Search

Although benzene and borazine are isoelectronic and isostructural, they have very different electronic structures, mainly due to the polar nature of the B-N bond. Herein, we present an experimental study of the charge density distribution obtained from the multipole model formalism and Hirshfeld atom refinement (HAR) based on high-resolution X-ray diffraction data of borazine B

Titanosilicate amide [(tBuO)3SiO]3TiNEt2 can be easily converted into the first examples of acyclic alkali titanosilicates [MOTi{OSi(OtBu)3}3]2 (M = Li–Cs).

In this paper, we present the NX2 unit found in several crystals from the Cambridge Structural Database and describe the features of the interactions within the unit.

A supra­molecular two-dimensional polymer structure of caesium tetra­methyl­dithio­imidodiphosphinate is reported., In the title crystal, the salt [CsMe2P(S)NP(S)Me2] is self-assembled as an undulating supra­molecular two-dimensional polymeric structure, poly[(μ4-tetra­methyl­dithio­imidodiphosphinato)caesium], [Cs(C4H12NP2S2)]n, which is parallel to the bc plane. The Cs cations are hexa­coordinated, being chelated by two thio­imidophosphinate groups and two sulfur atoms from neighboring ligands. The anions are linked to the Cs cations by Cs⋯S and Cs⋯N electrostatic inter­actions.

We report the first experimental investigation of porous organic cages (POCs) for the demanding challenge of SO2 capture. Three structurally related N‐containing cage molecular materials were studied. An imine‐functionalized POC (CC3) showed modest and reversible SO2 capture, while a secondary‐amine POC (RCC3) exhibited high but irreversible SO2 capture. A tertiary amine POC (6FT‐RCC3) demonstrated very high SO2 capture (13.78 mmol g−1; 16.4 SO2 molecules per cage) combined with excellent reversibility for at least 50 adsorption–desorption cycles. The adsorption behavior was investigated by FTIR spectroscopy, 13C CP‐MAS NMR experiments, and computational calculations., Porous organic cages (POCs) were investigated for the first time for the capture of SO2. A tertiary amine cage (6FT‐RCC3) demonstrated remarkably high SO2 capture that was perfectly reversible for at least 50 adsorption–desorption cycles.

The facile and green preparation of novel materials that capture sulfur dioxide (SO2) with significant uptake at room temperature remains challenging, but it is crucial for public health and the en...

MOFs are promising candidates for the capture of toxic gases since their adsorption properties can be tuned as a function of the topology and chemical composition of the pores. Although the main drawback of MOFs is their vulnerability to these highly corrosive gases which can compromise their chemical stability, remarkable examples have demonstrated high chemical stability to SO2, H2S, NH3 and NOx. Understanding the role of different chemical functionalities, within the pores of MOFs, is the key for accomplishing superior captures of these toxic gases. Thus, the interactions of such functional groups (coordinatively unsaturated metal sites, μ-OH groups, defective sites and halogen groups) with these toxic molecules, not only determines the capture properties of MOFs, but also can provide a guideline for the desigh of new multi-functionalised MOF materials. Thus, this perspective aims to provide valuable information on the significant progress on this environmental-remediation field, which could inspire more investigators to provide more and novel research on such challenging task., MOFs are promising candidates for the capture of toxic gases such as SO2, H2S, NH3 and NOx. Understanding the role of different chemical functionalities, within the pores of MOFs, is the key for accomplishing superior captures of these toxic gases.

The preparation of dinuclear aluminum and gallium complexes with controlled M···M proximity (intermetal separation of 3.28–4.35 A) was achieved through direct chelation of the multidentate bis(diph...

ispartof: CHEMISTRY OF MATERIALS vol:34 issue:2 pages:669-677 status: published

Metal–organic frameworks (MOFs) are some of the most interesting and promising candidates to sequester toxic H2S and SO2 gases. MOFs show interesting advantages over classic porous materials due to...

Partially fluorinated MIL-101(Cr) shows high SO2 capture (up to 18.4 mmol g−1 at 298 K and up to 1 bar), chemical stability towards dry and humid SO2 and an outstanding cycling performance with facile regeneration. In situ DRIFT spectroscopy demonstrated the preferential adsorption sites within MIL-101(Cr)-4F(1%).

The increased interest in white solid-state lighting devices addresses the urgent challenge to develop semiconductors with broad band emission. In recent years, low dimensional hybrid organic/inorganic lead perovskites have shown great potential as single white-light emitters. Herein, we show that it is possible to control the chirality of lead bromide perovskites by incorporating enantiopure (R or S) or racemic (RS) β-methylphenethylammonium. The incorporation of such cations allows us to control the chirality of the resulting materials and yields the first examples of 2D chiral perovskites that emit white light. Furthermore, we demonstrate that these materials exhibit second harmonic generation. Our results demonstrate the potential of this kind of materials for chiroptical applications and non-linear optics.

The facile and green preparation of novel materials that capture sulfur dioxide (SO

1,4-Thiazepines derivatives are pharmacologically important heterocycles with different applications in medicinal chemistry. In the present work, we describe the preparation of new bicyclic thiazolidinyl-1,4-thiazepines 3 by reaction between azadithiane compounds and Michael acceptors. The reaction scope was explored and the yields were optimized. The activity of the new compounds was evaluated against Nippostrongylus brasiliensis and Caenorhabditis elegans as anthelmintic models and Trypanosoma brucei brucei. The most active compound was 3l, showing an EC50 = 2.8 ± 0.7 μM against T. b. brucei and a selectivity index >71.

First examples of unprecedented silanol-based bifunctional HBD catalysts [(tBuO)2{(N(CH2CH2)3N)CH2CH2O}Si(OH)]+I− and (Rac)- and (R)-[(tBuO)2{(N(CH2CH2)3N)CH2(Et)CHO)}Si(OH)]+I− with tetraalkylammonium units directly incorporated into their structures were prepared from tailor-made silanols. These bifunctional silanols were used together with other mixed alkoxysilanols of general formula (tBuO)2(RO)SiOH (R = Me, Et, iPr, –CH2CH2I and –CH(Et)CH2I) in a systematic study of their catalytic properties for the preparation of cyclic carbonates using a library of epoxides and industrial-grade carbon dioxide. With 4 mol% catalyst loading in the absence of a solvent and an external nucleophile source, the bifunctional catalysts showed good to very good conversion of epoxides to the corresponding cyclic carbonates within 10 h at 70 °C and 75 psi of CO2. Furthermore, the developed synthetic approach used in the preparation of these mixed alkyl silanols via the hydrolysis of the corresponding acetoxysilyl alkoxides (tBuO)2(RO)Si(OAc) (R = organic moiety) allowed a straightforward route to the modification of the steric bulk around the silicon atom and the introduction of functional groups for further derivatization.

The heterobimetallic complexes [Co(LtzE)3K(THF)2] [LtzE = [{4,5-(P(E)Ph2)2}tz]−; tz = 1,2,3-triazole; E = S(3), Se(4)] featuring high-spin cobalt centres, and [Ni(LtzE)3K(THF)2] [E = S(5), Se(6)] were synthesized through the self-assembly reaction of HLtzE [E = S(1), Se(2)], KOH or K0 and MCl2 (M = Co, Ni). Compounds 3–6 exhibit an unusual metallascorpionate-type anion formed by the coordination of three triazole units via a κ2-N,E mode to the transition-metal atom, and this anion further coordinates to a potassium cation through a κ3-N′,N′′,N′′′ fashion. Compounds 3 and 5 were used in the synthesis of 3d-metal heterometallascorpionates [M(LtzS)3Cu(PPh3)] [M = Co, (7), M = Ni (8)] and the bimetallic complex [Ni(LtzE)3Ni(NO3)(THF)] (9) through metathesis reactions, pointing to stable metallascorpionate anions in solution. The solution behavior of 3–9 was investigated by UV-visible spectroscopy, high-resolution mass spectrometry, electrochemical methods and by magnetic-susceptibility measurements. The molecular structures of 3–6, 8 and 9 were determined by single-crystal X-ray diffraction studies and exhibit M⋯M′ distances ranging from 3.52 to 3.88 A.

Carbon dioxide is readily fixed when reacting with either alumoxane dihydride [{MeLAl(H)}2(μ-O)] (1) or aluminum dihydride [MeLAlH2] (2) (MeL = HC[(CMe)N(2,4,6-Me3C6H2)]2-) to produce bimetallic aluminum formates [(MeLAl)2(μ-OCHO)2(μ-O)] (3) and [(MeLAl)2(μ-OCHO)2(μ-H)2] (5), respectively. Furthermore, [(MeLAl)2(μ-OCHO)2(μ-OH)2] (4) is easily obtained upon the reaction of 3 or 5 with H2O. The stability of the unusual dialuminum diformate dihydride core observed in 5 stems from the proximity of the Al centers allowing the formation of two Al-HAl bridges and precluding further hydride transfer to the HCO2 moieties. Contrary to this behavior, 1 and 2 react with CS2 giving cyclic alumoxane and aluminum sulfides [(MeLAl)2(μ-S)(μ-O)] (6) and [{MeLAl(μ-S)}2] (7), respectively. The molecular structures of 3-7 were characterized by IR, Raman, solution or solid-state (MAS) NMR spectroscopy and mass spectrometry and for 4-7 were characterized by X-ray diffraction studies. NMR kinetic studies and DFT calculations suggest that the mechanisms for the formation of 6 and 7 involve the transfer of a hydride group forming transient aluminum thioformate intermediates which proceed to form Al-S-Al moieties through the cleavage of C-S bonds and insertion of a sulfur atom, followed by the elimination of thioformaldehyde.

The construction of hydrogen-bonded frameworks (HBFs) that express permanent porosity and functionality is challenging due to the delicateness of hydrogen bonds. We present UNAM-1, a robust 3D-HBF fully sustained by charge-assisted H-bonds between [CuIICuI12(HL)12]10− and [Me2NH2]+ units, which displays a surface area of 522 m2 g−1 and reversibly adsorbs SO2 (3.5 mmol g−1).

The partial functionalisation of MIL-101(Cr) with fluorine was successfully achieved, for the first time, with 2,3,5,6-tetrafluoro-1,4-benzenedicarboxylate (BDC-4F) affording MIL-101(Cr)-4F(1%). As a result of the functionalisation the acidity of the metal centres for MIL-101(Cr)-4F(1%) was enhanced, which was measured by cyclic voltammetry. The resulting adsorption properties of the new material were explored and compared to those of MIL-101(Cr). H2O sorption experiments demonstrated an augmented hydrophobicity of the material due to the incorporation of fluorine atoms. CO2 adsorption experiments exhibited an augmented CO2 interaction energy (ΔH) for MIL-101(Cr)-4F(1%). The diffusion time constant for CO2 showed a higher CO2 mobility inside the pores of MIL-101(Cr) than in MIL-101(Cr)-4F(1%), which was also associated with a higher selectivity (α) of MIL-101(Cr)-4F(1%) towards CO2. O2 sorption isotherms of MIL-101(Cr)-4F(1%), at a high pressure (up to 90 bar), demonstrated O2 uptakes among the highest values reported for a MOF material. H2 adsorption isotherms exhibited, at low pressures, higher H2 uptakes for the fluorine functionalised material. This was attributed to dipolar interactions of H2 molecules with the fluorine atoms and corroborated by the calculation of ΔH for H2. 129Xe NMR experiments were used to investigate the atypical pore-surface electron density of MIL-101(Cr)-4F(1%), demonstrating a huge effect of the polarising power of the fluorine atoms on the highly polarisable Xe atoms. Finally, the capture of I2 and H2S on MIL-101(Cr)-4F(1%) showed considerably higher values in comparison to MIL-101(Cr). This was attributed to the high dipolarity and polarisability of the fluorinated pores.

The molecular alumosilicates AlL{OSi(OtBu)2O}[OSi{(μ3-O)(MR2)2(μ-OtBu)}(OtBu)] (L = HC[CMeNAr]2-, where M = Al, R = Me (2), Et (3), and iBu (4) and M = Ga, R = Me (5)) were obtained from the reaction of AlL{OSi(OtBu)2(OH)}2 (1) with 1 or 2 equiv of the respective organometallic precursor. These compounds have a central bicyclic inorganic core formed by a six-membered AlSi2O3 alumosilicate ring with a Si-O-Si unit connected via a Si-O bond to a four-membered Al2O2 alumoxane ring. These compounds are formed even though 1 is specifically designed to yield 4R alumosilicate rings that would obey the Loweinstein's and Dempsey's rules about concatenation between silicon and aluminum tetrahedra in alumosilicates. We propose a mechanism for this rearrangement, based on the experimental evidence and density functional theory calculations, that involves a κ3μ2 coordination of a silicate unit to two AlMe2 groups, which weakens one Si-O bond and explains how aluminum atoms can cleave Si-O bonds. Furthermore, formation of the products experimentally confirms the theory that Al-O-Al groups can exist in alumosilicates if the oxygen atom belongs to an OH moiety.

The metal-organic framework (MOF)-type MFM-300(Sc) exhibits a combined physisorption and chemisorption capture of H2S, leading to a high uptake (16.55 mmol g-1) associated with high structural stability. The irreversible chemisorbed sulfur species were identified as low-order polysulfide (n = 2) species. The isostructural MFM-300(In) was demonstrated to promote the formation of different polysulfide species, paving the way toward a new methodology to incorporate polysulfides within MOFs for the generation of novel MOF-lithium/sulfur batteries.

The metal-organic framework (MOF)-type MFM-300(Sc) exhibits a combined physisorption and chemisorption capture of H

Two organotin compounds [{D(C6H4CH2)2}SnBr2] displaying intramolecular transannular Sn–D interactions (D = O, 3a; S, 3b) were synthesized by oxidation of elemental tin with the corresponding dibromo compounds D(C6H4CH2Br)2. Both organotin compounds were physicochemically characterized by EI-MS and NMR techniques and by single crystal X-ray crystallographic studies at room temperature. The spectroscopic and diffraction data agreed with the presence of a Sn–D intramolecular interaction. DFT calculations at the B3LYP/DGDZVP level were carried out. The topological analysis indicated that bond critical points are present along the Sn–D direction, and the electron localization function graphs showed the presence of electron lone pairs of the D donor atoms directed to the Sn acceptor atom.

In this study we examined the use of a new class of molecular building blocks with tetrahedral nodes based on organo-bis(silanetriols) (1,4-[(HO)3SiOCEt2]2C6H4 (1) and 4,4′-[(HO)3SiOCEt2]2-(1,1′-bi...

The reaction between 1-phenyl-tetrazole-5-thione (1) and the metal hydroxides MOH (M = Li, Na, K, Rb, Cs) in the presence of crown ethers led to the alkali metal complexes, [Li(15-crown-5)(SCN4Ph)] (2), [Na(15-crown-5)(SCN4Ph)] (5), [K(18-crown-6)(SCN4Ph)] (4), [Rb(18-crown-6)(SCN4Ph)] (5), [Cs(15-crown-5)2][SCN4Ph] (6), [{Cs(15-crown-5)(SCN4Ph)}] (6a), [Cs(18-crown-6)(SCN4Ph)] (7), [Cs(dibenzo-24-crown-8)(SCN4Ph)] (8) and [Cs2(dibenzo-24-crown-8)3(SCN4Ph)2] (8a). Compounds 2–8 were characterized by physical and analytical methods. X-ray diffraction studies performed on these compounds reveal that crown ether moiety precludes the ionic lattice formation. The tetrazole anion coordinates to the metal cation in a bidentate N,S fashion in 3–5 with the formation of a four-membered MSCN ring, whereas in 2, monodentate coordination through a N atom is observed. In contrast, cesium complexes 6, 6a, 7, 8 and 8a show a variety of structural arrangements including monomeric, dimeric and polymeric species, depending on the size of crown ether employed.

s The synthesis and characterization of the first three La(III) 2-amino-1-cyclopentene-1-carbodithioate (ACDA) complexes is reported including two ionic complexes, [NEt3H][La(ACDA4)] (1), [N(n-Bu)4][La(ACDA4] (2) and [La(ACDA)3)(1,10-phenanthroline)] (3). The single-crystal X-ray structures of 1–3 correspond to the first known structural determination of ACDA rare earth complexes. Compounds 1–3 show an S,S coordination mode, and due to hydrogen bonding present in the ligands, secondary interactions were observed. DFT calculations for all the lanthanide series indicate that the ACDA ligand binds in an isobidentate fashion through low covalent M–S bonds, as evidenced by natural population analysis. Furthermore, the S,S coordination mode is overwhelmingly preferred over the N,S coordination, as demonstrated by free energy calculations from the vibrational frequency analysis.

The reaction of MCp3 (M = Y, Nd, Sm, Gd) with the 4,5-bis(diphenylselenophosphoranyl)-1,2,3-triazole (LH) (1) in the presence of stoichiometric amounts of H2O afforded the trinuclear rare-earth metal complexes [(MCp)3(μ3-O)L4] [M = Y (3), Nd (4), Sm (5), Gd (4)]. The unforeseen formation of these multimetallic systems stems from the protonolysis reactions of the intermediate dicyclopentadienyl rare-earth complexes MCp2L with H2O. This was confirmed by the transformation of YCp2L (2) to (YCp)3(μ3-O)L4 (3) under controlled conditions. X-ray diffraction studies reveal that 3–6 possess a trinuclear [M3(μ3-O)] core with M–Se contacts featuring M⋯M interactions. The magnitude of the M⋯M separations is controlled by the constrictions imposed on the planar [M3(μ3-O)] core by the surrounding M2ON2 and M2ON ring systems. DFT calculations were performed on 3 which was used as a model compound for the heavier rare-earth metals providing insight into the nature of the Y–Se and Y–N contacts around the M3(μ3-O) core.

The ring opening transformation of three substituted 2-(2-pyridyl)benzothiazolines of general formula [(C 6 H 4 NCS)(C 5 H 4 N)R] (R = C 5 H 4 N, 1 ; R = C 6 H 5 , 2 ; R = H, 3 ) was studied by their reaction with metal chlorides of Ni(II), Pd(II), and Pt(II). In these reactions, the anionic tridentate Schiff bases { L n } − coordinated to metal ions were identified. Seven metallic complexes of type [M( L n )Cl] [M = Pd, n = 1, R = C 5 H 4 N, ( 1a ); n = 2, R = C 6 H 5 , ( 2a ); n = 3, R = H, ( 3a ). M = Pt, n = 1, R = C 5 H 4 N, ( 1b ); n = 2, R = C 6 H 5 , ( 2b ); n = 3, R = H, ( 3b ), and M = Ni, R = C 6 H 5 , ( 2c )] were characterized in solution by NMR and vibrational spectroscopy in solid state. Crystal structures of benzothiazolines 1 and 2 and complexes 1a – 3a , 1b ·DMSO, and 2c were analyzed by X-ray diffraction studies. In all cases, mononuclear complexes with a distorted square planar geometry were obtained. For compounds 1 – 3 , the predominance of the benzothiazoline (ring form) over the Schiff base (open form) as well as the formation of the [Pd( L n )Cl] (n = 1–3) complexes were studied by DFT calculations at the PBEPBE/(Def2-TZVP,SDD) level in gas phase.

The synthesis of five new complexes involving the ephedrinedithiocarbamate ligand (ephedtc) with group 13 and 15 metals (III) is reported. Complexes [As(ephedtc) 3 ] ( 1 ), [Sb(ephedtc) 3 ] ( 2 ), [Bi(ephedtc) 3 ] ( 3 ), and [In(ephedtc) 3 ] ( 5) were obtained from the ephedrinedithiocarbamate sodium salt [Na(ephedtc)] and the corresponding trichlorides MCl 3 , whereas for [Ga(ephedtc) 3 ], ( 4 ) Ga(NO 3 ) 3 was used. All compounds were characterized by elemental analyses, IR, mass spectrometry (FAB + ) and 1 H and 13 C NMR. In addition, single crystal structures of 2 and 5 were obtained showing two different coordination modes for the dithiocarbamate moiety, an anisobidentate coordination mode for 2 and an isobidentate coordination for 5 that generates a propeller-type structure. Compound 2 shows a distorted trigonal antiprismatic geometry around the metal atom while in 5 a distorted octahedral geometry is observed. Additionally, the crystalline structure of the ionic pair [ephedrinium] [ephedrinedithiocarbamate] ( 6 ) was determined. Antibacterial assay showed that 5 was the most active against ATCC bacterial strains and clinical isolate E. coli BLE (MIC 14.6–29.9 µM), and 3 against MRS strains (MIC 1.7 and 13.4 µM). The chemical hardness concept and the location of the HOMO and LUMO frontier orbitals on the molecular structures of 1 – 5 were employed to explain its particular antibacterial activity, using the DFT calculations.

The reaction of metalloxanes [{MeLM(OH)}2(μ-O)] [M = Al (1), Ga (2); MeL = CH{CMe(NAr)}2–, Ar = 2,4,6-Me3C6H2, Me = methyl] with an excess of BH3·D (D = tetrahydrofuran (THF), SMe2) affords annular metallaborate systems achieved through M–O–M cleavage. Compound 1 led exclusively to the formation of eight-membered ring systems [{MeLAl(μ-O){B(OnBu)}(μ-O)}2] (3) and [{MeLAl(μ-O)(BH)(μ-O)}2] (6), while for 2 the unprecedented six-membered ring systems [{(MeLGa)2(μ-O)}(μ-O)2{B(OnBu)}] (4) and [(MeLGa)(μ-O)2{(BOnBu)2(μ-O)}] (5) were observed. The use of BH3·THF with 1 and 2 led to the concomitant THF ring-opening reaction, while with BH3·SMe2 in THF no such reaction was observed. The metallaborates [MeLAl{OB(pinacol)}(OH)] (7) and [{MeLGa(OB(pinacol))}2(μ-O)] (8) were synthesized from pinacolborane and the corresponding metalloxane, providing structural evidence that supports the reaction pathways proposed for the formation of 3–6. Density functional theory studies were performed on 3–5 to assess the effect of ...

The bottleneck effect of confined N,N-dimethylformamide (DMF) molecules was observed in InOF-1 for the first time: CO2 capture was remarkably enhanced in samples of as-synthesized InOF-1, thermally activated in such a way that a small residual amount of DMF molecules remained confined within the pores (DMF@InOF-1). Dynamic CO2 adsorption experiments on DMF@InOF-1 exhibited a CO2 capture of 8.06 wt % [1.5-fold higher than that of a fully activated InOF-1 (5.24%)]. DMF@InOF-1 can reversibly adsorb/desorb 8.09% CO2 with no loss of CO2 capacity after 10 cycles, and the desorption is accomplished by only turning the CO2 flow off. Static CO2 adsorption experiments (at 196 K) demonstrated a 1.4-fold CO2 capture increase (from 5.5 mmol·g–1, fully activated InOF-1, to 7.5 mmol·g–1, DMF@InOF-1). Therefore, these CO2 capture properties are the result of the presence of residual-confined DMF molecules within the InOF-1 framework and their interactions via a very strong hydrogen bond with the In2(μ-OH) groups, which p...

This study examined the direct effect of solvent on the chemical composition and structure of supramolecular assemblies formed from triphenylboroxine ((PhBO)3) and piperazine (ppz) through N→B bonds. Oxygen-containing solvents with a molecular size smaller than 4.1 A produce 1D polymeric structures (1:1 boroxine/piperazine) of compositions {(PhBO)3(ppz)}n·nTHF (1a·THF) and {(PhBO)3(ppz)}n·nAcetone (1a·Acetone), in which the boroxine B3O3 rings are linked through N→B bonded piperazine molecules in a cis-conformation. In both cases, a pseudocavity is generated between two polymer chains, which is occupied by a solvent molecule interacting through bifurcated N–H···O···H–N hydrogen bonds with one of the chains. In contrast, oxygen-based solvents with a size larger than 6.3 A give rise to discrete 2:1 assemblies, {(PhBO)3}2(ppz)·2Ethyl acetate (2·AcOEt) and {(PhBO)3}2(ppz)·2Pentanone (2·Pentanone), with the piperazine molecule bridging two B3O3 rings and interacting with two solvent molecules via N–H···O hydro...

Crystalline framework materials have gained interest because of their many potential applications. A novel chiral tetrandrine salt (DNT) has been synthesized and characterized by conventional analytical techniques and single-crystal X-ray diffraction analysis, and its self-assembly behavior studied. In the solid state, 48 molecules of the compound self-assemble into an organic framework based on nanospherical aggregates formed exclusively through weak noncovalent interactions. Additionally, it was demonstrated by UV-vis spectroscopy and TGA that assembled DNT can include the Nile Red dye, giving a fluorescent material. To the best of our knowledge, these spherical assemblies are the largest among the purely synthetic organic self-assembled molecular crystals reported to date.

Carbon dioxide is readily fixed when reacting with either alumoxane dihydride [{MeLAl(H)}2(μ-O)] (1) or aluminum dihydride [MeLAlH2] (2) (MeL = HC[(CMe)N(2,4,6-Me3C6H2)]2-) to produce bimetallic aluminum formates [(MeLAl)2(μ-OCHO)2(μ-O)] (3) and [(MeLAl)2(μ-OCHO)2(μ-H)2] (5), respectively. Furthermore, [(MeLAl)2(μ-OCHO)2(μ-OH)2] (4) is easily obtained upon the reaction of 3 or 5 with H2O. The stability of the unusual dialuminum diformate dihydride core observed in 5 stems from the proximity of the Al centers allowing the formation of two Al-HAl bridges and precluding further hydride transfer to the HCO2 moieties. Contrary to this behavior, 1 and 2 react with CS2 giving cyclic alumoxane and aluminum sulfides [(MeLAl)2(μ-S)(μ-O)] (6) and [{MeLAl(μ-S)}2] (7), respectively. The molecular structures of 3-7 were characterized by IR, Raman, solution or solid-state (MAS) NMR spectroscopy and mass spectrometry and for 4-7 were characterized by X-ray diffraction studies. NMR kinetic studies and DFT calculations suggest that the mechanisms for the formation of 6 and 7 involve the transfer of a hydride group forming transient aluminum thioformate intermediates which proceed to form Al-S-Al moieties through the cleavage of C-S bonds and insertion of a sulfur atom, followed by the elimination of thioformaldehyde.

An easy and versatile method for the preparation of molecular alkoxysilanols as molecular organosilicates based on acetoxysilylalkoxides (ASA, (RO)(tBuO)nSi(OAc)3−n or (AcO)3−n(tBuO)nSi-O-R-O-Si(OtBu)n(OAc)3−n, R = organic group; n = 0 or 1) is presented. These ASA precursors are prepared from silicon tetraacetate and suitable alcohols and are cleanly hydrolyzed in water to the corresponding alkoxysilanols in the absence of a base or organic solvents. The compounds were characterized by common spectroscopic methods including X-ray structural analysis. Alkoxysilanols were tested in the catalytic conversion of CO2 to styrene carbonate and show quantitative conversion within 15 h at 60 °C and 1 atm of CO2.

The monosubstituted complex [MoO2Cl2{κ2-O,O′-{4,5-(P(O)Ph2)2tzH}}] (tz = 1,2,3-triazole) (4) and [Mo(NtBu)2{κ2-N,S-{4,5-(P(S)Ph2)2tz}}2] (12), and the disubstituted complexes, [MoO(NtBu){κ2-O,N-{4,5-(P(O)Ph2)2tz}}2] (8) and [Mo(NtBu)2{κ2-N,E-{4,5-(P(E)Ph2)2tz}}2] [E = O(9), S(10), Se(11)] were prepared using the corresponding ligands [{(4,5-(P(E)Ph2)2tz}H] [E = O(1), S(2), Se(3)] and molybdenum precursors, MoXYCl2(dme) (X = Y = O; X = O, Y = NtBu; X = Y = NtBu, dme = dimethoxyethane). The disubstituted complexes 4, 8, 9 and 11 were obtained regardless of the ligand/metal ratio used in the reaction (1:1 or 2:1). Complexes 8 and 9 exhibit one type of geometric isomer in solution while 10 and 11 show two types of isomers in solution. In these compounds at least one isomer with C2 symmetry is observed. Complexes 4, 8, 9 and 10 were characterized by X-ray diffraction analysis.

The reaction of ammonium salts of benzylferrocenyldithiophosphonate ligands [NH 4 ][S 2 P(OR)(Fc)] [R = Bz ( 1 ), 4-( i Pr)-Bz ( 2 ), 4-( t Bu)-Bz ( 3 ), 4-(Ph)-Bz ( 4 ), 3-(OBz)-Bz ( 5 ); Bz = benzyl, Fc = ferrocenyl] with organotin(IV) chlorides Ph 2 SnCl 2 , n Bu 2 SnCl 2 and Ph 3 SnCl, gave the corresponding organotin(IV) benzylferrocenyldithiophosphonates [Ph 2 Sn{S 2 P(OR)(Fc)} 2 ] [R = Bz ( 6 ), 4-( i Pr)-Bz ( 7 ), 4-( t Bu)-Bz ( 8 ), 4-(Ph)-Bz ( 9 ), 3-(OBz)-Bz ( 10 )], [ n Bu 2 Sn{S 2 P(OR)(Fc)} 2 ] [R = Bz ( 11 ), 4-(Ph)-Bz ( 12 )] and [Ph 3 Sn{S 2 P(OBz)(Fc)}] ( 13 ). Compounds 6 – 13 were characterized by elemental analyses, infrared, 1 H, 13 C{ 1 H}, 31 P{ 1 H} and 119 Sn{ 1 H}NMR spectroscopy and ESI mass spectrometry, while complexes 6 , 11 and 13 were also characterized by single-crystal X-ray diffraction studies. The dithiophosphonate ligands display an anisobidentate coordination mode upon interaction with the metal center. The solid-state structures of the disubstituted complexes 6 and 11 exhibit a trans arrangement for the ferrocenyl groups from the dithiophosphonate ligands.

Equimolar and excess ratio reactions of ligands [H{4,5-(P(E)Ph2)2tz}] [tz = 1,2,3-triazole; E = S (1), Se (2)] with Ti(NR2)4 (R = Me, Et) yielded the disubstituted complexes [Ti(NR2)2{κ2-N,E-(4,5-(P(E)Ph2)2tz}2] [E = S, R = Me (3), Et (4); E = Se, R = Me (5), Et (6)], while the reactions of 1 and 2 with Ti(NEt2)2Cl2 gave the monosubstituted complexes [Ti(NEt2)Cl2{κ2-N,E-(4,5-(P(E)Ph2)2tz}] [E = S (7), Se (8)]. The reaction of M(NR2)4 (M = Zr, Hf, R = Me, Et) with 1 and 2 failed. However, the zirconium and hafnium disubstituted complexes, [M(NR2)2{κ2-N,E-(4,5-(P(E)Ph2)2tz}2] [M = Zr, E = S, R = Me (11), Et (12); M = Hf, E = S, R = Me (13), Et (14); M = Zr, E = Se, R = Et (15); M = Hf, E = Se, R = Et (16)] were obtained from the silylated derivatives [SiMe3{κ1-N-(4,5-(P(E)Ph2)2tz}] [E = S(9), Se(10)] and the corresponding metal amides M(NR2)4. In addition, the facile hydrolysis of 5, 7 and 8 with trace amounts of water led to the isolation of compounds 17–19, which contain Ti–O–Ti frameworks.