Synthesis and Complexation Study of New Aminoalkynyl−amidinate Ligands

Abstract The current library of amidinate ligands has been extended by the synthesis of two novel dimethylamino‐substituted alkynylamidinate anions of the composition [Me 2 N−CH 2 −C≡C−C(NR) 2 ] − (R = i Pr, cyclohexyl (Cy)). The unsolvated lithium derivatives Li[Me 2 N−CH 2 −C≡C−C(NR) 2 ] ( 1 : R = i Pr, 2 : R = Cy) were obtained in good yields by treatment of in situ‐ prepared Me 2 N−CH 2 −C≡C−Li with the respective carbodiimides, R−N=C=N−R. Recrystallization of 1 and 2 from THF afforded the crystalline THF adducts Li[Me 2 N−CH 2 −C≡C−C(NR) 2 ] ⋅  n THF ( 1 a : R = i Pr, n =1; 2 a : R = Cy, n =1.5). Precursor 2 was subsequently used to study initial complexation reactions with selected di‐ and trivalent transition metals. The dark red homoleptic vanadium(III) tris(alkynylamidinate) complex V[Me 2 N−CH 2 −C≡C−C(NCy) 2 ] 3 ( 3 ) was prepared by reaction of VCl 3 (THF) 3 with 3 equiv. of 2 (75 % yield). A salt‐metathesis reaction of 2 with anhydrous FeCl 2 in a molar ratio of 2 : 1 afforded the dinuclear homoleptic iron(II) alkynylamidinate complex Fe 2 [Me 2 N−CH 2 −C≡C−C(NCy) 2 ] 4 ( 4 ) in 69 % isolated yield. Similarly, treatment of Mo 2 (OAc) 4 with 3 or 4 equiv. of 2 provided the dinuclear, heteroleptic molybdenum(II) amidinate complex Mo 2 (OAc)[Me 2 N−CH 2 −C≡C−C(NCy) 2 ] 3 ( 5 ; yellow crystals, 50 % isolated yield). The cyclohexyl‐substituted title compounds 2 a , 4 , and 5 were structurally characterized through single‐crystal X‐ray diffraction studies.imag

Alumino-mesostructured Ni catalysts for the direct conversion of ethene to propene

Ni/MCM-41 and Ni/AlMCM-41 were synthesized at different Si/Al ratios and tested in the direct conversion of ethene to propene (ETP-reaction). It was intended to evaluate the effect of modifying the catalyst acidity on the ETP-reaction rather than optimizing its performance. All catalysts were characterized by powder XRD, N2-physisorption, 29Si and 27Al MAS NMR, TEM, NH3-TPD, pyridine-DRITFS, H2-TPR, and TPO. Ni/MCM-41 showed low catalytic activity due to its low acidity. Ni/AlMCM-41 catalyst with a Si/ Al ratio of 60 had high catalytic activity. Characterization results revealed that the catalyst structure does not have effect on the catalytic activity. Al could be incorporated into the MCM-41 framework up to Si/Al ratio of 16. Two different Ni-composites on the surface of the MCM-41 and AlMCM-41 were observed. Deeper characterization is required to know the Ni state. Important deactivation was observed at 450 !C. The nature of the carbonaceous species and reaction mechanism require deeper characterization

A Synthetic Route to Quaternary Pyridinium Salt-Functionalized Silsesquioxanes

A synthetic route to potentially biocidal silsesquioxanes functionalized by quaternary pyridinium functionalities has been developed. N-Alkylation reactions of the precursor compounds 4-(2-(trimethoxysilyl)ethyl)-pyridine (5) and 4-(2-trichloro-silylethyl)pyridine (6) with iodomethane, n-hexylbromide, and n-hexadecylbromide cleanly afforded the corresponding N-alkylpyridinium salts (7–10). The synthesis of a 4-(2-ethyl)pyridine POSS derivative (2) was achieved by capping of the silsesquioxane trisilanol Cy7Si7O9(OH)3 (1) via two different preparative routes. Attempts to use compound 2 as precursor for quaternary pyridinium salt-functionalized POSS derivatives were met with only partial success. Only the reaction with iodomethane cleanly afforded the new N-methylpyridinium salt 12 in high yield, whereas n-hexylbromide and n-hexadecylbromide failed to react with 2 even under forcing conditions

Formation and structural characterization of a potassium amidinoguanidinate

The first potassium amidinoguanidinate complex, catena-poly[[bis(μ-1-amidinato-N,N′,N′′,N′′′-tetraisopropylguanidinato-κ5N1:N1,N2:N2,N4)dipotassium]-μ-1,2-dimethoxyethane-κ2O:O′], [K2(C14H32N4)2(C4H10O2)]n or [{iPrN= CHN(iPr)N(NiPr)2K}2(μ-DME)]n where DME is 1,2-dimethoxyethane, has been synthesized and structurally characterized. The title compound was isolated in 76% yield from a reaction of N,N′-diisopropylcarbodiimide with potassium hydride in DME. The single-crystal X-ray structure determination of the title compound revealed a polymeric chain structure comprising cage-like dimeric units, with the amidinoguanidinate ligand displaying a mixed σ-/π-coordination mode

Crystal structure of the high-energy-density material guanylurea dipicrylamide

The title compound, 1-carbamoylguanidinium bis(2,4,6-trinitrophenyl)amide [H2NC(=O)NHC(NH2)2]+[N{C6H2(NO2)3-2,4,6}2]− (= guanylurea dipicrylamide), was prepared as dark-red block-like crystals in 70% yield by salt-metathesis reaction between guanylurea sulfate and sodium dipicrylamide. In the solid state, the new compound builds up an array of mutually linked guanylurea cations and dipicrylamide anions. The crystal packing is dominated by an extensive network of N—H...O hydrogen bonds, resulting in a high density of 1.795 Mg m−3, which makes the title compound a potential secondary explosive

Unexpected Formation and Structural Characterization of a Dinuclear Sodium Half-Sandwich Complex

Treatment of N,N′-diisopropylcarbodiimide with sodium cyclopentadienide (NaCp) in a molar ratio of 1:1 in THF solution resulted in formation of the unexpected dinuclear sodium half-sandwich complex [NaC5H3{C(NHiPr)(=NiPr)}2-1,2]2 (1) as colorless crystals in low yield. The newly formed ligand, which belongs to the group of 6-aminofulvene-2-aldiminate ligands, coordinates to sodium in an η5-coordination mode via the cyclopentadienyl ring. Dimerization occurs through additional chelating κN,N′-coordination of the amidine substituents. The NMR data of 1 indicated a slow dimer/monomer equilibrium in solution. A serendipitously isolated hydrolysis product, {µ-(iPrNH)2C=O}2[NaC5H3{C(NHiPr)(=NiPr)}2-1,2]2 (2), contains the new 6-aminofulvene-2-aldiminate ligand in the N,N′-chelating coordination mode with the cyclopentadiene ring being uncoordinated. In this case, dimerization occurs through the presence of two bridging neutral N,N′-diisopropylurea ligands. Both compounds have been structurally characterized by single-crystal X-ray diffraction

Formation and structural characterization of a europium(II) mono(scorpionate) complex and a sterically crowded pyrazabole

The reaction of EuI2(THF)2 with potassium hydrotris(3,5-diisopropylpyrazolyl)borate (K[HB(3,5-iPr2pz)3] (= KTpiPr2, pz = pyrazolyl) in a molar ratio of 1:1.5 resulted in extensive ligand fragmentation and formation of the europium(II) mono(scorpionate) complex bis(3,5-diisopropyl-1H-pyrazole)[hydrotris(3,5-diisopropylpyrazolyl)borato]iodidoeuropium(II), [Eu(C27H46BN6)I(C9H16N2)2] or (TpiPr2)(3,5-iPr2pzH)2EuIII, 1, in high yield (78%). As a typical by-product, small amounts of the sterically crowded pyrazabole derivative trans-4,8-bis(3,5-diisopropylpyrazol-1-yl)-1,3,5,7-tetraisopropylpyrazabole, C36H62B2H8 or trans-{(3,5-iPr2pz)HB(μ-3,5-iPr2pz)}2, 2, were formed. Both title compounds have been structurally characterized through single-crystal X-ray diffraction. In 1, two isopropyl groups are each disordered over two orientations with occupancy ratios of 0.574 (10):0.426 (10) and 0.719 (16):0.281 (16). In 2, one isopropyl group is similarly disordered, occupancy ratio 0.649 (9):0.351 (9)

Chiral Discrimination in Host−Guest Supramolecular Complexes. Understanding Enantioselectivity and Solid Solution Behaviors by Using Spectroscopic Methods and Chemical Sensors

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