The chemistry of copper(I) β-diketonate compounds. Part V. Syntheses and characterization of (β-diketonate)CuLn species where L = PBu3, PPh3, and PCy3; n = 1 and 2; crystal and molecular structures of (acac)Cu(PCy3), (tfac)Cu(PCy3), (hfac)Cu(PCy3), and (hfac)Cu(PCy3)2

1992 ◽  
Vol 70 (12) ◽  
pp. 2954-2966 ◽  
Author(s):  
H.-K. Shin ◽  
M. J. Hampden-Smith ◽  
E. N. Duesler ◽  
T. T. Kodas
Keyword(s):  
Solid State ◽  
Molecular Structures ◽  
Lewis Acidity ◽  
High Yield ◽  
Monoclinic Crystal System ◽  
X Ray Diffraction ◽  
Monoclinic Crystal ◽  
Space Group ◽  
Crystal System ◽  
Copper Coordination

The compounds (β-diketonate)Cu(PR3)n, where β-diketonate = 1,1,1,5,5,5-hexafluoroacetylacetonate, hfac; 1,1,1-trifluoroacetylacetonate, tfac; and acetylacetonate, acac; R = n-butyl (n-Bu), phenyl (Ph), and cyclohexyl (Cy); n = 1 and 2, have been prepared. The monotriorganophosphine adducts were prepared in high yield by the reaction of the sodium salt of the corresponding β-diketonate with [ClCu(PR3)] with elimination of sodium chloride. The bis(triorganophosphine) adducts were prepared by the reaction of (β-diketonate)Cu(PR3) with one equivalent of triorganophosphine. These species were characterized by 1H, 13C, and 31P NMR spectroscopy, FTIR spectroscopy, mass spectroscopy, and by combustion elemental analysis. Four examples were structurally characterized by single crystal X-ray diffraction in the solid state. (acac)CuPCy3 crystallizes in the triclinic crystal system, space group [Formula: see text], where a = 13.502(6) Ǻ, b = 13.691(6) Ǻ, c = 5.781(6) Ǻ, α = 71.05(3)°, β = 67.50(3)°, γ = 64.81(3)°, Z = 4, and R = 5.42%. (tfac)CuPCy3 crystallizes in the monoclinic crystal system, space group P21/n, where a = 9.639(3) Ǻ, b = 22.717(7) Ǻ, c = 12.045(5) Ǻ, β = 111.67(3)°, Z = 4, and R = 7.22%. (hfac)CuPCy3 crystallizes in the monoclinic crystal system, space group P21/c, where a = 9.870(2) Ǻ, b = 17.314(4) Ǻ, c = 15.586(3) Ǻ, β = 99.74(2)°, Z = 4, and R = 5.29%. (hfac)Cu(PCy3)2 crystallizes in the monoclinic crystal system, space group P21/n, where a = 13.645(6) Ǻ, b = 19.252(13) Ǻ, c = 16.875(9) Ǻ, β = 102.02(4)°, Z = 4, and R = 7.20%. The compounds (β-diketonate)Cu(PCy3) are all monomeric in the solid state and possess approximately trigonal-planar copper coordination environments, although (tfac)Cu(PCy3) is significantly distorted from trigonal geometry. The Cu—O bond distances are significantly different in this species. The compound (hfac)Cu(PCy3)2 is monomeric in the solid state and possesses a distorted tetrahedral copper coordination environment. The distortion is believed to be due to the large steric demands of the PCy3 ligands that result in long Cu—P bond distances of 2.251(3) and 2.277(3) Ǻ, a large P—Cu—P angle of 141.3(1)°, long Cu—O distances of 2.213(5) and 2.251(5) Ǻ, and a small O—Cu—O angle of 80.8(2)° compared to the corresponding values for (hfac)Cu(PCy3). No trends in Cu—O bond distances between the compounds can be discerned, within the limits of error on the data, that would clearly enable a comparison of thermodynamic parameters such as bond length – bond strength relationships as a function of the β-diketonate substituents. However, the spectroscopic data revealed a number of trends as a function of the β-diketonate substituents, including an increase of ν(C=O and ν(C=C) in the order acac < tfac < hfac, analogous to the increase in their Lewis acidity. An increase in shielding of the 31P resonance of the triorganophosphine ligands was observed in the order hfac < tfac < acac, consistent with expected inductive effects based on the electronegativity of the β-diketonate substituents.

scholarly journals Solid state and solution structural investigation of homoleptic tin(IV) alkoxide compounds. Part I. Sn(O—t-Bu)4 and [Sn(O—i-Pr)4•HO—i-Pr]2

1991 ◽  
Vol 69 (1) ◽  
pp. 121-129 ◽  
Author(s):  
Mark J. Hampden-Smith ◽  
Teresa A. Wark ◽  
Arnold Rheingold ◽  
John C. Huffman
Keyword(s):  
Solid State ◽  
Variable Temperature ◽  
Equilibrium Concentration ◽  
Molecular Structures ◽  
Monoclinic Crystal System ◽  
Monoclinic Crystal ◽  
Space Group ◽  
Crystal System ◽  
Reversible Dissociation ◽  
C Nmr

The crystal and molecular structures of Sn(O—t-Bu)4• and [Sn(O—i-Pr)4•HO—i-Pr]2 have been determined by single-crystal X-ray diffraction. Sn(O—t-Bu)4 crystallizes in the monoclinic crystal system with space group C2/c, where a = 17.382(6) Å, b = 8.742(2) Å, c = 15.518(5) Å, β = 116.44(1)°, Z = 4, and R = 2.5%. Sn(O—t-Bu)4 is monomeric in the solid state, with a distorted tetrahedral tin coordination environment. [Sn(O—i-Pr)4•HO—i-Pr]2 crystallizes in the monoclinic crystal system with space group P21/n, where a = 11.808(3) Å, b = 14.356(3) Å, c = 12.380(2) Å, β = 95.27(2)°, Z = 2, and R = 4.9%. [Sn(O—i-Pr)4•HO—i-Pr]2 exhibits an edge-shared, bi-octahedral structure in the solid state that is distorted due to the presence of asymmetric hydrogen bonding between axially coordinated alcohol ligands and an isopropoxide ligand.13C NMR and IR spectroscopic data have been recorded for Sn(O—t-Bu)4 and Sn(O—t-Bu-d9)4 to establish criteria for unambiguous identification of solution structures of tin(IV) alkoxides. It is demonstrated that the two-bond [Formula: see text] coupling constant is larger for terminal alkoxide ligands than for μ2-alkoxide bridges, and the ν(Sn—O) stretching frequency has been assigned. The dynamic solution behaviour of [Sn(O—i-Pr)4•HO—i-Pr]2 has been studied using variable temperature 1H and 13C NMR spectroscopy. The data obtained are consistent with a process that involves rapid reversible dissociation of isopropanol at room temperature. Upon cooling, the equilibrium concentration of the species with coordinated alcohol increases, and the molecule undergoes rapid intramolecular proton transfer (AG≠ < 11.9 kcalmol−1). Upon further cooling, the 13C NMR data are consistent with a solution structure analogous to that found in the solid state. Key words: tin, alkoxide, NMR, dynamic, structure.

Synthesis and Structural Characterization of N,N´- Dipropyl-N,N,N´,N´-tetramethyl-1,2- ethylenediammonium Dichloride and Dibromide

2011 ◽  
Vol 66 (7) ◽  
pp. 755-758
Author(s):  
Sari M. Närhi ◽  
Janne Asikkala ◽  
Jatta Kostamo ◽  
Marja K. Lajunen ◽  
Raija Oilunkaniemi ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Water Molecules ◽  
Monoclinic Crystal System ◽  
X Ray Diffraction ◽  
Monoclinic Crystal ◽  
Triclinic Crystal System ◽  
Space Group ◽  
X Ray ◽  
Crystal System

N,N´-Dipropyl-N,N,N´ ,N´-tetramethyl-1,2-ethylenediammonium dichloride (1) and dibromide (2) were prepared by the reaction of N,N,N´,N´-tetramethyl-1,2-ethylenediamine and the corresponding 1-halopropane. The structures of the compounds were characterized by single-crystal X-ray diffraction. 1 · 2H2O crystallizes in the triclinic crystal system, space group P1, with Z = 1, and 2 in the monoclinic crystal system, space group P21/c, with Z = 2. The crystal structures of the salts consist of discrete dications and halide anions. The packing in 1 · 2H2O consists of layers of cations with the chloride anions and water molecules forming hydrogen-bonded chains between the cation layers. In 2, the strongest H· · ·Br hydrogen bonds of 2.8138(6) and 2.8187(7) °A link the cations and anions into doublestranded chains. In both salts, cations and anions are also linked together by a further weak C-H· · ·Cl/Br hydrogen bonding network.

scholarly journals Synthesis And Structural Characterization Of 1-Butyl-2,3-Dimethylimidazolium Bromide And Iodide

2007 ◽  
Vol 62 (6) ◽  
pp. 868-870 ◽  
Author(s):  
Johanna Kutuniva ◽  
Raija Oilunkaniemi ◽  
Risto S. Laitinen ◽  
Janne Asikkala ◽  
Johanna Kärkkäinen ◽  
...  
Keyword(s):  
Unit Cell ◽  
Monoclinic Crystal System ◽  
Monoclinic Crystal ◽  
Space Group ◽  
X Ray ◽  
Crystal System ◽  
H Nmr ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

1-Butyl-2,3-dimethylimidazolium bromide {(bdmim)Br} (1) and iodide {(bdmim)I} (2) were prepared conveniently by the reaction of 1,2-dimethylimidazole and the corresponding 1-halobutane. The compounds were characterized by 1H and 13C{1H} NMR spectroscopy as well as by X-ray single crystal crystallography. 1 crystallizes in the monoclinic crystal system, space group P21/n, with Z = 4, and unit cell dimensions a = 8.588(2), b = 11.789(1), c = 10.737(2) Å, β = 91.62(3)°. Compound 2 crystallizes in the monoclinic crystal system, space group P21/c, with Z = 8, and unit cell dimensions a = 10.821(2), b = 14.221(3), c = 15.079(2) Å , β = 90.01(3)°. The lattices of the salts are built up of 1-butyl-2,3- dimethylimidazolium cations and halide anions. The cations of 1 form a double layer with the imidazolium rings stacked together due to π interactions. The Br− anions lie approximately in the plane of the imidazolium ring, and the closest interionic Br···H contacts span a range of 2.733(1) - 2.903(1) Å. Compound 2 shows no π stacking interactions. The closest interionic I···H contacts are 2.914(1) - 3.196(1) Å

Reaktionen von Zintl-Phasen mit Trimethylphosphinkomplexen Strukturen mit ebenem Vierring Co2X2 (X = S, Se, Te) / Reactions of Zintl-Phases with Trimethylphosphine Complexes Structures Containing Planar Metallocycles Co2X2 (X = S. Se. Te)

1988 ◽  
Vol 43 (7) ◽  
pp. 830-838 ◽  
Author(s):  
Hans-Friedrich Klein ◽  
Michael Gaß ◽  
Udo Koch ◽  
Brigitte Eisenmann ◽  
Herbert Schäfer
Keyword(s):  
Phosphine Ligands ◽  
Molecular Structures ◽  
High Yield ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Zintl Phases ◽  
Triclinic Space Group ◽  
Space Group ◽  
Cobalt Compounds ◽  
Derivatives Of

Low-valent trimethylphosphine cobalt compounds are oxidized by tellurium, selenium, or sulfur to give the title compounds. Several high-yield syntheses are described. The crystal and molecular structures of (Me3P)3CoX3Co(PMe3)3 (1: X = Te. 2: X = Se. 3: X = S) have been determined by single crystal X-ray diffraction. Complex 1 crystallizes in the monoclinic space group P21/n; a = 933.8(6) pm. b = 1488.3(6) pm. c = 1257.9(6) pm. β = 92.82(6)°. Z = 2. Complex 2 crystallizes in the triclinic space group P1, a = 1785.6(7) pm. b = 1599.7(7) pm. c = 928.9(5) pm. α = 87.8(1)°. β = 85.2(1)°. γ = 73.3(1)°. Z = 3. Complex 3 crystallizes in the monoclinic space group P21/c; a = 952.6(5) pm. b = 1868.7(8) pm. c - 1893.1(8) pm. β = 90.19(6)°. Z = 4. All three structures contain centrosymmetric molecules with planar Co2X2 rings. In solution dissociation of phosphine ligands occurs followed by slow decomposition to produce [(Me3P)2Co(PMe2)]2 among other products. 1 reacts with carbon monoxide to afford a ditelluride [(Me3P)2(CO)2Co]2Te2. but no corresponding derivatives of 2 or 3 were obtained.

Crystal and Molecular Structures of the Free Base and the Monohydrochloride Salt of the Antileukemic Agent Glyoxal bis(Amidinohydrazone) [`Glyoxal bis(Guanylhydrazone)’]

1993 ◽  
Vol 48 (12) ◽  
pp. 1821-1827 ◽  
Author(s):  
Ilpo Mutikainen ◽  
Hannu Elo ◽  
Pirkko Tilus
Keyword(s):  
Solid State ◽  
Molecular Structures ◽  
Monoclinic Space Group ◽  
Free Base ◽  
X Ray Diffraction ◽  
Geometrical Isomers ◽  
Space Group ◽  
Crystal And Molecular Structures ◽  
Hydrogen Bond Networks ◽  
The Mean

The first study on the crystal and molecular structures of basic forms of bis(amidinohydrazones) is reported. The structures of the free base and the monohydrochloride salt of the antileukemic agent glyoxal bis(amidinohydrazone) (GBG) were determined by single crystal X-ray diffraction and were refined to R-values of 0.038 and 0.040, respectively. These structures are of special interest because recent results indicate that, in contrast to previous assumptions, the free base may be the actual antileukemic form of bis(amidinohydrazones) and that the monocation form is the predominant species of antileukemic bis(amidinohydrazones) at physiological conditions. In the crystals of the free base as well as in those of the monohydrochloride salt, GBG was found to exist solely in the all-trans configuration of the chain and to consist of one of the three possible geometrical isomers only. In the solid state, GBG free base consists solely of the endiamine tautomer instead of the 'classical’ carboximidamide tautomer, as does also the non-protonated part of GBG monocation in the monohydrochloride salt. Proton NMR measurements indicated that the free base consists of the endiamine tautomer also in dimethyl sulfoxide solution. In the solid state, both of the compounds studied consist of stacks of planes. In the case of the free base, the stacks are crisscross to each other. The distance between the mean planes of the molecules or the monocations is approximately 3.5 Å. The crystals of the monohydrochloride salt contain one molecule of water per each GBG monocation. In both compounds studied, the molecules in the crystals are held together by very extensive hydrogen bond networks and by the interaction of delocalized π-electrons. The crystal of C4H10N8 is monoclinic, space group C2/c with a = 15.874(6), b = 6.972(4), c = 7.8l3(5)Å, β = 90.34(4)° and Z = 4. The crystal of C4H13N8OC1 is monoclinic, space group P21/n with α = 7.010(3), b = 22.307(9), c = 7.028(3)Å, β = 66.33(3)° and Ζ = 4.

Crystal and Molecular Structures of the Functional Lithium Cyclopentadienides [Li(tmeda)][R2PCMe2C5H4], R = Ph, Me

2000 ◽  
Vol 55 (11) ◽  
pp. 1005-1010 ◽  
Author(s):  
Ulrich Jürgen Bildmann ◽  
Martin Winkler ◽  
Gerhard Müller Fachbereich
Keyword(s):  
Solid State ◽  
Functional Group ◽  
Molecular Structures ◽  
The Other ◽  
Monoclinic Space Group ◽  
Crystal Data ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Crystal And Molecular Structures

The crystal and molecular structures of the phosphinomethyl-substituted lithium cyclopentadienides [Li(tmeda)][R2PCMe2C5H4], R = Ph (1), Me (2) (tmeda = N,N,N',N'-tetramethylethylenediamine) were determined as their tmeda adducts on the basis of low temperature single crystal X-ray diffraction. (Crystal data: 1: monoclinic, space group P21/n, a = 8.511(5), b = 11.936(2), c = 24.20(1) Å, β = 90.02(3)°, Z = 4.2: monoclinic, space group P21/n, a = 10.887(2), b = 13.326(2), c = 13.131(2) Å, β= 92.872(6)°, Z = 4). In both compounds lithium has a slightly distorted 17 coordination to the cyclopentadienide (Cp) ring. There are no interactions between lithium and the phosphine donors in the solid state as the phosphinomethyl substituents are oriented to the other side of the Cp ring for steric reasons. The isopropene-substituted lithium cyclopentadienide, which is formed as a by-product in the synthesis of phosphinomethyl cyclopentadienides containing a CMe2 bridge, was also structurally characterized as its tmeda adduct [Li(tmeda)][H2C=CMeC5H4] (3). (Crystal data: monoclinic, P21/c, a = 8.00(2), b = 16.701(2), c = 11.942(6) Å, β= 112.68(7)°, Z = 4). As in 1 and 2, lithium is η5 -coordinated to the Cp ring, and there is no interaction of the functional group (isopropene) with lithium.

Unexpected beauty and diversity in the structures of three homologous 4,5-dialkoxy-1-ethynyl-2-nitrobenzenes: the subtle interplay between intermolecular C—H...O hydrogen bonds and alkyl chain length

2017 ◽  
Vol 73 (10) ◽  
pp. 814-819 ◽  
Author(s):  
Shalisa M. Oburn ◽  
Eric Bosch
Keyword(s):  
Nmr Spectra ◽  
Alkyl Chain ◽  
Alkyl Chain Length ◽  
Monoclinic Crystal System ◽  
Monoclinic Crystal ◽  
Triclinic Crystal System ◽  
Space Group ◽  
X Ray ◽  
Crystal System ◽  
C Nmr

The synthesis, 1H and 13C NMR spectra, and X-ray structures are described for three dialkoxy ethynylnitrobenzenes that differ only in the length of the alkoxy chain, namely 1-ethynyl-2-nitro-4,5-dipropoxybenzene, C14H17NO4, 1,2-dibutoxy-4-ethynyl-5-nitrobenzene, C16H21NO4, and 1-ethynyl-2-nitro-4,5-dipentoxybenzene, C18H25NO4. Despite the subtle changes in molecular structure, the crystal structures of the three compounds display great diversity. Thus, 1-ethynyl-2-nitro-4,5-dipropoxybenzene crystallizes in the trigonal crystal system in the space group R{\overline 3}, with Z = 18, 1,2-dibutoxy-4-ethynyl-5-nitrobenzene crystallizes in the monoclinic crystal system in the space group P21/c, with Z = 4, and 1-ethynyl-2-nitro-4,5-dipentoxybenzene crystallizes in the triclinic crystal system in the space group P{\overline 1}, with Z = 2. The crystal structure of 1-ethynyl-2-nitro-4,5-dipropoxybenzene is dominated by planar hexamers formed by a bifurcated alkoxy sp-C—H...O,O′ interaction, while the structure of the dibutoxy analogue is dominated by planar ribbons of molecules linked by a similar bifurcated alkoxy sp-C—H...O,O′ interaction. In contrast, the dipentoxy analogue forms ribbons of molecules alternately connected by a self-complementary sp-C—H...O2N interaction and a self-complementary sp 2-C—H...O2N interaction. Disordered solvent was included in the crystals of 1-ethynyl-2-nitro-4,5-dipropoxybenzene and its contribution was removed during refinement.

scholarly journals Synthesis and characterization of Ti(IV), Zr(IV) and Al(III) salen-based complexes

2021 ◽  
Vol 12 (2) ◽  
pp. 216-221
Author(s):  
Joana Hipolito ◽  
Luis Alves ◽  
Ana Martins
Keyword(s):  
Solid State ◽  
Molecular Structures ◽  
Monoclinic Space Group ◽  
Crystal Data ◽  
X Ray Diffraction ◽  
Tetrahedral Geometry ◽  
Triclinic Space Group ◽  
Space Group ◽  
High Yields

New Ti(IV), Zr(IV) and Al(III) salen-based complexes of formulae [(L)TiCl2], 2, [(L)ZrCl2], 3, and [(L){Al(CH2CH(CH3)2)2}2], 4, where L = meso-(R,S)-diphenylethylene-salen, were synthesized in high yields. [(L){Al(CH2CH(CH3)2)2}2] is a bimetallic complex that results from the reaction of H2L with either 1 or 2 equivalent of Al(CH2CH(CH3)2)3. The solid-state molecular structures of compounds 2 and 4·(C7H8) were obtained by single-crystal X-ray diffraction. Crystal data for C44H54Cl2N2O2Ti, (2a): monoclinic, space group C2/c (no. 15), a = 27.384(1) Å, b = 12.1436(8) Å, c = 28.773(2) Å, β = 112.644(2)°, V = 8830.6(9) Å3, Z = 8, μ(MoKα) = 0.350 mm-1, Dcalc = 1.146 g/cm3, 26647 reflections measured (5.204° ≤ 2Θ ≤ 50.7°), 8072 unique (Rint = 0.0967, Rsigma = 0.1241) which were used in all calculations. The final R1 was 0.0640 (I > 2σ(I)) and wR2 was 0.1907 (all data). Crystal data for C62H72Cl2N2O2Ti (2b): monoclinic, space group P21/c (no. 14), a = 19.606(1) Å, b = 12.793(1) Å, c = 23.189(2) Å, β = 105.710(4)°, V = 5599.0(7) Å3, Z = 4, μ(MoKα) = 0.291 mm-1, Dcalc = 1.182 g/cm3, 37593 reflections measured (3.65° ≤ 2Θ ≤ 50.928°), 10304 unique (Rint = 0.0866, Rsigma = 0.1032) which were used in all calculations. The final R1 was 0.0593 (I > 2σ(I)) and wR2 was 0.1501 (all data). Crystal data for C67H97Al2N2O2 (4·(C7H8)): triclinic, space group P-1 (no. 2), a = 10.0619(9) Å, b = 16.612(2) Å, c = 21.308(2) Å, α = 67.193(5)°, β = 78.157(6)°, γ = 77.576(5)°, V = 3176.8(6) Å3, Z = 2, μ(MoKα) = 0.088 mm-1, Dcalc = 1.063 g/cm3, 42107 reflections measured (5.382° ≤ 2Θ ≤ 51.624°), 12111 unique (Rint = 0.0624, Rsigma = 0.0706) which were used in all calculations. The final R1 was 0.0568 (I > 2σ(I)) and wR2 was 0.1611 (all data). The solid-state molecular structure of [(L){Al(CH2CH(CH3)2)2}2] reveals that both metal centres display a slightly distorted tetrahedral geometry bridged by the salen ligand. Both [(L)TiCl2] and [(L)ZrCl2] complexes display octahedral geometry with trans-chlorido ligands.

scholarly journals Synthesis and Catalytic Application of Two Mononuclear Complexes Bearing Diethylenetriamine Derivative Ligand

Molecules ◽  
2020 ◽  
Vol 25 (9) ◽  
pp. 2101
Author(s):  
Chao Liu ◽  
Zhao Yang ◽  
Hao Guo ◽  
Yu-Cai Zhao
Keyword(s):  
Catalytic Mechanism ◽  
Aromatic Aldehydes ◽  
Monoclinic Crystal System ◽  
Henry Reaction ◽  
Monoclinic Crystal ◽  
Space Group ◽  
Crystal System ◽  
Catalytic Application ◽  
Composition And Structure ◽  
Elemental Analyses

Two mononuclear zero-dimensional Ni(II) and Zn(II) complexes bearing diethylenetriamine derivative ligand, namely [NiL(CH3COO)2(H2O)] (1) and [ZnL(CH3COO)2] (2) [L = N, N’-bis(2-hydroxybenzyl)diethylenetriamine], were synthesized under reflux conditions. The molecular composition and structure of the complexes were identified by IR, PXRD, elemental analyses, and single crystal X-ray diffraction. Complex 1 belongs to a monoclinic crystal system with the P21/n space group, and Complex 2 belongs to a monoclinic crystal system with the C2/c space group. The Henry reaction of nitromethane with aromatic aldehydes was explored with Complexes 1 and 2 as the catalyst. Results from the catalytic reaction revealed that the complexes displayed excellent catalytic activities under the optimized conditions and that the substrate scope of aromatic aldehydes could be extended to a certain extent. In addition, the possible catalytic mechanism of the Henry reaction was also deduced.

Crystal structure determination of the conformation of two bicyclo[3.3.1]nonan-ones

1985 ◽  
Vol 63 (6) ◽  
pp. 1166-1169 ◽  
Author(s):  
John F. Richardson ◽  
Ted S. Sorensen
Keyword(s):  
Crystal Structure ◽  
Direct Methods ◽  
Chair Conformation ◽  
Molecular Structures ◽  
Boat Conformation ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Final Agreement

The molecular structures of exo-7-methylbicyclo[3.3.1]nonan-3-one, 3, and the endo-7-methyl isomer, 4, have been determined using X-ray-diffraction techniques. Compound 3 crystallizes in the space group [Formula: see text] with a = 15.115(1), c = 7.677(2) Å, and Z = 8 while 4 crystallizes in the space group P21 with a = 6.446(1), b = 7.831(1), c = 8.414(2) Å, β = 94.42(2)°, and Z = 2. The structures were solved by direct methods and refined to final agreement factors of R = 0.041 and R = 0.034 for 3 and 4 respectively. Compound 3 exists in a chair–chair conformation and there is no significant flattening of the chair rings. However, in 4, the non-ketone ring is forced into a boat conformation. These results are significant in interpreting what conformations may be present in the related sp2-hybridized carbocations.

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