Y16I19C8B4 – ein Yttriumboridcarbidhalogenid mit B2C4-Einheiten

Y₁₆I₁₉C₈B₄ – a Yttrium Boride Carbide Halide Containing B₂C₄ Units The new compound Y₁₆I₁₉C₈B₄ was prepared from Y, YI₃, C and B at 1050–1150 °C. The structure of a twinned crystal was determined by means of X-ray diffraction (space group P 1¯, a = 12.311(2) Å, b = 13.996(3) Å, c = 19.695(3) Å, α = 74.96(2)°, β = 89.51(2)°, γ = 67.03(2)°, Z = 2). Y₁₆I₁₉C₈B₄ is a semiconductor and contains nearly planar B₂C₄ units which are located in cages built up by 12 yttrium atoms. Assuming (B₂C₄)^12–, these units can be regarded as isoelectronic with B₂F₄. The yttrium cages are connected via faces to form rods, which are surrounded by iodine atoms. Bridging iodine atoms connect the rods so that layers are formed. The characteristic twinning observed can be understood from the geometry of the crystal structure.     

m -Terphenyl derivative of titanium(III): Cp2TiR (Cp=C5H5; R =2,6-(4-MeC6H4)2C6H3)

The title compound, Cp₂TiR (Cp=C₅H₅; R=2,6-(4-MeC₆H₄)₂C₆H₃), 1, was prepared by reaction of RLi with [Cp₂TiCl]₂. Compound 1 was characterized by elemental analysis, EPR, and single crystal X-ray crystallography. The title compound crystallizes in the monoclinic space group C2/c with the following unit cell dimensions: a=11.1466(7) Å, b=16.4429(11) Å, c=13.0786(8) Å; b=106.2040(10)^°;V=2301.9(3) ų. The EPR spectrum of 1 displays two signals, a high field signal at g=1.979 and a lower field signal at g=1.959. Significantly, 1 is a sterically encumbered m-terphenyl-stabilized trivalent titanocene paramagnetic complex and may be a practical one-electron reducing reagent.     

From Isolated Polyanions to 1‐D Structure: Synthesis and Crystal Structure of Hybrid Fluorides {[(C2H4NH3)3NH]4+}2 · (H3O)+ · [Al7F30]9– and {[(C2H4NH3)3NH]4+}2 · [Al7F29]8– · (H2O)2

Two new hybrid fluorides, {[(C₂H₄NH₃)₃NH]⁴⁺}₂ · (H₃O)⁺ · [Al₇F₃₀]^9– ( I ) and {[(C₂H₄NH₃)₃NH]⁴⁺}₂ · [Al₇F₂₉]^8– · (H₂O)₂ ( II ), are synthesized by solvothermal method. The structure determinations are performed by single crystal technique. The symmetry of both crystals is triclinic, sp. gr. P 1, I : a = 9.1111(6) Å, b = 10.2652(8) Å, c = 11.3302(8) Å, α = 110.746(7)°, β = 102.02(1)°, γ = 103.035(4)°, V = 915.9(3) ų, Z = 1, R = 0.0489, R_w = 0.0654 for 2659 reflections, II : a = 8.438(2) Å, b = 10.125(2) Å, c = 10.853(4) Å, α = 106.56(2)°, β = 96.48(4)°, γ = 94.02(2)°, V = 877.9(9) ų, Z = 1, R = 0.0327, R_w = 0.0411 for 3185 reflections. In I , seven corner‐sharing AlF₆ octahedra form a [Al₇F₃₀]^9– anion with pseudo 3 symmetry; such units are found in the pyrochlore structure. The aluminum atoms lie at the corners of two tetrahedra, linked by a common vertex. In II , similar heptamers are linked in order to build infinite (Al₇F₂₉)_n^8– chains oriented along a axis. In both compounds, organic moieties are tetra protonated and establish a system of hydrogen bonds N–H…F with four Al₇F₃₀^9– heptamers in I and with three inorganic chains in II .     

A Novel 3D Framework Coordination Polymer based on Succinato bridged Helical Chains Connected by 4, 4' ‐ Bipyridine: [Cu(bpy)(H2O)2(C4H4O4)]?2H2O

Blue needle—shaped crystals of [Cu(bpy)(H₂O)₂(C₄H₄O₄)]· 2H₂O were obtained by slow evaporation of a methanolic aqueous solution containing a fresh Cu(C₄H₄O₄)· 2H₂O precipitate, 4, 4′—bipyridine, and ammonia. Within the complex, the six—coordinated Cu atoms are linked by bis—monodentate gauche succinate anions into chains propagating helically around the [001] axis. The chains are interconnected by 4, 4′—bipyridine ligands into a 3D framework with the crystal H₂O molecules located in the channels along the [100], [010] and [110] directions. The Cu²⁺ ions are in distorted octahedral coordination of two nitrogen and four oxygen atoms (equatorial bonds: Cu—N 1.986(5), 2.015(5)Å; Cu—O 1.950(6), 1.954(6)Å; axial bonds Cu—O: 2.524(9), 2.539(8)Å). Furthermore, the thermal and magnetic behavior of the compound will be discussed. Crystal data: hexagonal, P6₁ (no. 169), a = 11.066(2)Å, c = 24.965(5)Å, V = 2647.5(8)ų, Z = 6, R = 0.0528 and wR₂ = 0.1103 for 1426 observed reflections (F_o² > 2σ(F_o²)) out of 2170 unique reflections.     

Crystal and Molecular Structure of Carbonyl (1,1,4,4-Tetrafluoro-2-tert-Butyl-1,4-Disilabut-2-Ene) (η5-Cyclopentadienyl) Cobalt (II)

(C₃H₅)Co(CO)(Si₂F₄C₄H₁₀) was synthesized by the photochemical reaction between dicarbonyl (η⁵-cyclopentadienyl) cobalt and 1,1,2,2-tetrafluoro-1,2,-disilacyclobutene. Its structure was identified by IR, NMR and mass spectrometry. The single crystal structure was studied for confirmation. The compound crystalized in a monoclinic space group P2₁/n with unit cell a=7.120 (6), b=20.334. (3), c=10.682(1) Å, β=90.97(8)°, Z=4 final R=0.050 for 3667 observed reflections. The molecule has a mirror plane symmetry about the Co atom coordination sphere. The reaction between the cobalt carbonyl and the 1,2-disilacyclobutene produces only silicon-cobalt σ bonds.     

Syntheses and structures of nine-coordinate K3[DyIII(nta)2(H2O)]·5H2O and eight-coordinate (NH4)3[DyIII(nta)2] complexes

K₃[Dy^III(nta)₂(H₂O)]·5H₂O and (NH₄)₃[Dy^III(nta)₂] have been synthesized in aqueous solution and characterized by IR, elemental analysis and single-crystal X-ray diffraction techniques. In K₃[Dy^III(nta)₂(H₂O)]·5H₂O the Dy^III ion is nine coordinated yielding a tricapped trigonal prismatic conformation, and its crystal belongs to monoclinic system and C2/c space group. The crystal data are as follows: a = 15.373(5) Å, b = 12.896(4) Å, c = 26.202(9) Å; β = 96.122(5)°, V = 5165(3) ų, Z = 8, D _c = 1.965 g·cm^?3, μ = 3.458 mm^?1, F(000) = 3016, R ₁ = 0.0452 and wR ₂ = 0.1025 for 4550 observed reflections with I ≥ 2σ(I). In (NH₄)₃[Dy^III(nta)₂] the Dy^III ion is eight coordinated yielding a usual dicapped trigonal anti-prismatic conformation, and its crystal belongs to monoclinic system and C2/c space group. The crystal data are as follows: a = 13.736(3) Å, b = 7.9389(16) Å, c = 18.781(4) Å; β = 104.099(3)°, V = 1986.3(7) ų, Z = 2, D _c = 1.983 g·cm^?3, μ = 3.834 mm^?1, F(000) = 1172, R ₁ = 0.0208 and wR ₂ = 0.0500 for 2022 observed reflections with I ≥ 2σ(I). The results indicate that the difference in counter ion also influences coordination numbers and structures of rare earth metal complexes with aminopolycarboxylic acid ligands.     

Crystal and molecular structure of 2,3-benzo-1,4,7,13-tetraoxa-10-selenacyclopentadeca-2-ene

The crystal structure of 2,3-benzo-1,4,7,13-tetraoxa-10-selenacyclopentadeca-2-ene was de-termined,C_(14)H_(20)O_4Se,M_r:331.27,orthorhombic,Pbca,a=18.445(3),b=16.334(4),c9.232(2),V=2781.3 ~3,Z=8,Dx=1.582 Mg m~(-3),λ(Mo K_α)=0.71073 ,μ=26.77 cm~(-1),F(000)=1360,T=297 K,R=0.0329,R_w=0.0438 for 2192 reflections with I>3 σ(I).The crystal structure is closelyrelated to that of benzo-15-crown-5(at 123 K),whereas the molecular geometry of the two coronandsis different according to their torsion angles calculated and the shapes exhibited.     

Open metallocenes XI. A pentadienyl compound of heavier rare earth element [2,4-(CH3)2-η5-C5H5]3Tb·1/2THF

The reaction of TbCl₃ with K[2,4-(CH₃)₂ C₅H₅] at 0°C in THF followed by crystallization at ?90°C led to a pale yellow hexagonal prismatic crystalline product [2,4-[CH₃)₂-η⁵-C₅H₅]₃-Tb·1/ 2THF , which is highly sensitive to air and water and rapidly efflorescent at ambient temperature. The single crystal X-ray diffraction data of the compound have been collected at low temperature (-60°C) and the crystal structure has been solved by heavy atom method. It belongs to triclinic system, space group P1 with lattice parameters α=8.477 Å , b=12.583 Å , c=12.858 Å , α=118.08°, β=91.38°, γ=108.75°, V=1120.36 ų and Z=2. Least-squares refinement converged to a final value R=0.043. The compound possesses an idealized C_3h symmetry with three 2,4dimethylpentadienyl ligands bound to the central terbium atom in a pentahapto mode (η⁵). Each unit cell contains two molecules of [2,4-(CH₃)₂-η⁵-C₅H₅]₃Tb and one molecule of solvent THF, of which the role in the lattice has been discussed in detail.     

The synthesis and crystal structure of a trinuclear molybdenum cluster compound [Mo3(μ-O)(μ-S)3(μ(μ-OAc)2(dtp)2·(Py)]·0.5H2O

[Mo₃,OS₃(dtp)₄(H₂O)] reacts with NaOAc·3H₂O in Py to give the title compound. The crystal data are as follows: [Mo₂OS₃)(OAc)₂(dtp)₂·Py]?0.5H,O(dtp = [S₃P(OC₂H₅)₂]^?, Py = C₅H₅N); M = 976.64; triclinic; space group P1 ; a=11.704(5), b=14.169(7), c= 11.688 (5) Å α=109.94(4) β = 91.53(4), γ = 91.93(4)°; V= 1819(1) Ų; Z=2; D_c = 1.78 g·cm^?3 λ(Mo Kα) = 0.71069 Å μ=15.15 cm^?1; F(000) = 970 T=296 K; final R=0.071 for 1652 reflections with I>3σ(I). In the molecule, the [Mo₃OS₃] core is surrounded by two bridging OAc groups and two terminal chelate dtp groups attached to the {Mo₃} triangle in a symmetric style, and the Py ligand is coordinated to the Mo atom at the apex of {Mo₃} triangle with the nitrogen. This novel configuration is obtained for the first time with Mo—N bond length being 2.27 (2) Å and three Mo—Mo bond lengths 2.584 (4), 2.587 (4) and 2.657(4) Å, respectively. As a whole, the molecule has a virtual C₂ symmetry.     

Synthesis,Crystal Structure and Thermal Decomposition Process of Complex [Sm(BA)3phen]2

A binuclear samarium(III) complex with benzoic acid and 1,10‐phenanthroline, [Sm(BA)₃phen]₂ was synthesized and characterized by elemental analysis, UV, IR and TG‐DTG techniques. The structure of the title complex was established by single crystal X‐ray diffraction. The crystal is triclinic, space group P1 with a = 10.8216(11) Å, b = 11.9129(13) Å, c = 12.425(2) Å, α = 105.007(2)°, β = 93.652(2)°, γ = 113.2630(10)°, Z = 1, D_c = 1.650 mg·m^?3, F(000) = 690. The carboxylate groups are bonded to the samarium ion in three modes: bidentate chelating, bidentate bridging, and tridentate chelating‐bridging. Each Sm³⁺ ion is coordinated to one bidentate chelating carboxylate group, two bidentate bridging and two tridentate chelating‐bridging carboxylate groups, as well as one 1,10‐phenanthroline molecule, forming a nine‐coordinate metal ion. Based on thermal analysis, the thermal decomposition process of [Sm(BA)₃phen]₂ has been derived.     

Syntheses of (C_5H_9C_5H_4)_2LnCl(THF)_n (Ln=Nd, Sm, Er, Yb) and crystal structure of [(C_5H_9C_5H_4)_2-LnCl(THF)_n]_2(Ln=Sm, n=1; Ln=Er, n=0)

Reactions of lanthanoid trichlorides with sodium cyclopentylcyclopentadienyl in THFafford bis(cyclopentylcyclopentadienyl) lanthanoid chloride complexes (C_5H_9C_5H_4)_2LnCl(THF)_n (Ln=Nd, Sm, n=1; Ln= Er, Yb, n= 0). The compound [CP'_2SmCl(THF)]_2 (2) (Cp' =cyclopentylcy-clopentadienyl) crystallizes from mixed solvent of hexane and THF in monoclinic space group P_2_1/cwith a = 11.583 (3), b = 23.019(6), c = 8.227 (2), β= 90.26 (2)°, V= 2194 (1)~3, D_c= 1.59 g/cm~3.μ= 28.6 cm~(-1), F(000) = 1060, Z= 2 (dimers). Its crystal molecule is a dimer with a crystallographicsymmetry center. The central metal atom Sm is coordinated to two Cp' rings, two bridging chlorineatoms and one THF forming a distorted trigonal bipyramid. The crystal of [Cp'_2ErCl]_2 (3) belongs tothe triclinic space group P with a = 11.264 (2), b= 13.296(5), c = 14.296(6), a = 96.99 (3), β=112.47(2), γ= 102.78(2)°, V= 1865(1)~3, D_c= 1.67 g /cm~3, μ= 48.0 cm~(-1), F(000) = 924, Z = 2 (dimers).The molecule is a dimer consisting of two Cp'_2 ErCl species bridged by two Cl atoms. The centralmetal atom Er is coordinated to two Cp' rings and two bridging chlorine atoms forming a pseudo-tetrahedron. All these complexes are soluble in THF, DME, Et_2O, toluene and hexane.     

Synthesis,crystal and molecular structure of [Na(B15C5)+]2[Hg3Cl8]2-·H2O

A crystal complex with the formula [Na(B15C5)⁺]₂ [Hg₃Cl₈]^2-·H₂O was synthesized by the reaction of benzo-15-crown-5 with sodium chloride and mercuric chloride. Its crystal and molecular structures were determined by X-ray diffraction. Crystal data: monoclinic, space group P2/n with cell dimensions of a= 17.809(4) Å, b= 13.938(4) Å, c= 17.984(4) Å, β=107.14°, Z=4, V= 4266.2 Ų. R and R_w are 0.043 and 0.053, respectively. The results obtained by spectral analysis are consistent with those of the structural analysis.     

Crystal Structure of [Co2(μ-dmg)2(μ-dmg H)(dmg H)(Pø3)] 1/2 dmg H2 · 1/2 CH3OH: A Crystal Containing Various Forms of dmg Ligand

The crystal structure of [Co₂(μ-dmg)₂(μ-dmg H)(dmg H)(Pø₃)] · 1/2 dmg H₂ · 1/2 CH₃OH has been determined by single crystal X-ray diffraction. The title complex crystallizes in triclinic space group P&1bar; with a=10.859(3), b=13.299(3), c=15.247(3)Å, α=98.52(2), β=99.26(2), γ=97.80(2)° and Z=2. The agreement indices are R(F)=0.062 and R_w(F)=0.085 for 5231 observations and 515 variables. Both cobalt atoms have an oxidation state of 3+ and are both six-coordinated; one Co(III) atom is bonded to a phosphorous atom of triphenylphosphine, four nitrogen atoms of two planar ligands, dmg^2? and dmgH^?, and one oxygen atom of another dmg^2? ligand. The other Co(III) atom is coordinated by four nitrogen atoms of two cis nonplanar ligands, dmg^2?, dmgH^?, and two oxygen atoms of the other dmg^2? and dmgH^? ligands. There are three N-O bridged ligands namely two dmg^2? and one dmgH^? between two Co(III) atoms. A free molecule of dmgH₂ and a molecule of CH₃OH are also found in the crystal lattice. The structure interestingly demonstrates the possible various forms of dmg, not only on their charge but also in different conformations upon coordination.     

Influence of the Organic Species and Oxoanion in the Synthesis of two Uranyl Sulfate Hydrates, (H3O)2[(UO2)2(SO4)3­(H2O)]·7H2O and (H3O)2[(UO2)2(SO4)3(H2O)]·4H2O,and a Uranyl Selenate‐Selenite [C5H6N][(UO2)(SeO4)(HSeO3)]

Two uranyl sulfate hydrates, (H₃O)₂[(UO₂)₂(SO₄)₃(H₂O)] · 7H₂O (NDUS) and (H₃O)₂[(UO₂)₂(SO₄)₃(H₂O)] · 4H₂O (NDUS1), and one uranyl selenate‐selenite [C₅H₆N][(UO₂)(SeO₄)(HSeO₃)] (NDUSe), were obtained and their crystal structures solved. NDUS and NDUSe result from reactions in highly acidic media in the presence of L ‐cystine at 373 K. NDUS crystallized in a closed vial at 278 K after 5 days and NDUSe in an open beaker at 278 K after 2 weeks. NDUS1 was synthesized from aqueous solution at room temperature over the course of a month. NDUS, NDUS1, and NDUSe crystallize in the monoclinic space group P2₁/n, a = 15.0249(4) Å,b = 9.9320(2) Å, c = 15.6518(4) Å, β = 112.778(1)°, V = 2153.52(9) ų,Z = 4, the tetragonal space group P4₃2₁2, a = 10.6111(2) Å,c = 31.644(1) Å, V = 3563.0(2) ų, Z = 8, and in the monoclinic space group P2₁/n, a = 8.993(3) Å, b = 13.399(5) Å, c = 10.640(4) Å,β = 108.230(4)°, V = 1217.7(8) ų, Z = 4, respectively.The structural units of NDUS and NDUS1 are two‐dimensional uranyl sulfate sheets with a U/S ratio of 2/3. The structural unit of NDUSe is a two‐dimensional uranyl selenate‐selenite sheets with a U/Se ratio of 1/2. In‐situ reaction of the L ‐cystine ligands gives two distinct products for the different acids used here. Where sulfuric acid is used, only H₃O⁺ cations are located in the interlayer space, where they balance the charge of the sheets, whereas where selenic acid is used, interlayer C₅H₆N⁺ cations result from the cyclization of the carboxyl groups of L ‐cystine, balancing the charge of the sheets.     

Adipato‐Bridged Mixed Ligand catena Complexes: ${_{\infty}^1}${[M(phen)(H2O)]L2/2} with M = NiII,CuII, ZnII; H2L = Adipic Acid

Three adipato bridged mixed ligand catena complexes {[M(phen)(H₂O)]‐(C₆H₈O₄)_2/2} with M = Ni^II ( 1 ), Cu^II ( 2 ), Zn^II ( 3 ) were synthesized. Structure determination based on X‐ray diffraction shows that they crystallize isostructurally in the monoclinic space group C2/c (no. 15) with cell dimensions of: 1 a = 22.451(4)Å, b = 9.041(1)Å, c = 17.440(2)Å, β = 103.41(1)°, U = 3443.4(9)ų, Z = 8; 2 a = 22.479(2)Å, b = 9.067(1)Å, c = 17.494(3)Å, β = 103.67(1)°, U = 3464.6(8)ų, Z = 8; 3 a = 22.635(3)Å, b = 9.052(1)Å, c = 17.571(3)Å, β = 103.24(1)°, U = 3504.5(9)ų, Z = 8. The crystal structure consists of 1D {[M(phen)(H₂O)]‐(C₆H₈O₄)_2/2} zigzag chains, in which the metal atoms are all octahedrally coordinated by two N atoms of one phen ligands and four O atoms of one H₂O molecule and two adipato ligands. The zigzag chains are held together by interchain π‐π stacking interactions and interchain hydrogen bonds.     

Hydrothermal Preparation,Crystal Structure and Properties of {[ZnTCPP(EtOH)][Zn(en)]2}n(EtOH)2n with a Novel Two‐Dimensional (2‐D) Motif

A novel zinc porphyrin, {[ZnTCPP(EtOH)][Zn(en)]₂}_n(EtOH)_2n ( 1 ) (TCPP=meso‐tetra(4‐carboxyphenyl)‐porphyrin; EtOH=ethanol; en=ethylenediamine) was obtained via a hydrothermal reaction and characterized by single‐crystal X‐ray diffraction. Complex 1 crystallizes in the space group C2/c of the monoclinic system with eight formula units in a cell: a=32.465(4) Å, b=10.527(3) Å, c=31.845(3) Å, β=95.524(6) °, V=10832(4) ų, C₅₈H₅₇N₈O₁₁Zn₃, M_r=1238.23, D_c=1.518 g/cm³, S=1.005, µ(Mo Kα) =1.388 mm^?1, F(000) =5112, R=0.0650 and wR=0.1574. Complex 1 features a novel 2‐D layered motif. The spectral data of UV‐vis, FT‐IR and fluorescence are reported.     

The crystal and molecular structure of 5,5-diphenyloctafluorogermanthrene, (C6H5)2GeC12F8

F---F steric interaction between the two 6,6′-fluorines of the C₆F₄ rings in C₁₂F₈Ge(C₆H₅)₂ cause quite distortions in the molecule as these two fluorine atoms are forced to within 2.419 Å of each other (Van der Waals distance ⋍ 2.7 Å). Crystal data: C₁₂F₈Ge(C₆H₅)₂, M_r 522.89, C2/c, a 29.065(2), b 8.066(2), c 23.000(3) Å, β 129.85°, U 4139.63 ų, Z = 8, D_x 1.678 Mg m⁻³, Mo-K_α, λ 0.7107 Å, μ 15.58 cm⁻¹, F(000) = 2064, T 293 K, R = 0.044 for 2264 reflections with I > 3σ(I); Δϱ ± 0.5 e⁻     

The synthesis and crystal structure of α-perthionaphthoatopyridinecopper(I) dimer Cu2(α-C10H7CSS2)2(Py)2

The title compound has been synthesized by the reaction of α-dithionaphthoic acid with CuCl₂ in pyridine or by recrystallizing Cu₄(α-C₁₀H₇CSS₂)₄ ? 1/2CS₂ in a mixture of pyridine and alcohol. The structure of the title compound is determined by a single-crystal X-ray diffraction analysis. The crystal belongs to triclinic space group with unit cell parameters: a=7.085(2)Å, b= 8.672(3)Å and c=13.598(5)Å; a=92.40(3)°, β=102.59(4)° and γ=105.67(4)°; V=780.6Ų; Z=1. The structure was refined to R=0.058 for 2390 reflections. The molecule of the title compound sits on a center of symmetry. The shorter Cu—Cu bond length (2.606Å) shows considerable interaction between copper atoms. If the Cu—Cu interaction is ignored, the neighbouring S and N atoms are coordinated to copper atom in a configuration of distorted tetrahedron.     

Synthesis and structure of the cluster μ3-sulfido-μ-–(diethylphosphorodithioato-S,S'-)-allylthioureocyclo-tris-[ (μ-sulfido)-χ-(diethylphosphorodithioato-S,S')-molybdenum(IV)], Mo3S4(C4H10O2S2P)4(C4H8N2S)

Title compound, M_r =1273.16, was synthesized by a substitution reaction and its crystal is triclinic belonging to space group P1 with cell parameters: a =13.944(2), b =14.143(7), c =14.233(3) Å, α =77.35(3)°, β =69.94(2)°, γ =63.50(3)°, V=2351(1) ų, Z=2, D_c =1.799g cm^?2. Room temperature, graphite-filtered Mo K_α radiation (λ =0.71073Å) was used for data collection. μ =14.988 cm^?1, F(000) =1280, R=0.051 for 7025 observed reflections. The crystal consists of decrete cluster molecules containing a cluster core [Mo₂(μ₃-S)]¹⁰⁺ with three μ-S, one μ-dtp(dtp =[S₂P(OC₂H₅)]^2-), three χ-dtp and one allylthioureo to form a local six-coordinated sphere around each Mo atom. The bonds of cluster skeleton [Mo₃(μ₃-S)(μ-S)₃]⁴⁺, Mo? Mo 2.744～2.766, Mo—(μ₂-S) 2.340～2.342 and Mo—(μ-S)2.272～2.296 Å, are comparable with those found in the related analogues.     

STRUCTURE and CONFORMATION OF PHOTOSYNTHETIC PIGMENTS and RELATED COMPOUNDS. 2. NICKEL (II) METHYL PYROPHEOPHORBIDE a–A SEVERELY ISTORTED CHLOROPHYLL DERIVATIVE*

The crystal structure of Ni(II) methyl pryopheophorbide a (3) (C_MH₃₄N₄Ni0₃, M_u= 605.4) was determined by x-ray diffraction methods in order to determine the influence of the nickel-ion on the ring conformation. The crystals were blue octahedrons and crystallized in the tetragonal space group P4₁2₁,2 with a= 14.727(4) Å, c = 26.666(12) Å, V= 5781(3) ųZ= 8, D= 1.391 mg/m³. (Mo Kα) = 0.71069 Åμ= 0.713 mm^?1, F(000) = 2544, 130 K. The final R value was 0.064 for 4096 observed reflections, wR = 0.065. The molecule is severely distorted and shows a saddle-shaped ring conformation, the β-pyrrole atoms being displaced up to 0.6 A out of the plane of the nitrogens. The severe deformation restricts the use of Ni-derivatives in spectroscopic model studies on chlorophylls and provides an example for the conformational flexibility of the phorbin macrocycle.