Solid state coordination chemistry of copper(II)/α-hydroxycarboxylato/2,2′-bipyridine systems

Four new two-ligand complexes of copper(II) with 2,2′-bipyridine and one of three different α-hydroxycarboxylic acids (lactic, H₂LACO; 2-methyllactic, H₂MLACO; and mandelic, H₂MANO) were prepared. Complexes 1–3 of general formula [Cu(HL)₂(bipy)]·nH₂O (HL=monodeprotonated acid), were characterized by elemental analysis, IR, electronic and EPR spectroscopy, magnetic measurements and thermogravimetric analysis. Complexes 1 (HL=HLACO, n=2), 2 (HL=HMLACO, n=1) and 3a (the result of attempted recrystallization of 3, of formula [Cu(HMANO)(bipy)₂](HMANO)·H₂MANO·CH₃CN were studied by X-ray diffractometry. The copper atom is in an elongated, tetragonally distorted octahedral environment in 1 and 2 and in 3a has a coordination polyhedron intermediate between a square pyramid and a trigonal bipyramid, as evaluated in terms of the parameter τ. In 1 and 2 the α-hydroxycarboxylato ligand is bidentate and monoanionic but in 3a there are three forms: a monodentate monoanion, a monoanionic counterion, and a neutral molecule.     

Copper(I)-catalysed homo-coupling of aryldiazonium salts: synthesis of symmetrical biaryls

Copper(I) triflate acts as an efficient stoichiometric reagent for the homo-coupling of aryldiazonium salts bearing electron-withdrawing group(s), to yield symmetrical biaryls in acetonitrile under mild reaction conditions. Aryldiazonium salts bearing electron-donating groups undergo the reaction by using catalytic amounts of a copper complex prepared in situ from copper(II) triflate and 2,2′-bipyridine with metallic copper as an ultimate reductant.     

Synthesis,structure and properties of aquabis(2,4′-bipyridine)di(propionato-O)copper(II)

The title complex has been synthesized and characterized by elemental and thermal analysis, IR and electronic spectroscopy, conductivity studies and X-ray crystallography. In the crystal, the complex has two-fold symmetry and the copper atom adopts square pyramidal coordination. Bond valences for Cu were computed. Cu–O_(propionate) bonds are slightly stronger than the Cu–N bonds, and the Cu–O_(water) bond is distinctly weaker. Molecules are linked by O–H···O hydrogen bonds to form infinite hydrogen-bonded chains along the y axis.     

Synthesis and spectral properties of ruthenium(II) complexes based on 2,2′-bipyridines modified by a perylene chromophore

Five new 2,2′-bipyridines functionalized with a perylene or a perylenediimide moiety were synthesized and the corresponding heteroleptic ruthenium(II) complexes ([Ru(bpy)₂(L)](PF₆)₂; bpy = 2,2′-bipyridyl, L = perylene-substituted bpy ligand) were prepared. The UV–vis spectra of the ruthenium(II) complexes showed red-shifted and intense absorption bands derived from the conjugated structure of the new ligands.     

Synthesis of chelating tertiary phosphine oxides via palladium-catalysed C–P bond formation

Bis(diphenylphosphine oxides) and bis(tert-butyl(phenyl)phosphine oxides) of 1,10-phenanthroline, 2,2′-bipyridine and pyridine were synthesised in good yields via the Pd(OAc)₂/dppf mediated cross-coupling reactions between 6,6′-dichloro-2,2′-bipyridine, 2,9-dichloro-1,10-phenanthroline, or 2,6-dichloropyridine and the corresponding secondary phosphine oxides. These compounds represent potential tetradentate chelating ligands for ions of f-block elements.     

Cu–Ni heterobimetallic compounds. Part 2: Study of the system Cu(II)–bpy–[Ni(CN)4] (bpy = 2,2′-bipyridine)

Two new complexes [Ni(bpy)₃][Cu(CN)₃]·4.5H₂O (1) and [Cu(bpy)₂(CN)]₂[Ni(CN)₄]·4H₂O (2) (bpy = 2,2′-bipyridine) have been synthesized from aqueous-ethanolic solution. The crystal structures of both 1 and 2 are ionic. The crystal structure of 1 is built up of [Ni(bpy)₃]²⁺ and [Cu(CN)₃]²⁻ complex ions, and disordered solvated water molecules. While the Ni(II) atom is octahedrally coordinated by three chelate bonded bidentate bpy ligands with Ni–N bond 2.0851(1) Å (6×), the Cu(I) atom is in trigonal coordination with Cu–C bond 1.9440(1) Å (3×). Crystal structure of 2 consists of a rare [Cu(bpy)₂(CN)]⁺ complex cations, [Ni(CN)₄]²⁻ complex anions (ratio 2:1) and solvated water molecules; in the complex cation the Cu(II) atom is penta-coordinated with terminal cyanido ligand. In both crystal structures the not coordinated water molecules are involved in hydrogen bonding. Thermal study on air of both 1 and 2 did not indicate formation of a stable intermediate; the solid residues are formed of a mixture of CuO and NiO. Magnetic susceptibilities of both 1 and 2 are described by Curie–Weiss behavior with θ values of −1.37 K (1) and −0.54 K (2) due to the action of weak antiferromagnetic interactions in 1 and 2, respectively.     

新的极谱催化体系连续测定岩溶地下水中钨和钼

钨、钼-二苯基乙醇酸-2,2′-联吡啶-钛铁试剂连测体系还未见报道。本文提出了在0.05mol/L的硫酸中,钨与二苯基乙醇酸,2,2′-联吡啶的络合物在-0.79V(vs.SEC)产生一个极其灵敏的极谱催化波,测定完钨后,加入少量钛铁试剂测定钼。钼于-0.20V(vis.SEC)处产生极灵敏的阴极化导数波,波形尖锐对称,易于测量。采用此种连测体系,钨钼的灵敏度都可满足要求,钨和钼的检出限分别为0.004、0.01μg/L。确定最佳条件和拟定了不经分离富集直接测定岩溶地下水中痕量钨和钼的方法。此外还对极谱波性质进行了探讨,讨论了阴、阳离子表面活性物质对极谱催化波的作用机理。     

Platinum(II) Chloride Complexes of Linear Alkyl-bridged 2,2′-Bipyridine/Catechol Ligands

Platinum(II) chloride can selectively be coordinated to the 2,2′-bipyridine moiety of the alkyl bridged sequential catechol/2,2′-bipyridine ligand 1 a-H₂ and of the related ligands 1 a/b-Me₂ and 2 . Reaction of ( 1 b-Me₂ )PtCl₂ with BBr₃ produces the platinum(II) complex ( 1 b-H₂ )PtCl₂ while ether cleavage of the uncoordinated ligand 1 b-Me₂ fails. Under basic conditions ( 1 a-H₂ )PtCl₂ forms polymeric/oligomeric species [( 1 a )Pt]_n besides traces of the dinuclear complex [( 1 a )Pt]₂.     

XPS,single crystal X-ray diffraction and cyclic voltammetric studies on 1,10-phenanthroline and 2,2′-bipyridine adducts of bis(piperidinecarbodithioato-S,S′)cadmium(II) with CdS4N2 environment – A stereochemical and electronic distribution investigation

(1,10-Phenanthroline)bis(piperidinecarbodithioato-S,S^′)cadmium(II), [Cd(pipdtc)₂(1,10-phen)] (1) and (2,2′-bipyridine)bis(piperidinecarbodithioato-S,S′)cadmium(II), [Cd(pipdtc)₂(bipy)] (2) adducts were prepared and the crystal structures are reported. Cd–S and Cd–N distances and the angles subtended at cadmium are almost the same in both complexes but the Cd–S distances in the adducts are longer than those in Cd(pipdtc)₂ (3) complexes due to the presence of an additional neutral ligand. Thioureide C–N distance in 1 and 2 are supported by νC–N bands observed at 1471 and 1470 cm⁻¹, respectively. S2p binding energies for the adducts show a significant reduction in value compared to the parent dithiocarbamate indicating the weakening of the Cd–S bond on adduct formation. The observed reduction in binding energy is due to the increased electron density on the metal in the adducts. The cyclic voltammetric study on the complexes also show an increase of electron density on cadmium in the adducts compared to Cd(pipdtc)₂.