Laser Raman and infrared spectra and normal coordinate analysis of CH3MCl3 (M  Si and Ge)

The vibrational spectroscopic data, including i.r., far-i.r. and Raman spectra, of methyltrichlorosilane CH₃SiCl₃ and methyltrichlorogermane CH₃GeCl₃ have been recorded. All the observed vibrational bands are assigned to vibrational modes. The normal modes of vibration were analysed and calculated and a force field for each of the two compounds is calculated.     

Resonance Raman and infrared spectra of [CH3C5H4NiPh2PC3H6PPh2]·B11H14

Resonance Raman and infrared spectra of (C₂H₅)₄NB₁₁H₁₄ are reported. Based on the appearance of several bands on going from (C₂H₅)₄NCl to (C₂H₅)₄NB₁₁H₁₄, a vibrational assignment is proposed for the B₁₁H⁻₁₄. These results are compared with corresponding results for several other amine boranes. Resonance Raman and infrared spectra of [CH₃C₅H₄NiPh₂PC₃H₆PPh₂]·B₁₁H₁₄ were obtained. An assignment of frequencies to the fundamental modes of vibration has been made for this compound. The Ni-P vibration frequencies are located at about 202 and 177 cm⁻¹. The Ni-MeCp vibration has also been assigned at about 359 and 230 cm⁻¹.     

Vibrational spectra and normal coordinate analysis of CF3 compounds—XVIII [1]. N(SCF3)3—14N and 15N versions

Infrared spectra have been recorded for the two molecules ¹⁴N(SCF₃)₃ and ¹⁵N(SCF₃)₃ in the gas, liquid and solid phases as well as isolated in a noble gas matrix; the Raman spectra of the liquids have also been measured. The removal of the degeneracy of CF₃ and NS₃ vibrations implies a relatively low symmetry for the N(SCF₃)₃ molecule, and the vibrational spectra have been assigned on the basis of a C_s model for the molecule. A normal coordinate analysis including all non-torsional vibrations and based on the structure recently determined by electron diffraction accommodates well the frequencies, isotopic shifts and polarization properties of the vibrational spectra. The ¹⁴N/¹⁵N shifts observed for several low-frequency bands show that the “symmetric” bending mode of the nearly planar NS₃ skeleton is strongly coupled with internal vibrations of the SCF₃ ligands. The vibrational spectrum of the phosphorus analogue N[P(CF₃)₂]₃ is discussed in the light of the present investigation.     

Why are [P(C6H5)4](+)N3- and [As(C6H5)4](+)N3- ionic salts and Sb(C6H5)4N3 and Bi(C6H5)4N3 covalent solids? A theoretical study provides an unexpected answer

A recent crystallographic study has shown that, in the solid state, P(C(6)H(5))(4)N(3) and As(C(6)H(5))(4)N(3) have ionic [M(C(6)H(5))(4)](+)N(3)(-)-type structures, whereas Sb(C(6)H(5))(4)N(3) exists as a pentacoordinated covalent solid. Using the results from density functional theory, lattice energy (VBT) calculations, sublimation energy estimates, and Born-Fajans-Haber cycles, it is shown that the maximum coordination numbers of the central atom M, the lattice energies of the ionic solids, and the sublimation energies of the covalent solids have no or little influence on the nature of the solids. Unexpectedly, the main factor determining whether the covalent or ionic structures are energetically favored is the first ionization potential of [M(C(6)H(5))(4)]. The calculations show that at ambient temperature the ionic structure is favored for P(C(6)H(5))(4)N(3) and the covalent structures are favored for Sb(C(6)H(5))(4)N(3) and Bi(C(6)H(5))(4)N(3), while As(C(6)H(5))(4)N(3) presents a borderline case.     

Raman and infrared spectra and normal coordinate analyses of zirconium and hafnium tetrachloride complexes with phosphoryl chloride,ZrCl4·2POCl3 and HfCl4·2POCl3

The vibrational Raman and i.r. spectra of 1:2 molecular complexes of ZrCl₄ and HfCl₄ with phosphoryl chloride have been recorded in the regions 4000–50 cm⁻¹ and 4000–180 cm⁻¹, respectively. The observed spectral data for powder samples have been analysed by comparison with those of related compounds and the resulting assignments have confirmed their octahedral cis-configurations with two non-equivalent POCl₃ ligands. The normal coordinate calculations have been studied to obtain the Urey—Bradley force constants and the potential energy distribution.     

Crystal structure and Raman spectra of [Fe(H2O)6]3+(ClO 4 ? )3·3H2O

Single crystal X-ray diffraction is used to study the structure of colorless crystals isolated from the saturated aqueous solution of trivalent iron perchlorate (TIP) in 67.5% perchloric acid. It is found that the compound crystallizes in the trigonal crystal symmetry; parameters of the hexagonal unit cell: a = b = 16.079(2) ?, c = 11.369(2) ?, ?? = ?? = 90°, ?? = 120°, space group R{ie907-1}(S ₆), Z = 6, ??_calc = 2.021 g/cm³. The structural form of the crystal hydrate is [Fe(H₂O)₆]³⁺(ClO ₄ ^? )₃·3H₂O. The structure contains two independent complex iron cations. Each of them is in the special position {ie907-2}, but retains the regular octahedral structure: average bond lengths are r(Fe-O) = 1.997(1) ?, {ie907-3}O-Fe-O bond angles differ from 90° by only 0.93°. Independent [Fe(H₂O)₆]³⁺ cations form short H-bonds (O??O 2.64 ?) with three crystallization water molecules and somewhat longer H-bonds (O??O 2.73 ?) with three ClO ₄ ^? anions. The ClO ₄ ^? anion is disordered over two positions with occupancies of 0.62(2) and 0.37(2). Both positions correspond to the general position. The outer-sphere crystallization water molecule is characterized by the tetrahedral direction of H-bonds, which it forms with two anions and two independent [Fe(H₂O)₆]³⁺ cations. All water molecules are in the general position. The Raman spectroscopic study of polycrystalline samples reveals weak bands belonging to the internal vibrations of two types of water molecules. The least broad bands are assigned to the transitions of crystallization water molecules whose symmetry is insignificantly lowered by two anion-molecular Hbonds. Anomalously broad bands are assigned to the transitions of a coordinated water molecule whose symmetry is more lowered by intermolecular and anion-molecular H-bonds.     

Synthesis and Crystal Structure of Copper(I) Chloride π-Complexes with N-Allyl- and N,N'-Diallylpiperazinium Dichlorides: [C3H5NH(CH2)4NH2]Cu2Cl4and [C3H5NH(CH2)4NHC3H5]0.5CuCl2

The crystals of copper(I) π-complexes with N-allyl piperazine derivatives, [C₃H₅NH(CH₂)₄NH₂]Cu₂Cl₄(I) and [C₃H₅NH(CH₂)₄NHC₃H₅]_0.5CuCl₂(II), were prepared by alternating-current electrochemical synthesis. X-ray diffraction study showed that compounds Iand IIcrystallize in the monoclinic system: for I, space group P2₁/a, a= 10.254(4) Å, b= 12.306(4) Å, c= 10.656(4) Å, γ = 98.83(3)°, V= 1329(2) ų, Z= 4, R= 0.0457 for 1334 independent reflections; for II, space group P2₁/n, a= 10.187(2) Å, b= 7.283(2) Å, c= 10.480(3) Å, γ = 100.72(2)°, V= 764.0(6) ų, Z= 4, R= 0.0371 for 1025 independent reflections. The structure of Iis composed of {Cu₂Cl₄(C₇H₁₆N₂)}₂dimers linked by fairly strong (N)H···Cl hydrogen bonds (2.35(4) Å). The structure of IIconsists of centrosymmetrical dimeric Cu₂Cl₄ ^2–anions, whose copper atoms coordinate the allyl groups of different centrosymmetrical organic cations. The dimer–ligand chains are stretched along the [ $ {11} $ 0] direction and are joined by hydrogen contacts (N)H···Cl (2.62(4) Å).     

Crystal structure,DSC and Raman studies in CH3C6H4NH(CH3)2·SbCl4

The salt para methyl phenyl dimethyl ammonium tetrachloroantimonate (III) crystallizes in the monoclinic system with space group Cc. The unit cell dimensions are: a=13.780(1) Å, b=14.943(2) Å, c=8.192(1) Å, β=113.39(1)°, with Z=4. The structure consists of ammonium cations and polynuclear anions in which distorted SbCl₅ square pyramids sharing a common Cl atom are held together in infinite chains parallel to the c axis. These chains are themselves interconnected by means of the NH⋯Cl hydrogen bonds. Differential scanning calorimetry study was carried out. The Raman of polycrystalline samples have been recorded at different temperatures between 77 and 300 K. A low-temperature phase transition at 230 K of order-disorder type was found.     

N,N′-methylenedipyridinium Pt(II) and Pt(IV) hybrid salts: synthesis, crystal and molecular structures of [(C5H5N)2CH2] · [PtCl4] and [(C5H5N)2CH2] · [PtCl6]

The highly insoluble organic-inorganic hybrid ionic compounds N,N??-methylenedipyridinium tetrachloroplatinate(II) [(C₅H₅N)₂CH₂] · [PtCl₄] and N,N??-methylenedipyridinium hexachloroplatinate(IV) [(C₅H₅N)₂CH₂] · [PtCl₆] were obtained by the treatment of N,N??-methylenedipyridinium dichloride monohydrate [(C₅H₅N)₂CH₂]Cl₂ · H₂O with K₂[PtCl₄] or (NH₄)₂[PtCl₆], respectively, in an aqueous solution. Both complexes were isolated, purified, characterised by elemental analysis, and their molecular structures were confirmed by powder X-ray diffraction. The crystal structure of both compounds consists of separated discrete dications [(C₅H₅N)₂CH₂]²⁺ and anions [PtCl _n ]^2? (n = 4 or 6). As anticipated, the dications formed a butterfly shape consisting of two pyridine rings bound to the methylene group via their N atoms, while the Pt centre had a square planar geometry in [(C₅H₅N)₂CH₂] · [PtCl₄] and an octahedral coordination in [(C₅H₅N)₂CH₂] · [PtCl₆]. Interestingly, both crystal structures are stabilised by intermolecular C-H??Cl non-standard hydrogen bonds, ??-?? ring interactions between two pyridine rings of adjacent dications, and also by Cl-?? interactions.     

Magnetic Properties of (C5H6N)5[Fe13O4F24(OCH3)12] · CH3OH · 4H2O

The static magnetic susceptibility of Fe(III) complex [Fe₁₃O₄F₂₄(OCH₃)₁₂]^5– was measured in the temperature range 2–300 K. The structure of the complex consists of four triangular Fe₃ fragments interacting with a central Fe atom. By disregarding weak exchange interactions through F bridges, an analytical solution of the exchange Hamiltonian was obtained with Nf 1.3 × 10¹⁰ levels. This made it possible to perform quantitative interpretation of the temperature dependence of the magnetic susceptibility. The obtained exchange parameters of the best approximation are –2J ₁ = 43 cm^–1, –2J ₂ 30 cm^–1. The ratio J ₂/J ₁ 0.70 suggests that the Fe₁₃ ground state has the spin of the ground state 23/2 or 15/2.     

Furfuryl alcohol—III. Infrared,matrix infrared and Raman spectra and ab initio and normal coordinate calculations

The i.r. spectra of furfuryl alcohol have been recorded for gaseous and liquid states and in argon and nitrogen matrices, and the i.r. spectrum of the OD deuterated analogue has been recorded in an argon matrix. The Raman spectra of the compounds in the liquid state were also recorded. In particular the modes related to the OH and OD vibrations were studied and the results are discussed.Ab initio STO-3G optimizations were carried out on five conformations of furfuryl alcohol. The rotation of the side group around the CC bond seems to be almost free: an ‘orthogonal’ conformer being the most stable form. Normal coordinate calculations were carried out on the most stable C_s conformer, using the general valence force field, and a vibrational assignment is presented. Force constants taken from the literature were employed for the in-plane vibrations of the furane ring, but for its out-of-plane modes a new force field was developed. This also gave good results for furane.     

An infrared and Raman spectroscopic study of Td-type 4,4′-bipyridylcadmium(II) tetracyanometallate (II) benzene (1/2) clathrates: Cd(C10H8N2)Cd(CN)4 · 2C6H6 and Cd(C10H8N2)Hg(CN)4 · 2C6H6

Two new benzene clathrates of the form Cd(4,4-bipyridyl)M(CN)₄ · 2C₆H₆, (M=Cd or Hg) have been prepared in powder form. Their spectral data were compared with those of the corresponding host complexes and found to be consistent with the host structure found in Td-type clathrates.     

The complexation of cadmium acetate and propionate by phenanthroline. Structure and properties of [Cd(CH3COO)2(C12H8N2)(H2O)] · H2O and [Cd(CH3CH2COO)2(C12H8N2)]2 · 2CH3CH2COOH

The coordination compounds [Cd(CH₃COO-κO ¹,O ²)₂(phenanthroline-kN ¹ N ²)(H₂O)] · H₂O (1) and [Cd{μ-(CH₃CH₂COO-κO ¹,O ²)}₂(phenanthroline-κN ¹,N ²)]₂ · 2CH₃CH₂COOH (2) were synthesized and characterized by elemental and thermal analysis and IR spectroscopy. Crystal and molecular structures of both compounds were determined. The complexes are air stable and fairly soluble in water. In both compounds the cadmium is seven-coordinate and contains chelating phenanthroline and two chelating carboxylate groups in the inner coordination sphere. The seventh coordinating oxygen belongs to water in 1 and to bridging carboxylate in 2. All carboxylate groups are bonded unsymmetrically to the central atom. The coordination polyhedra can be described as distorted pentagonal bipyramid (compound 1) and distorted capped tetragonal bipyramid (compound 2). In the structure of 1 intermolecular O(water)–H ··· O (water/carboxylate) hydrogen bonds create a two-dimensional net along the crystallographic a0c plane. Each molecule of 2 is connected to two propionic acid molecules via hydrogen bonds. In both compounds exist π-stacking interactions.     

IR and polarized Raman spectra of K2Mg(SO4)2 · 6H2O

IR and polarized Raman spectra of K₂Mg(SO₄)₂ · 6H₂O have been recorded and analyzed. From the spectra, the vibrations due to SO²⁻₄ ion, the complex [Mg(H₂O)₆]²⁺ and the water molecules have been identified. The splitting of the nondegenerate ν₁ mode of the SO²⁻₄ ion indicates the presence of a factor group interaction between vibrating ions in the crystal. It has been inferred that the angular distortion of SO²⁻₄ is greater than the bond distortion. Separate bands for the three different water molecules have been observed.     

Vibrational spectra and normal coordinate analysis of CF3 compounds—XXXVIII[1]. Trifluoromethylgermanes CF3GeH3-nDn

The gas phase i.r. and liquid phase Raman spectra of CF₃GeH₃, CF₃GeH₂D, CF₃GeHD₂ and CF₃GeD₃ are reported and assigned. The assignments are supported by a normal coordinate analysis yielding ƒ(GeH) 2.70, ƒ(CF) 5.69 and ƒ(GeC) 2.21 [N cm₋₁]. Some perpendicular bands of CF₃GeH₃ have been investigated in the i.r. with a resolution of 0.05 cm⁻¹. The observed fine structure is in agreement with the computed Coriolis ζ constants and Ge isotopic shifts.     

Coordination behavior of 1,4-diallylpiperazinium and 1-allyloxybenzotriazole toward silver(I) in the crystalline π-complexes [Ag2(C4H8N2(C3H5)2(H+)2)(H2O)2(NO3)2](NO3)2 and [Ag(C6H4N3(OC3H5)(NO3))]

Reactions of a solution of AgNO₃ in aqueous methanol with solutions of 1,4-diallylpiperazine (acidified with HNO₃ to pH = 4) and 1-allyloxybenzotriazole in ethanol gave the crystalline silver(I) π-complexes [Ag₂(C₄H₈N₂(C₃H₅)₂(H⁺)₂)(H₂O)₂(NO₃)₂](NO₃)₂ (I) and [Ag(C₆H₄N₃(OC₃H₅)(NO₃))] (II). Their crystal structures were determined by X-ray diffraction. Crystals of complexes I and II are monoclinic, space group P2₁/c; for I: a = 7.053(3)Å, b = 9.389(3)Å, c = 15.488(4)Å, β = 91.60°, V = 1025.3(6)ų, Z = 4; for II: a = 10.650(4)Å, b = 15.062(5)Å, c = 7.412(4)Å, β = 104.20(3)°, V = 1152.6(8)ų, Z = 4. In both structures, the organic components act as bidentate ligands forming with AgNO₃ 34- and 14-membered topological rings, respectively. In complex I, the nearly tetrahedral environment of the Ag(I) atom is made up of the olefinic C=C bond, the O atoms of the nitrate anions, and the water molecule. 1-Allyloxybenzotriazole in structure II causes the deformation of the coordination polyhedron of Ag into a trigonal pyramid via inclusion of the ligand N atom in its coordination sphere. The topological units of the complexes form infinite polymer layers linked by anionic NO ₃ ^? bridges. In structure I, these layers are united through a system of hydrogen bonds into a three-dimensional framework.     

Synthesis of the dimetal compounds [FeW{μ-PPh2 · CH · CH2 C(C6H4Me-4)}(CO)5(η5-C5Me5)] and [FeMo{μ-PPh2 · CH · CH2 · C(C6H4Me-4)}(CO)5(η5-C5H5)]; molecular structure of the iron-tungsten compound

Reactions between diphenyl(vinyl)phosphine and the compounds [FeW(μ-CC₆H₄Me-4)(CO)₅(η⁵-C₅Me₅)] and [FeMo(μ-CC₆H₄Me-4)(CO)₆(η⁵-C₅H₅)] result in a coupling of the vinyl and p-tolylmethylidyne groups at the dimetal centres to produce the PPh₂ · CH · CH₂ · C(C₆H₄Me-4) fragment, which bridges the metal-metal bonds. This was confirmed by an X-ray diffraction study on [FeW{μ-PPh₂ · CH · CH₂ · C(C₆H₄Me-4)}(CO)₅(η⁵-C₅Me₅)].     

An infrared and raman spectroscopic study of pyrazinecadmium (II) tetracyanometalate (II) Benzene (1/1) clathrates: Cd(C4H4N2)Cd(CN)4⁗C6H6 and Cd(C4H4N2)Hg(CN)4⁗C6H6

Two new benzene clathrates of the form Cd(Pyrazine)M(CN)₄C₆H₆, where M = Cd or Hg, have been prepared and their infrared and Raman spectra are reported.