X-ray structural and molecular mechanics investigation of cyclopentadienyl-carbonyl-triphenylophosphine-phenylacetyliron, (η5-C5H5)Fe(CO)(PPh3)(COCH2C6H5)

The crystal and molecular structure of cyclopentadienyl-carbonyl-triphenylphosphine-phenylacetyl-iron (1) has been determined on the basis of X-ray data. The crystals are triclinic, space groupP¯1 (Z=2) with cell dimensions:a=9.546(1),b=10.233(1),c=5.012(2) Å,=93.70(1),=101.12(1), =112.58(1)°. The structure was solved by direct methods and refined anisotropically by a full-matrix, least-squares procedure against 4964 independent reflections, givingR=0.0416. The MM calculations done for a model of1 reproduced satisfactorily the X-ray structure.On leave from the Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China.     

Synthesis, characterization, and single crystal X-ray diffraction studies of cis-Ph2C2H2(η5-C5H4)2Ca(THF)2

cis-[(1,2-diphenyl-1,2-dicyclopentadienyl)ethanediyl]bis(tetrahydrofuran)calcium is prepared by reductively coupling phenylfulvene with activated calcium to produce cis and trans isomers which can be separately crystallized. The cis isomer crystallizes in the monoclinic space group P2₁/c. The cell parameters are: a = 9.7006(1), b = 18.9839(1), c = 14.2018(2) Å, = 91.263(1)°, V = 2614.70(5) ų, D _calc = 1.252 mg/m³, and Z = 4. Spectroscopic and crystallographic data for the cis-isomer are presented and discussed.     

Synthesis,spectroscopic studies,and X-ray crystallographic analysis of the organophosphorus carbohydrate: methyl 4,6-O-benzylidene-3-deoxy-3-C-diphenylphosphinyl-α-D-altropyranoside

The synthesis and molecular structure determination of an organophosphorus carbohydrate are reported. In the solid state the molecules of methyl 4,6-O-benzylidene-3-deoxy-3-C-diphenyl-phosphinyl--D-altropyranoside are linked together by intermolecular hydrogen bonding involving the oxygen attached to phosphorus and the hydroxy group. The five-valent phosphorus atom is in a distorted tetrahedral environment. The chiral molecules crystallize in the monoclinic space groupP2₁ withZ+2. Results from¹ H.¹³C and³¹P NMR investigations together with IR data are presented.     

X-ray structural and molecular mechanics investigations of cyclopentadienyl-carbonyl-triphenylphosphine-methoxyacetyl-iron (η5-C5H5)Fe(CO)(PPh3)(COCH2OMe)

The crystal and molecular structure of cyclopentadienyl-carbonyl-triphenylphosphine-methoxy-acetyl-iron (2) has been determined by X-ray. The crystals are monoclinic:P2₁/n,Z=4,=7.881(1),b=19.111(3),c=15.271(2) Å and=93.44(1)°. The structure was solved by direct methods, and refined anisotropically by full-matrix least-squares against 3419 independent reflections, givingR=0.0446. Molecular mechanics calculations reproduce satisfactorily the X-ray structure.On leave from the Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China.     

X-ray diffraction studies of 6-methyl-5-acetyl-4-α-furyl-2-keto-1,2,3,6-tetrahydropyrimidine and 6-methyl-5-acetyl-4-γ-bromophenyl-2-thio-1,2,3,6-tetrahydropyrimidine

6-Methyl-5-acetyl-4-α-furyl-2-keto-1,2,3,6-tetrahydropyrimidine (I) and 6-methyl-5-acetyl-4-γ-bromophenyl-2-thio-1,2,3,6-tetrahydropyrimidine (II) are prepared by the modified Biginelli reaction, and their crystal and molecular structures are studied. It is shown that, in crystals I and II, the pyrimidine ring has an amide tautomeric form and adopts a sofa conformation. The IR absorption spectra are analyzed, and the stability of the tautomers of the pyrimidine fragments is evaluated using quantum-chemical calculations.     

Synthesis and molecular structure of the organometallic zwitterion (η5-C5H3MeBCl3)Fe(CO)3: evidence for alternative sites of nucleophilicity within the [(η5-C5R5)Fe(CO)2 − anion

The organometallic zwitterion (⁵-C₅H₃MeBCl₃)Fe(CO)₃ (2) is isolated as a minor product from the reaction between the sodium salt of the anion [(⁵-C₅H₄Me)Fe(CO)₂]^– and boron trichloride. The crystal structure of 2 [P2₁/n, a = 7.3927(5) Å, b = 13.8027(9) Å, c = 12.2759(9) Å, = = 90°, = 92.517(3)°] features discrete molecules in which the coordination sphere of the iron center comprises three carbonyls and a novel ( ⁵-C₅H₃MeBCl₃) ligand, derived from attack of BCl₃ on the ( ⁵-C₅H₄Me) moiety of the parent compound. The isolation of 2 confirms that the nucleophilic properties of organometallic anions of the type [( ⁵-C₅R₅)M(CO) _n ]^– (M = Fe, Ru, n = 2; M = Mo, W, n = 3) are not confined to the metal center, or to the carbonyl oxygens (examples of which have previously been reported) but also encompass the cyclopentadienyl ligand.     

Synthesis and crystal structure of a dinuclear organometallic phosphonium ylid complex, [(η5-C5H5(CO)C2(ε-CO)(ε-CHP(C6H5)3)+][PF – 6 ]

The title compound crystallizes in the centrosymmetric monoclinic space group P2₁/n withZ=4. The cation consists of two (⁵-C⁵h⁵)Fe(CO) units which are linked via a metal-metal bond (Fe(1)–Fe(2)=2.530(1) Å), a bridging carbonyl ligand (Fe(1)–C(4)=1.912(8) Å. Fe(2)–C(4)=1.940(9) Å) and a bridging phosphonium ylid ligand (Fe(1)–C(1)=1.991(6) Å, Fe(2)–C(1)=1.985(6) Å and C(1)–P(1)=1.781(6) Å).     

Synthesis and crystal structure of (η5-C5H5)2Ti(NH(2,4-(C$${\equiv}$$CSiMe3)2C6H3))2

The crystal structure of the bis-amido complex of Ti(IV) (η⁵-C₅H₅)₂Ti(NH(2,4-(C CSiMe₃)₂C₆H₃))₂ is reported. This complex was prepared in 52% yield from the reaction of (η⁵-C₅H₅)₂TiCl₂ with two equivalents of LiNH(2,4-(C CSiMe₃)₂C₆H₃) (prepared in situ in THF at −78^∘C). The substituted aniline H₂N(2,4-(C CSiMe₃)₂C₆H₃) was prepared in 70% yield from the reaction of 2,4-dibromoaniline with Me₃SiC CH using conventional Pd/Cu coupling methodology. The molecular structure of (η⁵-C₅H₅)₂Ti(NH(2,4-(C CSiMe₃)₂C₆H₃))₂ (monoclinic, space group C2/c, Z = 4, a = 29.7523(5) Å, b = 9.5339(2) Å, c = 15.8864(3) Å, β = 93.022(1)^∘ features a titanium (IV) center with a distorted tetrahedral geometry which lies on a crystallographic twofold axis. The amido units are arranged so that steric interactions are minimized. The Ti– N distance is 2.016(2) Å.     

Studies on the conformation of α-arylcinnamic acids and their esters: Crystal structures of methyl (E)-2,3-bis(3,4-dimethoxyphenyl)propenoate and methyl (Z)-2,3-bis(3,4-dimethoxyphenyl)propenoate

The conformations of stereoisomers of -arylcinnamic acids and their esters are discussed based on crystal structures of the E and Z forms of 2,3-bis(3,4-dimethoxyphenyl)propenoic acid and its methyl ester. In the E forms of the cinnamic acid and the cinnamic acid ester, the plane of the -aryl substituent is approximately perpendicular to that of the rest of the molecule. In the Z forms the plane of the carboxyl or methoxycarbonyl group is approximately perpendicular to that of the ethylenic group, and both the aromatic group planes are significantly twisted out of the ethylenic group plane. Crystal structures of methyl (E)-2,3-bis(3,4-dimethoxyphenyl)propenoate (space group P2₁/n with a = 8.1697(5), b = 11.3882(9), c = 19.7766(9) Å, = 90.058(4)°, V = 1840.0(2) ų, and Z = 4), monoclinic methyl (Z)-2,3-bis(3,4-dimethoxyphenyl)propenoate (space group P2₁/n with a = 11.183(2), b = 5.640(2), c = 29.737(7) Å, = 99.19(2)°, V = 1851.4(9) ų, and Z = 4), and orthorhombic methyl (Z)-2,3-bis(3,4-dimethoxyphenyl)propenoate (space group P2₁2₁2₁ with a = 8.849(4), b = 24.288(9), c = 8.734(3) Å, V = 1877(1) ų, and Z = 4) are reported.     

Regiospecific ligand addition to the donor–acceptor compound Ru2(CO)6(bpcd): syntheses and X-ray diffraction structures of Ru2(CO)5L(bpcd) and Ru2(CO)5L[μ-C=C(PPh2)C(O)CH2C}(O)](μ2-PPh2) (where L = PMe3 and tBuNC)

Thermal and Me₃NO-assisted activation of the donor–acceptor complex Ru₂(CO)₆(bpcd) (1) [where bpcd = 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione] with PMe₃ or ^tBuNC affords the mono-substituted complexes Ru₂(CO)₅L(bpcd), as a result of regiospecific ligand attack at the diphosphine-substituted ruthenium center. Solution NMR measurements (¹H and ³¹P) reveal that the PMe₃ derivative exists as a noninterconverting mixture of axial (3a) and equatorial (3e) isomers, with the only the equatorial isomer being observed for Ru₂(CO)₅(^tBuNC)(bpcd) (5). Near-UV irradiation of 1 in the presence of added ligand yields Ru₂(CO)₅L(bpcd), in addition to the known ₂-phosphido complex Ru²(CO)⁶ [-C=C(PPh₂)C(O)CH₂C(O)](₂-PPh₂) (2) and the corresponding phosphido-substituted complexes Ru²(CO)_5L[-{C =C(PPh₂)C(O)CH₂C}(O)]₂-PPh₂)[4 (L = PMe₃); 6 (L = ^tBuNC)]. As with compounds 3a, 3e, and 5, both 4 and 6 exhibit ligand attachment at the diphosphine-substituted ruthenium center. The molecular structures of 3e, 4, 5, and 6 were determined by X-ray crystallography. 3e, as the 1/2 C₆H₆ solvate, crystallizes in the monoclinic space group C2/c: a = 40.573(3) Å, b = 10.2663(9) Å, c = 18.347(1) Å, = 95.371(6)°, V = 7609(1) ų and Z = 8; 4, crystallizes in the monoclinic space group P2₁/n: a = 10.8241(8) Å, b = 18.074(1) Å, c = 19.194(1) Å, = 96.968(6)°, V = 3727.3(5) ų, and Z = 4; 5, as the 1/2CH₂Cl₂ solvate, crystallizes in the monoclinic space group C2/c: a = 40.955(3) Å, b = 9.7230(6) Å, c = 20.542(1) Å, = 106.596(5)°, V = 7839.2(9) ų, and Z = 8; 6, as the 1/2C₅H₁₂ solvate, crystallizes in the monoclinic space group P2₁/c: a = 21.773(2) Å, b = 10.907(3) Å, c = 18.744(4) Å, = 114.68(1)°, V = 4045(1) ų, and Z = 4. The site occupied by the PMe₃ and ^tBuNC ligands in these compounds is discussed relative to the steric size/electronic properties of the ancillary ligand and its interaction with the bpcd ligand.     

Assignment of relative configurations and conformational analysis of α-phenylacyliron complexes (η5-C5H5)Fe(CO)(PPh3)(COCHRPh). X-ray structural determinations of two complexes (η5-C5H5)Fe(CO) (PPh3)(COCHPhR), R=CHOHCH3 and R=COH(CH3)2

Conformational analysis of the alkylation and aldol condensation products of phenylacetyliron complex (4), based on¹H-NMR chemical shifts and¹H-¹H vicinal coupling constants, permitted the assignment of relative configurations to all products obtained. Configurations and conformations of two aldol condensation products,12A and13F, were determined by X-ray structural analysis and were compared with the structures deduced from¹H-NMR data. The crystals of12A and13F are monoclinic, space group of12A isP2₁/_n with cell dimensions:a=10.937(2),b=17.278(5),c=16.412(3)Å, andβ=107.52(2)°; space group of13F isP2₁/c, with cell dimensions:a=11.576(4),b=21.180(2),c=11.854(4)Å, andβ=99.80(3)°. Both structures were solved by direct methods, and refined by a full-matrix, least-squares procedure giving for12A R=0.0599 and for13F R=0.0459.     

X-ray and NMR structural investigations of (±) (u) N-(1-phenylethyl)-1-t-butylsulfinyl-1-propenyl-2-amine,C15H23NOS

The structure of the title compound has been investigated in the solid state and in solution by X-ray and NMR-NOE methods, respectively. The crystals are monoclinic:P2₁/c,a=9.828(1),b=12.326(2),c=13.976(2) Å,=107.36(1)°. The structure was solved by direct methods, and refined against 2495 unique reflections by a full-matrix, least-squares procedure givingR=0.046. In the solid state the compound exists as theE isomer with unlike relative configurations on asymmetric atoms. In solution the compound is found as a mixture of a single enamine and two imine forms. The MM calculations suggest that of the two possible geometrical isomers of both diastereoisomersu andl of the enamine, theZ forms should be of lower energy. The total recognition of the homonuclear¹H NMR-NOE data interpreted in terms of their distance dependence in the two geometrical forms also favors theZ isomer in both diastereomers.     

Anticancer agent development. 5. X-ray structure and1H nmr spectral analysis of (1α,2α,5α,6α)-2,6-bis(3,4-methylenedioxyphenyl)-3,7-dioxabicyclo[3.3.0]octane-4,8-dione

The title compound, C₂₀H₁₄O₈, Mr=382.3, crystallized from chloroform in the centric space group P¯1 witha=6.516(4),b=6.798(3),c=9.545(7) Å,=85.31(5),=73.87(5), =79.59(4)°,V=399.2 ų, and D_calc=1.59 g cm^–3 forZ=1. Least-squares refinement of 1035 observed [F_o5(F_o)] reflections led to the final agreement index ofR=0.074. The molecule resides on a crystallographic center of inversion and is disordered into two different conformations. This manifests itself as a 50/50 disorder at O(4), C(2), and C(3). The observed structure reveals acis relationship between the bridgehead hydrogen atoms and the aryl rings. The 90 MHz¹H nmr spectrum of the title compound exhibits an AAXX spin system with a H(1)C(2) to H(1)C(3) and H(1)C(2) to H(1)C(3) coupling constant of 2.8 Hz. Computer spectral simulation and Karplus equation analysis are utilized to illustrate a relaxation of the torsion angles between H(1)C(2) and H(1)C(3), and H(1)C(2) and H(1)C(3) is solution.     

Synthesis, redox chemistry, and X-ray structure of the mixed-metal cluster Fe2(CO)6(μ3-S)2Ni(dppf)

The reaction between the dianion [Fe₂(CO)₆(₂-S)₂]^2– and NiCl₂(dppf) occurs readily at room temperature to give the mixed-metal cluster Fe₂(CO)₆(₃-S)₂Ni(dppf) in moderate yield. Fe₂(CO)₆(₃-S)₂Ni(dppf) was isolated by preparative chromatography and its solid-state structure established by X-ray diffraction analysis. Fe₂(CO)₆(₃-S)₂Ni(dppf) crystallizes in the monoclinic space group C2/c, a = 20.320(6), b = 13.114(2), c = 15.622(2) Å, = 110.25(2)°, V = 3905.4(11) ų, Z = 4, and d _calc = 1.630 g/cm.³ The X-ray structure of Fe₂(CO)₆(₃-S)₂Ni(dppf) exhibits an Fe₂S₂Ni arachno polyhedral core, with the pendant dppf ligand attached to an essentially square planar Ni center. The redox chemistry of Fe₂(CO)₆(₃-S)₂Ni(dppf) was investigated by cyclic voltammetry which showed a reversible, one-electron oxidation localized on the Fe₂S₂ core along with an irreversible, one-electron reduction that is antibonding with respect to the Fe—Fe and Fe—S bonds. The electrochemical assignments were confirmed by carrying out extended Hückel MO calculations on the model cluster Fe₂(CO)₆(₃-S)₂Ni(H₄-dppf).     

The synthesis and X-ray structure of [Sr2(OSiPh3)4(NH3)5]·0.5C7H8

The title complex [Sr₂(OSiPh₃)₄(NH₃)₅]·0.5C₇H₈ was prepared by the reaction of strontium metal granules with triphenylsilanol in an ammoniacal-toluene solution at –40°C. It crystallizes in monoclinic space group P2₁/n with a = 14.465(3), b = 20.715 (6), c = 25.199(6) Å, = 95.98(2)°, and Z = 4. The complex has a dimeric structure with one terminal and three bridging triphenylsiloxy ligands, the remaining coordination sites being occupied by five ammonia molecules. The central Sr₂O₄N₅ moiety adopts a distorted M₂X₉ face-sharing bioctahedral arrangement.     

Substituted cyclopentadienyl complexes. 5. Crystal and molecular structure of [(η5-C5H4Me)Fe(CO)(L)I] [L = 2,6-Me2C6H3NC,P(OMe)3, and P(C6H11)3]

The crystal and molecular structures of three derivatives of [( ⁵-C₅H₄Me)Fe(CO)(L)I] [L=2,6-Me₂C₆H₃NC, P(OMe)₃, and P(C₆H₁₁)₃] have been determined. [( ⁵-C₅H₄Me)Fe(CO)(CNC₆H₃Me₂-2,6)I] (1): Space groupP¯1,Z=2,a=13.193(7),b=8.183(5),c=7.465(4) Å,=95.13(5),=94.39(5), =91.09(5)°. [( ⁵-C₅H₄Me)Fe(CO)[P(OMe)₃]I] (2): Space groupP2₁/c,Z=4,a=7.296(3),b=24.471(6),c=8.877(3) Å,=111.92(4)°. [( ⁵-C₅H₄Me)Fe(CO)[P(C₆H₁₁)₃]I] (3): Space groupP2₁/c,Z=4,a=9.809(3),b=14.147(2),c=8.276(3) Å,=103.07(2)°. The structures were refined toR values of 0.045, 0.070, and 0.061, respectively. Disorder was observed in the P(OMe)₃ ligands on2. Structural data for1 and3 reveal (i) a small movement of the Fe atom away from the ringC atom containing the methyl group, (ii) a larger movement of ring C atoms away from the ring least-squares plane for3 than for1, and (iii) a shift toward an allyl-ene bond length variation in the ring distances for3. Molecular mechanics calculations performed on2 produce a low-energy conformation similar to that found in the crystal structure determination of2 with an energy barrier to ring rotation of ±5 kcal mol^–1. A correlation of the structural and molecular mechanics data with the nmr spectra of complexes1 to3 indicates that the steric influence ofL on the ring rotation could be due to ring distortion and/or interaction with the ring methyl group.     

Steroids and related studies,Part 76: Crystal and molecular structure of 4,17a-di(2-hydroxyethyl)-4,17a-diaza-d-homo-5α-androstane (HS461)

The crystal structure of 4,17a-di(2-hydroxyethyl)-4,17a-diaza-d-homo-5-androstane, C₂₂N₂O₂H₄₀ (HS461), the tertiary amine related to HS781, a potential bisquaternary neuromuscular blocking agent, has been determined by direct methods and refined by full-matrix least squares toR=0.0867 for 2049 reflections (R=0.0597), CuK radiation 65°. The space group is P2₁2₁2₁ a=20.295(4),b=7.278(6),c=14.052(4) Å,Z=4. The rings in the modified steroid nucleus are alltrans connected symmetrical chairs. Hydroxyethyl side groups at N(4) and N(17a) both have an equatorial disposition, and the side chains assumetrans conformations.     

Synthesis,crystal structure and spectral studies of the complex [Ni(C3H4N2)4(H2O)2]·(C6H4COSO2N)2

The title compound has been synthesized and its crystal structure determined at room temperature.M _r =731.39, triclinic, space groupP¯1,a=9.020(3),b=11.280(7),c=7.784(2)Å,=97.05(4),=97.08(2), =105.32(4)°, U=748(1)ų,Z=1,D _calc.=1.624 g/cm³. The finalR is 0.030 for 3095 independent observed reflections withI3(I). The crystal structure consists of repeated [Ni(im)₄(H₂O)₂]²⁺ cations and noncoordinated saccharin anions. In the complex cation [Ni(im)₄(H₂O)₂]²⁺, Ni² is bonded to four N atoms from four imidazole molecules and two O atoms from two water molecules forming an approximately square octahedral stereochemistry. The d-d transition spectrum of the title compound is also reported and is explained perfectly with the scaling radial theory which was proposed by us.