Sue-Lein Wang

Crystal and molecular structure of a five-coordinate zinc complex of meso-tetraphenyltetrabenzoprophyrin

Abstract The crystal and molecular structure of a five-coordinate zinc tetrabenzoporphyrin, (tetrahydrofuran)(meso-tetraphenyltetrabenzoporphyrin)zinc(II), [(TPTBP)Zn (THF)], has been determined. The molecule is severely non-planar and assumes a saddle shape. The average absolute displacement of Cb from the mean plane is 0.7652 A. The predominant feature of the crystal structure is layers of three saddle-shaped macrocycles stacked with infinite cylindrical channels along the crystallographic c-axes. The results of this study indicate that extension of the π-electron system of the porphyrinato core results in significant effects for both molecular and crystal structure.

Bonding properties of penta-coordinate CuII-N chromophores: structures and electronic spectra of copper(II) complexes of tris(2-aminoethyl)amine (tren). Molecular structures of [Cu(tren)(N-acetylhistamine)](ClO4)2 and [Cu(tren)(2-methylimidazole)](ClO4)2

Abstract Tris(2-aminoethyl)aminecopper(II) perchlorate complexes, [Cu(tren)L](ClO4)2 [tren is tris(2-aminoethyl)amine and L are neutral N-donor ligands including imidazoles, pyridines and amines], have been synthesized and characterized. The X-ray crystal structures of [Cu(tren)(achmH)](ClO4)2 (1) and [Cu(tren)(2MImH)](ClO4)2 (2) (achmH = N-acetylhistamine; 2MImH = 2-methylimidazole) have been determined. Their structures consist of discrete perchlorate anions and distorted trigonal-bipyramidal [Cu(tren)(N-donor)]2+ cations with the three primary amine groups of the tren ligand forming the equatorial plane, where one of the equatorial angles is larger than the other two and the Cuue5f8N opposite the largest equatorial Nue5f8Cuue5f8N angle is significantly longer than the other two. Electronic and EPR spectra are reported for these complexes. The LF spectra are analysed in trigonalbipyramidal symmetry with the Jahn-Teller effect being considered in the excited state and the effect of geometric distortions. The d-orbitals are assigned in a sequence of dz2 >> dx2-y2 > dxy > dxz ≈ dyz. The bonding properties of the CuN5 chromophores are elucidated and discussed with reference to the electronic structures of the complexes, suggesting no π-interaction in the axial Cuue5f8N bonds.

Bonding properties of copper(II)—N chromophores: Molecular and electronic structures of copper(II) complexes containing ethylenediamine and heterocyclic diimine ligands

Abstract Mixed ligand ethylenediaminecopper(II) perchlorate complexes, [Cu(en)LL (H2O)](ClO4)2, en = ethylenediamine and LL stands for 2,2′-bipyridine (bipy), 1,10-phenanthroline (phen), and N,N,N′,N′-tetramethylethylenediamine (tmen), have been prepared and characterized by elementary analyses, and electronic, vibrational, and EPR spectroscopic measurements. The crystal and molecular structures of [Cu(en)(bipy) (H2O)](ClO4)2 (1) and [Cu(en)(phen)(H2O)](ClO4)2 (2) have been determined from single-crystal, three-dimensional X-ray diffraction data. Both complexes, crystallized in triclinic P 1 − group, contain discrete copper(II) cations having a CuN4 basal plane and a H2O on the apex. A similar structure was suggested for [Cu(en)(tmen)(H2O)](H2O)](ClO4)2 (3). The single-crystal polarized electronic spectra of 1 and 2 were measured and resolved into a set of three Gaussian component peaks for each spectrum. Gaussian analyses performed on the crystal and the powder LF bands for these complexes yielded a one-electron orbital sequence dxy > dz2 > dx2−y2 > dyz > dxz. Bonding properties of the bidentate ligands are elucidated suggesting virtually no π-interactions between the heterocyclic diimine ligands and the central copper(II) ion in these ethylene-diamine complexes.

Bonding properties of copper(II)-imidazole chromophores: electronic and molecular structure of tetrakis(imidazole)bis(tetrafluoroborato)copper(II)bis(hexamethylphosphoramide)

SummaryThe crystal and molecular structure of [Cu(HIm)4(BF4)2]-2hmpa (HIm=imidazole; hmpa=hexamethylphosphoramide) has been determined using three-dimensional x-ray diffraction data. The CuII ion is coordinated centrosymmetrically by four imidazole ligands forming a basal plane, mean Cu−N 2.005 Å, and by two tetrafluoroborate anions on the z axis, mean Cu−F 2.506 Å. The four imidazole ligands are inclined at 64.6±0.5° to the CuN4 coordination plane. The discrete CuII complexes and hexamethylphosphoramide molecules are interconnectedvia hydrogen bonding between the imidazole N−H group and hmpa oxygen atom. The hmpa has a tetrahedral configuration around P with P=O 1.489 Å and mean P−N 1.629 Å. The deconvoluted d-d absorptions of the title compound yield an orbital sequence: dx2−y2>dz2>dxy>dyz=dxz. The properties of the Cu-imidazole bonds are discussed with reference to the electronic structures of the chromophores of tetrakis(imidazole)copper(II) complexes having effective local symmetriesD4h andD2h.

The reaction between unsaturated tetrarhenium cluster H4Re4(CO)12 and tris(diphenylphosphino)methane

Abstract The reaction between the unsaturated cluster H 4 Re 4 (CO) 12 and tripod (HC(PPh 2 ) 3 ) was investigated. After refluxing the reactants in CH 2 Cl 2 for 8 h, four compounds were isolated. They are identified by NMR, mass, IR and elemental analysis to be HRe(CO) 3 (η 2 - tripod), H 2 Re 2 (CO) 6 (η 3 -μ 2 -tripod), H 3 Re 3 (CO) 9 (η 3 -μ 3 -tripod) and H 4 Re 4 (CO) 12 (η 3 - μ 3 -tripod). The structures of the trirhenium and tetrarhenium cluster products were determined by X-ray diffraction method. In H 3 Re 3 (CO) 9 (tripod), the tripod ligand is capping on top of the Re 3 plane. The three rhenium atoms and the three phosphorus atoms form a slightly distorted trigonal prism. Though the Reue5f8Re and Reue5f8P bond distances show the presence of steric strain, H 3 Re 3 (CO) 9 (tripod) is thermally much more stable than the uncapped H 3 Re 3 (CO) 12 . In H 4 Re 4 (CO) 12 (tripod), the four rhenium atoms form a spiked triangular configuration. Re4 is bonded to Re1 and is nearly perpendicular to the Re1ue5f8Re2ue5f8Re3 triangle. The three phosphorus atoms are coordinated to Re2, Re3 and Re4. A novel feature of this tetranuclear cluster is that one of the phenyl groups is coordinated in η 2 -fashion through a double bond to Re4 which is in the spiked position. This is the first example of phenyl group coordination in tripod chemistry. The tetra rhenium cluster is also stable in refluxing CH 2 Cl 2 in the presence of tripod.

Bonding properties of copper(II)-imidazole chromophores: structures and electronic properties of tetrakis imidazole copper(II) complexes. Molecular structures of Cu(N-methylimidazole)4(ClO4)2 and [Cu(N-methylimidazole)4(H2O)2]Cl2(H2O)

Abstract The crystal and molecular structures of [Cu(NMIm)4(ClO4)2] ({Bd1}) and [Cu(NMIm)4(H2O)2]Cl2·(H2O) ({Bd2}) (NMIm = N-methylimidazole) have been determined from three-dimensional X-ray diffraction data. The structure of {Bd1} consists of discrete centrosymmetric [Cu(NMIm)4(ClO4)2] units having a CuN4 plane with a set of two trans N-methylimidazole ligands nearly perpendicular to the CuN4 plane (dihedral angle 87.8°)) and another set approximately parallel (dihedral angle 4.4°), and two perchlorates on the long z-axis with Cuue5f8O length of 2.718(13) A. The structure of {Bd2} comprises two discrete structurally similar centrosymmetric [Cu(NMIm)4(H2O)2] cations interconnected with Cl− ions and hydrate molecules by hydrogen bonds. The dihedral angles between the imidazole and the CuN4 planes are 98.8° and 57.6° for one unit and 97.0° and 50.6° for another. Electronic and EPR spectra are reported for {Bd1} and {Bd2} and also for tetrakis complexes of imidazole, 4-methylimidazole, 4-phenylimidazole and benzimidazole. Analysis of the electronic spectra of {Bd1} and {Bd2} reveals that the former has D2h symmetry with non-degenerate dxz and dyz orbitals, and the latter has D4h symmetry with degenerate dxz and dyz. This is ascribed to the difference in donor abilities of the axial ClO4− and H2O ligands. In solution, all tetrakis species exhibit different structures depending on the donor abilities of the solvent molecules.

Synthesis and molecular structure of meso-tetra(4-pyridyl) porphyrinatothallium(III) cyanide : Tl(tpyp)(CN)

Abstract The new compound meso-tetra(4-pyridyl) porphyrinatothallium(III) cyanide, Tl(tpyp)(CN), has been synthesized and its molecular structure determined by X-ray analysis. The thallium-carbon(cyanide) distances are 2.163 (12) A [for thallium (1)] and 2.121 (28) A [for thallium (2)], respectively, with thallium(1) situated 0.825 A above the porphyrin ring and thallium(2) located 0.900 A below the ring. The characteristic band observed at 2163 cm−1 in the FTIR spectrum confirms that the Cue5fcN group is present in the Tl(tpyp)(CN) complex. The 13C resonance of the axial cyano ligand was observed at 137.7 ppm (24°C) (with 1J(205Tl-13C) coupling constant 5852 Hz and 1J(203Tl-13C) coupling constant 5795 Hz). The Correlation Spectroscopy via Long-Range Coupling technique (COLOC) was used to resolve two quaternary carbons ie. Cα and C-1 at 149.3 and 149.1 ppm, respectively.

Crystal structures of chloro(meso-tetraphenylporphyrinato)germanium(IV), Ge(tpp)Cl2, and dihydroxo(meso-tetraphenylporphyrinato)germanium(IV), Ge(tpp)(OH)2, and two-stage hydrolysis of its homologue dimethoxo(meso-tetraphenylporphyrinato)germanium(IV), Ge(tpp)(OMe)2

Abstract The crystal structures of chloro(meso-tetraphenylporphyrinato)germanium(IV), Ge(tpp)Cl2, dimethoxo(meso-tetraphenylporphyrinato)germanium(IV), Ge(tpp)(OMe)2, and dihydroxo(meso-tetraphenylporphyrinato)germanium(IV), Ge(tpp)(OH)2, were determined. The coordination sphere of the Ge4+ ion is a distorted octahedron in which the apical sites are occupied by two monodentate Cl− (or OMe−, OH−) groups. The geometry around the germanium centre of the Ge(tpp)Cl2 molecule has Ge(1)ue5f8Cl(1) = 2.262(1) and Ge(1)ue5f8N(1) = 2.019(2) A. In the structure of Ge(tpp)(OMe)2 the germanium(1)-oxygen distance is 1.826(3), average Ge(1)ue5f8N = 2.032(3), and O(1)ue5f8C(23) = 1.331(6) A. The structure of Ge(tpp)(OH)2 has Ge(1)ue5f8O(1) = 1.809(3) and Ge(1)ue5f8N(1) = 2.027(2) A. Two-stage hydrolysis of Ge(tpp)(OMe)2 was studied by 1H and 13C NMR spectroscopy. The use of a limited amount of water in CDCl3 (or CD2Cl2) allowed the hydrolysis intermediate, hydroxomethoxo(meso-tetraphenylporphyrinato)germanium(IV), Ge(tpp)(OMe) (OH), and hydrolysis product, dihydroxo(meso-tetraphenylporphyrinato)germanium(IV), Ge(tpp)(OH)2, to be identified. X-ray diffraction data and solid-state 13C CP/MAS spectra of Ge(tpp)(OMe)2 provide evidence for two monodentate methoxo groups coordinated to the germanium(IV) atom.

Structure of the organometallic radical, di-t-butylbenzoquinonetricarbonyltriphenylphosphinerhenium, DTBQ.-Re(CO)3PPh3

Abstract The compound DTBQ . -Re(CO) 3 PPh 3 , was prepared by photochemical reaction of DTBQ with Re 2 (CO) 10 , followed by triphenylphosphine substitution. The structure of the deep-blue crystal has been established by X-ray diffraction studies at room temperature (monoclinic, space group P 2 1 / n , Z = 4, a 13.191(4) A, b 17.856(3) A, c 14.082(5) A, β 98.55(3)°, R = 0.032 for 4680 independent reflections, 2θ ≤ 50°). Judging from the DTBQ Cue5f8O bond length of 1.297 A, the X-ray data indicate that DTBQ coordinates to Re as a semiquinone, with electron transfer from rhenium to the π * orbital of DTBQ.

Bonding properties of copper(II)—N chromophores: Preparation, structure, and spectroscopic properties of ethylenediaminecopper(II) complexes. Molecular structure of [Cu(ethylenediamine)(pyridine)2(ClO4)2]

SummaryEthylenediaminecopper(II) perchlorate complexes of the [Cu(ethylenediamine)L2(ClO4)2] type, where L = imidazole, N-methylimidazole, 2-methylimidazole, 4-methylimidazole, and pyridine, have been prepared and characterized by elemental analyses, and electronic, vibrational, and e.p.r. spectroscopic measurements. The molecular structure of [Cu(ethylenediamine)(pyridine)2(ClO4)2] has been determined by three-dimensional X-ray diffraction data. The CuII ion is coordinated by one ethylenediamine and two pyridine ligands forming an equatorial plane, and by two perchlorate anions located on the z axis. The pyridine ligands incline at 54.9 ° to the CuN4 plane suggesting virtually no π -interaction in the complex. Similar structures with a CuN4 coordination plane are proposed for other complexes based on the spectroscopic data. The bonding properties of these complexes are elucidated and discussed with reference to the electronic structures deduced from Gaussian analyses of their LF spectra.