Crystal Structure of [Zn(2-Bromobenzoato)<Subscript>2</Subscript>]<Subscript><Emphasis Type="Italic">n</Emphasis></Subscript> and [Zn(2-Bromobenzoato)<Subscript>2</Subscript>(<Emphasis Type="Italic">N</Emphasis>-Methylnicotinamide)]<Subscript>2</Subscript>

Abstract  

The syntheses and structural characterizations of two novel 2-bromobenzoatozinc(II) complexes—[Zn(2-BrC₆H₄COO)₂] _n (I) and [Zn(2-BrC₆H₄COO)₂(mnad)]₂ (II), where mnad is N-methylnicotinamide are reported. Compound (I) crystallized with a monoclinic lattice (space group P2₁/c) and is polymeric in solid state. Its cell parameters are: a = 7.37220(10) Å, b = 19.9639(3) Å, c = 30.2756(5) Å, β = 94.7510(7)°, V = 4440.59(12) ų, Z = 4. The coordination environments of all zinc atoms are distorted tetrahedra built from four carboxylate oxygen atoms coming from four 2-bromobenzoato ligands. Compound (II) crystallized with a monoclinic lattice (space group P2₁/c) with a = 11.7488(2) Å, b = 20.3683(3) Å, c = 9.30130(10) Å, β = 100.3941(11)°, V = 2189.30(5) ų, Z = 2. This dimeric molecule features a paddle-wheel [Zn₂O₈] cage in solid state; the coordination environment of the central atom is square pyramidal consisting of four carboxylate oxygen atoms and the pyridine N atom of the mnad ligand.     

A Tetranuclear Nickel(II) Cubane Complex with <Emphasis Type="Italic">O</Emphasis>-Vanillin Ligand

Abstract  

A novel cubane complex with formula of [Ni(μ₃-OCH₃)L(CH₃OH)]₄ (1) has been successfully assembled by using o-vanillin as multidentate ligand. Each Ni(II) ion is six coordinate, being bound to four oxygen atoms from four methanol molecules, one phenoxido oxygen atom and one aldehyde oxygen atom from the o-vanillin ligand. The cubane structure is characterized by a Ni₄O₄ core assembled from four nickel atoms and four deprotonated, bidentate o-vanillin ligands and the cubic array of alternating nickel and oxygen atoms give intracluster metal–metal separations of 3.054(1) and 3.076(1) ? respectively. Preliminary magnetic studies suggest the existence of a weak antiferromagnetic coupling between the nickel ions.     

Synthesis and Crystal Structure of Bis[<Emphasis Type="Italic">N</Emphasis>-{(<Emphasis Type="Italic">S</Emphasis>)-1-Phenylethyl}-<Emphasis Type="Italic">N</Emphasis>-{1-(2-Pyridinyl)Methyl}Amine] Zinc(II) Perchlorate

Abstract  

The reaction of N-[(S)-1-phenylethyl]-N-[1-(2-pyridinyl)methyl]amine (PEPMA) with Zn(ClO₄)₂ affords (PEPMA)₂Zn(ClO₄)₂ at room temperature. The complex is characterized by elemental analysis, ¹H-MNR and X-ray crystallography. The crystal system is orthorhombic with space group of P2₁2₁2₁ and unit cell parameters: a = 8.6911(4), b = 9.7755(7), c = 37.275(2) ?, V = 3166.9(3) ?³, Z = 4, D _x  = 1.445 Mg/m³. The crystal structure reveals that zinc metal is ligated by two PEPMA ligands in a distorted tetrahedral fashion. Interestingly, both nitrogen atoms of amine at PEPMA to the central zinc metal exhibit (R)-configuration.     

Synthesis and Crystal Structures of Two <Emphasis Type="Italic">N</Emphasis>-Heterocyclic Carbene Adducts of CrCl<Subscript>2</Subscript>

Abstract  

The reactions of CrCl₂ with two N-heterocyclic carbenes (NHC) have afforded the complexes, trans-[CrCl₂(NHC)₂] (NHC = :C{N(C₆H₃Pr₂ⁱ-2,6)C(H)}₂ 1 or :C{N(Prⁱ)C(Me)}₂ 2). The cell parameters of the compounds are 1: P2₁2₁2₁, a = 12.9445(4), b = 20.7364(5), c = 21.2841(6); 2: Pca2₁, a = 21.7583(14), b = 9.9465(8), c = 11.4414(9). The crystal structures of the complexes are the first for NHC adducts of CrCl₂, and both exhibit square planar chromium centers.     

Crystal Structure and Conformational Analysis of 4-[(<Emphasis Type="Italic">p</Emphasis>-<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-Dimethylamino)Benzylidene]-2-Phenyloxazole-5-One

Abstract  

Molecular and crystal structure of 4-[(p-N,N-dimethylamino)benzylidene]-2-phenyloxazol-5-one, C₁₈H₁₆N₂O₂, have been determined by single crystal X-ray diffraction study. The title compound is monoclinic, with a = 12.1704(23) ?, b = 3.9810(5) ?, c = 30.9603(56) ?, β = 101.176(15)°, Z = 4, D _x = 1.32 g/cm³, μ(Mo Kα) = 0.087 mm⁻¹, and space group is P12₁/c1. The structure was solved by direct methods and refined to a final R = 0.047 for 3166 reflections with I > 2σ(I). The crystal structure is stabilized by C–H⋯O and C–H⋯N type intra-molecular, C–H⋯O type inter-molecular interactions. To enlighten the flexibility and the geometric isomerism (E or Z) of the title compound, the selected torsion angle is varied from −180 to 180° in every 10° separately and molecular energy profile is calculated and analyzed.     

Synthesis,Characterization and Antibacterial Activity of <Emphasis Type="Italic">N</Emphasis>-(<Emphasis Type="Italic">N</Emphasis>-Acetic Acid-yl-Phthalimide-5-yl) Maleamic Acid Dihydrate

Abstract  

The compound N-(N-acetic acid-yl-phthalimide-5-yl) maleamic acid (C₁₄H₁₀N₂O₇, M _r  = 318) was synthesized and its structure was characterized by elemental analysis, ¹H NMR and IR spectra. The single crystal of the title compound (C₁₄H₁₄N₂O₉, M _r  = 354.27) was cultured and its structure was determined by single crystal X-ray diffraction. The crystal belongs to monoclinic system, space group P21/c with a = 14.3859(19), b = 12.5835(18), c = 8.6934(15) ?, β = 102.824(2)°, V = 1534.5(4) ?³, Z = 4, D _c  = 1.534 g cm⁻³, μ(Mo Kα) = 0.131 mm⁻¹, F(000) = 736. The final refinement gave R = 0.0652, wR(F ²) = 0.1239 for 2,703 observed reflections with I > 2σ(I). X-ray diffraction analysis reveals that the asymmetric unit of the title compound contains one N-(N-acetic acid-yl-phthalimide-5-yl) maleamic acid molecule and two water molecules. One of the two water molecules is disordered. The phthalimide group is essentially planar. The crystal structure of the title compound is stabilized by N–H…O and O–H…O hydrogen bonds interactions. The compound N-(N-acetic acid-yl-phthalimide-5-yl) maleamic acid possesses moderate antibacterial activity.     

Synthesis,Crystal Structure and Spectroscopy of <Emphasis Type="Italic">catena-</Emphasis>poly-bis(azido-<Emphasis Type="Italic">N1,N1</Emphasis>)(2-Aminopyrimidine)Copper(II)

Abstract The compound [Cu(ampym)(μ_1,1-N₃)₂]_n (ampym = 2-aminopyrimidine) has been synthesized and characterized by X-ray crystallography and infrared spectroscopy. In addition, Ligand Field and powder EPR measurements have been performed. The structure is solved in space group P21/c with a = 7.303(2), b = 19.716(4), c = 5.949(1) ?, β = 98.17(3), V = 847.9(3) ?³, Z = 2 with final R = 0.0382. The coordination geometry around the Cu(II) ion is distorted square pyramidal, with four nitrogen atoms of four bridging azido anions in the basal plane with Cu–N distances that range from 1.998(3) to 2.069(3) ?. The apical position is occupied by a nitrogen atom of the ampym molecule at a Cu–N distance of 2.169(3) ?. The trans-basal angles are 165.7(1) and 143.9(1)°. Weak hydrogen bonding is observed between the two amine hydrogen atoms and nitrogen of an azide anion and the pyrimidine-ring nitrogen atom of a neighbouring molecule (N···N distances 3.174(5), 3.106(4) ?). These last hydrogen bonds (N7···N3) are forming so-called “Watson-Crick type” hydrogen bonds. In the infrared the vibrations of the coordinated azide anion are observed at 2,062, 1,273 and 655 cm⁻¹, while the Cu–N vibrations are observed at 370 and 224 cm⁻¹. Ligand-field and EPR spectra are uneventful and give spectral parameters expected in the range for such Cu(II) compounds. Magnetic susceptibility measurements reveal a weak antiferromagnetic interaction between the Cu(II) ions. Index Abstract A new Cu(II) compound, [Cu(2-aminopyrimidine)(μ_1,1-N₃)₂]_n has been synthesized and characterized by X-ray crystallography and by IR, Ligand Field, EPR spectroscopy and magnetic susceptibility. The coordination geometry around the Cu(II) ion is distorted square pyramidal, with four nitrogen atoms of four bridging azido ligands in the basal plane with Cu–N distances that range from 1.998(3) to 2.069(3) ?. The apical position is occupied by a nitrogen atom of the ampym molecule at a Cu–N distance of 2.169(3) ?. Also a very interesting hydrogen bond system occurs between pairs of ligands in the lattice. .     

Structure of 6,13-bis(<Emphasis Type="Italic">N</Emphasis>, <Emphasis Type="Italic">N</Emphasis>-dimethylcarbamoyl) thioquinanthrene

The crystal structure of 6,13-bis-(N,N-dimethylcarbamoyl)thioquinanthrene 3 has been determined as monoclinic, with space group P2(1)/c with lattice parameters a = 10.044(2) Å, b = 21.385(4) Å, c = 10.889(3) Å, = 102.92(3)°, Z = 4 and D_calc = 1.342 Mg/m³. The middle 1,4-dithiin ring in the title compound 3, C₂₄H₂₀N₄O₂S₂ is in a boat conformation with the dihedral angle between the planes of the aromatic rings 132.45(8)°.     

Synthesis and structure of a terephthalato-bridged nickel complex [Ni(tpt)(imi)<Subscript>3</Subscript>(H<Subscript>2</Subscript>O)]<Emphasis Type="Italic">n</Emphasis>

At room temperature, a new coordination polymer [Ni(tpt)(imi)₃(H₂O)]n was synthesized by the reaction of NiCl₂?6H₂O, terephthalic acid, and imidazole in aqueous solution. The structure was determined by X-ray crystallography. It crystallizes in monoclinicP2₁/n space group with the crystal cell parameters ofa = 9.8626(4) Å,b = 15.2498(3) Å, andc = 12.7681(3)Å, β = 90.309(2)^°,V = 1920.33(10) ų, andZ = 4. The crystal X-ray analysis shows that each nickel atom is coordinated by three imidazole ligands, two terephthalate ions, and one water molecule. Each terephthalate ion bridges two nickel atoms to form a zigzag chain. The chains are further linked together via hydrogen bonds to a three-dimensional network.     

Synthesis and Characterization of <Emphasis Type="Italic">N,N</Emphasis>-di(prop-2-ynyl)-<Emphasis Type="Italic">p</Emphasis>-toluidine

Abstract  

In order to investigate the intramolecular [4 + 2] cycloaddition, we prepared some new tertiary N-(5-substituted-2-furfuryl)-N-prop-2-ynyl-p-toluidines [Hergold-Brundić et al., Acta Cryst C56:e520, 2000; Mance and Jakopčić, Mol Divers 9:229, 2005; Mance, “unpublished results”] by the alkylation of secondary N-(5-substituted-2-furfuryl)-p-toluidines with the propargyl-bromide [Mance and Šindler-Kulyk, Synth Commun 26:923, 1996]. In the course of preparation of N-(5-methoxy-2-furfuryl)-N-prop-2-ynyl-p-toluidine [Mance, “unpublished results”], besides the main product (compound 1) (Scheme 1) we obtained N,N-di(prop-2-ynyl)-p-toluidine (compound 2) as the colourless crystals. The title compound 2, N,N-di(prop-2-ynyl)-p-toluidine, C₁₃H₁₃N, crystallizes in monoclinic C 2/c space group with unit cell parameters: a = 19.5319(9) ?, b = 7.5230(3) ?, c = 15.9000(7) ?, β = 112.554(5)°, V = 2157.64(18) ?³, Z = 8. The crystal structure is dominated by van der Waals forces only. The bond distances around amine N atom correspond to σ dominated bonds (1.467(2), 1.462(2) and 1.419(2) ?). The angles sum around amine N atom is in accord with sp³ hybridization (343°).     

Lead (II) selenite halides Pb<Subscript>3</Subscript>(SeO<Subscript>3</Subscript>)<Subscript>2</Subscript><Emphasis Type="Italic">X</Emphasis><Subscript>2</Subscript> (<Emphasis Type="Italic">X</Emphasis> = Br,I): Synthesis and crystal structure

Two lead selenite halides, Pb₃(SeO₃)₂Br₂ and Pb₃(SeO₃)₂I₂, have been prepared by solid-phase synthesis and structurally characterized. These compounds are isotypic and can be considered 3D with a microporous framework composed of lead polyhedra (distorted Archimedean antiprisms formed by oxygen and halogen atoms). The framework contains channels oriented in the [010] direction. These channels contain selenium atoms, which are bound with framework oxygen atoms belonging to different lead polyhedra.     

Supramolecular organization of the crystal structure of <Emphasis Type="Italic">cis</Emphasis>-bis(thiosemicarbazide)palladium(II) <Emphasis Type="Italic">ortho</Emphasis>-hydrophthalate

This paper reports on the synthesis of a new palladium(II) thiosemicarbazide complex of the composition [Pd(HL)₂](HPht)₂ · 4H₂O(I) (where HL is N(1)H₂-N(2)H-C(3)(=S)-N(4)H₂ and HPht ⁻ is a monoanion of ortho-phthalic acid) and the results of an investigation of its structure. It has been demonstrated that two organic ligands are bidentately coordinated in the neutral form through a set of N and S donor atoms, which are located in the cis position with respect to the central metal atom. Three independent water molecules are joined by hydrogen bonds into the centrosymmetric associate {H₂O}₆. In the crystal, thiosemi-carbazide cationic complexes of palladium(II), monophthalate anions, and water molecules are self-organized into a supramolecular system with the formation of a three-dimensional structure based on ionic and hydrogen bonds.     

Crystal and Molecular Structures of Di-1-Adamantylthiophosphinic Chloride, <Emphasis Type="Italic">P</Emphasis>,<Emphasis Type="Italic">P</Emphasis>-Diphenyl-<Emphasis Type="Italic">N</Emphasis>-Benzyl Phosphinothioic- and Selenoic- Amides

Abstract  Synthesis and X-ray structural determination of three phosphorus compounds are reported. (3b) is monoclinic P2(1)/c with a = 11.852(1), b = 12.825(1), c = 12.445(1) ?, β = 103.693(1)o; (4a) and (4b) are monoclinic P2(1)/n with a = 12.1422(16), b = 9.0860(12), c = 14.845(2) ?, β = 96.498(3)o for (4a), and a = 12.2714(16), b = 9.2812(12), c = 14.800(2) ?, β = 97.176(2)o for (4b). They all exhibit distorted tetrahedral geometry about the P atom. Ph₂P(X)NHC₇H₇ (X=S (4a) and X=Se (4b)) show typical P–S and P–Se double bond distances and P–N single bonds, while P–S bond in 1-Ad₂P(S)Cl (3b) is comparable to P–S single bonded probably due to the largeness of 1-adamantyl groups. Graphical Abstract  Synthesis and X-ray structural determination of 1-Ad₂P(S)Cl (3b), Ph₂P(S)NHC₇H₇ (4a) and Ph₂P(Se)NHC₇H₇ (4b) are reported.      

Crystal Structure of 2-(4,5-Bis(4-methoxyphenyl)-5<Emphasis Type="Italic">H</Emphasis>-chromeno[4,3-<Emphasis Type="Italic">b</Emphasis>]pyridin-2-yl)phenol

Abstract  

The title compound 2-(4,5-bis(4-methoxyphenyl)-5H-chromeno[4,3-b]pyridin-2-yl)- phenol (C₃₂H₂₅NO₄, Mr = 487.53) was synthesized and crystallized. The crystal belongs to monoclinic, space group P2(1)/c with a = 12.4170 (11), b = 18.313 (2), c = 11.7103 (10) ?, β = 111.569(2)°, V = 2476.4(4) ?³, Mr = 487.53, Z = 4, Dc = 1.308 g/cm³, μ(MoK _α ) = 0.086 mm⁻¹, F(000) = 1024, the final R ₁ = 0.0632 and wR ₂ = 0.1454. X-ray analysis reveals that the atoms of C(1), C(2), C(3), C(4), C(5) and N(1) form a planar six-membered ring, while the atoms of C(1), C(2), C(6), C(7), C(12) and O(1) form a six-membered ring of envelope conformation.     

X-Ray Crystallographic Structure and Absolute Configuration of the Cyclic Di-amino Acid Peptide: Cyclo(<Emphasis Type="SmallCaps">l</Emphasis>-HomoCySH-<Emphasis Type="SmallCaps">l</Emphasis>-HomoCySH)

Abstract  

The cyclic di-amino acid peptide cyclo(l-homoCySH-l-homoCySH) [(3S, 6S)-3, 6-bis(2-sulfanylethyl) piperazine-2,5-dione, C₈H₁₄N₂O₂S₂, crystallizes in the orthorhombic space group P2₁2₁2₁ with unit cell parameters a = 6.1509(2) ?, b = 18.0217(9) ?, c = 29.6166(14) ?, V = 3283.0(2) ?³, Z = 12 (3 molecules, A, B and C, per asymmetric unit), D _c = 1.422 g cm⁻³ and a linear absorption coefficient of 0.464 mm⁻¹. The crystal structure determination was carried out with MoKα X-ray data measured at 120(2) K. In the final refinement cycle the data/restraints/parameter ratios were 5595/0/385 and goodness-of-fit on F ² = 1.084. Final R indices for [I > 2sigma(I)] were R1 = 0.0746, wR2 = 0.1356 and R indices (all data) R1 = 0.1092, wR2 = 0.1529. The largest electron density difference peak and hole were 0.526 and −0.445e ?⁻³. The DKP rings in all three molecules are essentially, and unusually, planar and the C=O oxygen atoms are co-planar with the ring in each case. Ring atom rms deviations, including the =O groups, are 0.0668, 0.0658 and 0.0656 ? in molecules A, B and C, respectively. Details of the molecular geometry are compared with the compound cyclo(Gly-Gly) (Degeilh R, Marsh RE Acta Cryst 12:1007, 1959) and in addition some cyclic di-amino acid peptides in which the DKP rings have more puckered boat conformations.     

Synthesis,redox properties,and X-ray diffraction structure of 2,3-<Emphasis Type="Italic">bis</Emphasis>(ethylthio)-<Emphasis Type="Italic">N</Emphasis>-(<Emphasis Type="Italic">p</Emphasis>-MeOC<Subscript>6</Subscript>H<Subscript>4</Subscript>)maleimide

Refluxing 2,3-dichloromaleic anhydride with p-anisidine in benzene with water removal gives the condensation product 2,3-dichloro-N-(p-MeOC₆H₄)maleimide (1) 75% yield. This new maleimide compound reacts with added ethanethiol in the presence of Et₃N or DBU to furnish the bidentate sulfide ligand 2,3-bis(ethylthio)-N-(p-MeOC₆H₄)maleimide (2) in 85% yield. Each product has been characterized in solution by IR, NMR, and UV-vis spectroscopies, and the solid-state structure of 2,3-bis(ethylthio)-N-(p-MeOC₆H₄)maleimide was unequivocally established by single-crystal X-ray diffraction analysis. 2,3-bis(Ethylthio)-N-(p-MeOC₆H₄)maleimide crystallizes in the monoclinic space group C2/c, a = 20.035(3)Å, b = 9.188(1)Å, c = 16.887(2)Å, = 93.696(2)°, V = 3102.3(8)ų, Z = 8, and D_calcd = 1.385 mg/m³; R = 0.0268, R_w = 0.0676 for 2025 reflections with I > 2 (I). The nature of the LUMO in 2,3-bis(ethylthio)-N-(p-MeOC₆H₄)maleimide (2) has been determined by extended Hückel molecular orbital calculations, and these data are discussed relative to the cyclic voltammetry results and other structurally relevant compounds prepared in our labs.     

Structure of Triammonium <Emphasis Type="Italic">fac</Emphasis>-Trichloridotrioxidorhenate(VII) Chloride with <Emphasis Type="Italic">C</Emphasis><Subscript>3<Emphasis Type="Italic">v</Emphasis></Subscript> Crystallographic Symmetry of the Complex Anion

Abstract  

The unstable crystals of triammonium fac-trichloridotrioxidorhenate(VII) chloride have been obtained from ammonium rhenate(VII) solution in concentrated hydrochloric acid. The crystal structure consists of fac-trichloridotrioxidorhenate(VII) anions, chloride anions and ammonium cations. Each fac-trichloridotrioxidorhenate(VII) anion and each chloride anion lies in special position of 3m site symmetry (cell parameters: a = 9.026(3) Å; c = 7.690(4) Å; space group: P6₃ mc). The ammonium cation lies in special position of m site symmetry. The following anion geometrical parameters of the fac-trichloridotrioxidorhenate(VII) anion have been obtained: Re–O bond length of 1.720(2) Å, Re–Cl bond length of 2.5428(9) Å, the bond angles: O–Re–O of 103.5(1)° and Cl–Re–Cl of 79.8(1)°.     

Structural Features of <Emphasis Type="Italic">Ortho</Emphasis>-hydroxy Bis-phenols and Their Comparison with <Emphasis Type="Italic">Para</Emphasis>-hydroxy Bis-phenols

Abstract The crystal structures of four bis-phenols are reported to substantiate the fact that the weak interactions play a major role in the crystal packing of bis-phenols. The reaction of 2,4-dimethylphenol with aldehydes such as 2-naphthaldehyde, terephthaldehyde in the presence of trifluoracetic acid gave 2-[bis(2-hydroxy 3,5-dimethylphenyl)methyl]naphthalene (1) and 4-[bis(2-hydroxy 3,5-dimethylphenyl) methyl]benzaldehyde (2), respectively. The 2-[bis-(2-hydroxy 3,5-dimethylphenyl)-methyl]naphthalene (1) crystallizes in orthorhombic, Pbca, a = 11.905(3) ?, b = 18.788(5) ?, c = 18.894(5) ?, 4-[bis(2-hydroxy 3,5-dimethylphenyl)methyl] benzaldehyde (2) in monoclinic, Cc, a = 8.880(3) ?, b = 16.394(7) ?, c = 13.700(5) ?, γ = 104.542(2)°. The reaction of 2-nitrobenzaldehyde with 2,4-dimethylphenol gave 2-benzo[c] isoxazo-3-yl 4,6-dimethylphenol (3) and its crystal parameters are orthorhombic, P2₁2₁2₁, a = 7.737(6) ?, b = 11.885(9) ?, c = 13.336(8) ?. The reaction of 2,6-dimethylphenol with 4-nitrobenzaldehyde and 2-chlorobenzaldehyde gave bis(4-hydroxy 3,5-dimethylphenyl)(4-nitrophenyl)methane (4) and bis(4-hydroxy 3,5-dimethylphenyl)(2-chlorophenyl)methane (5), respectively. The bis(4-hydroxy 3,5dimethylphenyl)(4-nitrophenyl)methane (4) crystallizes in monoclinic, C2/c, a = 25.921(1) ?, b = 12.202(4) ?, c = 15.6084(7) ?, β = 122.172(4)°, and bis(4-hydroxy 3,5-dimethylphenyl) (2-chlorophenyl)methane crystallizes as acetonitrile solvate (5) in triclinic, P-1, a = 12.314(3) ?, b = 14.111(3) ?, c = 15.078(5) ?, α = 98.268(2)°, β = 111.268(2)°, γ = 114.304(1)˚. The unit cell of 5 contains two pairs of crystallographically unsymmetric molecules of bis-phenols. Index abstract The crystal structures of four bis-phenols are reported to substantiate the fact that the weak interactions plays a major role in crystal packing and can induce symmetry non-equivalence among bis-phenols in unit cell of bis-phenols.      

Crystal structure of <Emphasis Type="Italic">L</Emphasis>-alanine phosphate

The crystal structure of L-alanine phosphate (C₃O₂NH₇ · H₃PO₄) is determined by the single-crystal diffraction technique; a = 11.918(1) Å, b = 9.117(1) Å, c = 7.285(1) Å, γ = 104.7(1)°, space group P2₁, and Z = 4. The amino group of the alanine is protonated by the hydrogen atom of the phosphoric acid. Pairs of H₂PO ₄ ^? hydrogen-bonded ions are packed into layers alternating with layers of alanine molecules in the crystal. No hydrogen bonds are formed immediately between the alanine molecules.     

Reaction of (<Emphasis Type="Italic">n</Emphasis>-Bu<Subscript>4</Subscript>N)<Subscript>2</Subscript>[Re<Subscript>2</Subscript>Cl<Subscript>8</Subscript>] with a 2-Oxocarboxylic Acid: Crystallographic Characterization of a New Dirhenate(III) Complex

Abstract  

The reaction of tetra-n-butylammonium-octachloridodirhenate(III), (Bu₄N)₂[Re₂Cl₈], with molten 2-oxobutanoic acid Et(CO)CO₂H at 75 °C afforded pale-green tetra-n-butylammonium-hexachlorido-(2-oxobutanoato)-dirhenate(III), (Bu₄N)[Re₂(O₂C(CO)Et)Cl₆]. Slow evaporation of a solution in CHCl₃ yielded shiny, mint-green crystals of the dirhenate complex. The X-ray crystal structure determination (monoclinic, P2₁/n, a = 11.6557(3) ?, b = 20.5382(5) ?, c = 13.9281(3) ?, β = 112.508(1)°, Z = 4) revealed the presence of [Re₂(O₂C(CO)Et)Cl₆]⁻ anions and tetra-n-butylammonium cations. The central [Re₂]⁶⁺ core with a Re≣Re quadruple bond of 2.2263(3) ? length is μ₂-bridged by one 2-oxobutanoato ligand and additionally coordinated by six chlorido ligands. Each dirhenate unit is linked via two Re···Cl contacts to dimeric, centrosymmetric entities of the constitution {[Re₂(O₂C(CO)Et)Cl₆]₂}²⁻. In the crystal, these dimers of dinuclear complexes are separated from each other by the bulky tetra-n-butylammonium cations.