E. O. Schlemper

Dinuclear complexes of rhenium(V) with amine-phenol ligands: Synthesis, characterization and x-ray crystal structures

Abstract Rhenium(V) complexes from three amine-phenol ligands prepared by reducing Schiff bases derived from salicylaldehyde and 1,3-diaminopropane and 1,4-diaminobutane, as well as 1,3-diaminopropane and 2-hydroxyacetophenone, have been synthesized. 1H and 13C NMR and IR spectroscopy were used for characterization of two of the complexes. X-ray diffraction data of all the three complexes were collected by the θ–2θ scan method using Mo-Kα radiation. The structures were solved by Patterson and Fourier methods and refined to final R factors of 0.046, 0.032 and 0.052, respectively for the three complexes. The complexes are dinuclear with OREOREO backbones and near octahedral ReV coordination. Two of the structures of the complexes are isomorphous with the structures obtained earlier for corresponding technetium complexes.

The dibenzylideneactone adducts of uranyl bis(β-diketonates). The low temperature NMR behaviour and molecular structure of [UO2(TTA)2·DBA]

Abstract Uranyl complexes of the type [UO2( OO )2·DBA] ( OO = TTA, DBM and BA) have been prepared and characterized by 1H, 19F and 13C{1H} NMR, IR spectroscopic techniques and elemental analyses. The low temperature behaviour of the complex [UO2 (TTA)2·DBA] was studied by the 19F NMR technique and its structure solved by single- crystal X-ray diffraction. The structure determination shows that the uranium atom has pentagonal-bipyramidal geometry with the four oxygen atoms of TTa and one oxygen atom of DBA lying on the basal plane and two uranyl oxygen atoms occupy the apices.

Macrocyclic nickel(II) complexes: Spectroscopic studies and crystal structure of bis(difluoroboron-alpha-furilglyoximato)nickel(II)

Abstract Bis (difluoroboron - α - furilglyoximato) nickel (II), C 20 H 12 O 8 N 4 B 2 F 4 Ni, was prepared by cyclization of its hydrogen-bonded precursor with BF 3 ·OEt 2 . The compound crystallizes in the space group P 2 1 / c with a = 11.162(2), b = 5.569(2), c = 19.527(3) A, β = 100.08(1)°, U = 1195.1(3) A 3 , and Z = 2. The structure was refined to an R value of 0.033 using 2371 unique reflections collected with a CAD4-SDP diffractometer system. Unlike the corresponding planar macrocyclic as well as hydrogen-bonded dimethylglyoximates, the title compound neither dimerizes not exhibits columnar stacked structure. The 14-member macrocycle is planar except the B atoms, and no metal-metal interactions are observed in this compound. The complexation and cyclization reactions were investigated using spectral data. The structure is compared with other macrocyclic complexes.

Cobaloxime derivatives: synthesis and spectroscopic studies of alpha-furilglyoximate of cobalt(III), X-ray structure of bis(thiourea)bis(alpha-furilglyoximato)cobalt(III) nitrate

Abstractα-Furilglyoxime (H2afdo) complexes of cobalt(III) were used to synthesize H2afdo-cobaloximes with thiourea, triphenylphosphine, and aniline astrans-axial ligands. Encapsulation of the H-bonded species with BF3∶OEt2 resulted in stable BF2-capped macrocycles which mimic the central metal core of the biological molecules such as vitamin B12 etc. Solution chemistry and spectroscopic measurements of the BF2-macrocycles as well as H-bonded cobaloximes revealed six-coordinated cobalt(III) as the central atom and a short hydrogen bond in the case of latter. X-Ray structure of a representative complex [Co(Hafdo)2(thiourea)2]NO3 (Haldo=α-furilglyoxime anion) confirmed a pseudo-octahedral geometry around cobait(III) with thiourea bonded to axial positions. The oxygen atoms of furyl groups are not involved in any kind of bonding and the overall structure of the complex differs from that of the H2dmg-cobaloximes (H2dmg=dimethylglyoxime).

Dinuclear complex of rhodium(III) with an amine-phenol ligand: synthesis and X-ray crystal structure

A new rhodium(III) complex of an amine-phenol ligand N,NN′-bis-(2-hydroxybenzyl)1,3-diaminopropane was synthesized and characterized by X-ray diffraction studies. Diffraction data were collected by theθ-2θ scan method using MoKα. radiation. The structure was solved by conventional methods resulting in a final R factor of 0.037 for 1954 independent reflections (Fo>2σ(Fo)). The structure consists of a dinuclear complex with two μ-hydroxy bridges between the two Rh atoms. The overall charge of the molecule is neutral due to deprotonation of all phenolic groups. Crystal data: triclinic, space groupP¯1,a=7.308(3)Å;b=9.586(3)Å,c=12.686(5)Å, α=87.51(2), β=88.28(2), γ=71.70(3)°,V=866.6(6)Å3;Z=2.

Palladium(II) complexes of N2O2 and N2S2 ligands: Syntheses and X-ray crystal structures

Palladium(II) complexes of an imine-thiophene ligand N,N′ bis(1-methylenethiophene)-1,3-diaminopropane and an amine-phenol ligand N,N′-bis(2-hydroxybenzyl)1,3-diamino-2,2-dimethylpropane were synthesized by reacting K2PdCl4 with alcoholic solutions of the ligands. X-ray structures of the complexes were determined using data from a CAD-4 Nonius diffractometer (MoKα radiation). The structures were solved by conventional methods resulting inR factors of 0.044 and 0.061 using 1841 and 2241 independent reflections, respectively. Crystal data: Complex I, orthorhombic, space groupPbca,a=11.323(2),b=14.819(2),c=23.873(3)Å,V=4006(1)Å3,Z=8. Complex II: Space groupP21/c,a=9.169(2),b=31.920(4),c=8.902(6),β=90.38(2)°,V=2605(1)Å3.Z=4. Both complexes showed coordination of the ligands through the nitrogens only while the sulphur and the oxygen atoms were uncoordinated. Square planar coordination is completed bycis chloro ligands.

A combined neutron and X-ray diffraction study of hydrogenbis(NN-dimethylacetamide) tetrachloroaurate(III) revealing a short hydrogen bond

A combined room-temperature neutron and X-ray diffraction study of the title compound [{(CH3)2NC(CH3)O}2H]-[AuCl4] is reported. The compound crystallizes with two molecules in a monoclinic unit cell of space group P21/a with lattice parameters a= 11.597(3), b= 10.404(2), c= 7.657(2)A, and β= 108.61(1)°. The structure has been solved by the heavy-atom method and the final values for R(F02) were 0.088 for 617 neutron data and 0.082 for 817 X-ray data. It consists of distinct [AuCl4]– anions and [(dma)2H]+ cations (dma = dimethyl-acetamide) with the gold and the bridging hydrogen atoms located at centres of symmetry. The hydrogen bond is ‘symmetrical’ as a result of crystallographic requirements. The O ⋯ O distance is 2.430(16)A. Thermalmotion analysis of neutron data indicates that methyl groups attached to nitrogen have higher rotational amplitudes resulting in short apparent C–H bond lengths [average 0.96(4)A] compared with the methyl group attached to carbonyl carbon which has an average C–H bond length of 1.02(2)A. Other average, uncorrected, neutron-determined bond distances are: Au–Cl 2.265(3); C–O 1.259(8); N–CH3 1.473(9); N–C 1.299(6); and C–C 1.502(8)A. The structural analysis clearly indicates that earlier conclusions about the presence of six-co-ordinate gold and nitrogen-co-ordinated dma based upon spectroscopic data are erroneous.

Transition-metal chemistry of quinuclidinone-containing ligands. Part V. Crystal structure of dichloro[trans-2-(2-quinolyl)methylenequinuclidin-3-one]cobalt(II)

The crystal structure of the title compound has been determined from 2829 independent reflections measured by diffractometer. Crystals are triclinic, space group P, with the (non-conventional) unit-cell parameters, a= 9·492(4), b= 9·754(5), c= 9·243(5)A, α= 89·91(5)°, β= 90·28(5)°, γ= 108·30(2)°, and Z= 2. The structure was solved by Patterson and Fourier techniques, and refined by full-matrix least-squares methods to R= 3·4%. The compound consists of cobalt(II) ions co-ordinated in a pseudotetrahedral manner to the two nitrogen donor atoms in the ligand and to the two chloride ions. The two Co–CI distances are slightly different [2·219(1) and 2·227(1)A], and the Co–N (quinoline) bond distance [2·014(2)A] is somewhat shorter than Co–N (quinuclidinone)[2·064(2)A]. The bond angles about Co are distorted from their pure tetrahedral value, the smallest being [100·35(9)°] the chelate ‘bite’ angle. The ligand is almost planar (excluding the two ethylene bridges), and the molecule therefore possesses an approximate mirror plane bisecting the Cl–Co–Cl angle.

Crystal structure of hydrogenbis(pyridine N-oxide) tetrachloroaurate-(III), revealing a short hydrogen bond

An X-ray diffraction study of the title compound [H(pyo)2][AuCl4](pyo = pyridine N-oxide) was done to investigate the dimeric cation [H(pyo)2]+ with a short hydrogen bond. The compound crystallizes in the triclinic space group P and has lattice parameters a= 7.276(6), b= 8.631(3). c= 6.799(8)A, α= 105.4(3), β= 96.4(3), and γ= 67.9(2)°. The structure was solved both by the direct method and by the heavy-atom method using a CAD-4 SDP system. The final value for R(F0) was 0.044 for 1 343 unique reflections. The structure consists of discrete [AuCl4]– anions and [H(pyo)2]+ cations with the gold and the bridging hydrogen atoms located at centres of symmetry. The hydrogen bond is symmetric as a result of crystallographic requirements. Two pyridine N-oxide molecules are hydrogen-bonded to form the planar dimeric cation,[H(pyo)2]+. The [AuCl4]– anion has no bonded interaction with any adjacent anion or cation, indicating four-co-ordinated planar gold. The 0 ⋯ 0 distance [2.41(1)A] is within the usual range observed for short hydrogen bonds. The structure of this compound, its spectral data, and its comparison with the structures of known compounds having similar dimeric cations are of significance because of the importance of gold complexes in chrysotherapy (gold treatment).

A palladium(II) complex of a tetradentate amine-phenol ligand

A palladium(II) complex of an amine-phenol ligand N,N′-bis(2-hydroxybenzyl)1,4-diaminobutane has been synthesized and characterized by NMR, IR, and X-ray diffraction studies. Diffraction data were collected with a Nonius CAD-4 diffractometer with θ-2θ scan and MoKα radiation. The structure was solved by conventional methods resulting in anR factor of 0.022 for 1058 independent reflections. The X-ray structure shows a discrete mononuclear square planar complex in which the Pd is coordinated to the two nitrogens and two oxygens of the ligand. The complex is neutral with the Pd(II) charge balanced by deprotonation of both phenolic oxygens. Crystal data: Space group Pna21,a+8.223 Å,b+22.477 Å,c+9.190 Å;V+1698.8 Å3;Z+4.