Reaction Of 1a Research Articles

Unique Reactivity of (Arylimido)vanadium(V)–Alkyl Complexes with Phenols: Fast Phenoxy Ligand Exchange in the Presence of Vanadium(V)–Alkyls

Reactions of the aryloxo-modified (arylimido)vanadium(V) mono- or dialkyl complexes, V(NAr)(CH2SiMe3)2(OAr) or V(NAr)(CH2SiMe3)(OAr)2 (Ar = 2,6-Me2C6H3), with various phenols in C6D6 have been explored. The reaction of V(NAr)(CH2SiMe3)2(OAr) (1a) with ArOH in C6D6 did not take place at 25 °C even after 24 h, and the reaction affording V(NAr)(CH2SiMe3)(OAr)2 (2a) was complete after 50 h at 60 °C. In contrast, the reaction of 1a with C6F5OH took place rapidly at 25 °C, affording another monophenoxide, V(NAr)(CH2SiMe3)2(OC6F5) (1b), in addition to formation of the corresponding bis(phenoxide), V(NAr)(CH2SiMe3)(OAr)(OC6F5) (2b). The immediate ligand exchange was also observed when V(NAr)(CH2SiMe3)(OAr)2 (2a) was added to C6F5OH at 25 °C, affording 2b exclusively without reaction with the vanadium(V)–alkyl bond: further, subsequent reaction of 2b with C6F5OH or ArOH did not take place or was very slow at 25 °C. The exchange of 1a (in C6D6 at 25 °C) with various phenols (Ar′OH) proceeded in the order Ar′ = C6F5 > 4-FC6H4 > C6H5 > 2,6-F2C6H3 ≫ 2,6-Me2C6H3 (too slow or no reaction). The results clearly suggest that the reactions proceeded by coordination of phenols on the vanadium metal center.

The reactivity of NbX5 (X = F, Cl) with lactons, lactams, and the synthesis of the first nucleobase-containing niobium complex

NbX5 (X=F, 1a; X=Cl, 1b) reacted with γ-butyrolactone (but), ε-caprolactam (cap), δ-valerolactam (val) in 1:1M ratio in chlorinated solvent, affording either the neutral coordination adducts NbCl5L (L=but, 2a; L=val, 2b) or the ionic ones [NbX4L2][NbX6] (X=F, L=but, 3a; X=F, L=val, 3b; X=F, L=cap, 3c; X=Cl, L=cap, 3d). The reaction of 1a with equimolar amount of guanine (gua) in CH3CN resulted in the formation of the complex [NbF4(gua)2][NbF6], 3e. The addition of two equivalents of organic substrate to 1 gave selectively the compounds NbCl5L2 (L=but, 4a; L=val, 4b) or [NbF4L4][NbF6] (L=but, 5a; L=val, 5b; L=cap, 5c). The 1:2M reaction of 1b with ε-caprolactam proceeded with C–N bond activation and afforded the derivative ▪, 6, in high yield.

Heterogeneously Catalyzed Diastereoselective Synthesis of 2-Nitro-1,3-di(pyridin-2-yl)propane-1,3-diols

2-Nitro-1,3-di(pyridin-2-yl)propane-1,3-diols 4a, 4b are prepared via nitroaldol (Henry) reaction in two separate steps by straightforward procedures. The employment of two solids as catalysts, namely the hydrotalcite Syntal 696® and the ion exchange resin Amberlyst A21® allows a simple work-up and leads to the diastereoselective formation of the (R,R)- and (S,S)-isomers. The solid-state structures of 4a, 4b as well as of their precursor compounds 3a and 3b were determined. Reaction of 4a with zinc chloride yields a mononuclear zinc chloride complex. To circumvent retro-reactions, trialkylsilyl protective groups are deployed.

Rhenium Nitrosyl Complexes Bearing Large-Bite-Angle Diphosphines

A series of [ReBr2(MeCN)(NO)(P∩P)] complexes (P∩P = 1,1′-bis(diphenylphosphino)ferrocene (dppfc) (1a), 1,1′-bis(diisopropylphosphino)ferrocene (diprpfc) (1b), 2,2′-bis(diphenylphosphino)diphenyl ether (dpephos) (1c), 10,11-dihydro-4,5-bis(diphenylphosphino)dibenzo[b,f]oxepine (homoxantphos) (1d), 4,6-bis(diphenylphosphino)-10,10-dimethylphenoxasilin (Sixantphos) (1e)) were prepared with diphosphines varying in the P–Re–P bite angles. 1a,c–e were obtained from the reaction of [ReBr5(NO)][NEt4]2 with an excess of the respective diphosphine in MeCN or MeCN/THF mixtures at elevated temperatures. Compound 1b was obtained by an alternative route, cleaving the dinuclear [{ReBr(μ2-Br)(NO)(diprpfc)}2] unit (2b) with MeCN. 2b was prepared from the reaction of [ReBr5(NO)][NEt4]2 with diprpfc in EtOH. The reaction of 1a–d with HSiEt3 gave the seven-coordinate [ReBr(H)2(SiEt3)(NO)(P∩P)] compounds 4a–d, of which 4a,c,d are only stable in solution in the presence of HSiEt3. The SiMe3 (4f) and SiCl3 (4g) derivatives of 4b were also prepared by applying the reaction of 1b with HSiMe3 and HSiCl3. 1a,c,e, 2b, and 4f,g were structurally characterized. For 1c,e, 2b, and 4f,g NO/Br disorder was observed, which originates from the presence of two isomeric forms in the crystals of the respective compounds. For 1c,d fast interconversion of these isomers could be observed in their 31P{1H} NMR spectra at room temperature.

Uranium(IV) Nucleophilic Carbene Complexes

The mono-, bis-, and tris-carbene uranium complexes [Li(THF)2U(SCS)Cl3(THF)] (2a), [U(SCS)2(THF)2] (3a), and [{Li(OEt2)}2U(SCS)3] (1) were synthesized in good yields by reactions of UCl4 and the stoichiometric amount of Li2(SCS) [(SCS)2– = [Ph2P(═S)]2C2–]. Complex 3a was also obtained by comproportionation reaction of 1 and 0.5 molar equiv of UCl4 and further reacted with 1 molar equiv of UCl4 to give the neutral mono-carbene [U(SCS)Cl2(THF)2] (5a). Treatment of U(NEt2)4 with H2C(Ph2PS)2 in THF led to a mixture of 3a and [U(SCS)(NEt2)2] (6), while the same reaction in Et2O gave the mixed alkyl-carbene compound [U(SCS)(SCHS)(NEt2)] (7) in 85% yield. The cationic uranium carbene complex [U(SCS)(NEt2)(THF)3][BPh4] (9) was isolated in almost quantitative yield from reaction of [U(NEt2)3][BPh4] and H2C(Ph2PS)2. Mono-carbenes 2a, 5a, and 9 were used as precursors for the synthesis of Cp and COT derivatives (Cp = C5H5, COT = C8H8). Treatment of 2a with 1 or 2 molar equiv of TlCp gave [Tl{U(Cp)(SCS)}2(μ-Cl)3] (10) and [U(Cp)2(SCS)] (11) in 90% and 79% yield, respectively, whereas [U(Cp*)2(SCS)] (12) (Cp* = C5Me5) was obtained only by reaction of [U(Cp*)2Cl2] and Li2(SCS). Reactions of 5a or 9 with K2COT gave [U(COT)(SCS)(THF)] (13) in 78% and 99% yield, respectively. 2a, [Li(THF)(Et2O)U(SCS)(μ-Cl)3]2 (2b), [U(SCS)2(py)2]·1.5py·0.5THF (3b·1.5py·0.5THF), [U(SCS){CS(Ph2PS)2}(py)] (4), 7·toluene, [Li(THF)2U(SCS)(NEt2)(μ-O)]2 (8), 10·2toluene, 11, 12, and 13·0.5pentane were characterized by X-ray diffraction. The crystal data revealed that, in contrast to transition metal complexes, changes in the coordination sphere of the U(IV) center have little influence on the U═C bond. This feature was explained by DFT analysis of analogous U(IV) and Zr(IV) compounds [M(SCS′)Cl2(py)2] and [M(SCS′)(Cp)2] [M = U, Zr; SCS′ = C(H2PS)2]. Although the 5f orbitals are more radially contracted than the 6d atomic orbitals, the 5f AOs are lower in energy in uranium and can lead to greater angular overlaps in symmetry-constrained systems. As a result, the seven 5f orbitals play a “buffer” role by engaging in covalent interactions with the carbon center to stabilize the nucleophilic carbene lone pairs.

Synthesis and characterization of aluminum and zinc complexes supported by pyrrole-based ligands and catalysis of the aluminum complexes toward the ring-opening polymerization of ɛ-caprolactone

Reaction of quinolin-8-amine with 1 H-pyrrole-2-carbaldehyde or 5- tert-butyl-1 H-pyrrole-2-carbaldehyde catalyzed by HCO 2H forms N-((1 H-pyrrol-2-yl)methylene)quinolin-8-amine (≡ HL, 3a) or N-((5- tert-butyl-1 H-pyrrol-2-yl)methylene)quinolin-8-amine (≡ HL′, 3b). Treatment of 3a and 3b respectively with AlMe 3 or AlEt 3 in toluene affords corresponding aluminum complexes LAlMe 2 ( 4a), L′AlMe 2 ( 4b) and LAlEt 2 ( 4c). Reaction of 3a and 3b with an equivalent of ZnEt 2 in toluene generates L 2Zn and L′ 2Zn, respectively. A related compound N-((1 H-pyrrol-2-yl)methylene)-2-(3,5-dimethyl-1 H-pyrazol-1-yl)benzenamine (≡ HL″, 7) was prepared by reaction of 2-(3,5-dimethyl-1 H-pyrazol-1-yl)benzenamine with 1 H-pyrrole-2-carbaldehyde in the presence of HCO 2H. Reaction of 7 with AlMe 3 gives L″ 2AlMe ( 8), and with ZnEt 2 yields L″ 2Zn ( 9). All new compounds were characterized by NMR spectroscopy and elemental analysis. The structures of complexes 4b, 5b and 8 were additionally characterized by single crystal X-ray diffraction analyses. Complexes 4a– 4c, and 8 were proved to be active catalysts for the ring-opening polymerization (ROP) of ɛ-caprolactone (ɛ-CL) in the presence of BnOH. The kinetic study of the polymerization reactions catalyzed by 4a and 8 was performed.

Acylation of Heteroaromatic Amines: Facile and Efficient Synthesis of a New Class of 1,2,3-Triazolo[4,5-b]pyridine and Pyrazolo[4,3-b]pyridine Derivatives

1,2,3-Triazolo[4,5-b]pyridines and pyrazolo[4,3-b]pyridines can be readily prepared via cyanoacetylation reactions of 5-amino-1,2,3-triazoles 1a,b and 4-amino- pyrazole 2 followed by subsequent cyclization of the formed cyanoacetamides. Reactions of amines 1a,b with a mixture of p-nitrophenylacetic acid and acetic anhydride under microwave irradiation conditions afforded the corresponding amides 15a,b that underwent cyclization to form 1,2,3-triazolo[4,5-b]pyridines 16a,b upon heating in DMF solutions containing sodium acetate. Reactions of 1a,b with active methylene compounds, including 17a-c, in the presence of zeolites as catalyst also afforded 1,2,3-triazolo[4,5-b]pyridine derivatives 20a-f via the intermediacy of triazole derivatives 19 and not 18.

Iridium(I) and Rhodium(I) Carbonyl Complexes with the Bis(3-tert-butylimidazol-2-ylidene)borate Ligand and Unusual B−H Fluorination

Iridium(I) and rhodium(I) carbonyl complexes [H2B(ImtBu)2]M(CO)2 (M = Ir, 1a; M = Rh, 1b) with the bis(3-tert-butylimidazol-2-ylidene)borate ligand have been prepared. Reactions of 1a,b with [FeCp2][PF6] or AgPF6 unexpectedly yielded the B−F products [F2B(ImtBu)2]M(CO)2 (M = Ir, 2a; M = Rh, 2b), respectively. IR peaks of the CO ligands have been used to evaluate the electronic effects of bis(3-tert-butylimidazol-2-ylidene)borate and its fluorinated derivative.

Synthesis of New Visnagen and Khellin Furochromone Pyrimidine Derivatives and Their Anti-Inflammatory and Analgesic Activity

6-[(4-Methoxy/4,9-dimethoxy)-7-methylfurochromen-5-ylideneamino]-2-thioxo-2,3-dihydropyrimidin-4-ones 1a,b were prepared by reaction of 6-amino-2-thiouracil with visnagen or khellin, respectively. Reaction of 1a,b with methyl iodide afforded furochromenylideneaminomethylsulfanylpyrimidin-4-ones 2a,b. Compounds 2a,b were reacted with secondary aliphatic amines to give the corresponding furochromen-ylideneamino-2-substituted pyrimidin-4-ones 3a-d. Reaction of 3a-d with phosphorus oxychloride yielded 6-chlorofurochromenylidenepyrimidinamines 4a-d, which were reacted with secondary amines to afford furochromenylideneamino-2,6-disubstituted pyrimidin-4-ones 5a-d. In addition, reaction of 5a-d with 3-chloropentane-2,4-dione gave 3-chloro-furochromenylpyrimidopyrimidines 6a-d. The latter were reacted with piperazine and morpholine to give 1-(furochromenyl)-pyrimidopyrimidine-3,6,8-triylpiperazines or-3,6,8-triylmorpholines 7a-d. The chemical structures of the newly synthesized compound ware characterized by IR, 1H-NMR, 13C-NMR and mass spectral analysis. These compounds were also screened for their analgesic and anti-inflammatory activities. Some of them, particularly 3-7, exhibited promising activities.

Tetra-, Penta-, and Hexanuclear Yttrium Hydride Clusters from Half-Sandwich Bis(aminobenzyl) Complexes Containing Various Cyclopentadienyl Ligands

The novel series of half-sandwich tetrahydrofuran (THF)-free yttrium bis(aminobenzyl) complexes [(C5Me4R)Y(CH2C6H4NMe2-o)2] (R = SiMe3 (1a), Me (1b), Et (1c), H (1d)) was prepared by treatment of [Y(CH2C6H4NMe2-o)3] with C5Me4RH, and their reactions with H2 and with PhSiH3 in aromatic solvents or in THF were examined. The reaction of 1a with H2 in benzene gave the pentanuclear yttrium decahydride complex [{Cp′Y(μ-H)2}5] (Cp′ = η5-C5Me4SiMe3) (3), which could not be obtained by the reaction of the corresponding THF-coordinated dialkyl complex [Cp′Y(CH2SiMe3)2(THF)] with H2. The reaction of 1b with H2 in toluene gave the partially hydrogenated tetranuclear mixed aminobenzyl/hydride complex [(Cp*Y)2(CH2C6H4NMe2-o)(μ-H)3]2 (4; Cp* = η5-C5Me5), and no further hydrogenation reaction occurred, whereas the corresponding reaction of 1b with H2 in THF gave the pentanuclear yttrium polyhydride complex [{Cp*Y(μ-H)2}5(THF)2] (5). Hydrogenolysis of the sterically less demanding C5Me4H-ligated complex 1d with H2 in THF ...

Reactivity Differences of Palladium(II) Dimers Bearing Heterocyclic Carbenes with Two, One, or No α-Nitrogen Atoms toward Isocyanides

Pd(II) dimers [PdI2(rNHC)]2 (1a,b) of pyrazole-based remote N-heterocyclic carbenes (rNHCs) have been synthesized through oxidative addition of 4-iodopyrazolium iodides (A, B) to [Pd2(dba)3]. Reaction of 1a with aromatic (CN-Xyl) or aliphatic (CN-Cy) isocyanides led to the template-assisted formation of novel Pd(II) dimers 8 and 9 bearing betainic C-imino ligands via isocyanide insertion into Pd−CrNHC bonds and subsequent dimerization. In contrast, both isocyanides reacted with the dimers [PdI2(Me2-indy)]2 (2) and [PdI2(Me2-bimy)]2 (3) bearing indazolin-3-ylidenes and benzimidazolin-2-ylidenes with formation of mononuclear mixed carbene/isocyanide complexes 4−7. Notably, only dimer 8 underwent further bridge cleavage with excess isocyanide, yielding the mixed C-imino/CN-Xyl complex 10, while dimer 9 remained intact. These results highlight the uniquely different reactivities of complexes with carbenes having no α-nitrogen versus those with one or two α-nitrogen atoms, as a result of their decreasing donor...

A flow chemistry route to 2-phenyl-3-(1H-pyrrol-2-yl)propan-1-amines

The Knoevenagel condensation of pyrrole-2-carboxaldehyde (1) with a range of substituted benzyl nitriles (2a–e) afforded rapid access to a family of α,β-unsaturated nitriles (3a–e) in good yields (67–78%). Flow hydrogenation (ThalesNano H-cube™) at 60°C, 50bar H2 pressure, 1.0mL/min through a 10% Pd-C catalyst selectively, and quantitatively, hydrogenated the olefin double bond (4a–e). Use of a Raney Nickel catalyst at 70°C, 70bar H2 pressure and flow rates of 0.5–1.0mL/min afforded quantitative conversion into the corresponding saturated amines with the reduction of both the olefin and nitrile bonds (5a–e). The versatility of this approach was further exemplified by reaction of 5a and 5c with norcantharidin to afford acid amide norcantharidin analogues 7 and 8 as novel protein phosphatase 1 and 2A inhibitors.

Biaryl sulfonamides from O‐acetyl amidoximes: 1,2,4‐Oxadiazole cyclization under acidic conditions

AbstractA series of 4‐cyanobenzenesulfonamides (1a, 1b, 1c, 1d, 1e, 1f, 1g, 1h) was converted to the corresponding O‐acetylated amidoximes (2a, 2b, 2c, 2d, 2e, 2f, 2g, 2h). The reaction of 1a was exemplarily investigated with respect to the formation of a byproduct, which was identified as 1,2,4‐oxadiazole derivative 3a. This observation led to the development of an improved procedure for the preparation of 2a, 2b, 2c, 2d, 2e, 2f, 2g, 2h. Compounds 2 could be transformed to 1,2,4‐oxadiazoles 3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h in high yields and purity upon heating in acetic acid. J. Heterocyclic Chem., (2011).

Ortho-Hydroxyphenylhydrazo-β-Diketones: Tautomery, Coordination Ability, and Catalytic Activity of Their Copper(II) Complexes toward Oxidation of Cyclohexane and Benzylic Alcohols

New hydrazone o-HO-phenylhydrazo-β-diketones (OHADB), R(1)NHN═CR(2)R(3) [R(1) = HO-2-C(6)H(4), R(2) = R(3) = COMe (H(2)L(1), 1), R(2)R(3) = COCH(2)C(Me)(2)CH(2)CO (H(2)L(2), 2), R(2) = COMe, R(3) = COOEt (H(2)L(4), 4); R(1) = HO-2-O(2)N-4-C(6)H(3), R(2)R(3) = COCH(2)C(Me)(2)CH(2)CO (H(2)L(3), 3), R(2) = COMe, R(3) = COOEt (H(2)L(5), 5), R(2)R(3) = COMe (H(2)L(6), 6A)], and their Cu(II) complexes [Cu(2)(CH(3)OH)(2)(μ-L(1))(2)] 7, [Cu(2)(H(2)O)(2)(μ-L(2))(2)] 8, [Cu(H(2)O)(L(3))] 9, [Cu(2)(μ-L(4))(2)](n) 10, [Cu(H(2)O)(L(5))] 11, [Cu(2)(H(2)O)(2)(μ-L(6))(2)] 12A and [Cu(H(2)O)(2)(L(6))] 12B were synthesized and fully characterized, namely, by X-ray analysis (4, 5, 7-12B). Reaction of 6A, Cu(NO(3))(2) and ethylenediamine (en) leads, via Schiff-base condensation, to [Cu{H(2)NCH(2)CH(2)N═C(Me)C(COMe)═NNC(6)H(3)-2-O-4-NO(2)}] (13), and reactions of 12A and 12B with en give the Schiff-base polymer [Cu{H(2)NCH(2)CH(2)N═C(Me)C(COMe)═NNC(6)H(3)-2-O-4-NO(2)}](n) 14. The dependence of the OHADB tautomeric equilibria on temperature, electronic properties of functional groups, and solvent polarity was studied. The OHADB from unsymmetrical β-diketones exist in solution as a mixture of enol-azo and hydrazo tautomeric forms, while in the solid state all the free and coordinated OHADB crystallize in the hydrazo form. The relative stabilities of various tautomers were studied by density functional theory (DFT). 7-14 show catalytic activities for peroxidative oxidation (in MeCN/H(2)O) of cyclohexane to cyclohexanol and cyclohexanone, for selective aerobic oxidation of benzyl alcohols to benzaldehydes in aq. solution, mediated by TEMPO radical, under mild conditions and for the MW-assisted solvent-free synthesis of ketones from secondary alcohols with tert-butylhydroperoxide as oxidant.

Metal-promoted synthesis of amidines containing the model nucleobases 1-methylcytosine and 9-methyladenine

The amidine complexes cis-[L(2)PtNH==C(R){1-MeCy(-2H)}]NO(3) (R = Me, 1a; Ph, 1b, Me(3)C, 1c; Ph(2)(H)C, 1d) and cis-[L(2)PtNH==C(R){9-MeAd(-2H)}]NO(3) (R = Me, 2a; Ph, 2b; Me(3)C, 2c; Ph(2)(H)C, 2d), are formed when cis-[L(2)Pt(μ-OH)](2)(NO(3))(2) (L = PPh(3)) reacts with 1-methylcytosine (1-MeCy) and 9-methyladenine (9-MeAd) in solution of MeCN, PhCN, Me(3)CCN and Ph(2)(H)CCN. Reaction of 1a,b and 2a,b with HCl affords the protonated amidines [NH(2)==C(R){1-MeCy(-H)}]NO(3) (R = Me, 3a; Ph, 3b) and [NH(2)==C(R){9-MeAd(-H)}]NO(3) (R = Me, 4a; Ph, 4b) and cis-(PPh(3))(2)PtCl(2) in quantitative yield. Treatment of 3b and 4b with NaOH allows the isolation of the neutral benzimidamides NH(2)-C(Ph){1-MeCy(-2H)} (5b) and NH(2)-C(Ph){9-MeAd(-2H)} (6b). In the solid state 3b shows a planar structure with the hydrogen atom on N(4) cytosine position involved in a strong H-bond with the NO(3)(-) ion. Intermolecular H-bonds between the oxygen of the cytosine ring and one of the H atoms of the amidine-NH(2) group allow the dimerization of the molecule. A detailed analysis of the spectra of 3b in DMF-d(7) at -55 °C indicates the presence of an equilibrium between the species [NH(2)==C(R){1-MeCy(-H)}]NO(3) and [NH(2)==C(R){1-MeCy(-H)}](2)(NO(3))(2), exchanging with trace amounts of water at 25 °C. [(15)N,(1)H]-HMBC experiments for 5b and 6b indicate that the amino tautomer H(2)N-C(Ph){nucleobase(-2H)}, is the only detectable in solution and such structure has been confirmed in the solid state. The reaction of 5b and 6b with cis-L(2)Pt(ONO(2))(2) (L = PPh(3)), in chlorinated solvents, determines the immediate appearance of a pale yellow colour due to the coordination of the neutral amidine, likely in its imino form HN==C(Ph){nucleobase(-H)}, to give the adducts cis-[L(2)PtNH==C(Ph){nucleobase(-H)}](2+). In fact, addition of "proton sponge" leads to the immediate deprotonation of the amidine ligand with formation of the starting complexes 1b and 2b.

Synthesis and Anti-Aphid Aphis Gossypii Glover Activity of Some New Quinoline Derivatives

A series of quinoline derivatives have been elaborated from reaction of 2-(m- and p-acetylanilino)-quinolines 6a-b with aldehydes under Claisen-Schmidt conditions followed by cyclization with phenyl hydrazine and hydroxylamine. Reaction of 6a and 6b with hydrazine, semicarbazide and thiosemicarbazide, cyanoacetylhydrazide and some subsequent condensation reactions led to diverse quinoline derivatives. Anti-Aphid Aphis gossypii that harm cotton crop in Egypt was screened. Compound 12 showed an LC₅₀ value of 19429E-10 ppm which is much more active than Marshal (Carbosulfan), one of the broad spectrum insecticides widely used in this field.

Chelating or bridging Pd(ii) and Pt(ii) metalloligands from the functional phosphine ligand N-(diphenylphosphino)-1,3,4-thiadiazol-2-amine. New heterometallic Pd(ii)/Pt(ii) and Pt(ii)/Au(i) complexes

The reaction of two equivalents of the functional phosphine ligand N-(diphenylphosphino)-1,3,4-thiadiazol-2-amine Ph2PNHC=NNCHS (2) with [PdCl2(NCPh)2] in the presence of NEt3 gives the neutral, P,N-chelated complex cis-[Pd(Ph2PN=CNN=CHS)2] ([Pd(2-H)2], 3b), which is analogous to the Pt(II) analogue cis-[Pt (Ph2PN=CNN=CHS)2] ([Pt(2-H)2], 3a) reported previously. These complexes function as chelating metalloligands when further coordinated to a metal through each of the CH-N atoms. In the resulting complexes, each endo-cyclic N donor of the thiadiazole rings is bonded to a different metal centre. Thus, the heterodinuclear palladium/platinum complexes cis-[Pt(Ph2PN=CNN=CHS)2PdCl2]([Pt(2-H)2·PdCl2], 4a) and cis-[Pd(Ph2PN=CNN=CHS)2PtCl2]([Pd(2-H)2·PtCl2], 4b) were obtained by reaction with [PdCl2(NCPh)2] and [PtCl2(NCPh)2], respectively. In contrast, reaction of 3a with [AuCl(tht)] occurred instead at the P-bound N atom, and afforded the platinum/digold complex cis-[Pt{Ph2PN(AuCl)=CNN=CHS}2] ([Pt(2-H)2(AuCl)2], 5). For comparison, reaction of 4a with HBF4 yielded cis-[Pt(Ph2PNH=CNN=CHS)2PdCl2](BF4)2([H24a](BF4)2, 6), in which the chelated PdCl2 moiety is retained. Complexes 3b, 4a·CH2Cl2, 4b·0.5C7H8, 5·4CHCl3 and 6 have been structurally characterized by X-ray diffraction.

N-heterocyclic carbene tethered amido complexes of palladium and platinum

With a view to applications in bifunctional catalysis, a modular cross-coupling strategy has been used to prepare amine bis(imidazolium) salts (3a and 3b) and an amine mono(imidazolium) salt (6) as precursors to chelating amido-NHC ligands. Treating the pro-ligands 3 with 3 equivalents of the bulky base KHMDS and Pd(OAc)(2) or PtCl(2)(COD) gave the four amido bis(N-heterocyclic carbene) pincer complexes [CNC-R]M-I [M = Pd (7) or Pt (8); R = i-Pr (a) or n-Bu (b)], including the first examples of platinum complexes of a CNC ligand. The reaction of 7a with AgOTf in pyridine gave the cationic complex {[CNC-i-Pr]Pd-py}OTf (9a). Heating a mixture of amine mono(imidazolium) salt 6 with PdCl(2) or K(2)PtCl(4), K(2)CO(3) and KI in pyridine at 100 °C gave the complexes [C,NH]MI(2)py [M = Pd (10) or Pt (11)], in which the amine arm of the NHC ligand is not deprotonated and does not coordinate to the metal. For a solution of 10 in 1,4-dioxane, deprotonation of the amine occurred in a biphasic reaction with aqueous KOH at 40 °C, giving the dimeric amido complex {[C,N]Pd(μ-OH)}(2) (12). The more inert Pt analogue 11 was unreactive under the same conditions. Solid-state structures of the complexes 7a, 7b, 9a, 10, 11 and 12 have been determined by single crystal X-ray diffraction.

The reactivity of TMSN 3 with ruthenium cyclopropenyl complexes containing different ligands and different substituent at Cγ

Ruthenium vinylidene complexes 2a– 2c containing indenyl and bidentate dppe ligands can be obtained in efficient yields. Treatment of the cationic ruthenium vinylidene complexes with n-Bu 4NOH in acetone yields the neutral cyclopropenyl products ( η 5-C 9H 7)(dppe)Ru–C C(Ph)CHR ( 3) ( 3a, R = Ph; 3b, R = CN; 3c, R = p-C 6H 4–CN) via the deprotonation reaction. Reaction of complexes 3a and 3c with Me 3SiN 3 (TMSN 3) the N-coordinated complexes 4a and 4c can be obtained as stable products. Complex 3b containing CN group at Cγ in the cyclopropenyl ring reacts with TMSN 3 yielded the tetrazolate complex 5b. Similar cyclopropenyl products containing indenyl and two triphenylphosphine ligands 3′ can also be synthesized. Reaction of complex 3b′ with TMSN 3 also yielded the tetrazolate complex as the major product. And the minor products are [Ru]–N 3 and organic compound 6b. Reaction of 3a′ and 3c′ with TMSN 3 yielded [Ru]–N 3. The corresponding organic products can also be obtained via the N 3 − attacking the metal center in the N-coordinated complexes 4a′ and 4c′.

Synthesis and biological activity studies of new hybrid molecules containing tryptamine moiety

The synthesis of N′-(4-substitutedphenylsulfonyl)-2-{4-[2-(1H-indol-yl)ethyl]-3-(4-chlorobenzyl)-5-oxo-4,5-dihydro-1H-1,2,4-triazol-1-yl}acetohydrazides (3a–c), 2-{4-[2-(1H-indol-3-yl)ethyl]-3-(4-chlorobenzyl)-5-oxo-4,5-dihydro-1H-1,2,4-triazol-1-yl}-N′-aryl methylidene acetohydrazides (4a–f) and 4-[2-(1H-indol-3-yl)ethyl]-5-(4-substitutedbenzyl)-2-[(5-sulfanyl-1,3,4-oxadiazol-2-yl)methyl]-2,4-dihydro-3H-1,2,4-triazol-3-ones (5a, b) was performed starting from the corresponding acid hydrazides (2a, b) which was reported earlier. The treatment of 1,3,4-oxadiazole derivatives (5a, b) with hydrazine hydrate produced 4-amino-5-sulfanyl-4H-1,2,4-triazol-3-yl derivatives (6a, b). Then, compound 6b was converted to the corresponding Schiff base (7) by the treatment with anisaldehyde. The synthesis of 5-(4-chlorobenzyl)-4-[2-(1H-indol-3-yl)ethyl]-2-[(4-benzyl-5-oxo-4,5-dihydro-1H-1,2,4-triazol-3-yl)methyl]-2,4-dihydro-3H-1,2,4-triazol-3-one (8) and 5-(4-methylbenzyl)-4-[2-(1H-indol-3-yl)ethyl]-2-[(4-benzyl-5-oxo-4,5-dihydro-1H-1,2,4-triazol-3-yl)methyl]-2,4-dihydro-3H-1,2,4-triazol-3-one (10) was carried out by the reaction of acid hydrazides (2a, b) with aryl iso(thio)cyanates either via the formation of the intermediates (9a, b) (for 10) or direct cyclization (for 8). 1,3-Oxa(thia)zol-2(3H)-ylidene]acetohydrazide derivatives (11a, b) were obtained by the reaction of 9a, b with 4-chlorophenacyl bromide. All newly synthesized compounds were screened for their antimicrobial activities and some of which was found to be active against the test microorganisms.