Jan Moncol

Crystal and molecular structure of copper(II)(pyridine-2,6-dicarboxylato)(2,6-dimethanolpyridine)

Abstract Copper(II)(pyridine-2,6-dicarboxylato)(2,6-dimethanolpyridine) has been prepared and studied by the single crystal X-ray diffraction methods at 293(2) K. The compound crystallises in an orthorhombic system, space group Pbcn with a=8.196(2), b=13.124(3), c=25.612(5) A, and Z=8 (R=0.0374 for 3175 independent reflections with I>2σ(I)). Crystal structure analysis revealed that the copper(II) atom is surrounded by two non-equivalent terdentate ligands making up an ‘all-trans’ elongated octahedral arrangement. In consequence of Jahn–Teller distortion, considerable differences are found between the ligands for the pyridine-2,6-dicarboxylate anion with the values Cu–N 1.892(3), Cu–O 2.033(2) and 2.063(2) A, while for the 2,6-dimethanolpyridine ligand the values are 1.943(3), 2.341(3) and 2.433(2) A. There is a relationship between the Cu–L bond distances and the five-membered metallocyclic rings (O–Cu–N). The data are compared and discussed with those found in familiar CuL2 compounds with the CuO4N2 chromophore. Based on the molecular structure, the electronic, IR and EPR spectra are discussed.

Copper(ii) halogenopropionates: low-temperature crystal and molecular structure of bis(2,2-dichloropropionato)-di(methyl-3-pyridylcarbamate)copper(ii) and bis(2-bromopropionato)-di (2-pyridylmethanol)copper(ii)

The synthesis and characterization of [Cu(CH3CCl2CO2)2(3-mpyc)2] (1) (3-mpyc = methyl-3-pyridylcarbamate) and [Cu(CH3CHBrCO2)2(2-pyme)2] (2) (2-pyme = 2-pyridylmethanol) are reported. The compounds under study were characterized by IR, electronic spectroscopy and X-ray analysis. The molecular structure of both Complexes 1 and 2 is mononuclear. The coordination environment around each copper(II) atom is a distorted tetragonal bipyramid.

A study of copper(II) carboxylato complexes with the biological ligands nicotinamide and papaverine

The X-band Electron Spin Resonance spectra, ESR, of Cu(II) complexes with the carboxylic acids, HCOOH, CH3COOH, ClCH2COOH, Cl2CHCOOH, Cl3CCOOH, F2ClCOOH, CH3CH2COOH, niflumic acid and the ligands nicotinamide and papaverine have been studied. The compounds form either mononuclear or binuclear structures which can be qualitatively correlated with the strengths of the acid and base. Analysis of the spin Hamiltonian parameters for the monomeric species indicate that the molecule has nearly axial symmetry ðgk . g’Þ with the unpaired electron in the dx2 –y 2 orbital. In many cases the perpendicular feature is sufficiently well resolved showing superhyperfine features due to the nitrogen ligand nuclei. Ak varies over the range 130 ! 188 G and the variation appears to arise as a consequence of changes in gk: The dimeric species show ESR spectra typical of Cu(II)-carboxylate complexes which consist of 3 (4 if E – 0) lines. These are assigned to Bz1; Bx2;y2 and Bz2 since the Q-band spectra of similar molecules indicate that the Bx1;y1 transition(s) lies below Bz2 which is itself near zero field. The observed seven-line hyperfine coupling on the Bz1 transition of some of the dimeric complexes is due to the two equivalent copper nuclei ðI ¼ I1 þ I2 ¼ 3Þ: The singlet – triplet separation has been estimated from the spin Hamiltonian parameters to give values of l2Jl in the range of approximately 220– 290 cm 21 which are typical of the compounds of this type.

Structure and spectral study of copper(II) pyridinecarboxylates: crystal and molecular structure of trans-diaqua-bis(N,N-diethylnicotinamide-N)bis(2-chloronicotinate-O)copper(II)

Abstract New copper(II) pyridinecarboxylate compounds of the composition [CuX2(Et2nia)2(H2O)2] (where X=2-methylthionicotinate (2-MeSnic), 2-chloronicotinate (2-Clnic), 2,6-dichloronicotinate (2,6-Cl2nic), isonicotinate (isonic) and Et2nia=N,N-diethylnicotinamide) have been prepared. All the [CuX2(Et2nia)2(H2O)2] compounds seem to possess octahedral copper(II) stereochemistry with differing tetragonal distortions. An X-ray analysis of [Cu(2-Clnic)2(Et2nia)2(H2O)2] was carried out and it featured a tetragonal-bipyramidal geometry around the copper(II) atom. The tetragonal plane is created by 2-chloronicotinate anions bonded to the copper(II) atom via the unidentate carboxylate oxygen atoms [Cu–O1=1.965(2) A] and the pyridine ring nitrogen atoms of the neutral ligand N,N-diethylnicotinamide [Cu–N1=2.015(2) A], whilst in axial positions are water molecules [Cu–O1w=2.503(2) A].

Self-assembly of hydrogen-bonded supramolecular structures of two copper(II) 2-bromobenzoate complexes with 4-pyridylmethanol and nicotinamide

The structures of [Cu(2-Brbz)2(4PM)2(H2O)] (1) and [Cu(2-Brbz)2(NIA)2] · 2H2O 2 [where 2-Brbz is the 2-bromobenzoate anion, 4-PM is the 4-pyridylmethanol and NIA is nicotinamide] have been determined by X-ray and characterized by EPR spectroscopy. The Cu2+ cation in 1 is coordinated by a pair of oxygens from monodentate 2-bromobenzoate anions by a pair of pyridine nitrogens from monodentate 4-pyridylmethanol ligands and finally by a water forming a tetragonal-pyramidal coordination polyhedron. The Cu2+ cation in 2 is coordinated by two pairs of oxygens from the asymmetric bidentate 2-bromobenzoate anions and by a pair of pyridine nitrogen atoms from the monodentate nicotinamide in trans positions, forming an extremely elongated bipyramid. The molecules of both complexes are linked by O–H ··· O, C–H ··· O and for 2 by N–H ··· O hydrogen bonds, which create three-dimensional hydrogen-bonding networks. EPR spectra of 1 and 2 are in agreement with X-ray data. Nicotinamide as well as 4-pyridylmethanol are suitable ligands for construction of hydrogen bonding coordination polymers.

Crystal structures and spectroscopic behaviour of polymeric copper(II) chloroacetate adducts with 3- and 4-pyridylmethanol

The structural and spectroscopic properties for polymeric complexes, Cu(Cl2CHCOO)2(3-PM)2, Cu(Cl3CCOO)2(3-PM)2, Cu(ClCH2COO)2(4-PM)2 and Cu(Cl2CHCOO)2(4-PM)2 (PM ¼ pyridylmethanol), are reported. The characterization is based on elemental analysis, infrared, electronic and EPR spectra. The Cu(Cl2CHCOO)2(3-PM)2 as well as Cu(Cl3CCOO)2(3-PM)2 adopt polymeric structures as revealed by X-ray structure analysis. The polymeric structure of Cu(Cl2CHCOO)2(3-PM)2 is centrosymmetric and centred at the inversion center of the space group P1bar (Z ¼ 2), while the structure of Cu(Cl3CCOO)2(3-PM)2 contains two crystallographically independent centrosymmetrical molecules, which are centred at the inversion centres of the space group P21/c (Z ¼ 4). 2003 Elsevier B.V. All rights reserved.

Spin crossover and high spin electroneutral mononuclear iron(III) Schiff base complexes involving terminal pseudohalido ligands

Investigations into a series of six novel mononuclear iron(III) Schiff base complexes with the general formula [Fe(L)X] (where H2L is a pentadentate Schiff-base ligand, X = pseudohalido ligand) are reported. Several different aromatic 2-hydroxyaldehyde derivatives were used in combination with N,N′-bis(2-aminoethyl)-1,3-propanediamine (compounds 1–5) and 2,2′-diaminodiethylamine (for 6) to synthesize the H2L Schiff base ligands. The consecutive reactions with iron(III) chloride resulted in the preparation of the [Fe(L)Cl] precursor complexes which were left to react with pseudohalido ligands (NCS− for 1, 2, 3, 4, 6; N3− for 4). Structural investigations revealed a usual coordination of the pentadentate Schiff base ligands via N3O2 donor atoms and the sixth coordination place is occupied by the N donor of the corresponding pseudohalido ligand. The spin crossover was observed in two cases with transition temperatures: Tc = 83 K (hysteresis width of ΔT = 2 K) for 1 and Tc = 174 K for 2. Magnetic investigations of compounds 3–6 revealed high spin behaviour. The magnetic data of all compounds were analysed using the spin Hamiltonian formalism including the zero-field splitting term and the molecular field effect. In the case of the spin crossover complexes 1 and 2, the Ising-like model was applied.

Synthesis, structure, spectral and magnetic properties of 4-methoxy- and 3-methylsalicylatocopper(II) complexes with 2-pyridylmethanol

The synthesis and characterization of [Cu(4-MeOsal)2(2-pyme)2] (1) and [Cu(3-Mesal)2(2-pyme)2] (2) (where 4-MeOsal = 4-methoxysalicylate, 3-Mesal = 3-methylsalicylate and 2-pyme = 2-pyridylmethanol) are reported. The composition and stereochemistry as well as the mode of coordination have been determined by elemental analysis, IR, electronic and EPR spectra as well as magnetization measurements over the temperature range 1.8–300 K. The crystal structures of Cu(4-MeOsal)2(2-pyme)2 and Cu(3-Mesal)2(2-pyme)2 have been determined.

Caffeine in copper(II) complexes: crystal and molecular structure of di(caffeine)tetrakis(naproxenato)dicopper(II)

Abstract The crystal and molecular structure of di(caffeine)tetrakis(naproxenato)- dicopper(II) was determined by direct method and Fourier techniques. The structure was refined by full-matrix least-squares methods to a weighted R factor of 0.0705. The compound is binuclear with square pyramidal geometry at each copper(II) centre. The two copper(II) atoms are bridged by four carboxylate groups, while the apical ligands are caffeine molecules. The Cu–Cu distance is 2.649(2) A. The Cu atoms are displaced by 0.217 A from the plane containing four oxygen atoms bonded to Cu towards the apical caffeine molecules. The structural data are compared with those found in similar [Cu2(RCOO)4(caf)2] (caf = caffeine) complexes.

Self-assembled hydrogen-bonded coordination networks in two copper(II) carboxylates with 4-pyridylmethanol

The crystal and molecular structure of [Cu(nif)2(4-PM)2]·CH3OH (1) and [Cu(2-Clbz)2(4-PM)2(H2O)] (2), (where nif = niflumate anion, 2-Clbz = 2-chlorobenzoate anion and 4-PM is the 4-pyridylmethanol), have been determinated by X-ray crystallography. The Cu2+ cation in (1), is coordinated by two pairs of oxygen atoms from asymmetric bidentate niflumate anions and by a pair of pyridine nitrogen atoms from monodentate 4-pyridylmethanol ligands in trans position forming an extremely elongated bipyramid. The Cu2+ cation in (2), is coordinated by a pair of oxygen atoms from monodentate 2-chlorobenzoate anions, further by a pair of pyridine nitrogen atoms from monodentate 4-pyridylmethanol ligands and finally by a water oxygen atom forming a tetragonal-pyramidal coordination polyhedron. The molecules of both complexes in crystal structures are linked by O-H…O hydrogen bonds, which created a three-dimensional hydrogen-bonding networks. The Π-Π stacking interactions are also observed in crystal structures of complex 2. The spectral properties (IR and electronic spectra) of both complexes were also investigated.