Further Examples of the P‐O‐P Connection in Borophosphates: Synthesis and Characterization of Li2Cs2B2P4O15, LiK2BP2O8, and Li3M2BP4O14 (M=K,Rb)

A new series of anhydrous mixed alkali‐metal borophosphates—Li₂Cs₂B₂P₄O₁₅ ( 1 ), LiK₂BP₂O₈ ( 2 ), Li₃K₂BP₄O₁₄ ( 3 ), and Li₃Rb₂BP₄O₁₄ ( 4 )—have been successfully synthesized by using the conventional solid‐state reaction method. Compound 1 contains a novel fundamental building unit (FBU), [B₄P₈O₃₀], with B/P=1:2. Compound 2 contains an FBU of [B₂P₄O₁₆] with B/P=1:2. Compounds 3 and 4 are isotypic, and they have a [B(P₂O₇)₂] unit as their FBU. In all four compounds, their FBUs are connected through corner sharing to generate layered anionic partial structures, and then further linked with metallic polyhedra to form three‐dimensional (3D) frameworks. Most interestingly, three of the four compounds contain direct P‐O‐P connections in their structures, which is extremely rare among borophosphates. Thermal analyses, IR spectroscopy, and UV/Vis/near‐IR diffuse reflectance spectroscopy have also been performed on the four title compounds.     

Single-crystal X-ray study of Ba2Cu2Te4O11Br2 and its incommensurately modulated superstructure companion

Compounds containing lone-pair elements such as Te(IV) are very interesting from the structural point of view, as the lone-pair nonbonding regions create low-dimensional geometrical arrangements. We have synthesized two new compounds with these features-Ba(2)Cu(2)Te(4)O(11)Br(2) (I) and Ba(2)Cu(2)Te(4)O(11-delta)(OH)(2delta)Br(2) (II, delta approximately equal to 0.57)-as members of the AE-M-Te-O-X (AE=alkaline-earth metal, M=transition metal, X=halide) family of compounds by solid-state reactions. Preliminary single-crystal X-ray analysis indicated that compound I crystallizes in the orthorhombic system, but attempts at refinement proved unsatisfactory. Closer inspection of the reciprocal lattice revealed systematic, non-crystallographic absences that indicate twinning. The structure is in fact triclinic, space group C_1 (equivalent to P_1), with unit cell parameters (at 120 K) of a=10.9027(9), b=15.0864(7), c=9.379(2) A, beta=106.8947 degrees . It is layered and built from [TeO(3)E] tetrahedra, [TeO(3+1)E] trigonal bipyramids (where E is the lone pair of Te(IV)), [CuO(4)] squares and irregular [BaO(10)Br] polyhedra. The crystal structure of II shows the same basic structure as I but contains additional oxygen, probably in the form of OH groups. The presence of satellites reveals that ordering on this O site creates an incommensurate modulation, primarily affecting Br and Te. The modulated structure of II was solved in the triclinic superspace group X$\bar 1$(alphabetagamma)0 with the vector q approximately equal to1/16 c*.     

Transition‐Metal‐Mediated Cleavage of Fluoro‐Silanes under Mild Conditions

Si?F bond cleavage of fluoro‐silanes was achieved by transition‐metal complexes under mild and neutral conditions. The Iridium‐hydride complex [Ir(H)(CO)(PPh₃)₃] was found to readily break the Si?F bond of the diphosphine‐ difluorosilane {(o‐Ph₂P)C₆H₄}₂Si(F)₂ to afford a silyl complex [{[o‐(iPh₂P)C₆H₄]₂(F)Si}Ir(CO)(PPh₃)] and HF. Density functional theory calculations disclose a reaction mechanism in which a hypervalent silicon species with a dative Ir→Si interaction plays a crucial role. The Ir→Si interaction changes the character of the H on the Ir from hydridic to protic, and makes the F on Si more anionic, leading to the formation of H^δ+???F^δ? interaction. Then the Si?F and Ir?H bonds are readily broken to afford the silyl complex and HF through σ‐bond metathesis. Furthermore, the analogous rhodium complex [Rh(H)(CO)(PPh₃)₃] was found to promote the cleavage of the Si?F bond of the triphosphine‐monofluorosilane {(o‐Ph₂P)C₆H₄}₃Si(F) even at ambient temperature.     

Easy Access to Modified Cyclodextrins by an Intramolecular Radical Approach

A simple method to modify the primary face of cyclodextrins (CDs) is described. The 6^I‐O‐yl radical of α‐, β‐, and γ‐CDs regioselectively abstracts the H5^II, located in the adjacent D ‐glucose unit, by an intramolecular 1,8‐hydrogen‐atom‐transfer reaction through a geometrically restricted nine‐membered transition state to give a stable 1,3,5‐trioxocane ring. The reaction has been extended to the 1,4‐diols of α‐ and β‐CD to give the corresponding bis(trioxocane)s. The C₂‐symmetric bis(trioxocane) corresponding to the α‐CD is a stable crystalline solid whose structure was confirmed by X‐ray diffraction analysis. The calculated geometric parameters confirm that the primary face is severely distorted toward a narrower elliptical shape for this rim.     

Effect of para-Substituents on meso-Functionalized Oxidovanadium(IV) Porphyrins as Catalysts for Oxygen Atom Transfer Mediated Oxidation of Benzoin to Benzil under Mild Conditions

Systematic analysis of the effect of para-substituents (H, Cl, Br and OMe) on the meso-phenyl group in vanadyl meso-tetraphenylporphyrins ([V^IVO(TPP)] (R=H, 1 ), [V^IVO(TCPP)] (R=Cl, 2 ), [ V^IVO(TBPP)] (R=Br, 3 ) and [V^IVO(TMPP)] (R=OMe, 4 )) on their properties and catalytic oxygen atom transfer (OAT) for oxidation of benzoin to benzil using DMSO as well as 30 % aqueous H₂O₂ as the sacrificial oxygen source have been studied. Electrochemical and theoretical (density functional theory) studies are in good agreement with the influence of these substituents on the catalytic property of these complexes. Complex [V^IVO(TCPP)] ( 2 ) displayed the best catalytic activity for the conversion (92 %) of benzoin to benzil in 30 h with >99 % product selectivity when DMSO was used as an oxygen source, whereas excellent conversion (~100 %) of benzoin to benzil was noticed in 18 h with 95 % product selectivity when 30 % aqueous H₂O₂ was used as a source of oxygen. Furthermore, among these complexes, the electron-withdrawing nature of the chloro substituent at the p-position of meso-phenyl group significantly influences the oxygen atom transfer. Experimental and simulated EPR studies confirmed the +4 oxidation of vanadium in these complexes. The structure of 2 , 3 and 4 , confirmed by single crystal X-ray diffraction method, are domed in shape, and the displacement of V(IV) ion from the mean porphyrin plane follows the order: 2 (0.458 Å) < 3 (0.459 Å) < 4 (0.479 Å). We observed that the electron-withdrawing nature of chloro substituent at the p-position of meso-phenyl group influence the oxygen atom transfer from vanadyl porphyrin to dimethyl sulfide much.     

Three Alkali‐Metal Erbium Thiophosphates: From the Layered Structure of KEr[P2S7] to the Three‐Dimensional Cross‐Linkage in NaEr[P2S6] and Cs3Er5[PS4]6.

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