title: Preparation and characterization of mixed-ligand cobalt(III) complexes containing (3-aminopropyl)dimethylphosphine (pdmp). Conformation of the six-membered pdmp chelate ring.
abstract: Several new cobalt(III) complexes containing (3-aminopropyl)dimethylphosphine (pdmp) have been prepared, and their molecular structures have been determined. A dichloro complex of trans(Cl,Cl)-cis(P,P)-[CoCl(2)(pdmp)(2)]PF(6) (1) was prepared from trans-[CoCl(2)(py)(4)]Cl.6H(2)O and pdmp. X-Ray crystallography confirmed the (C(2))-chair(2) conformation of two six-membered pdmp chelate rings in 1, while the analogous 1,3-bis(dimethylphosphino)propane (dmpp) complex trans-[CoCl(2)(dmpp)(2)]ClO(4) (3) exhibited the (D(2d))-twist(2) conformation. Substitution reactions of 1 for ethane-1,2-diamine (en), pentane-2,4-dionate (acac), and N,N-dimethyldithiocarbamate (dtc) gave the mixed-ligand tris(chelate)-type complexes of [Co(en)(2)(pdmp)]Cl(2)(PF(6)) (5), [Co(acac)(pdmp)(2)](PF(6))(2) (7), and [Co(dtc)(3-n)(pdmp)(n)](PF(6))(n) [n = 1 (9) or 2 (10)], respectively. The conformer of the complex cation in 5 was assigned as lel.ob.chair by X-ray analysis. In the case of the acac complex 7, both trans(P,N) (7a) and trans(N,N) (7b) isomers were isolated, and the complex cations were characterized as syn-chair(2) and anti-chair(2) conformers, respectively, with respect to the six-membered pdmp chelate rings. These conformers coincide with the most stable ones anticipated by the DFT optimum geometry calculations. In the crystal structure of trans(P,N)-[Co(dtc)(pdmp)(2)](BPh(4))(2) (10') one of the pdmp chelate rings adopted a skew-boat (twist) conformation, which reduced the intramolecular steric ring-ring interaction effectively. The DFT optimized geometries for several isomers and/or conformers of [CoCl(2)(pdmp)(2)](+) were compared.
authors.affiliation: Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka 560-0043, Japan. suzuki@chem.sci.osaka-u.ac.jp
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Suzuki
authors.forename: Katsuhiro
authors.initials: K
authors.lastname: Fujiiwara
authors.forename: Hideo D
authors.initials: HD
authors.lastname: Takagi
authors.forename: Kazuo
authors.initials: K
authors.lastname: Kashiwabara
mesh_terms: D002614:Chelating Agents / Q000737:chemistry*; D003035:Cobalt / Q000737:chemistry*; D008024:Ligands; D008958:Models, Molecular; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D002614:Chelating Agents; D008024:Ligands; D009942:Organometallic Compounds; D003035:Cobalt