH3)P:C(OH)2and H3P:C(OH)2are stabilized by O-H⋅⋅⋅P hydrogen bonds. The H2XP:OHC complexes have non-coplanar structures that are also stabilized by P-C covalent bonds or pnicogen bonds. The H2(CH3)P:OHC and H3P:OHC complexes in which the symmetry plane of the complex and the local symmetry plane of the carbene are perpendicular are stabilized by P⋅⋅⋅π bonds with P acting as the electron-pair donor to the OHC π system. The H2XP:C(NH2)2, H2XP:C(OH)2, and H2XP:OHC complexes are described in terms of their binding energies, charge-transfer energies, electron density properties, and equation-of-motion coupled cluster singles and doubles spin-spin coupling constants.
authors.affiliation: Department of Chemistry, Youngstown State University, Youngstown, Ohio, 44555, USA.
authors.forename: Janet E
authors.identifier: http://orcid.org/0000-0002-9037-2822
authors.initials: JE
authors.lastname: Del Bene
authors.affiliation: Instituto de Química Médica(IQM-CSIC), Juan de la Cierva, 3, E-28006, Madrid, Spain.
authors.forename: Ibon
authors.identifier: http://orcid.org/0000-0001-6876-6211
authors.initials: I
authors.lastname: Alkorta
authors.affiliation: Instituto de Química Médica(IQM-CSIC), Juan de la Cierva, 3, E-28006, Madrid, Spain.
authors.forename: José
authors.initials: J
authors.lastname: Elguero
keywords: carbenes; charge transfer; covalent bonds; hydrogen bonds; noncovalent interactions