Syntheses and structures of highly hindered N-functionalised alkyl and amido group 12 complexes MR2 (M=Zn, Cd, and Hg), [MRCl]2 (M=Zn and Hg)

The reaction of MCl₂ (M=Zn, Cd and Hg) with Li(2-(C(SiMe₃)₂)(6-Me-C₅H₃N)), [Li(MeR)], affords mononuclear metal(II) alkyls. These, in the solid state, show intramolecular M-N interactions in their four-membered chelate rings, which progressively weaken down the series, the C-M-C angles becoming more open (〈M-N〉= 2.30(2), 2.52(2), 2.913(4) Å, C-M-C=160.7(2), 168.5(2), 180(-)°). Alkylmercury chloride complexes have been prepared by the reaction of HgCl₂ with [Li(MeR)], Li(2-(C(SiMe₃)₂)(C₅H₄N)), [Li(HR)], or Li(2-(NSiMe₃)(6-Me-C₅H₃N)), [Li(mpsa)], or from the redistribution reaction of the dialkyl (or amido) mercury complex with HgCl₂. The alkylmercury chloride complexes are dimeric or polymeric in nature with near-linear 2-coordination; (Hg-Cl=2.329(5), 2.318(4), 2.272(8) Å, Cl-Hg-C(N)=175.0(4), 174.7(4), 175.6(5)°). Cd(2-(CH(SiMe₃))(6-Me-C₅H₃N))₂(tmen), prepared from the reaction of Li(2-(CH(SiMe₃))(6-Me-C₅H₃N)) and CdCl₂ in the presence of tmen, has also been structurally authenticated as the rac isomer with the ipso protons directed towards the tmen.     

Synthetic and structural chemistry of groups 11 and 12 metal complexes of the zwitterionic ammonium thiolate ligands

The chemistry of metal complexes of the zwitterionic ammonium thiolates has expanded dramatically in the recent years. This review is intended to summarize the synthesis and crystal structures of groups 11 and 12 metal zwitterionic ammonium thiolate complexes. Seven methods for the synthesis of these metal complexes of the zwitterionic ammonium thiolates are outlined: proton transfer reaction, precursor reaction, ligand exchange reaction, oxidation–reduction reaction, solid-state reaction, electrochemical reaction and hydro(solvo)thermal reaction. These metal complexes of the zwitterionic ammonium thiolates are classified according to the number of metal atoms; their specific structures are briefly discussed.     

Darstellung, 11B-, 13C-, 1H-NMR- und Schwingungsspektren von Monoethoxyhydro-closo-Dodecaborat(2–) sowie Kristallstruktur von [(C5H5N)2CH2][B12H11(OC2H5)]

Preparation, ¹¹B, ¹³C, ¹H NMR and Vibrational Spectra of Monoethoxyhydro-closo-dodecaborate(2–), and the Crystal Structure of [(C₅H₅N)₂CH₂][B₁₂H₁₁(OC₂H₅)] By treatment of Na₂[B₁₂H₁₂] with dry HF in ethanol Na₂[B₁₂H₁₁(OC₂H₅)] is formed which has been separated by ion exchange chromatography on diethylaminoethyl(DEAE) cellulose from the starting compound and by-products. The X-ray structure determination of [(C₅H₅N)₂CH₂][B₁₂H₁₁(OC₂H₅)] (monoclinic, space group P2₁/m, a = 9.1906(3), b = 12.6612(8), c = 9.3640(12) Å, β = 112.947(6)°, Z = 2) reveals the complete ordering of the anion sublattice. The ¹¹B nmr spectrum exhibits the characteristic feature (1:5:5:1) of a mono substituted B₁₂ cage with a strong down-field shift of ipso-B at +6.5 ppm. In the ¹³C nmr spectrum a triplet at 67.9 ppm of the methylene group and a quartet at 19.5 ppm of the methyl group is observed. Correspondingly, the ¹H nmr spectrum shows two multiplets at 3.7 and 1.3 as expected for an ethoxy substituent, and a multiplet at 2.1 ppm due to the protons of the boron cluster. The i.r. and Raman spectra exhibit strong CH stretching vibrations between 2 963 and 2 863 cm^?1, and in the i.r. spectrum the CO and BO stretching frequencies of the B? O? C bridge are observed at 1 175 and 1 140 cm^?1.     

One-Pot Synthesis of N-Boc-2, 5-bis(trimethylsilyl)pyrrolidine

Since Daly reported the structure of epibatidine and its potent analgesic activity in 19921, study on the synthesis of epibatidine and its derivatives and relationships between the structure and activity of epibatidine has received much attention2. During the course of our research for the synthesis of epibatidine derivatives, N-boc-2, 5-bis(trimethylsilyl)pyrrolidine 4 was used as the key intermediate to construct the skeleton of epibatidine via the 1, 3-dipolar cycloaddition (Scheme 1). Ac…     

Formation of a PIII−C(sp2) bond by addition of diphenyl(trimethylsilyl)phosphine to activated acetylenes

Diphenyl(trimethylsilyl)phosphine reacts with alkoxy(alkyl)acetylenes to give mixtures of addition products, (2-alkoxy-2-trimethylsilylalkenyl)diphenylphosphines and (2-alkoxyalkenyl)diphenylphosphines. The reaction is sensitive to the solvent; in MeCN, it gives only nonsilylated products. (1-Alkoxyethenyl)diphenylphosphines were obtained as the main products upon the reaction of Ph₂PSiMe₃ with terminal alkoxyalkynes, irrespective of the reaction conditions. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1792–1796, September, 1998.     

Small Chains of Main Group Elements by BH3 Adduct Formation of tBu2E-N(H)-EtBu2 (E = P,As)

Borane adducts of bis(di-tert-butylphosphanyl)amine ( 1a ) and bis(di-tert-butylarsino)amine ( 1b ) are reported. Based on quantum-chemical investigations in combination with experimental results, it is demonstrated that the tautomerism known for tBu₂P-N(H)-PtBu₂ ( 1a ), can be observed for the mono adduct tBu₂P-N(H)-P(BH₃)tBu₂ ( 2a ) as well, whereas for the corresponding arsenic compound 2b only one stable isomer is found. The bis-borane adduct tBu₂(BH₃)As-N(H)-As(BH₃)tBu₂ ( 3b ) is a rare example of a structurally characterized, tertiary arsine borane adduct, which can be directly compared with the corresponding phosphorus compound tBu₂(BH₃)P-N(H)-P(BH₃)tBu₂ ( 3a ). Deprotonation of mixtures containing 2a by nBuLi leads to the lithium-containing coordination polymer 4a , in which the actual chain consists only of non-carbon atoms.     

1-[4-(1,2,4-三唑-5-硫酮)]-3-对甲氧基苯甲酰基硫脲镍配合物的晶体结构

采用缓慢蒸发法培养出化合物1-[4-(1,2,4-三唑-5-硫酮)]-3-对甲氧基苯甲酰基硫脲镍配合物晶体,并通过X-射线单晶衍射法测定了晶体结构,它为P2/n空间群的单斜晶体,晶胞参数为α=1.2577(2)nm,b=0.88790(17)nm,c=1.2628(2)nm,V=1.3304(4)nm3,R1=0.0291和wR2=0.0694.     

Recent studies on metal and metalloid bis(trimethylsilyl)methyls and the transformation of the bis(trimethylsilyl)methyl into the azaallyl and β-diketinimato ligands

Recent results (post-1990) on the synthesis and structures of bis(trimethylsilyl)methyls M(CHR₂)_m (R = SiMe₃) of metals and metalloids M are described, including those of the crystalline lipophilic [Na(μ-CHR₂)]_∞, [Rb(μ-CHR₂)(PMDETA)]₂, K₄(CHR₂)₄(PMDETA)₂, [Mg(CHR₂)(μ-CHR₂)]_∞, P(CHR₂)₂ (gaseous) and P₂(CHR₂)₄, [Yb(CHR₂)₂(OEt₂)₂] and [{Yb(CR₃)(μ-OEt)(OEt₂)}₂]; earlier information on other M(CHR₂)_m complexes and some of their adducts is tabulated. Treatment of M(CHR₂) (M = Li or K) with four different nitriles gave the X-ray-characterized azaallyls or β-diketinimates , and (LL′ = N(R)C(^tBu)CHR, L′L′ = N(R)C(Ph)C(H)C(Ph)NR, LL″ = N(R)C(Ph)NC(H)C(Ph)CHR, R = SiMe₃ and Ar = C₆H₃Me₂-2,5). The two lithium reagents were convenient sources of other metal azaallyls or β-diketinimates, including those of K, Co(II), Zr(IV), Sn(IV), Yb(II), Hf(IV) and U(VI)/U(III). Complexes having one or more of the bulky ligands [LL′]⁻, [L′L′]⁻, [LL]⁻, [LL″]⁻, [L″L]⁻, [LL]⁻ and [{N(R)C(^tBu)CH}₂C₆H₄-2]²⁻ are described and characterized (LL = N(H)C(Ph)C(H)C(Ph)NH, L″L = N(R)C(^tBu)C(H)C(Ph)NR, LL = N(R)C(^tBu)CHPh). Among the features of interest are (i) the contrasting tetrahedral or square-planar geometry for and , respectively, and (ii) olefin-polymerization catalytic activity of some of the zirconium(IV) chlorides.     

Synthesis and characteristics of novel pentanuclear complexes [(OC)3Mn(η1,η5-C5H4)Fe(CO)2(η1,η5-C5H4CO2)]2M(η5-C5H5)2 (M=Ti, Zr)

The reaction of Cp₂MCl₂ complexes (M=Ti and Zr) with 2 equiv. of (OC)₃Mn(η¹,η⁵-C₅H₄)Fe(CO)₂(η⁵-C₅H₄COONa) results in the formation of the pentanuclear complexes (OC)₃Mn(η¹,η⁵-C₅H₄)Fe(CO)₂(η⁵-C₅H₄CO₂)]₂M(η⁵-C₅H₅)₂, which are characterized by IR and¹H NMR spectroscopy and cyclic voltammetry. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1055–1058, May, 1997.     

Synthesis, structure and reactivity of new yttrium bis(dimethylsilyl)amido and bis(trimethylsilyl)methyl complexes of a tetradentate bis(phenoxide) ligand

The reactions of a bulky amino-methoxy bis(phenolate) ligand H₂L with Y(CH₂SiMe₃)₃(THF)₂ and Y[N(SiHMe₂)₂]₃(THF)₂ under mild condition leads to the selective formation of the thermally stable complexes [L]Y(CH₂SiMe₃)(THF) (1) and [L]Y[N(SiHMe₂)₂](THF) (2). The X-ray structures revealed very similar binding of the [ONOO] ligand core to the metal for both complexes, which feature an octahedral geometry involving coordination of the methoxy side-arm of the ligand and of a remaining THF molecule. ¹H-NMR spectroscopy indicates that the solid state structure of 1 and 2 is retained in hydrocarbon solutions with THF coordinated to yttrium. Alkyl complex 1 showed no activity in ethylene polymerization, presumably due to the presence of coordinated THF. The amido complex 2 catalyzed sluggishly the polymerization of methyl methacrylate to give isotactic-rich PMMA but is very active for the ring-opening polymerization of ε-caprolactone.     

Synthesis, characterization and antifungal activity of group 12 metal complexes of 2-acetylpyridine-N-ethylthiosemicarbazone (H4EL) and 2-acetylpyridine-N-oxide-N-ethylthiosemicarbazone (H4ELO)

Reaction of group 12 metal halides in ethanol with the thiosemicarbazones 2-acetylpyridine-⁴N-ethylthiosemicarbazone (H4EL) and 2-acetylpyridine-N-oxide-⁴N-ethylthiosemicarbazone (H4ELO) produced the compounds [M(H4EL)X₂] and [M(H4ELO)X₂] [M=Zn(II), Cd(II) or Hg(II), X=Cl, Br or I]. The ligands and complexes were characterized by elemental analysis and by IR and NMR (¹H, ¹³C, ¹¹³Cd, ¹⁹⁹Hg) spectroscopy, and the structures of H4ELO·H₂O and the complexes [Cd(H4EL)I₂]·2DMSO, [Hg(H4EL)Br₂]–DMSO, [Zn(H4ELO)Cl₂] and [Zn(H4ELO)Br₂] were determined by X-ray diffraction. The metal centers in the complexes have coordination number five, H4EL and H4ELO behaving as neutral NNS- and ONS-tridentate ligands, respectively. The coordination polyhedra are close to tetragonal pyramids, the degree of distortion towards trigonal bipyramids was estimated by τ calculation. Against the pathogenic fungi Aspergillus niger and Paecilomyces variotii, the mercury complexes of H4ELO had activities that at some doses exceeded that of nystatin.     

Human liver dihydrodiol dehydrogenase 1-catalyzed reaction generating 9alpha,11beta-prostaglandin F2 from prostaglandin D2 followed by micellar electrokinetic chromatography

An enzyme reaction converting prostaglandin D2 (PGD2) into 9alpha,11beta-prostaglandin F2 (9alpha,11beta-PGF2) by a human liver-originated recombinant dihydrodiol dehydrogenase 1 (DD1) has been studied using CE. Four prostaglandins, viz. PGD2, 9alpha,11beta-PGF2, PGE2, and PGF2a (see Fig. 1, the latter two major PGs are possibly coexisting compounds in the assay mixtures), were completely separated by using SDS or PEG as buffer additives. Because analysis times in the SDS system were shorter than in the PEG system, SDS was employed in measurements of the enzyme activity of DD1. The pH dependence and the reaction temperature dependence of enzyme activity have been studied. The present method enabled us to detect all of the participants in the enzyme reaction: PGD2, 9alpha,11beta-PGF2, nicotinamide adenine dinucleotide phosphate (NADPH), and NADP+. Thus, direct, comprehensive, and reliable analysis of the enzyme reaction becomes possible. Enzyme activity has hitherto been estimated indirectly from the decrease of fluorescence derived from NADPH as an index of progress of the enzyme reactions in batch methods employed in conventional studies. In addition, the low sample consumption characteristic of CE should be a significant advantage of the present method in characterization of less commonly available enzymes such as the recombinant species used in this work.     

Group 12 metal coordination polymers of 1,2-bis(diphenylphosphino)ethane dioxide: A persistent 1D chain motif and consequent 2D and 3D architectures

A series of group 12 metal coordination polymers with 1,2-bis(diphenylphosphino)ethane dioxide (dppeO₂), {[ZnCl₂(μ-dppeO₂)]·CH₂Cl₂}_n (1·CH₂Cl₂), [ZnBr₂(μ-dppeO₂)]_n (2), [CdI₂(μ-dppeO₂)]_n (4), [(HgI₂)₂(μ-dppeO₂)]_n (5), [Zn(SCN)(μ-SCN)(μ-dppeO₂)]_n (6), and [Cd(NO₃)(μ-SCN)(μ-dppeO₂)]_n (7), have been synthesized and structurally characterized. The structures of the compounds are all based on an infinite 1D chain constructed by four-coordinate metal ions and dppeO₂ ligands adopting the trans bridging coordination fashion. In the coordination polymers 1, 2 and 4, the halide ions act as terminal ligands, leading to discrete 1D chains with alternative MX₂ and dppeO₂ repeating units. The mercury compound 5 features a unique square-wave-like inorganic chain –[Hg(1)–I–Hg(2)–I]–, and the 1D HgI₂(μ-dppeO₂) chains are further linked by HgI₂ bridges to form a 3D network. In the thiocyanate-containing compounds 6 and 7, the 1D chains are linked by one (6) or two (7) bridging SCN^– ions to result in 2D layered structures. Solid-state emission spectra of the coordination polymers show different variations compared to the free dppeO₂ ligand, such as enhancement (1, 2, 6 and 7), shift (3 and 4) and quenching (5) upon metal coordination.     

Palladium(II) and Platinum(II) Complexes with Bisphosphanes, [S2C=C(CN)2]2– and [Se2C=C(CN)2]2– as Chelating Ligands

The palladium(II) and platin(II) 1, 1‐dicyanoethylene‐2, 2‐dithiolates [(L–L)M{S₂C=C(CN)₂}] (M = Pd: L–L = dppm, dppe, dcpe, dpmb; M = Pt: dppe, dcpe, dpmb) were prepared either from[(L–L)MCl₂] and K₂[S₂C=C(CN)₂] or from [(PPh₃)₂M{S₂C=C(CN)₂}] and the bisphosphane. Moreover, [(dppe)Pt{S₂C=C(CN)₂}]was obtained from [(1, 5‐C₈H₁₂)Pt{S₂C=C(CN)₂}] and dppeby ligand exchange. The 1, 1‐dicyanoethylene‐2, 2‐diselenolates[(dppe)M{Se₂C=C(CN)₂}] (M = Pd, Pt) were prepared from[(dppe)MCl₂] and K₂[Se₂C=C(CN)₂]. The oxidation potentials of the square‐planar palladium and platinum complexes were determined by cyclic voltammetry. The reaction of [(dcpe)Pd(S₂C=O)] with TCNE led to a ligand fragment exchange and gave the 1, 1‐dicyanoethylene‐2, 2‐dithiolate [(dcpe)Pd{S₂C=C(CN)₂}] in good yield.     

Thromboxane A2 modulates migration, proliferation, and differentiation of adipose tissue-derived mesenchymal stem cells

Prostanoid metabolites are key mediators in inflammatory responses, and accumulating evidence suggests that mesenchymal stem cells (MSCs) can be recruited to injured or inflamed tissues. In the present study, we investigated whether prostanoid metabolites can regulate migration, proliferation, and differentiation potentials of MSCs. We demonstrated herein that the stable thromboxane A₂ (TxA₂) mimetic U46619 strongly stimulated migration and proliferation of human adipose tissue-derived MSCs (hADSCs). Furthermore, U46619 treatment increased expression of α-smooth muscle actin (α-SMA), a smooth muscle marker, in hADSCs, suggesting differentiation of hADSCs into smooth muscle-like cells. U46619 activated ERK and p38 MAPK, and pretreatment of the cells with the MEK inhibitor U0126 or the p38 MAPK inhibitor SB202190 abrogated the U46619-induced migration, proliferation, and α-SMA expression. These results suggest that TxA₂ plays a key role in the migration, proliferation, and differentiation of hADSCs into smooth muscle-like cells through signaling mechanisms involving ERK and p38 MAPK.     

Synthesis, Crystal Structure and Antibacterial Activity of 1-（（2-Chloroquinolin-3-yl）-methyl）-pyridin-2（1H）-one

On the basis of the interesting structures and biological activities exhibited by several heterocyclic systems possessing the pyridone nucleus such as mappcine and camptothecin, we have planed to design the synthesis, crystal studies and antibacterial activity of the new 1-((2- chloroquinolin-3yl)-methyl)-pyridine-2(1H)-one building block. An X-ray analysis has provided valuable insight into the effect of steric factors on the three-dimensional shape of this compound which serves as a useful advanced intermediate in the synthesis of these biologically active molecules. A multistep synthesis of camptothecin (5) has been designed by retrosynthetic analysis as part of an ongoing program on lead anticancer drug.     

Preparation and crystal structures of five organoantimony halides; (p-tolyl)antimony(III) dichloride and dibromide, diphenylantimony(III) bromide, 2′-diyl)antimony(III) chloride and bis-(2′-chlorobiphenyl-2-yl)antimony(V) trichloride

Crystal structures are reported for four organoantimony(III) halides, i.e. (p-tolyl)antimony dichloride (1) and dibromide (2), diphenylantimony bromide (3), (biphenyl-2,2′-diyl) antimony chloride (4) and a new antimony(V) compound, bis(2′-chlorobiphenyl-2-yl)antimony(V) trichloride (5), obtained by oxidising (4) with an excess of chlorine. The two tolyl compounds (1) and (2), which are isostructural and also isostructural with the corresponding phenyl derivatives, contain pyramidal CSbX₂ units. These are interlinked by (a) two weak intermolecular Sb halogen interactions (mean 3.54 and 3.69 Å for the chloride and bromide, respectively), raising the antimony coordination number to five giving infinite chains, and (b) weak contacts between antimony and three of the carbon atoms of a symmetry-related tolyl group (mean 3.41 and 3.42 Å for the chloride and bromide, respectively).

There are no intermolecular Sb Br contacts in 3 but two Sb C interactions (mean 3.64 Å) interconnect the pyramidal monomers. Such Sb C interactions (mean 3.43 Å) are also present in the biphenylyl derivative 4, in which the C---Sb---C angle in the pyramidal monomer is constrained to 81.0° by the short bite of the biphenylyl group. Loose dimers are formed in the solid state by Sb Cl contacts at 3.71 Å.

In contrast to the chlorine bridged dimeric structure of Ph₂SbCI₃, compound 5 is a distorted trigonal bipyramidal monomer in the solid state, providing the first example of an antimony(V) compound with chlorine atoms in both axial and equatorial sites. As expected, distances to the two axial chlorines are substantially longer (2.420(3), 2.421(3) Å) than that to the equatorial atom (2.280(3) Å). The greatest distortion is shown by the equatorial C---Sb---C angle, which is increased to 137.1°, probably as a consequence of the steric requirements of the bulky chlorobiphenylyl groups.     

Group 15 ligand migration in the heteronuclear clusters RuOs3(μ-H)2(CO)12(EPh3) (E = P, As, Sb)

The monosubstituted clusters RuOs₃(μ-H)₂(CO)₁₂(EPh₃) (where E = P, As, Sb) exhibit isomers in which the group 15 ligand is on an Os or an Ru vertex. Evidence is presented for hydride fluxionality and EPh₃ ligand migration. These processes have been examined by variable temperature NMR studies, and the kinetic parameters estimated.     

Synthesis of 1,1-bis(trifluoromethyl)alkyl isocyanates, carbamates, and ureas

A convenient preparative method for the synthesis of 1,1-bis(trifluoromethyl)alkyl isocyanates was proposed. The reactions of the isocyanates with alcohols, phenols, and alkyl-, aryl-, and hetarylamines were studied. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1205–1209, July, 2000.