title: Oligomeric complexes of some heteroaromatic ligands and aromatic diamines with rhodium and molybdenum tetracarboxylates: 13C and 15N CPMAS NMR and density functional theory studies.
abstract: Seven new oligomeric complexes of 4,4'-bipyridine; 3,3'-bipyridine; benzene-1,4-diamine; benzene-1,3-diamine; benzene-1,2-diamine; and benzidine with rhodium tetraacetate, as well as 4,4'-bipyridine with molybdenum tetraacetate, have been obtained and investigated by elemental analysis and solid-state nuclear magnetic resonance spectroscopy, (13)C and (15)N CPMAS NMR. The known complexes of pyrazine with rhodium tetrabenzoate, benzoquinone with rhodium tetrapivalate, 4,4'-bipyridine with molybdenum tetrakistrifluoroacetate and the 1 : 1 complex of 2,2'-bipyridine with rhodium tetraacetate exhibiting axial-equatorial ligation mode have been obtained as well for comparison purposes. Elemental analysis revealed 1 : 1 complex stoichiometry of all complexes. The (15)N CPMAS NMR spectra of all new complexes consist of one narrow signal, indicating regular uniform structures. Benzidine forms a heterogeneous material, probably containing linear oligomers and products of further reactions. The complexes were characterized by the parameter complexation shift Δδ (Δδ = δcomplex  - δligand). This parameter ranged from around -40 to -90 ppm in the case of heteroaromatic ligands, from around -12 to -22 ppm for diamines and from -16 to -31 ppm for the complexes of molybdenum tetracarboxylates with 4,4'-bipyridine. The experimental results have been supported by a density functional theory computation of (15)N NMR chemical shifts and complexation shifts at the non-relativistic Becke, three-parameter, Perdew-Wang 91/[6-311++G(2d,p), Stuttgart] and GGA-PBE/QZ4P levels of theory and at the relativistic scalar and spin-orbit zeroth order regular approximation/GGA-PBE/QZ4P level of theory. Nucleus-independent chemical shifts have been calculated for the selected compounds.
authors.affiliation: Institute of Organic Chemistry, Polish Academy of Sciences, Warsaw, Poland.
authors.forename: Arkadiusz
authors.initials: A
authors.lastname: Leniak
authors.forename: Bohdan
authors.initials: B
authors.lastname: Kamieński
authors.forename: Jarosław
authors.initials: J
authors.lastname: Jaźwiński
mesh_terms: D002247:Carbon Isotopes / Q000032:analysis / Q000737:chemistry; D002264:Carboxylic Acids / Q000737:chemistry*; D003198:Computer Simulation; D003959:Diamines / Q000737:chemistry; D019281:Dimerization; D006841:Hydrocarbons, Aromatic / Q000032:analysis / Q000737:chemistry*; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008956:Models, Chemical; D008982:Molybdenum / Q000737:chemistry*; D009587:Nitrogen Isotopes / Q000032:analysis / Q000737:chemistry; D012238:Rhodium / Q000737:chemistry*
chemical_list: D002247:Carbon Isotopes; D002264:Carboxylic Acids; D003959:Diamines; D006841:Hydrocarbons, Aromatic; D008024:Ligands; D009587:Nitrogen Isotopes; D008982:Molybdenum; D012238:Rhodium
keywords: 13C CPMAS NMR; 15N CPMAS NMR; DFT calculation; coordination polymer; rhodium tetracarboxylate