title: Theoretical study on carbon-carbon short contact of ∼2.3 Å: intermediate state between nonbonding and σ-covalent bonding.
abstract: An unusual intermolecular carbon-carbon short contact, observed previously in the crystal structure of the copper complex of pyridoxal-5-phosphate- pyridoxamine-5-phospate Schiff base, was investigated from a standpoint of quantum chemistry by DFT calculations with plane wave basis sets. The DFT-optimized structure qualitatively reproduced the short contact (2.6-2.8 Å) of the intermolecular carbon-carbon pairs for the dimer of the copper complexes in the unit cell, compared to that (∼2.3 Å) of the X-ray diffraction data. By the occupied and unoccupied orbitals, the dimer showed the in-phase and out-of-phase interactions along the direction of the intermolecular distance. The dimer of the copper complexes was confirmed as the stable intermediate between nonbonding and σ-covalent bonding by the electronic energy curve along the distance of the monomers.
authors.affiliation: RIKEN , 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Hatakeyama
authors.forename: Koji
authors.initials: K
authors.lastname: Ogata
authors.forename: Toshimasa
authors.initials: T
authors.lastname: Ishida
authors.forename: Kunihiro
authors.initials: K
authors.lastname: Kitamura
authors.forename: Shinichiro
authors.initials: S
authors.lastname: Nakamura
mesh_terms: D002244:Carbon / Q000737:chemistry*; D003300:Copper / Q000737:chemistry; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000737:chemistry*; D011732:Pyridoxal Phosphate / Q000737:chemistry; D011733:Pyridoxamine / Q000031:analogs & derivatives / Q000737:chemistry; D011789:Quantum Theory; D012545:Schiff Bases / Q000737:chemistry
chemical_list: D009942:Organometallic Compounds; D012545:Schiff Bases; D011732:Pyridoxal Phosphate; D011733:Pyridoxamine; D002244:Carbon; D003300:Copper; C010627:pyridoxamine phosphate