Interaction of neptunium(V) with picolinic, nicotinic and isonicotinic acids

Abstract

SummaryThe interaction of Np(V) with all isomers of pyridinemonocarboxylic acid has been investigated, stability constants have been calculated using NIR spectroscopy. Single crystals of [NpO2(Pic)(H2O)2] (1), Cs[NpO2(Pic)2(HPic)]·3H2O (2), [NpO2(Nic)(H2O)] (3), and [NpO2(iso-Nic)(H2O)] (4) have been synthesized. Compound1contains infinite chains; compound2consists of isolated Cs+, [NpO2(Pic)2(HPic)]-groups and water molecules. In both3and4neptunoyl-ion NpO2acts as monodentate ligand with one of the O atoms of NpO2group entering in coordination polyhedron of the adjacent Np atom. Compounds3and4have layered and three-dimensional topologies, respectively. Crystallographic data: [NpO2(Pic)(H2O)2], space groupP¯1, triclinic,a= 6.380(2),b= 7.733(2),c= 10.700(4) Å, α = 96.49(3), β = 106.78(3), γ = 103.83(3)°, andZ= 2 (1); Cs[NpO2(Pic)2(HPic)]·3H2O, space groupP¯1, triclinic,a= 8.707(2),b= 9.777(2),c= 14.640(3) Å, α = 76.633(15), β = 78.75(2), γ = 86.55(2)°, andZ= 2 (2); [NpO2(Nic)(H2O)], space groupP21/n, monoclinic,a= 11.901(4),b= 5.5628(15),c= 12.124(3) Å, β = 101.05(2)°, andZ= 4 (3); [NpO2(iso-Nic)(H2O)], space groupP212121, orthorhombic,a= 5.742(3),b= 8.550(5),c= 18.512(10) Å, andZ= 4 (4). Electron and IR spectra of solid compounds have been measured.