Fernando Scordari

THE BETTI BASE : ABSOLUTE CONFIGURATION AND ROUTES TO A FAMILY OF RELATED CHIRAL NONRACEMIC BASES

Abstract A detailed protocol for the resolution of the Betti base [i.e. 1-(α-aminobenzyl)-2-naphthol] was investigated and the absolute configuration of the two isomers was established by means of an X-ray diffractometric study. A series of optically active derivatives was also prepared. The list includes the N-benzyl- and the N,N,O-trimethyl derivatives. The N,N-dimethyl derivative was prepared in racemic form by means of the Betti reaction and was resolved into the two enantiomers with an extremely easy and efficient procedure. The O-methyl derivative was prepared in a racemic form and subjected to resolution. The configuration of each base was determined by correlation with the configuration of the Betti amine.

Synthesis and Crystal Structure of Bis(2,3‐dihydro‐3‐methylbenzothiazole‐2‐ylidene)palladium(II) Diiodide: The First Palladium Complex with Benzothiazole Carbene Ligands Suitable for Homogeneous Catalysis

The first diiodo palladium complex with nucleophilic benzothiazole carbenes as ligands has been synthesized and characterized. The complex, which is extraordinarily stable towards heat, oxygen, and moisture, has been found to show good catalytic activity in the Heck coupling reaction.

Crystal chemistry of kimzeyite from Anguillara, Mts. Sabatini, Italy

A single garnet crystal of kimzeyite from Anguillara Sabazia, Sabatini Volcanic District (Rome), has been studied by electron probe microanalysis (EPMA), single crystal X-ray diffraction (XRD) and Raman spectroscopy (RS). X-ray intensities for the structure refinement were collected by means of both a conventional four circle diffractometer (CD) and an area detector (AD) diffractometer. Salient crystallographic data from AD measurements are: a = 12.397(4) A, V = 1905.24 A 3 , μ= 25 cm −1 , crystal dimension ∼ 40 μm, D x =3.83 g cm −3 . The chemical analyses allowed to ascertain that Ca, Ba, Fe, Al, Mg, REE, Zr, Si and Ti are present in the structure. The transition element distribution is: Fe 3+ (Y) ≪ Fe 3+ (Z), and Ti as Ti 4+ occurs only at Y. No hydrogen atoms were detected. The problem of the correct distribution of Ba and REE (essentially Eu and Gd) is dealt with, but not fully solved in the present study. Because of the very small amount of sample available and of the strong dilution of Ba and REE (∼0.03 and 0.02 atoms per formula unit respectively) the correct distribution of these atoms over the X and Y sites is problematical. The radius ratio rule and electrostatic requirements suggest Ba at X and REE at Y. From these principles, the following site distribution can be deduced: Ca 2+ and Ba 2+ at X; Mg 2 +, REE 3+ , Zr 4+ , Ti 4+ , Fe 3+ at Y; Si 4+ , Al 3+ , Fe 3+ at Z. On the other hand, structural details and the best fit between EPMA and XRD site populations indicate REE at X and Ba at Y. Bond strength theory arguments support this hypothesis. The main substitution mechanisms can be summed up as follows: 1) Ti 4+ (Y) + Fe 3+ (Z) ↔ Si 4+ (Z) + M 3+ (Y) [schorlomite substitution]; 2) Zr 4+ (Y) + M 3+ (Z) ↔ Si 4+ (Z) + M 3+ (Y) [kimzeyite substitution]; 3) Mg 2+ (Y) + Zr 4+ (Y) ↔ 2M 3+ (Y) [morimotoite-like substitution], where M 3+ = (Al, Fe). In addition, following the bond strength theory indications, another mechanism which possibly involves the X and Y sites is also taken into account: 4) REE 3+ (X) + Ba 2+ (Y) ↔ Ca 2+ (X) + M 3+ (Y).

Ti-rich phlogopite from Mt. Vulture (Potenza, Italy) investigated by a multianalytical approach : substitutional mechanisms and orientation of the OH dipoles

Trioctahedral mica samples, collected at Cava St. Antonio (Mt. Vulture, Italy) were studied by combining electron-microprobe and C-H-N elemental analyses, single-crystal X-ray diffraction refinement, Mossbauer and Fourier transform infrared spectroscopies. Electron-microprobe analyses show the crystals to be quite homogeneous with TiO 2 ∼3 wt% and F ranging from 0.42 to 0.59 wt%. Quantitative analyses of H combined with ferric/ferrous ratios from Mossbauer data allowed reliable crystal-chemical formulae to be derived. The results suggest that the entry of both Ti 4+ and Fe 3+ in the structure occurs through R-oxy substitution mechanisms involving deprotonation at O(4). This inference is supported by X-ray structure-refinement results (notably the c cell-parameter, the off-centering of the M2 cation towards O(4), the bond-length distortions of the cis -M2 octahedron) obtained using anisotropic thermal parameters in space group C2/ m . The amount of oxy-substitutions from both electron-microprobe and X-ray data is in agreement with carbon-hydrogen-nitrogen analyses which give an average anion composition (OH 1.25 O 0.65 F 0.10 ). Polarized-light infrared spectroscopy shows a complex OH-stretching spectrum which is composed of several overlapping (at least five) components. These can be assigned to the main octahedral local configurations that are compatible with the chemical composition. Pleochroic Fourier transform infrared spectroscopy measurements done along the principal optical directions show that the O-H bond axis is tilted from [001] and provide the average orientation of the O-H dipole in the structure: O-H ⁁ α ∼ 23° and O-H ⁁ γ ∼ 56°.

Fluorophlogopite from Biancavilla (Mt. Etna, Sicily, Italy): Crystal structure and crystal chemistry of a new F-dominant analog of phlogopite

Abstract Fluorophlogopite, a new F-dominant mineral of the mica group, was found at Monte Calvario, Biancavilla, lower southwestern flanks of Mt. Etna volcano (Catania, Sicily, Italy). The mineral occurs in autoclasts of gray-red altered benmoreitic lavas, primarily associated with fluoro-edenite, alkali-feldspars, clino- and ortho-pyroxenes, fluorapatite, hematite, and pseudobrookite. It was formed by metasomatism of the original lava rocks from very hot fluid enriched in F, Cl, and other incompatible elements. Fluorophlogopite occurs as very thin laminae with a diameter of 200 to 400 μm. Main physical properties are pale yellow in color; yellowish-white in thin section; vitreous to resinous luster; transparent; non-fluorescent; Mohs’ hardness 2-3; brittle and malleable; perfect cleavage on {001}; biaxial (-), αcalc = 1.5430(8), β = 1.5682(5), γ = 1.5688(5) (λ = 589 nm); 2Vmeas = 17(2)°; α = acute bisectrix ⊥ (001); nonpleochroic; Dcalc = 2.830 g/cm3 (using empirical formula and single-crystal unit-cell parameters), Dcalc = 2.842 g/cm3 (using empirical formula and powder cell constants). Infrared spectrum did not show a significant absorption band in the OH-stretching region (3800-3600 cm-1) confirming that the F content of the fluorophlogopite from Biancavilla is close to the stoichiometric value. Unit-cell parameters from X-ray powder-diffraction data (114.6 mm diameter Gandolfi camera, CuKα) are a = 5.305(2), b = 9.189(3), c = 10.137(4) Å, β = 100.02(3)°. These data agree with those obtained by single-crystal X-ray studies on a very thin (~15 μm) fluorophlogopite crystal, i.e., Monoclinic (1M polytype); Space Group C2/m; a = 5.3094(4), b = 9.1933(7), c = 10.1437(8) Å, β = 100.062(5)°, V = 487.51(6) Å3, Z = 2. Structure refinements using anisotropic displacement parameters converged at R = 3.50, Rw = 4.37, Rsym = 3.72%. Electron microprobe analysis performed on the same crystal used for X-ray investigation gave: SiO2 = 45.75(39), TiO2 = 1.05(5), Al2O3 = 9.60(19), MgO = 27.92(30), MnO = 0.16(3), FeOtot = 1.25(6), BaO = 0.09(5), K2O = 8.22(11), Na2O = 0.61(30), Cl = 0.02(1) wt%. Secondary Ion Mass Spectrometry (SIMS) was used to estimate light elements [Li2O = 0.30(1) and H2O = 0.16(2) wt%] and fluorine content [F = 8.69(24) wt%]. The new mineral fluorophlogopite and its name were approved by IMA-CNMMN (2006/011).

Cation-site partitioning in Ti-rich micas from Black Hill (Australia): A multi-technical approach

The crystal chemistry of Ti-rich trioctahedral micas of plutonic origin, cropping out at Black Hill (South Australia) has been investigated by combining electron microprobe analysis, single crystal X-ray diffraction, Mössbauer spectroscopy and X-ray photoelectron spectroscopy. Chemical analyses have shown the samples taken to be quite homogeneous and Ti-rich (TiO2 ≈ 7 wt.%). Mössbauer investigation yielded Fe2+/Fe3+ ≈ 30. X-ray photoelectron spectroscopy analysis seems to suggest the occurrence of three Ti species: octahedral Tr4+(60%), octahedral Ti3+(26%), and tetrahedral Ti4+(14%). The analyzed sample belongs to the 1M polytype and the relevant crystal data from structure analysis are: a = 5.347(1) Å, b = 9.261(2) Å, c = 10.195(2) Å, β = 100.29°(1). Anisotropic structure refinement was performed in space group C2/m, and converged at R = 2.62, Rw = 2.80. Structural details (the c cell parameter, the off-center shift of the M2 cation towards 04, the bond-length distortions of the cis-M2 octahedron, the interlayer sheet thickness, the projection of K−O4 distance along c*, the difference outer-inner) support the occurrence of the Ti-oxy substitution (VIR2+ + 2(OH)− ⇌ Ti4+ + 202− + H2) in the sample. Analysis of structural distortions as a function of the Ti content revealed that the positions of the oxygens 03 and 04 are displaced in opposite senses along [100]. This produces an enlargement of the M1 site with respect to the M2 site and a shortening of the interlayer distance. This trend seems to be in common with other Ti-rich 1M micas of plutonic origin.

XRD, micro-XANES, EMPA, and SIMS investigation on phlogopite single crystals from Mt. Vulture (Italy)

Abstract Selected phlogopite flakes from Mt. Vulture in southern Italy were studied using a combination of single-crystal techniques: electron microprobe analysis (EMPA), secondary ion mass spectrometry (SIMS), single-crystal X-ray diffraction (SCXRD), and micro-X-ray absorption near-edge spectroscopy (XANES). The latter technique was employed to analyze the structure of the Fe-K absorption edge over the region from 7080-8100 eV and to determine Fe3+/∑Fe at a micrometer scale, albeit with large error bars due to known effects of orientation on pre-edge energy. The annite component, Fe/(Mg-i-Fe), of the samples studied ranged from 0.16 to 0.31, the Ti content from 0.11 to 0.27 atoms per formula unit (apfii) and the Ba content from 0.03 to 0.09 apfu. SIMS analysis showed H2O (wt%) = 1.81-3.30, F (wt%) = 0.44-1.29, and Li2O (wt%) = 0.001-0.027. The intra single-crystal chemical variability for major/minor elements (Mg, Fe, Al, Ba, Ti, and K) was found particularly significant for samples VUT191_11 and PG5_1, less significant for the other samples of the set. SIMS data relative to crystals VUT187_24, VUT191_10, VUT191_11, and VUT187_28 showed a noteworthy variation in the concentrations of some light elements (H, Li, and F) with coefficient of variation CV (as 1σ%) up to -18% for H2O. The analyzed micas belong to the 1M polytype. Structure refinements using anisotropic displacement parameters were performed in space group Clim and converged at 3.08 <R < 3.63,3.32 <RW < 3.98%. Micro-XANES results yielded Fe3+/£Fe from 51-93%. Previous Mossbauer data from powdered samples suggested Fe3+/∑Fe values ranging from 49-87%. However, the Fe3+ content determined by both techniques is sometimes remarkably different, in part because of the large errors (±10-15%) presently associated with the micro-XANES technique and m part because the Fe3+ content of a single crystal may significantly depart from the average value obtamed from routine Mossbauer analysis. The combination of EMPA, SIMS, and micro-XANES resulted in the characterization of the samples at a comparable spatial scale. By means of in-situ data and the results of crystallographic investigations, the occurrence of different relative amounts of M3*-oxy [VIM2+ + (OH)- ↔ VIM3+ + O2- + ½H2↑], Ti-oxy substitutions [VIM2+ + 2(OH)- ↔VITi4+ + 2O2- + H2↑], and Ti-vacancy (⃞) substitution (2VIM2+ ↔ + VITi4+ + VI⃞) was ascertained for the studied samples.

Thermal behavior of a Ti-rich phlogopite from Mt. Vulture (Potenza, Italy): An in situ X-ray single-crystal diffraction study

Abstract The structural evolution of a trioctahedral mica from Cava St. Antonio, Mt. Vulture, Potenza, Italy, has been studied in the temperature range 100-1023 K using in situ single-crystal X-ray diffraction techniques. The sample used shows a Ti-rich composition close to the phlogopite-annite join with the following crystal-chemical formula: (K0.85Na0.11Ba0.03)(Al0.17Mg1.98Mn0.01Fe2+0.29Fe3+0.37Ti0.18)(Si2.75Al1.25) O10.66(F0.13OH1.20Cl0.01). In the present study, the chemical and structural changes and the deprotonation process involved during heating have been characterized. Analysis of the data showed that a, b, and c cell parameters expand almost linearly up to 823 K, while the β angle remains constant. A sharp decrease in the unit-cell dimensions was observed at 873 and 1023 K. Linear trends obtained during reversal experiments from 1023 K to room temperature demonstrated the irreversibility of these events. Structure refinements of single-crystal XRD data collected at 100, 200, 298, 473, 673, 873, and 1023 K converged to 2.14 ≤ R (%) ≤ 8.47, 2.47 ≤ Rw (%) ≤ 10.83. In the temperature range 100-673 K, the thermal expansion along the c direction is mainly due to interlayer thickness dilation. The tetrahedral ring approaches the ideal hexagonal shape with increasing temperature to match the expanding octahedral sheet. In the range 873-1023 K, a strong shrinking of the interlayer is associated with the shortening of the M1-O4 and M2-O4 distances and to the consequent reduction of octahedral thickness. Such structural features indicate the occurrence of Fe oxidation process, involving loss of structural H, which is responsible for a phase transition. Mössbauer spectroscopy supported this hypothesis.

An electron microprobe analysis, secondary ion mass spectrometry, and single-crystal X-ray diffraction study of phlogopites from Mt. Vulture, Potenza, Italy: Consideration of cation partitioning

Abstract Mt. Vulture trioctahedral micas-1M mainly consist of phlogopite-annite solid solutions with a minor component of brittle micas. However, both Li-free and Li- and F-rich compositions may coexist in the same volcano-stratigraphic level. We report the results of electron microprobe analysis (EMPA), secondary ion mass spectrometry (SIMS), and single-crystal X-ray diffraction (SCXRD) for three crystals (LC7-27Go, LC7-3Go, and LC7-1R) that are representative of both compositions. EMPA and SIMS showed that sample LC7-1R is richer in TiO2 , Li2O, and F and poorer in H2O than the other samples. Structure refinements using anisotropic displacement parameters for the three samples, performed in space group C2/m, converged at 3.46 ≤ R ≤ 4.34, 3.89 ≤ Rw ≤ 4.39. When considering bond distances, the three samples can be described as homo-octahedral whereas mean atomic numbers suggest that only LC7-1R is meso-octahedral. Significant differences occur among the samples for some distortion parameters commonly used for micas. In particular, LC7-1R displays higher values of BLDM2, shiftM2 and lower values of ΔK-O4 and tK-O4 than those of samples LC7-3Go and LC7-27Go. These differences are ascribed to F- and Ti-substitutions. Cation distributions were obtained by combining EMPA, SIMS, and SCXRD data after analysis of the effect of normalization schemes commonly used in mica formula recalculation. In LC7-3Go and LC7-27Go, Ti is incorporated according to the Ti-Tschermak mechanism, whereas more than one Ti-substitution mechanism occurs in LC7-1R. For the latter sample, octahedral vacancies are present leading to a complex substitution pattern and complex structural distortions related to the special octahedral compositions that were determined.

Sideronatrite, Na2Fe(SO4)2(OH)·3H2O: Crystal structure of the orthorhombic polytype and OD character analysis

Sideronatrite, Na2Fe(SO4)2(OH)·3H2O, is a secondary hydrated sulfate occurring in desert areas as the result of pyrite alteration. It is one of the environmental indicators of soil-water processes operating in specific landscapes, and, as a consequence, an important marker of acid mine drainage pollution. Sideronatrite has been demonstrated from its peculiar diffraction pattern to belong to a family of OD structures formed by equivalent layers. In this work, a crystal with weak diffuse streaks proved to be suitable for a single-crystal X-ray diffraction study. The crystal structure was solved by direct methods and refined by full matrix leastsquares (R = 7.4% and RW = 8.0%) in the space group P212121 with a = 7.265(2), b = 20.522(6), c = 7.120(2) Å, V = 1061.5(5) Å3, and Z = 4, using 798 reflections with I > 3.0 σ(I). Sideronatrite is characterized by infinite [Fe3+(SO4)2(OH)]2- octahedral-tetrahedral chains of the type [M(TO4)2φ] running parallel to the c axis. These chains are cross-linked by a columnar system of corner-sharing, Na-distorted octahedra along c to form corrugated sheets parallel to the (010) plane. Adjacent sheets are hydrogen-bonded through water molecules coordinated by Na atoms. The present results allow a complete description of the OD character of the structure, with the derivation of the OD groupoid and MDO polytypes. Finally, chemical and structural relationships are taken into account to explain the possible paragenetic sequence concerning several sulfates associated with sideronatrite