An EXAFS spectroscopic, large-angle X-ray scattering, and crystallographic study of hexahydrated, dimethyl sulfoxide and pyridine 1-oxide hexasolvated mercury(II) ions

The structure of the solvated mercury(II) ion in water and dimethyl sulfoxide has been studied by means of large-angle X-ray scattering (LAXS) and extended X-ray absorption fine structure (EXAFS) techniques. The distribution of the Hg-O distances is unusually wide and asymmetric in both solvents. In aqueous solution, hexahydrated [Hg(OH(2))(6)](2+) ions in a distorted octahedral configuration, with the centroid of the Hg-O distance at 2.38(1) A, are surrounded by a diffuse second hydration sphere with HgO(II) distances of 4.20(2) A. In dimethyl sulfoxide, the six Hg-O and HgS distances of the hexasolvated [Hg{OS(CH(3))(2)}(6)](2+) complex are centered around 2.38(1) and 3.45(2) A, respectively. The crystal structure of hexakis(pyridine 1-oxide)mercury(II) perchlorate has been redetermined. The space group R(-)3 implies six equal Hg-O distances of 2.3416(7) A for the [Hg(ONC(5)H(5))(6)](2+) complex at 100 K. However, EXAFS studies of this compound, and of the solids hexaaquamercury(II) perchlorate and hexakis(dimethyl sulfoxide)mercury(II) trifluoromethanesulfonate, also with six equidistant Hg-O bonds according to crystallographic results, reveal in all cases strongly asymmetric Hg-O distance distributions. Vibronic coupling of valence states in a so-called pseudo-Jahn-Teller effect probably induces the distorted configurations.     

Studies of molybdenum thiolato-complexes. The crystal and molecular structures of two triply bridged Mo(V) dimers, [Bu 4 n N][Mo2O2Cl5(SPh)2] and [Mo2O3(SPh)2(S2CNMe2)2]

Summary The complex [Bu ₄ ⁿ N][Mo₂O₂Cl₅(SPh)₂] has been prepared by reaction of [Bu ₄ ⁿ N][MoO(SPh)₄] with stoichiometric amounts of HCl and characterised by single crystal X-ray structure analysis. The dimer is bridged by two oxo-groups and one chloride and each Mo has pseudo-octahedral co-ordination. The related compound [Mo₂O₃(SPh)₂(S₂CNMe₂)₂] was synthesised by reaction of [MoO₂(S₂CNMe₂)₂] with thiophenol in methanol and has also been characterised crystallographically. In this case the triple-bridge consists of two thiophenolate sulphurs and one oxo-group, each molybdenum having pseudo-octahedral geometry. These structures are compared with other triply-bridged species.     

Structure and dynamics of halogenoethanol-water mixtures studied by large-angle X-ray scattering, small-angle neutron scattering, and NMR relaxation

To clarify the structure of solvent clusters formed in halogenoethanol-water mixtures at the molecular level, large-angle X-ray scattering (LAXS) measurements have been made at 298 K on 2,2,2-trifluoroethanol (TFE), 2,2,2-trichloroethanol (TCE), and their aqueous mixtures in the TFE and TCE mole fraction ranges of 0.002 < or = x(TFE) < or = 0.9 and 0.5 < or = x(TCE) < or = 0.9, respectively. The radial distribution functions (RDFs) for TFE-water mixtures have shown that the structural transition from inherent TFE structure to the tetrahedral-like structure of water takes place at x(TFE) approximately 0.2. In the TCE-water mixtures inherent TCE structure remains in the range of 0.5 < or = x(TCE) < or = 1. Small-angle neutron scattering (SANS) experiments have been performed on CF(3)CH(2)OD- (TFE-d(1)-) D(2)O and CF(3)CD(2)OH- (TFE-d(2)-) H(2)O mixtures in the TFE mole fraction range of 0.05 < or = x(TFE) < or = 0.8. The SANS results in terms of the Ornstein-Zernike correlation length have revealed that TFE and water molecules are most heterogeneously mixed with each other in the TFE-water mixture at x(TFE) approximately 0.15, i.e., both TFE clusters and water clusters are most enhanced in the mixture. To evaluate the dynamics of TFE and ethanol (EtOH) molecules in TFE-water and ethanol-water mixtures, respectively, (1)H NMR relaxation rates for the methylene group within alcohol molecules have been measured by using an inversion-recovery method. The alcohol concentration dependence of the relaxation rates for the TFE-water and ethanol-water mixtures has shown a break point at x(TFE) approximately 0.15 and x(EtOH) approximately 0.2, respectively, where the structural transition from alcohol clusters to the tetrahedral-like structure of water takes place. On the basis of the present results, the most likely structure models of solvent clusters predominantly formed in TFE-water and TCE-water mixtures are proposed. In addition, effects of halogenation of the hydrophobic groups on clustering of alcohol molecules are discussed from the present results, together with the previous ones for ethanol-water and 1,1,1,3,3,3-hexafluoro-2-propanol- (HFIP-) water mixtures.     

High pressure study of Ru3(CO)12 by X-ray diffraction, Raman, and infrared spectroscopy

The single-crystal X-ray structure of Ru(3)(CO)(12) is reported at 8 pressures ranging from 1 atm (0.0 GPa) to 8.14(5) GPa. Although intramolecular bonding parameters remain relatively constant, intramolecular and intermolecular nonbonding contact distances decrease by an average of 4% and 15%, respectively. At 8.14 GPa, O...O, C...O, and C...C intermolecular distances as short as 2.54(4), 2.64(6), and 3.07(4) A, respectively, are observed, and the unit cell compresses to 75% of the ambient pressure volume. Raman and infrared spectroscopic measurements show that carbonyl stretching frequencies shift to higher wavenumber values by as much as 80 cm(-)(1), even though Ru-C and C-O distances stay roughly constant throughout the entire pressure range studied. Compression of the sample to above 18 GPa with laser radiation results in an irreversible transformation due to either decomposition or a total collapse of D(3)(h) molecular geometry accompanied by color darkening.     

Thermal properties and mixing state of ethylene glycol-water binary solutions by calorimetry, large-angle X-ray scattering, and small-angle neutron scattering

Thermal properties and mixing states of ethylene glycol (EG)-water binary solutions in the entire mole fraction range of EG, 0 < or = x(EG) < or = 1, have been clarified by using differential scanning calorimetry (DSC), large-angle X-ray scattering (LAXS), and small-angle neutron scattering (SANS) techniques. The DSC curves obtained have shown that the EG-water solutions over the range of EG mole fraction 0.3 < or = x(EG) < or = 0.5 are kept in the supercooling state until approximately 100 K, and those in the range of 0.6 < or = x(EG) < or = 0.8 are vitrified, and those in the ranges of 0 < x(EG) < or = 0.2 and 0.9 < or = x(EG) < 1 are crystallized. The radial distribution function (RDF) for pure EG obtained from the LAXS measurements has suggested that a gauche conformation of an EG molecule is favorable in the liquid. The RDFs for the EG-water solutions have shown that the structure of the binary solutions moderately changes from the inherent structure of EG to the tetrahedral-like structure of water when the water content increases. The SANS intensities for deuterated ethylene glycol (HOCD2CD2OH) (EGd4)-water solutions at x(EG) = 0.4 and 0.6 have not been significantly observed in the temperature range from 298 to 173 K, showing that EG and water molecules are homogeneously mixed. On the other hand, the SANS intensities at x(EG) = 0.2 and 0.9 have been strengthened when the temperature decreases due to crystallization of the solutions. On the basis of all the present results, a relation between thermal properties of EG-water binary solutions and their mixing states clarified by the LAXS and SANS measurements has been discussed at the molecular level.     

Anion-cation charge-transfer properties and spectral studies of [M(phen)3][Cd4(SPh)10] (M = Ru, Fe, and Ni)

Three anion-cation compounds 1-3 with formula [M(phen)(3)][Cd(4)(SPh)(10)]·Sol (M = Ru(2+), Fe(2+), and Ni(2+), Sol = MeCN and H(2)O) have been synthesized and characterized by single-crystal analysis. Both the cations and anion are well-known ions, but the properties of the co-assembled compounds are interesting. Molecular structures and charge-transfer between the cations and anions in crystal and even in solution are discussed. These compounds are isomorphous and short inter-ion interactions are found in these crystals, such as π···π stacking and C-H···π contacts. Both spectroscopic and theoretical calculated results indicate that there is anion-cation charge-transfer (ACCT) between the Ru-phen complex dye and the Cd-SPh cluster, which plays an important role in their photophysical properties. The intensity of the fluorescent emission of the [Ru(phen)(3)](2+) is enhanced when the cation interacts with the [Cd(4)(SPh)(10)](2-) anion. The mechanism for the enhancement of photoluminescence has been proposed.     

Synthesis,characterization, X-ray structure and DFT calculation of two Mo(VI) and Ni(II) Schiff-base complexes

In this study, the syntheses of two new Mo(VI) and Ni(II) complexes with H₂L tridentate (ONO) Schiff-base ligand have been described and fully characterized by means of elemental analysis, FT–IR, electronic, ¹H-NMR spectroscopy and single-crystal X-ray diffraction. In both complexes, the Schiff-base completely deprotonates and coordinates to the metal ion as a dianionic tridentate ligand via the donor oxygens and nitrogen atoms. The coordination numbers of Mo(VI) and Ni(II) are six and four, respectively. The DFT-B3LYP/6–31 + G (d,p) and PBEPBE/6–31 + G (d,p) calculations are carried out for the determination of the optimized structures. Frequency calculations and NBO analysis are also performed for characterization. According to the theoretical analysis of the complexes, ligand-to-metal donation is greater than back donation. NBO data revealed that the main contribution of the frontier orbitals belongs to L⁻².     

Solvation of the bismuth(III) ion by water, dimethyl sulfoxide, N,N'-dimethylpropyleneurea, and N,N-dimethylthioformamide. An EXAFS, large-angle X-ray scattering, and crystallographic structural study

The structure of the solvated bismuth(III) ion in aqueous, dimethyl sulfoxide, N,N'-dimethylpropyleneurea, and N,N-dimethylthioformamide solution has been studied by means of EXAFS and large-angle X-ray scattering (LAXS). The crystal structures of the solid compounds octakis(dimethyl sulfoxide)bismuth(III) perchlorate, [Bi(OS(CH3)2)8](ClO4)3, hexakis(N,N'-dimethylpropyleneurea)bismuth(III) perchlorate, [Bi(OCN2(CH2)3(CH3)2)6](ClO4)3, and nonaaquabismuth(III) trifluoromethanesulfonate, [Bi(H2O)9](CF3SO3)3 (redetermination), have been determined. The aqueous solutions must be strongly acidic, since the hydrated bismuth(III) ion starts to hydrolyze into Bi6O4(OH)4(6+) complexes already at an excess of strong acid at 1.0 mol.dm-3. For very acidic aqueous perchlorate solutions, the LAXS and EXAFS data gave a satisfactory fit for eight-coordination of the bismuth(III) ion, with a mean Bi-O bond distance of 2.41(1) A. The crystal structure of octakis(dimethyl sulfoxide)bismuth(III) perchlorate shows that the bismuth(III) ion coordinates eight dimethyl sulfoxide molecules via the oxygen atoms in a distorted square antiprismatic configuration. The mean Bi-O bond distance is 2.43 A and the mean Bi...S distance 3.56 A. For the dimethyl sulfoxide solution, the corresponding mean distances were found to be 2.411(6) and 3.535(12) A. The N,N'-dimethylpropyleneurea-solvated bismuth(III) ion is octahedrally coordinated in both solid state and solution with the Bi-O bond distances of 2.324(5) and 2.322(3) A, respectively. The bismuth(III) ion is six-coordinated in the sulfur donor solvent N,N-dimethylthioformamide with a mean Bi-S bond distance of 2.794(8) A. A comparison with the structure of the solvated lanthanum(III) ion shows that the bismuth(III) ion is smaller for all coordination numbers. New effective ionic radii for the bismuth(III) ion in different coordination numbers are proposed, based on results in this study and in the literature.     

Steric effects control the structure of the solvated lanthanum(III) ion in aqueous, dimethyl sulfoxide, and N,N'-dimethylpropyleneurea solution. An EXAFS and large-angle X-ray scattering study

The structure of the solvated lanthanum(III) ion has been determined in aqueous, dimethyl sulfoxide, and N,N'-dimethylpropyleneurea solution by means of the EXAFS and large-angle X-ray scattering (LAXS) techniques. The close agreement between the EXAFS spectra of solid nonaaqualanthanum(III) trifluoromethanesulfonate and of an aqueous lanthanum(III) perchlorate solution shows that the hydrated lanthanum(III) ion in aqueous solution most probably has the same structure as in the solid, i.e., nine water molecules coordinated in a tricapped trigonal prismatic configuration. The data analysis from EXAFS and LAXS measurements of the aqueous solution resulted in the La-O bond distances 2.52(2) and 2.65(3) A to the water molecules in the prism and the capping positions, respectively. The LAXS study shows a second hydration sphere consistent with approximately 18 water molecules at 4.63(2) A. The EXAFS spectra of solid octakis(dimethyl sulfoxide)lanthanum(III) trifluoromethanesulfonate and a dimethyl sulfoxide solution of this salt are also similar. The data analysis of EXAFS and LAXS measurements assuming eight-coordination around lanthanum yielded an La-O bond distance of 2.50(2) A, and an La...S distance of 3.70(3) A, giving an La-O-S angle of 133(2) degrees. The EXAFS data of an N,N'-dimethylpropyleneurea solution of lanthanum(III) trifluoromethanesulfonate gave the La-O bond distance 2.438(4) A and the La...C distance 3.41(2) A, which correspond to an La-O-C angle of 131(2) degrees. The La-O bond distance is consistent with seven-coordination around lanthanum, on the basis of the variation of the ionic radii of the lanthanum(III) ion with different coordination numbers.     

Thermal properties and mixing state of diol-water mixtures studied by calorimetry, large-angle X-ray scattering, and NMR relaxation

Differential scanning calorimetry (DSC) has been performed on aqueous mixtures of three diols, which involve a linear carbon chain, HO-(CH 2) n -OH ( n = 3, 4, and 5), over the whole mole fraction range of diols. The DSC results have shown the alkyl chain parity for the freezing process of the aqueous mixtures: aqueous mixtures of 1,3-propanediol (PrD) and 1,5-pentanediol (PeD) are kept in the supercooled state or vitrified over a wide mole fraction range, while those of 1,4-butanediol (BuD) are easily crystallized. The structure of PrD-water mixtures has been elucidated by using the large-angle X-ray scattering (LAXS) technique. It has been suggested that the structural change of PrD-water mixtures occurs at PrD mole fractions of x PrD = 0.4 and 0.8: in the range of x PrD < or = 0.4 where the tetrahedral-like structure of water predominates, in the range of 0.4 < x PrD < 0.8 where both PrD and water structures coexist, and in the range of x PrD > or = 0.8 where the inherent structure of PrD is mainly formed. (17)O and (1)H NMR relaxation measurements have been made on aqueous mixtures of ethylene glycol (EG, n = 2), PrD, and BuD to clarify the dynamics of H 2 (17)O and diol molecules. The (17)O NMR relaxation rates have suggested that the rotational motion of water molecules is gradually retarded in the diol-water mixtures with increasing diol content and that the restriction of the motion is more remarkable in the order of EG < PrD < BuD. On the basis of all the results, together with comparison with those of methanol-water, ethanol-water, and 1-propanol-water mixtures previously reported, the mixing state of diol-water mixtures has been discussed at the molecular level.     

The hydration of the scandium(III) ion in aqueous solution and crystalline hydrates studied by XAFS spectroscopy, large-angle X-ray scattering and crystallography

The structures of the hydrated scandium(III) ion and of the hydrated dimeric hydrolysis complex, [Sc2(mu-OH)2]4+, in acidic aqueous solutions have been characterized by X-ray absorption fine structure (XAFS) and large-angle X-ray scattering (LAXS) methods. Comparisons with crystalline reference compounds containing hydrated scandium(III) ions in well characterized six-, seven- and eight-coordinated polyhedra have been used to evaluate the coordination numbers and configurations in aqueous solution. In strongly acidic aqueous solution the structure of the hydrated scandium(III) ion is found to be similar to that of the eight-coordinated scandium(III) ion with distorted bicapped trigonal prismatic coordinating geometry in the crystalline [Sc(H2O)(8.0)](CF3SO3)3 compound. The EXAFS data reveal for the solution, as for the solid, a mean Sc-O bond distance of 2.17(1) Angstrom to six strongly bound prism water molecules, 2.32(4) Angstrom to one capping position, with possibly another capping position at about 2.5 Angstrom. The LAXS study supports this structural model and shows furthermore a second hydration sphere with approximately 12 water molecules at a mean Sc...O(II) distance of 4.27(3) Angstrom. In less acidic concentrated scandium(III) aqueous solutions, the dimeric hydrolysis product, [Sc2(mu-OH)2(H2O)10]4+, is the predominating species with seven-coordinated scandium(III) ions in a double hydroxo bridge and five terminal water molecules at a mean Sc-O bond distance of 2.145 Angstrom. Hexahydrated scandium(III) ions are found in the crystal structure of the double salt [Sc(H2O)6][Sc(CH3SO3)6], which crystallizes in the trigonal space group R3[combining macron] with Z = 6 and the unit cell dimensions a = 14.019(2) and c = 25.3805(5) Angstrom. The Sc-O distances in the two crystallographically unique, but nearly identical, [Sc(H2O)6]3+ entities (both with 3[combining macron] imposed crystallographic symmetry) are 2.085(6) and 2.086(5) Angstrom, while the mean Sc-O distance in the near octahedral [Sc(OSO2CH3)6]3- entities (with three-fold symmetry) is 2.078 Angstrom.     

On the molecular mobility in amorphous polymers, inorganic glasses, and amorphous metal alloys in the glass transition range

The transition of kinetic units (atoms or groups of atoms) in amorphous media from one quasi-equilibrium state to another is determined by fluctuations of both energy and entropy of the system. In the glass transition range of liquids and polymers, the entropic mechanism plays a determining role: the fluctuation of packing of particles turns out to be more important than accumulation of energy. Above the glass transition range, the energy mechanism begins to play a dominant role. The procedure that is currently used to calculate the constant for the Bartenev equation, which relates the relaxation time to the cooling rate at the glass transition temperature, leads to overestimated values. A procedure for the calculation of this parameter was proposed with allowance for the temperature dependence of the entropy of activation in the region of the liquid-glass transition. The use of this equation in the relaxation spectrometry of amorphous polymers, inorganic glasses, and amorphous metal alloys is discussed.     

Liquid structure of acetic acid-water and trifluoroacetic acid-water mixtures studied by large-angle X-ray scattering and NMR

The structures of acetic acid (AA), trifluoroacetic acid (TFA), and their aqueous mixtures over the entire range of acid mole fraction xA have been investigated by using large-angle X-ray scattering (LAXS) and NMR techniques. The results from the LAXS experiments have shown that acetic acid molecules mainly form a chain structure via hydrogen bonding in the pure liquid. In acetic acid-water mixtures hydrogen bonds of acetic acid-water and water-water gradually increase with decreasing xA, while the chain structure of acetic acid molecules is moderately ruptured. Hydrogen bonds among water molecules are remarkably formed in acetic acid-water mixtures at xA相似文献   

Polymere Thiolatokomplexe [M(SPh)3]∞ der Metalle Molybdän,Wolfram, Eisen und Ruthenium mit linearen Metallketten. Synthese und Struktur von (OC)3Fe(SPh)3Fe(SPh)3Fe(CO)3 · 2(CH3)2CO

Polymeric Thiolato Complexes [M(SPh)₃]∞ of the Metals Mo, W, Fe, and Ru with Linear Metal Chains. Synthesis and Crystal Structure of (OC)₃Fe(SPh)₃Fe(SPh)₃Fe(CO)₃ · 2(CH₃)₂CO At high temperature the reaction of the metal carbonyls Mo(CO)₆, W(CO)₆ and Fe(CO)₅ with S₂Ph₂ (Ph = C₆H₅) yields the polymeric complexes [M(SPh)₃]∞. Similarly [Ru(SPh)₃]∞ can be obtained from ruthenium(III) acetylacetonate and HSPh. At room temperature under UV-irradiation Fe(CO)₅ reacts with S₂Ph₂ to form the oligomeric complex (OC)₃Fe(SPh)₃Fe(SPh)₃Fe(CO)₃. The polymeric complexes [M(SPh)₃]∞ (M = Mo, W, Fe, Ru) are composed of linear chains with bridging SPh-ligands between the metal atoms. Of these complexes [Fe(SPh)₃]∞ is paramagnetic, whereas the others exhibit antiferromagnetic behaviour. The spin coupling is presumably connected with the formation of metal pairs, resulting in alternating shortened and extended distances in the metal chain. The oligomeric complex (OC)₃Fe(SPh)₃Fe(SPh)₃Fe(CO)₃ crystallizes triclinic in the space group P1 with z = 2. It has almost the symmetry D_3d with a linear arrangement of the Fe atoms. The paramagnetism of Fe₃(CO)₆(SPh)₆ can be explained by a d⁶ high spin configuration of the central atom and low spin behaviour of the two other Fe atoms, which are bonded to CO.     

Heterobimetallic, cubane-like Mo(3)S(4)M' cluster cores containing the noble metals M' = Ru, Os, Rh, Ir. Unprecedented tri(mu-carbonyl) bridge between ruthenium atoms in [(eta(5)-Cp')(3)Mo(3)S(4)Ru)2(mu-CO)3]2+

Reaction of the methylcyclopentadienyl (Cp') cluster compound [(eta(5)-Cp')(3)Mo(3)S(4)][pts] (pts = p-toluenesulfonate) with noble metal alkene complexes resulted in the formation of four new heterobimetallic cubane-like Mo(3)S(4)M' cluster cores (M' = Ru, Os, Rh, Ir). Thus, reaction with [(1,5-cod)Ru(CO)(3)] or [(1,3-cod)Os(CO)(3)] (cod = cyclooctadiene) afforded [(eta(5)-Cp')(3)Mo(3)S(4)M'(CO)(2)][pts] (M' = Ru: [1][pts]; M' = Os: [2][pts]). When [1][pts] was kept in CH(2)Cl(2)/pentane solution, partial loss of carbonyl ligands occurred and the carbonyl-bridged dicubane cluster [((eta(5)-Cp')(3)Mo(3)S(4)Ru)(2)(mu-CO)(3)][pts](2) was isolated. An X-ray crystal structure revealed the presence of the hitherto unobserved Ru(mu-CO)(3)Ru structural element. The formation of cluster compounds containing Mo(3)S(4)Rh and Mo(3)S(4)Ir cores was achieved in boiling methanol by reacting [(eta(5)-Cp')(3)Mo(3)S(4)][pts] with [M'Cl(cyclooctene)(2)](2) (M' = Rh, Ir) in the presence of PPh(3). In this way [(eta(5)-Cp')(3)Mo(3)S(4)M'Cl(PPh(3))][pts] (M' = Rh, Ir) could be isolated. An alternative route to the Mo(3)S(4)Rh cluster core was found in the reaction of [(eta(5)-Cp')(3)Mo(3)S(4)][pts] with [RhCl(1,5-cod)](2), which yielded [(eta(5)-Cp')(3)Mo(3)S(4)Rh(cod)][pts](2) ([7][pts](2)). Substitution of the cod ligand in [7][pts](2) by 1,3-bis(diphenylphosphanyl)propane (dppp) gave [(eta(5)-Cp')(3)Mo(3)S(4)Rh(dppp)][pts](2).     

Crystal structure of lead(II) acetylacetonate and the structure of the acetylacetone solvated lead(II) ion in solution studied by large-angle X-ray scattering

The crystal structure of bis(acetylacetonato)lead(II) and the structure of the acetylacetone solvated lead(II) ion in solution have been determined by single-crystal X-ray diffraction and large-angle X-ray scattering (LAXS), respectively. The acetylacetone is deprotonated and acts as a bidentate anionic ligand (acac-) in the solid Pb(acac)2 compound. The lead(II) ion binds four oxygen atoms strongly in a nearly flat pyramidal configuration with Pb-O bond lengths in the range 2.32-2.37 A, and additionally three oxygens from neighboring complexes at 3.01-3.26 A. Acetylacetone acts as a solvent (Hacac) at dissolution of lead(II) trifluoromethanesulfonate forming a pentasolvate with a mean Pb-O bond distance of 2.724(5) A. The 6s2 lone electron pair on the lead(II) ion becomes stereochemically active in the crystalline acetylacetonate complex, while it is inactive in the solvate in solution. The solution was also analysed using IR and 1H NMR spectroscopy.     

Structure of amorphous poly-(ethylmethacrylate): a wide-angle x-ray scattering study

The local, temperature dependent structure of poly-(ethylmethacrylate) was studied with wide-angle x-ray scattering. The results were set into context to recent wide-angle neutron scattering results as well as to the results from a multitude of studies of the dynamics of this polymer. The temperature dependence of the wide angle x-ray results point to the development of local order which is backed by the neutron scattering results and which is connected to characteristic temperatures of the relaxation dynamic T(g) and T(c). The poly-(ethylmethacrylate) was studied in its predominantly syndiotactic as well as predominantly isotactic state displaying vastly different local structures as manifested in the x-ray results.