Spectra and structure of phosphorus-boron compounds,XII1 Vibrational spectra and molecular symmetry of tetramethylbiphosphine-bisborane

The infrared (200–3500 cm^–1) and Raman (50–3500 cm^–1) spectra of two isotopic species of tetramethylbiphosphine-bisborane, (CH₃)₄P₂·2BH₃ and (CH₃)₄P₂·2BD₃, in the solid state at low temperatures have been recorded. The spectra have been interpreted in detail on the basis ofC _2h molecular symmetry. The P-B stretching modes were assigned to bands at 599 and 567 cm^–1 in the Raman and infrared spectra of the light compound, respectively. Only one P-P stretching mode was observed in the Raman spectra. The vibrational data appear to be consistent with the presence of only one conformer in the solid state, which is at variance with the conclusions from an X-ray study. Considerable splitting of the low-frequency bending modes was observed for both compounds; this splitting has been attributed to the factor group.For part XI, see J. D. Odom, V. F. Kalaskinsky, and J. R. Durig,Inorg. Chem. 14, 2837 (1975).Taken in part from the thesis of R. W. MacNamee which was submitted to the Department of Chemistry in partial fulfillment of the Ph.D. degree (1974).     

Raman spectrum of solid glyoxal

The Raman spectrum of solid glyoxal has been recorded from 100 to 3500 cm^–1. Fundamental frequencies were observed at 2882, 1729, 1364, 1078, 1050, and 551 cm^–1 and assigned as the C—H stretching, C=O stretching, C—H in-plane bending, C—C stretching, C—H out-of-plane bending and COH rocking modes, respectively. The infrared spectrum of the solid has been investigated from 33 to 4000 cm^–1, and the values observed for the fundamentals are compared with those previously reported from studies of the vapor. The unusual frequency shifts upon solidification are discussed. A comparison of the infrared and Raman bands in the crystal shows that the mutual exclusion principle is operative. It is concluded from this alternate forbiddance that the molecule has a centrosymmetric structure in the crystal and that each molecule occupies a C _i (¯1) site. The factor group of the crystal is believed to be eitherC _2h (2/m) orD _2h (mmm) with two or four molecules per primitive unit cell.We thank the National Aeronautics and Space Administration for supporting this research by Grant NGR-41-002-003.     

Spectres de vibration du Cristal de Biphényle à Basse Température

Abstract

Low-temperature infrared and Raman spectra of Crystalline biphenyl have been investigated in the 3100–25 cm^?1 range, and those of biphenyl-D₁₀ between 200 and 25 cm^?1. The infrared dichroism of an Oriented crystal at 77°K has been measured in the 3100–400 cm^?1 region. The assignment for the internal modes V ₅(B_2u), v ₆ (B_2u), v ₁(B_1u), v ₁₀(B_1g), v ₂(B_2g) et v ₃ (B_3g) is given.

The band splitting is analized and hte components due ot the correlation effect in the fundamentals are separated from the components due to combinations. Isotopic shifts are used to assign the nine external vibrations as well as the torsional mode. The temperature effect on the frequencies occuring below 500 cm^?1 is discussed.     

The structure of dimethylcrocetin

The structure of dimethylcrocetin (DMCRT), prepared by alkaline hydrolysis in methanol of the glucosidic carotenoids extracted from the stigmata of theCrocus sativus L. flowers, has been determined. The molecule has the all-trans configuration and is planar forming a long conjugated system. The C–O bond length values of the two ester groups are shortened as expected. The compound (C₁₁H₁₄O₂)₂ crystallizes in the orthorhombic space group Pbcn witha=12.5907(7),b=7.5639(5) andc=21.963(2)Å. Dimethylcrocetin has characteristic Infrared absorptions at 1697 cm^–1 (C=O) and 1229 cm^–1 (C–O) and characteristic Raman vibrational modes at 1542 cm^–1 (C=C) and 1166 cm^–1 (C–C).     

Low frequency vibrations and molecular structure of (CH3)2NPF2

The far infrared spectrum, from 33 to 500 cm^–1, of (CH₃)₂NPF₂ has been recorded in both the gaseous and solid states. The Raman spectrum of both the liquid and solid was also recorded. The three low frequency PF₂ and three NC₂ bending modes as well as the P-N torsion have been assigned. If these bending modes are sensitive to conformational changes, as found in previous studies, then the molecule exists in only one conformation in the gaseous, liquid and solid states for the temperature range –190 to 150 °C. A methyl torsion was assigned at 189 cm^–1 and a barrier to internal rotation of 2·1 kcal/mole was calculated. This low barrier value is discussed in terms of a planar NC₂ moiety.     

Crystal structure and vibrational spectra of hydrazinium(2+) aquatetrafluoroindate(III), N2H6(InF4H2O)2

The crystal structure of hydrazinium(2+) aquatetrafluoroindate(III), N₂H₆(InF₄H₂O)₂, has been determined by X-ray diffraction. The compound crystallizes in the triclinic space group (C _i ¹) with a = 6.759(2) Å, b = 6.228(1) Å, c = 5.7854(7) Å, = 80.28(2)°, = 88.79(1)°, = 69.96(2)°, V = 225.3(1) ų, and Z = 1. The structure comprises hydrazinium(2+) cations and InF₂F_4/2O^– anions in which In appears to be seven-coordinated in the form of a pentagonal bipyramid by four bridging fluorine atoms, two terminal fluorine atoms, and one oxygen atom. Pentagonal bipyramids are interconnected and form chains along a axis. Bands in vibrational spectra were assigned to the vibrations in N₂H₆ ²⁺ cations and anionic InF₂F_4/2O^– entities. The rather intensive band appearing at 1042 cm^–1 in Raman spectrum, which is absent from infrared, is characteristic of the N₂H₆ ²⁺ cation, in line with the predictions of the unit-cell group analysis for the studied system.     

Spectra and structure of organophosphorus compounds,XVIII: Infrared and Raman spectra of [(CH3)2PS]2, [(CD3)2PS]2, and [(CH3CH2)2PS]2 in the solid state

The infrared (80–3500 cm^–1) and Raman (10–3500 cm^–1) spectra of solid [(CH₃)₂PS]₂, [(CD₃)₂PS]₂, and [(CH₃CH₂)₂PS]₂ have been recorded. A complete vibrational assignment is proposed for tetramethyldiphosphine disulfide on the basis ofC _2h molecular symmetry. The observed intermolecular vibrations indicate little factor group effects, and no frequency differences were observed for the normal modes of the two different molecules which exist in the crystal as reported from the x-ray study. Most of the observed bands in the spectrum of tetraethyldiphosphine disulfide have been assigned. At least two of the three optical librational modes were observed in the Raman effect.     

Optical phonon modes and transmissivity in BaWO4 single crystal

Barium tungstate (BaWO₄) single crystal has been grown using Czochralski technique. It belongs to the scheelite structure, forming the space group I 4₁/a at room temperature and the primitive cell contains two molecular units. The polarized Raman spectra were recorded by a micro‐Raman spectrophotometer system in the backscattering geometry. All the observed Raman modes were assigned. The Raman mode at 924 cm^–1, which belongs to the totally symmetrical A_g optical modes, has the strongest intensity and its linewidth is 4.6 cm^–1. The infrared active lattice vibrations have been studied, eight optical modes were observed and assigned. The ultraviolet absorption edge is at 256 nm and the optical transparency range is up to 2500 nm at room temperature. The energy gap E_g of this crystal was obtained from the optical transmission spectra. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Raman,infrared, and optical spectra of some silver(I) sulfamides

Raman and infrared spectra of disilver sulfamide, Ag₂(HNSO₂NH), and tetrasilver sulfamide, Ag₄(NSO₂N), together with their¹⁵N and²H derivatives (at 300 and 80 K), are reported and interpreted. Resonance conditions for the Raman spectrum of the deep red tetrasilver sulfamide is assumed, but no overtone progression of any band is observed. Silver-nitrogen stretching bands appear in the frequency region 300–200 cm^–1. Although the X-ray crystal structures of the compounds reveal short AgAg distances, no frequency assignable to metalmetal stretching vibrations could be clearly located except for Ag₄(NSO₂N) in the case of the strong band at 288 cm^–1 appearing in the infrared only. This band is assigned to a lattice vibration having high frequency due to strong metalmetal interaction. Optical diffuse reflectance and fluorescence emission/excitation spectra are included and compared to the literature data for silver-exchanged zerolites.     

Synthesis, crystal structure, and spectroscopy of (azido-N1)bis(2,2′-bi-imidazoline)copper(II) perchlorate

The compound [Cu(biz)₂(N₃)](ClO₄) (biz = 2,2-bi-imidazoline) has been synthesized and characterized by X-ray crystallography and infrared spectroscopy. In addition, EPR and magnetic measurements have been performed. The compound crystallizes in the monoclinic space group P2₁/c, with a = 9.2716(2), b = 27.6454(4), c = 7.4285(1) Å, = 102.1417(6)°, V = 1861.46(5) ų, and Z = 4. The coordination geometry around the Cu(II) ion is distorted square pyrimidal, with 4 nitrogen atoms of 2 bis-chelating ligand molecules in the basal plane and one nitrogen of the azide molecule in the apical position. The perchlorate ion is noncoordinating. In the infrared the vibrations of the coordinated azide anion are observed at 2050, 1286, and 620 cm^–1, while the vibrations of the free perchlorate anion are observed at 1071, 1035, and 919 cm^–1; Cu—N vibrations are observed at 418 and 336 cm^–1. The molecules are connected in the lattice via relatively strong hydrogen bonding between the N—H groups at the back of the biz ligand and the N1 and N3 atoms of the azide ligand forming layers. No intermolecular magnetic interaction was observed for this compound.     

Vibrational spectra oftrans-dichlorodiiodoethylene

The infrared spectra oftrans-dichlorodiiodoethylene as a solid and in solution were recorded in the region 4000–25 cm^–1. Raman spectra of the compound were obtained and semiquantitative polarization data were calculated.The mutual exclusion between the infrared and Raman frequencies are in agreement with the expectedC _2h (2/m) symmetry for this molecule. The fundamentals have been assigned and a normal coordinate analysis carried out. Thermodynamic functions and the root mean square amplitudes of vibration have been obtained.The authors wish to acknowledge financial support from theNorwegian Research Council for Science and the Humanities.     

Synthesis,properties, and structure of 1,3-dimethyl-2(3H)-imidazolethione hydrogen bromide

The compound dmit·HBr (dmit=1,3-dimethyl-2(3H)-imidazolethione) has been synthesized and characterized. The crystal and molecular structure of dmit·HBr has also been determined. The compound, C₅H₉BrN₂S, crystallizes in space groupP2₁/c with four formula units in a cell of dimensionsa= 7.331(1),b=7.744(2),c=14.626(4) Å, and=99.56(2)°. The calculated and observed densities are 1.678 and 1.68(2) g cm^–3, respectively. X-ray results along with physical characterization show this compound to be a molecular adduct of dmit and hydrogen bromide which is sensitive to air, light, and moisture. Specific conductivity (10^–3 M in PhNO₂), infrared, and¹H-NMR data have also been obtained. X-ray results reveal intermolecular contracts between S and Br to be primarily van der Waals in nature. Molecular units are linked through long zigzag Br-S-Br-S chains.     

Crystal structure and spectroscopic study oftrans-diaquabis(2-benzoylpyridine)copper(II) nitrate

trans-Diaquabis(2-benzoylpyridine)copper(II) nitrate has been prepared and characterized by spectroscopic methods and X-ray crystallography. The complex exhibits strong infrared carbonyl absorption at 1655 cm^–1 and a broad d-d band centered about 14,090 cm^–1. The crystals are monoclinic, space groupP2₁/c witha=7.872(1),b=14.573(3),c=11.132(1) Å,=102.79(1)°,Z=2, andR _F =0.049 for 2440 observedMo-K reflections. The crystal structure consists of a packing of centrosymmetric [Cu(2-benzoylpyridine)₂(H₂O)₂]²⁺ cations and nitrate ions, which are interlinked by hydrogen bonds to form thick layers corresponding to the (100) family of planes. The coordination geometry about the copper atom is an elongated octahedron with aqua ligands occupying the axial positions. The measured bond distances are: Cu-O(aqua)=2.256(3), Cu-O(L)=2.068(2), and Cu-N=1.965(2) Å.Mr. Wang is on leave from Central Laboratory, Nankai University, Tianjin, China.     

Raman Scattering From TMTSF-Salts

Abstract

Experimental results for Raman scattering from TSeF, TMTSF-D12, (TMTSF)₂PF₆ and (TMTSF)₂AsF₆ excited with blue-green laser light at liquid nitrogen temperature are reported. A strong resonance effect for excitation of TMTSF with 4579 Å was observed and an assignment for the a_g modes was obtained by comparison with results from TTF. Methyl group modes were identified at 328 cm^?1, 472 cm^?1 and 916 cm^?1, respectively. Charging the TMTSF molecule resulted in a strong frequency shift of -122 cm^?1 and -76 cm^?1 for the a_gu₂ mode, respectively. A study of the temperature dependence of the scattering from molecular modes between 2 K and 300 K did not reveal any correlation with the phase transitions in the conducting compounds.     

The molecular structure of 3(5)-methyl-4,5(3)-trimethylenepyrazole hydrochloride and its13C and15N NMR spectroscopy

The title compound (C₇N₂H₁₀, HC1, 1/2H₂O) crystallizes in the space groupC2/c with cell parameters:a=11.651(9),b=16.309(1),c=9.167(1)Å,=94.95(3)°,Z=8, withd=1.287 g cm^–3. One of the chlorine atoms lies on a twofold axis, the second and the oxygen atom of the water molecule have disordered positions. Intermolecular interactions through hydrogen bonds are established between nitrogen atoms of the pyrazole ring and chlorine atoms or the water molecule. In this way, chains of molecules are built; these chains, through van der Waals interactions, form layers which are stacked in the a direction. The¹H,¹³C, and¹⁵N NMR (this last using the double labelled compound) have been recorded in solution and the¹³C NMR spectrum also in the solid state (CP/MAS technique). The NMR parameters ( andJ's) thus obtained are discussed using the molecular structure.     

Complexes of azobisindoles with π-organic acceptors

Complexes of azobisindoles with tetracyanoethylene and tetracyanoquinodimethane were studied by UV-Vis, FT-IR, Raman, NMR and X-ray spectroscopies. FT-IR and Raman spectra, as well as X-ray analysis, gave useful information on the participation of various sites to the association, through analysis of CN and N=N vibrational modes, while UV-Vis and NMR spectra were less helpful. The crystal structure of complexes 1-ethyl-2-phenyl-3-(1-ethyl-2-phenyl-3-azoindole)indole/TCNE,3a and 1,2-diphenyl-3-(1,2-diphenyl-3-azoindole)indole/TCNQ,5b are reported. In the two complexes, the distances between donor and acceptor planes range between 3.4 and 3.5 Å; in3a tetracyanoethylene faces the phenyl ring of the indole, while in5b the superposition of tetracyanoquinodimethane with the donor is negligible. Compound3a,P–1,a=9.504(2),b=9.513(3),c=8.941(2) Å, =97.81(4), =103.38(3), =84.14(2)°,Z=2,D _calc=2.55 g cm^–3; compound5b,P–1,a=12.648(3),b=12.205(2),c=7.263(3) Å, =103.69(2), =91.23(3), =110.61(2)°,Z=2,D _calc=2.53 g cm^–3.     

Crystal structure of bromofluoroacetic acid: a chiral molecule

The crystal structure of bromofluoroacetic acid has been determined from three-dimensional counter data, and refined by full-matrix least-squares techniques. The crystals belong to the monoclinic space groupP2₁/c, witha = 8.529(4),b = 5.632(3),c = 9.500(4) Å, = 105.52(4) °, andD _x = 2.37 g cm^–3 forZ = 4. The finalR factor for 654 independent observed reflections is 0.081. The compound exists as hydrogen-bonded dimers in the solid state.     

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.     

Synthesis,crystal and molecular structure and vibrational characterization of N,N-dimethyl-oxathioamidate monohydrate

The title compound (SO₂NC₄H₆) has been prepared and characterized by X-ray diffraction and infra-red and Raman spectra. The structure has been refined using single-crystal X-ray diffraction data measured at 295K [MoK-radiation with =0.71073 Å]. The crystals are monoclinic, space groupP2₁/n,Z=4,a=6.240(2),b=6.786(2),c=19.988(1)Å, =108.47(2)°,V=802.8(7)ų.D _calc.=1.566 Mg m^–3,F(000)=392, =8.582 cm^–1. The final agreement factors for 1906 observed refections [I>3(I)] were:R=0.030 andR _w=0.043. The dihedral angle between de C–C–S–N plane and the C–C–O–O plane is 88.31(4). The potassium atom within the title compound structure has a slightly distorted trigonal bipyramidal coordination. Infrared and Raman spectra of the normal CH₃/CD₃ and H₂O/D₂O isotopes and the waterfree compounds at different temperatures made it possible to perform isotopes complete vibrational analysis and clearly shows the very special hydrogen bonded water molecule in the crystal.     

Metal-betaine interactions. I. Crystal structure of polymeric trans-diaquabis(pyridine betaine)manganese(II) dichloride

A new polymeric betaine complex of manganese(II), of stoichiometry [Mn(C₅H₅NCH₂COO)₂ (H₂O)₂]C1₂, has been prepared and characterized by infrared spectroscopy and X-ray crystallography. The complex exhibits strong carboxylate absorptions at 1624, 1396, 1384, and 715 cm^–1. The crystal structure has been refined toR _F =0.057 for 2342 observed (F ₀>6F ₀) MoK data. The complex consists of a packing ofsyn-anti carboxylate-bridged, one-dimensional polymeric chains running parallel to thea axis. Each Mn(II) atom is located at an inversion center, with aqua ligands occupying the trans positions in a slightly distorted octahedron. The chloride ions and aqua ligands are alternately linked by O-HCl hydrogen bonds into a (Cl^–·H₂O) zigzag chain also running parallel to thea axis.