Phosphino[tris(trimethylsilyl)methyl]Boranes and 2,4‐Bis[tris(trimethylsilyl)methyl]‐1,3,2,4‐diphosphadiboretanes [1]

The reaction of tris(trimethylsilyl)methylboron dihalides (Me₃Si)₃CBX₂ (X = Cl, F) with the lithium phosphides LiPHtBu and LiPHmes leads to the phosphinoboranes (Me₃Si)₃CBX‐(PHR), (Me₃Si)₃CB(PHR)₂ or the 1,3,2,4‐diphosphadiboretanes [(Me₃Si)₃CB(PR)]₂, depending on the ratio of the reagents, the reaction temperature and concentration. High dilution and low temperatures are required for the synthesis of (Me₃Si)₃CB(Hal)PHR ( 1–3 ) in order to prevent the formation of (Me₃Si)₃CB(PHR)₂ ( 4 and 5 ). The latter compounds are best prepared in a two step phosphination from (Me₃Si)₃CBHal₂ and LiPHR. At higher temperatures the four‐membered 1,3,2,4‐diphosphadiboretanes [(Me₃Si)₃CB(PR)]₂ 6 and 7 are the most stable compounds. On the other hand, compounds of type (Me₃Si)₃CB(Hal)PR₂, 8 and 9 , are thermally more stable than the monophosphinoboranes 1 – 3 . Phosphinoboranes of type (Me₃Si)₃CB(PR₂)₂ (R = tBu, mes) could not be prepared. NMR and mass spectral data are in accord with the monomeric nature of compounds 1 to 9 .     

Cycloadditionsreaktionen von Isocyaniden an Bis[tris(trimethylsilyl)methyl]diphosphen

Cycloaddition Reactions of Isocyanides with Bis[tris(trimethylsilyl)methyl]diphosphene The [2 + 1] cycloaddition reactions of isocyanoacetonitrile ( 1 a ), pentacarbonyl(diisocyanomethane)chromium ( 1 b ), and 2,2,2-trifluoroethylisocyanide ( 1 c ) with the diphosphene R–P=P–R (R = C[Si(CH₃)₃]) ( 2 ) yield the expected diphosphirane imines 3 a – c . All compounds are thermally very stable and show no evidence for a [2 + 1] cycloreversion reaction. The structures of 3 a : triclinic, P 1, a = 918.0(2), b = 1174.7(4), c = 1821.9(5) pm, α = 93.83(2), β = 97.22(2)°, γ = 97.08(2)°, Z = 2, R₁ = 0.069; 3 c : monoclinic, P2₁, a = 928.6(2), b = 1659.8(3), c = 1261.2(3) pm, β = 107.65(2)°, Z = 2, R₁ = 0.073, and 1,2-Bis[tris(trimethylsilyl)]methyl-N-trifluormethyl-3-diphosphiranimin: monoclinic, P2₁/n, a = 1374.6(3), b = 1685.9(1), c = 1658.6(5) pm, β = 108.99(9)°, Z = 4, R₁ = 0.092, were elucidated by X-ray crystallography. All three compounds possess a similar three membered PCP ring system with an exocyclic C–N double bond.     

Thiacalix[4]arene‐Supported Tetranuclear TbIII and EuIII Compounds: Synthesis,Structure, Luminescence,and Magnetism

Two tetranuclear compounds [Ln₄Na(μ₄‐OH)(TC4A)₂(acac)₄] [Ln = Tb ( 1 ), Eu ( 2 )] (acac = acetylacetonate) were synthesized and characterized based on p‐tert‐butylthiacalix[4]arene (H₄TC4A). Compounds 1 and 2 are isostructural and crystallize in the monoclinic C2/c space group. There are two crystallographically independent metal atoms in one asymmetric unit. Ln1, Ln2, and two metal atoms generated by the symmetry operation are bridged by one μ₄‐OH group to form a planar tetragonal Ln₄(μ₄‐OH) unit. Each Ln₄(μ₄‐OH) unit is surrounded by four acac anions and two disordered sodium ions in the planar direction. The upper and lower positions of the Ln₄(μ₄‐OH) unit are further coordinated by two cone‐shaped TC4A ligands to form a sandwich‐type molecular structure. Luminescent measurements reveal that both compounds 1 and 2 exhibit good photoluminescent properties. Moreover, the static and dynamic magnetic properties of compound 1 were also investigated, which demonstrates that 1 is one functional material candidate combining luminescent and antiferromagnetic properties in one molecule.     

Bis(enaminones) as Versatile Precursors for Novel Bis([1,2,4]triazolo[1,5‐a]pyrimidines) and Bis(2‐thioxo‐2,3‐dihydropyrido[2,3‐d]pyrimidin‐4(1H)‐ones)

Novel bis([1,2,4]triazolo[1,5‐a]pyrimidines) and bis(2‐thioxo‐2,3‐dihydropyrido[2,3‐d]pyrimidin‐4(1H)‐ones) were prepared utilizing bis(enaminones) as precursors. The structures of the prepared compounds were elucidated by several spectral tools as well as elemental analyses.     

Synthesis and reactions of [tris(trimethylsilyl)methyl]ethyl dichlorosilane

The crowded dichlorosilane TsiSiEtCl₂, (1), (Tsi = (Me₃Si)₃C) was prepared from the reaction between EtSiCl₃ and TsiLi, then it was reduced with LiAlH₄ to give TsiSiEtH₂, (2). The hydride (2) was then treated with two equivalents of ICl/CCl₄ or Br₂/CCl₄ to produce TsiSiEtI₂, (3), and TsiSiEtBr₂, (4), respectively. The reaction of compound (2) with one equivalent of ICl/CCl₄ gives TsiSiEtHI, (5). This product reacted with H₂O/dioxane in the presence of AgClO₄ or with dry MeOH to produce TsiSiEtHOH, (6), and TsiSiEtHOMe, (7), respectively. The compound (3) reacted with H₂O in DMSO/CH₃CN to give TsiSiEt(OH)₂, (8), and the compound TsiSiEtIOMe, (9), was prepared from the reaction of the compound (7) with ICl/CCl₄. When the dichloride (1) was treated with NaOMe/MeOH it gave (Me₃Si)₂CHSiEt(OMe)₂. It is suggested that the reaction proceeds through an elimination-addition mechanism. The dichloride (1) was also treated with KSCN, NaN₃ or NaOCN in CH₃CN to give S_N2 substitution products. All the new products were characterized by FTIR, ¹H NMR, and ¹³C NMR spectroscopy, mass spectrometry and elemental analysis.     

Synthesis,Crystal Structure,Fluorescent and Antioxidation Properties of Cerium(III) and Europium(III) Complexes with Bis(3‐methoxysalicylidene)‐3‐oxapentane‐1,5‐diamine

Two aliphatic ether Schiff base lanthanide complexes (Ln = Eu, Ce) with bis(3‐methoxysalicylidene)‐3‐oxapentane‐1,5‐diamine (Bod), were synthesized and characterized by physicochemical and spectroscopic methods. [Eu(Bod)(NO₃)₃] ( 1 ) is a discrete mononuclear species and [Ce(Bod)(NO₃)₃DMF]_∞ ( 2 ) exhibits an inorganic coordination polymer. In the two complexes, the metal ions both are ten‐coordinated and the geometric structure around the Ln^III atom can be described as distorted hexadecahedron. Under excitation at room temperature, the red shift in the fluorescence band of the ligand in the complexes compared with that of the free ligand can be attributed to coordination of the rare earth ions to the ligand. Moreover, the antioxidant activities of the two complexes were investigated. The results demonstrated that the complexes have better scavenging activity than both the ligand and the usual antioxidants on the hydroxyl and superoxide radicals.     

Synthesis and Biological Evaluation of Novel Bis[1,2,4]triazolo[3,4‐b] [1,3,4]oxadiazoles

A series of novel 6‐2‐methoxy‐5‐[4‐methoxy‐3‐(3‐aryl[1,2,4]triazolo[3,4‐b][1,3,4]oxadiazol‐6‐yl)benzyl]phenyl‐3‐aryl[1,2,4]triazolo[3,4‐b][1,3,4]oxadiazoles 7a , 7b , 7c , 7d , 7e , 7f , 7g , 7h , 7i , 7j has been synthesized and characterized via IR, ¹H NMR, ¹³C NMR, MS, and elemental analyses. Compounds 7a , 7b , 7c , 7d , 7e , 7f , 7g , 7h , 7i , 7j were also screened for their antibacterial activity against Gram‐positive bacteria viz. Bacillus subtilis (MTCC 441), Bacillus sphaericus (MTCC 11), and Staphylococcus aureus (MTCC 96), and Gram‐negative bacteria viz. Pseudomonas aeruginosa (MTCC 741), Klobsinella aerogenes (MTCC 39), and Chromobacterium violaceum (MTCC 2656). The antibacterial screening reveal that the presence of 2,4‐difluorophenyl ( 7e ) or 4‐nitrophenyl ( 7f ) of 2‐pyrazyl ( 7i ), or 2‐furyl ( 7j ) on the triazole moiety exhibited potent inhibitory activity comparable with the standard drug streptomycin, at the tested concentrations, and emerged as potential molecules for further development.     

Synthesis and Structural Characterization of Bis(tetrahydro­pyran)calcium Bis[bis(trimethylsilyl)amide]

Transmetalation of Sn[N(SiMe₃)₂]₂ with calcium granules in tetrahydropyran (thp) yields colorless [(thp)₂Ca{N(SiMe₃)₂}₂] ( 1 ) which is soluble in common organic solvents. The calcium center is in a distorted tetrahedral environment with Ca–N and Ca–O bond lengths of 231.08(11) and 240.23(9) pm, respectively. The molecular structure is dominated by steric factors leading to a NCaN bond angle of 119.43(6)°.     

Crystallographic report: Bis[tris(2‐methyl‐2‐phenylpropyl)tin] piperazinyldithiocarbamate

The centrosymmetric structure of bis[tris(2‐methyl‐2‐phenylpropyl)tin]piperazinyldithiocarbamate contains four‐coordinated tin and monodentate dithiocarbamate ligands. Copyright © 2004 John Wiley & Sons, Ltd.     

Synthese und Kristallstrukturen von (2‐Methylpyridinium)3[TbCl6] und (2‐Methylpyridinium)2[TbCl5(1‐Butanol)]

Preparation and Structure of (2‐Methylpyridinium)₃[TbCl₆] and (2‐Methylpyridinium)₂[TbCl₅(1‐Butanol)] The complex chlorides (2‐Methylpyridinium)₃[TbCl₆] (1) and (2‐Methylpyridinium)₂[TbCl₅(1‐Butanol)] (2) have been prepared for the first time. The crystal structures have been determinated from single crystal X‐ray diffraction data. 1 crystallizes in the monoclinic space group C2/c (Z = 8) with a = 3241,2(5) pm, b = 897,41(9) pm, c = 1774,2(2) pm and β = 97,83(2)°, 2 in the monoclinic space group P2₁/n (Z = 4) with a = 1372,96(16) pm, b = 997,57(9) pm, c = 1820,5(2) pm and β = 108,75(1)°. The structures contain isolated octahedral building units [TbCl₆]^3– and [TbCl₅(1‐Butanol)]^2–, respectively.     

Synthese und Kristallstrukturen von (3‐Methylpyridinium)3[DyCl6] und (3‐Methylpyridinium)2[DyCl5(Ethanol)]

Preparation and Structure of (3‐Methylpyridinium)₃[DyCl₆] and (3‐Methylpyridinium)₂[DyCl₅(Ethanol)] The complex chlorides (3‐Methylpyridinium)₃[DyCl₆] ( 1 ) and (3‐Methylpyridinium)₂[DyCl₅(Ethanol)] ( 2 ) have been prepared for the first time. The crystal structures have been determined from single crystal X‐ray diffraction data. 1 crystallizes in the trigonal space group R3c (Z = 36) with a = 2953.3(3) pm, b = 2953.3(3) pm and c = 3252.5(4) pm, compound 2 crystallizes in the triclinic space group P1 (Z = 2) with a = 704.03(8) pm, b = 808.10(8) pm, c = 1937.0(2) pm, α = 77.94(1)°, β = 87.54(1)° and γ = 83.26(1)°. The structures contain isolated octahedral building units [DyCl₆]^3– and [DyCl₅(Ethanol)]^2–, respectively.     

Bis[tris(trimethylsilyl)silyl]zink, -cadmium und -quecksilber,schwingungsspektroskopische Daten und Strukturanalysen

Bis[tris(trimethylsilyl)silyl] Zinc, Cadmium, and Mercury – a Structural Study by IR and Raman Spectroscopy and X-Ray Analyses Raman and FT-IR spectra of bis[tris(trimethylsilyl)silyl] zinc ( 1 ), cadmium ( 2 ) and mercury ( 3 ) were recorded. The vibrational data are in agreement with either D_3h or a D_3d symmetry. The latter had been shown to be the correct one at least for the solid state by X-ray diffraction experiments. All three compounds crystallize isomorphically in the triclinic centrosymmetric space group P1 . [ 2 (T = 293 K): a = 9.4388(11); b = 9.744(2); c = 12.926(2); α = 68.200(12); β = 71.971(10); γ = 60.925(10); Z = 1; (T = 173 K): a = 9.336(6); b = 9.585(5); c = 12.488(8); α = 68.77(4); β = 72.28(4); γ = 62.06(4); 3 : a = 9.467(2); b = 9.749(2); c = 12.885(2); α = 67.840(14); β = 71.510(14); γ = 60.890(14); Z = 1]. The Hg—Si bondlength in 3 was found to be 246.9(2)pm, somewhat shorter then in all disilylmercury derivatives investigated sofar and even shorter than the Cd—Si bond in 2 (250.4(1)pm). Bondlengths and angles within the tris(trimethylsilyl)silyl group are virtually equal in all three group 12 derivatives and lie in the expected range.     

The Reaction of Transient 1,1‐Bis(trimethylsilyl)silenes with Tris(trimethylsilyl)silyllithium – Synthesis and Structure of Sterically Congested 1‐Trimethylsilylalkylpolysilanes

Tris(trimethylsilyl)silyllithium ( 3 ) reacted with aldehydes and ketones (molar ratio 2 : 1) according to a modified Peterson mechanism under formation of transient silenes, which were immediately trapped by excess 3 to give the organolithium derivatives (Me₃Si)₃SiSi(SiMe₃)₂C(Li)R¹R² ( 7 ). Hydrolysis of 7 afforded the alkylpolysilanes (Me₃Si)₃SiSi(SiMe₃)₂CHR¹R² ( 8 ). Depending on the substituents R¹ and R², 7 proved to be rather unstable in THF solution and underwent a rapid rearrangement, involving a 1,3‐Si,C‐trimethylsilyl migration, resulting in the formation of the lithium silanides (Me₃Si)₂Si(Li)Si(SiMe₃)₂C(SiMe₃)R¹R² ( 9 ), which were hydrolized during the aqueous workup to give the H‐silanes (Me₃Si)₂Si(H)Si(SiMe₃)₂C(SiMe₃)R¹R² ( 10 ). Reaction of 9 with chlorotrimethylsilane produced the 1‐trimethylsilylalkylpolysilanes (Me₃Si)₃SiSi(SiMe₃)₂C(SiMe₃)R¹R² ( 11 ). The structures of the products described were elucidated by comprehensive spectral analyses. The results of X‐ray crystal structure analyses, performed for 8 l (R¹ = H, R² = 2,4,6‐(MeO)₃C₆H₂), 10 d (R¹ = H, R² = Mes) and 11 d (R¹ = H, R² = Mes) are discussed and confirm the expected extreme sterical congestion of the molecules.     

Synthesis and Molecular Structure of Two Zinc Complexes of 1,2‐Bis[(trimethylsilyl)imino]acenaphthene

The reaction of 1,2‐bis[(trimethylsilyl)imino]acenaphthene ( 1 , tms‐BIAN) with ZnCl₂ and ZnI₂ in THF and Et₂O afford (tms‐BIAN)ZnCl₂ ( 2 ) and (tms‐BIAN)ZnI₂ ( 3 ), respectively. The compounds 2 and 3 were characterized by IR‐ and NMR spectroscopy as well as by single crystal X‐ray analysis.     

1,3‐Bis(trimethylsilyl)‐1,3,2‐diazaphospha‐[3]ferrocenophanes

The 2‐tert‐butyl, 2‐phenoxy, and 2‐diethylamino derivatives of 1,3‐bis(trimethylsilyl)‐1,3,2‐diazaphospha‐[3]ferrocenophane were prepared, and the molecular structure of the latter was determined by X‐ray diffraction. The phosphines could be oxidized by their slow reactions with sulfur or selenium, and the molecular structures of three sulfides and one selenide were determined. In contrast, the synthesis of oxides was less straightforward. All new compounds were characterized in solution by multinuclear magnetic resonance methods (1D and 2D ¹H, ¹³C, ¹⁵N, ²⁹Si, ³¹P, and ⁷⁷Se NMR spectroscopy).