无催化剂条件下4-羟基烷基-2-炔酸乙酯与N-杂环芳基甲基-N-2,2-二氟乙基-1-胺的串联反应（英文）

开发了无催化剂条件下4-羟基烷基-2-炔酸乙酯与N-杂环芳基甲基-N-2,2-二氟乙基-1-胺的串联反应.应用该反应在甲醇中回流,以39%～83%的收率合成了一系列4-(N-(2,2-二氟乙基)(N-杂环芳基甲基)氨基)-5,5-二取代呋喃-2(5H)-酮,其结构经~1H NMR, ~(13)C NMR和HR-ESI-MS表征,并进一步通过3-氯-4-((N-2,2-二氟乙基)(N-嘧啶-5-基甲基胺基)-5,5-螺(4-甲氧基环己基)呋喃-2(5H)-酮(8)的晶体衍射间接证实.测试了所合成化合物的生物活性,结果表明,在600μg·mL~(-1)浓度时4-((N-2,2-二氟乙基)(N-6-氯吡啶-3-基甲基胺基)-5,5-二甲基呋喃-2(5H)-酮(3a)和4-((N-2,2-二氟乙基)(N-6-氟吡啶-3-基甲基胺基)-5,5-二甲基呋喃-2(5H)-酮(3c)对桃蚜的死亡率均为100%.     

新型CCR5拮抗剂——N-【1-{5-溴-2-[(4-氯苄基)氧基]苄基}-4-哌啶基】-N-乙基吡啶甲酰胺的合成

以5-溴水杨醛和4-氯苄氯为原料,通过消去、还原及溴化反应制得中间体4-溴-2-溴甲基-1-[(4-溴苄基)氧]苯(3);哌啶-4-酮经Boc保护、还原等4步反应制得中间体N-乙基-N-(4-哌啶基)吡啶甲酰胺(7);3与7通过消去反应合成了一种新型CCR5拮抗剂——N-【1-{5-溴-2-[(4-氯苄基)氧基]苄基}-4-哌啶基】-N-乙基吡啶甲酰胺,其结构经1H NMR,13C NMR和ESI-MS表征。     

3-(N-取代苯基-2-乙酰胺基)硫基-4-N-取代邻羟苯基亚胺基-5-甲基-1,2,4-三唑类化合物的合成及生物活性研究

以对称二氨基硫脲为原料,与冰醋酸反应生成5-甲基-4-氨基-1,2,4-三唑-3-硫酮(1);在弱酸性条件下,1与取代水杨醛反应生成席夫碱中间体5-甲基-4-(N-取代邻羟苯基)亚胺基-1,2,4-三唑-3-硫酮(2a～2c);最后在碱性条件下分别与N-取代苯基-2-氯乙酰胺发生烷基化反应生成15种未见报道的目标化合物3-(N-取代苯基-2-乙酰胺基)硫基-4-(N-取代邻羟苯基)亚胺基-5-甲基-1,2,4-三唑(3a～3o),其结构经IR,1H NMR,13C NMR确证.初步生物测试表明,质量分数为0.01%时,3a～3o对白色念珠菌的抑菌率均达90%以上,具有很强的抑菌活性;对金黄色葡萄球菌、大肠杆菌的抑菌率达80%以上,具有较强的抑菌活性.     

新型含氮杂环酰胺类衍生物的合成

根据结构拼合原理,分别将1,2,4-三唑和嘧啶连接到酰胺骨架上,设计并合成了两个新型的含氮杂环酰胺类衍生物——3-[N-3-(3-甲基-1H-1,2,4-三唑-1-基)-5-(三氟甲基)苯基硫代乙酰胺基-N-(2-氯苯基次甲基)]-5-(2,4-二氯苯基)-4H-1,2,4-三唑-4-胺和N-【3-【5-氯-2-N-{[2-甲氧基-4-(4-甲基哌嗪-1-基)苯胺]}嘧啶-4-氧醚】】苯基-1-{2-[5-(呋喃-2-基)-1,4-戊二烯-3-酮]苯氧醚}乙酰胺,其结构经1H NMR,13C NMR,19F NMR,IR,ESI-MS和元素分析表征。     

含三氟甲基吡啶酰胺结构的N-氰基磺酰亚胺衍生物的合成及生物活性

采用活性亚结构拼接法,设计合成了系列新型含三氟甲基吡啶酰胺结构的N-氰基磺酰亚胺类衍生物,其结构经1H NMR、~(13)C NMR、~(19)F NMR和HRMS进行了表征.评估了它们对柑橘溃疡病菌(Xanthomonas axonopodis pv. citri)、烟草青枯病菌(Ralstoniasolanacearum)和水稻白叶枯病菌(Xanthomonasoryzaepv.oryzae)的杀菌活性及对小菜蛾(Plutella xylostella)的杀虫活性.结果表明,部分化合物表现出了良好的抗菌活性和中等的杀虫活性.其中,在200 mg/L质量浓度下,3-氯-(2-(N-氰基-S-(3,4-二氟苄基)磺酰亚胺酰基)乙基)-5-(三氟甲基)吡啶酰胺(G10)对柑橘溃疡病菌、烟草青枯病菌和水稻白叶枯病菌的抑制率分别为67%、53%和48%,3-氯-(2-(N-氰基-S-(2,5-二氟苄基)磺酰亚胺酰基)乙基)-5-(三氟甲基)吡啶酰胺(G17)对柑橘溃疡病菌的抗菌活性为69%,(2-(S-(2-溴-4-氟苄基)-N-氰基磺酰亚胺基)乙基)-3-氯-5-(三氟甲基)吡啶酰胺(G14)对水稻白叶枯病菌的抑制率为49%.在100 mg/L时,(2-(S-(4-溴-2-氟苄基)-N-氰基磺酰亚胺基)乙基)-3-氯-5-(三氟甲基)吡啶酰胺(G1)、3-氯-(2-(N-氰基-S-(3-氟苄基)磺酰亚胺基)乙基)-5-(三氟甲基)吡啶酰胺(G7)、3-氯-(2-(N-氰基-S-(2,4-二氟苄基)磺酰亚胺酰基)乙基)-5-(三氟甲基)吡啶酰胺(G8)和G10也有中等的杀菌活性,在测试浓度下,部分化合物的活性略高于对照药剂或与之相当.此外,在500mg/L时,化合物G10和3-氯-(2-(N-氰基-S-(4-异丙基苄基)磺酰亚胺基)乙基)-5-(三氟甲基)吡啶酰胺(G11)对小菜蛾的致死率分别为77%和70%.     

(E)-3-(1-亚胺基乙基)-5,5-二取代-4-甲氨基呋喃-2(5H)-酮的合成及其意外的杀虫活性（英文）

为了提高化合物对植物病原菌的杀菌活性及扩大多样性导向合成策略建立的分子库,以甲氨基替换3-(1-亚胺基乙基)-5,5-二取代-4-苯基呋喃-2(5H)-酮的苯基,设计合成了18个新颖的(E)-3-(1-亚胺基乙基)-5,5-二取代-4-甲氨基呋喃-2(5H)-酮,结构经过~1H NMR, ~(13)C NMR, HR-ESI-MS表征.(E)-3-(1-(4-甲氧基苄氧亚胺基)乙基)-4-甲氨基-1-氧杂螺[4.5]癸-3-烯-2-酮(5O)还经过X射线衍射表征.生物活性测试结果表明,所有化合物对测试的四种植物病原菌均未显示明显的活体杀菌活性,但是意外地发现多个化合物在600μg/mL浓度时对桃蚜、粘虫和小菜蛾的致死率均为100%,显示出良好的杀虫活性.     

无外加催化剂条件下芳香醛与活性亚甲基化合物的缩合反应和迈克尔加成反应

在DMF溶剂中,不外加催化剂使芳香醛(1)与2,2-二甲基-1,3-二氧六环-4,6-二酮(2)发生缩合反应生成2,2-二甲基-5-芳亚甲基-1,3-二氧六环-4,6-二酮(3a～f)。在同样条件下,芳香醛与5,5-二甲基-1,3-环己二酮(4)则发生缩合和迈克尔加成反应生成2,2’-芳亚甲基双(3-羟基-5,5-二甲基-2-环己烯-1-酮)(5a～h)。用单晶X-射线分析法确定了产物5b的晶体结构。     

含4-噻唑啉酮环的新烟碱类化合物的合成及生物活性

根据生物等排原理和新烟碱类化合物与乙酰胆碱酯酶的作用机理, 以4-噻唑啉酮(4)为中间体设计合成了2-取代-3-(2-氯-5-吡啶亚甲基)-4-氰基亚胺基-1,3-噻唑烷(8a~8c)和5-芳基次甲基-2-芳基-3-(2-氯-5-吡啶亚甲基)-4-噻唑啉酮(5a~5e)两类化合物. 中间体(4)由醛、胺和巯基乙酸缩合得到. 所有化合物的结构均经元素分析和1H NMR确证. 初步生物活性试验结果表明, 部分化合物具有一定的杀菌活性和促进黄瓜子叶生根活性, 化合物8b显示出很好的抗HIV-1蛋白酶活性.     

N-(5-邻氯苯基-2-呋喃甲酰氨基)丙氨酰胺衍生物的合成和 生物活性测定

以5-邻氯苯基-2-呋喃甲酰氯和丙氨酸为起始原料, 通过非均相法得到N-(5-邻氯苯基-2-呋喃甲酰氨基)丙氨酸, 再与10种不同取代苯胺反应, 通过N,N’-二环己基碳二亚胺和4-二甲氨基吡啶(DCC/DMAP)偶合法设计合成了10个未见文献报道的N-(5-邻氯苯基-2-呋喃甲酰氨基)丙氨酰胺类衍生物4a～4j. 通过元素分析, 1H NMR, IR 和MS确定化合物的结构, 初步生物活性测试表明标题化合物具有一定的除草活性.     

新型2，6-双（3，5-二取代吡唑基-1-羰基）吡啶的合成

报道了四种吡唑衍生物和它们四种新型的杂环酰胺衍生物的合成，它们是3，5-二甲基吡唑(1)，5-甲基-3-苯基吡唑(2)，3，5-二苯基吡唑(3)，5-甲基-3-二茂铁基吡唑(4)，2，6-双(3，5-二甲基吡唑基-1-羰基)吡啶(5)，2，6-双(5-甲基-3-苯基吡唑基-1-羰基)吡啶(6)，2，6-双(3，5-二苯基吡唑基-1-羰基)吡啶(7)和2，6-双(5-甲基-3-二茂铁基吡唑基-1-羰基)吡啶(8)．并对它们进行了元素分析，FT-IR，^1H NMR和^13C NMR等波谱分析．     

Synthesis of novel pyrimidine derivatives with (pyridin-3-ylmethyl)thio and phenylamino moieties and evaluation of their antifungal activity

A series of novel pyrimidine derivatives with (pyridin-3-ylmethyl)thio and phenylamino moieties were synthesized from ethyl acetoacetate, thiourea, 3-pyridinylmethyl chloride hydrochloride, and substituted anilines by multi-step reactions. The structures of the target compounds were characterized by IR, ¹H NMR, ¹³C NMR and elemental analysis. The in vitro antifungal activities against Botrytis cinerea and Sclerotinia sclerotiorum were evaluated. The result showed that N-phenyl-6-methyl-2- ((pyridin-3-ylmethyl)thio) pyrimidin-4-amine (4a) displayed high inhibition activity against Botrytis cinerea with 87.5%inhibition at 100 µg/mL; 4a, and N-(4-isopropylphenyl)-6-methyl-2-((pyridin-3-ylmethyl)thio)pyrimidin-4-amine (4c), N-(4-methoxyphenyl)-6-methyl-2-((pyridin-3-ylmethyl)thio)pyrimidin-4-amine (4d) and N-(2-hydroxy-5-chloro)-6-methyl-2-((pyridin-3-ylmethyl)thio)pyrimidin- 4-amine (4h) exhibited sufficient activities against Sclerotinia sclerotiorum with 86.6% –93.7% inhibitions at the same concentration.     

The role of Zn-OR and Zn-OH nucleophiles and the influence of para-substituents in the reactions of binuclear phosphatase mimetics

Analogues of the ligand 2,2'-(2-hydroxy-5-methyl-1,3-phenylene)bis(methylene)bis((pyridin-2-ylmethyl)azanediyl)diethanol (CH(3)H(3)L1) are described. Complexation of these analogues, 2,6-bis(((2-methoxyethyl)(pyridin-2-ylmethyl)amino)methyl)-4-methylphenol (CH(3)HL2), 4-bromo-2,6-bis(((2-methoxyethyl)(pyridin-2-ylmethyl)amino)methyl)phenol (BrHL2), 2,6-bis(((2-methoxyethyl)(pyridin-2-ylmethyl)amino)methyl)-4-nitrophenol (NO(2)HL2) and 4-methyl-2,6-bis(((2-phenoxyethyl)(pyridin-2-ylmethyl)amino)methyl)phenol (CH(3)HL3) with zinc(II) acetate afforded [Zn(2)(CH(3)L2)(CH(3)COO)(2)](PF(6)), [Zn(2)(NO(2)L2)(CH(3)COO)(2)](PF(6)), [Zn(2)(BrL2)(CH(3)COO)(2)](PF(6)) and [Zn(2)(CH(3)L3)(CH(3)COO)(2)](PF(6)), in addition to [Zn(4)(CH(3)L2)(2)(NO(2)C(6)H(5)OPO(3))(2)(H(2)O)(2)](PF(6))(2) and [Zn(4)(BrL2)(2)(PO(3)F)(2)(H(2)O)(2)](PF(6))(2). The complexes were characterized using (1)H and (13)C NMR spectroscopy, mass spectrometry, microanalysis, and X-ray crystallography. The complexes contain either a coordinated methyl- (L2 ligands) or phenyl- (L3 ligand) ether, replacing the potentially nucleophilic coordinated alcohol in the previously reported complex [Zn(2)(CH(3)HL1)(CH(3)COO)(H(2)O)](PF(6)). Functional studies of the zinc complexes with the substrate bis(2,4-dinitrophenyl) phosphate (BDNPP) showed them to be competent catalysts with, for example, [Zn(2)(CH(3)L2)](+), k(cat) = 5.70 ± 0.04 × 10(-3) s(-1) (K(m) = 20.8 ± 5.0 mM) and [Zn(2)(CH(3)L3)](+), k(cat) = 3.60 ± 0.04 × 10(-3) s(-1) (K(m) = 18.9 ± 3.5 mM). Catalytically relevant pK(a)s of 6.7 and 7.7 were observed for the zinc(II) complexes of CH(3)L2(-) and CH(3)L3(-), respectively. Electron donating para-substituents enhance the rate of hydrolysis of BDNPP such that k(cat)p-CH(3) > p-Br > p-NO(2). Use of a solvent mixture containing H(2)O(18)/H(2)O(16) in the reaction with BDNPP showed that for [Zn(2)(CH(3)L2)(CH(3)COO)(2)](PF(6)) and [Zn(2)(NO(2)L2)(CH(3)COO)(2)](PF(6)), as well as [Zn(2)(CH(3)HL1)(CH(3)COO)(H(2)O)](PF(6)), the (18)O label was incorporated in the product of the hydrolysis suggesting that the nucleophile involved in the hydrolysis reaction was a Zn-OH moiety. The results are discussed with respect to the potential nucleophilic species (coordinated deprotonated alcohol versus coordinated hydroxide).     

Luminescent rhenium(I) polypyridine fluorous complexes as novel trifunctional biological probes

We present the synthesis, characterization, and photophysical properties of three luminescent rhenium(I) polypyridine fluorous complexes [Re(Me(2)bpy)(CO)(3)(L)](PF(6)) (Me(2)bpy = 4,4'-dimethyl-2,2'-bipyridine; L = 3-amino-5-(N-((3-perfluorooctyl)propyl)aminocarbonyl)pyridine (py-Rf-NH(2)) (1), 3-isothiocyanato-5-(N-((3-perfluorooctyl)propyl)aminocarbonyl)pyridine (py-Rf-NCS) (2), 3-ethylthioureidyl-5-(N-((3-perfluorooctyl)propyl)aminocarbonyl)pyridine (py-Rf-TU-C(2)H(5)) (3)). The isothiocyanate complex 2 has been used to label bovine serum albumin (BSA) and glutathione (GSH). The photophysical properties of the resultant bioconjugates have been studied. The isolation of the luminescent fluorous rhenium-GSH conjugate from a mixture of 20 amino acids has been demonstrated using fluorous solid-phase extraction (FSPE). Additionally, the cytotoxicity of complexes 1 and 3 toward HeLa cells has been examined by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium bromide (MTT) assay. The cellular uptake properties of complex 3 have also been investigated by laser-scanning confocal microscopy.     

Biimidazole and bis(amide)bipyridine molybdenum carbonyl complexes as anions receptors

Compounds [Mo(CO)4(N-N)] (N-N = 4,4'-bis((4-methylphenyl)carbamoyl)-2,2'-bipyridine, bipy', 1; or 2,2'-biimidazole, H2biim, 2), [MoCl(eta3-methallyl)(CO)2(N-N)] (N-N = bipy', 3; H2biim, 4), and [Mo(eta3-methallyl)(CNtBu)(CO2)(N-N)]BAr'4 (Ar' = 3,5-bis(trifluoromethyl)phenyl; N-N= bipy', 5; H2biim, 6) were synthesized and characterized, and their behavior toward anions was investigated in solution (IR and 1H NMR) and in solid state (X-ray diffraction).     

Unique example of flexible phenol coordination in mononuclear manganese compounds

The synthesis and characterization of six novel mononuclear Mn(II) and Mn(III) complexes are presented. The tripodal ligands 2-((bis(pyridin-2-ylmethyl)amino)methyl)-4-nitrophenol (HL1), 2-[[((6-methylpyridin-2-yl)methyl)(pyridin-2-ylmethyl)amino]methyl]-4-nitrophenol (HL2), (2-pyridylmethyl)(6-methyl-2-pyridylmethyl)(2-hydroxybenzyl)amine (HL3) and 2-((bis(pyridin-2-ylmethyl)amino)methyl)-4-bromophenol were used. All ligands provide an N3O donor set. The compounds [Mn(II)(HL1)Cl2].CH3OH (1), [Mn(III)(L1)Cl2] (2), [Mn(II)(HL2)(EtOH)Cl2] (3), [Mn(II)(HL3)Cl2].CH3OH (4), [Mn(III)(HL4)Br2] (5) and [Mn(III)(L1)(tcc)] (6), with tcc = tetrachlorocatecholate dianion, were synthesized and characterized by various techniques such as X-ray crystallography, mass spectrometry, IR and UV-vis spectroscopy, cyclic voltammetry, and elemental analysis. Compound 1 crystallizes in the triclinic space group P1, compounds 2, 3 and 4 were solved in the monoclinic space group P2(1)/c, whereas the structure determination of and succeeded in the orthorhombic space groups Pbca and P2(1)2(1)2(1), respectively. Notably, the crystal structures of 1 and 3 are the first Mn(II) complexes featuring a non-coordinating phenol moiety. Compound 2 oxidizes 3,5-di-tert-butylcatechol to 3,5-di-tert-butylquinone exhibiting saturation kinetics at high substrate concentrations with a turnover number of kcat = 173 h(-1). The electronic influence of different substituents in para position of the phenol group is lined out.     

Syntheses, luminescence behavior, and assembly reaction of tetraalkynylplatinate(II) complexes: crystal structures of [Pt((t)Bu(3)trpy)(Ctbd1;CC(5)H(4)N)Pt((t)Bu(3)trpy)](PF(6))(3) and [Pt(2)Ag(4)(Ctbd1;CCtbd1;CC(6)H(4)CH(3)-4)(8)(THF)(4)

A series of tetraalkynylplatinate(II) complexes, (NBu(4))(2)[Pt(Ctbd1;CR)(4)] (R = C(6)H(4)N-4, C(6)H(4)N-3, and C(6)H(3)N(2)-5), and the diynyl analogues, (NBu(4))(2)[Pt(Ctbd1;CCtbd1;CR)(4)] (R = C(6)H(5) and C(6)H(4)CH(3)-4), have been synthesized. These complexes displayed intense photoluminescence, which was assigned as metal-to-ligand charge transfer (MLCT) transitions. Reaction of (Bu(4)N)(2)[Pt(Ctbd1;CC(5)H(4)N-4)(4)] with 4 equiv of [Pt((t)Bu(3)trpy)(MeCN)](OTf)(2) in methanol did not yield the expected pentanuclear platinum product, [Pt(Ctbd1;CC(5)H(4)N)(4)[Pt((t)Bu(3)trpy)](4)](OTf)(6), but instead afforded a strongly luminescent 4-ethynylpyridine-bridged dinuclear complex, [Pt((t)Bu(3)trpy)(Ctbd1;CC(5)H(4)N)Pt((t)Bu(3)trpy)](PF(6))(3,) which has been structurally characterized. The emission origin is assigned as derived from states of predominantly (3)MLCT [d(pi)(Pt) --> pi((t)Bu(3)trpy)] character, probably mixed with some intraligand (3)IL [pi --> pi(Ctbd1;C)], and ligand-to-ligand charge transfer (3)LLCT [pi(Ctbd1;C) --> pi((t)()Bu(3)trpy)] character. On the other hand, reaction of (Bu(4)N)(2)[Pt(Ctbd1;CCtbd1;CC(6)H(4)CH(3)-4)(4)] with [Ag(MeCN)(4)][BF(4)] gave a mixed-metal aggregate, [Pt(2)Ag(4)(Ctbd1;CCtbd1;CC(6)H(4)CH(3)-4)(8)(THF)(4)]. The crystal structure of [Pt(2)Ag(4)(Ctbd1;CCtbd1;CC(6)H(4)CH(3)-4)(8)(THF)(4)] has also been determined. A comparison study of the spectroscopic properties of the hexanuclear platinum-silver complex with its precursor complex has been made and their spectroscopic origins were suggested.     

Synthesis and characterisation of low valent Mn-complexes as models for Mn-catalases

In this work we report the synthesis of two novel manganese complexes, [L1(3)Mn(II)(6)](ClO(4))(6) (1·(ClO(4))(6)) and [L2Mn(II)(2)(μ-OAc)(μ-Cl)](ClO(4))(2) (2·(ClO(4))(2)), where L1(2-) is the 2,2'-(1,3-phenylenebis(methylene))bis((2-(bis(pyridin-2-ylmethyl)amino)ethyl)azanediyl)diacetic acid anion and L2 is N1,N1'-(1,3-phenylenebis(methylene))bis(N2,N2'-bis(pyridin-2-ylmethyl)ethane-1,2-diamine). The ligands Na(2)L1 and L2 are built on the same backbone, L2 only contains nitrogen donors, while two carboxylate arms have been introduced in Na(2)L1. The two complexes have been characterized by single-crystal X-ray diffraction, magnetic susceptibility, EPR spectroscopy, and electrochemistry. X-Ray crystallography revealed that 1 is a manganese(II) hexamer and 2 is a manganese(II) dimer featuring an unprecedented mono-μ-acetato, mono-μ-chlorido bridging motif. The ability of the complexes to catalyse H(2)O(2) disproportionation, thereby acting as models for manganese catalases, has been investigated and compared to the activity of two other related manganese complexes. The introduction of carboxylate donors in the ligands, leading to increased denticity, resulted in a drop in H(2)O(2) disproportionation activity.     

Luminescent ruthenium(II) polypyridine biotin complexes: synthesis, characterization, photophysical and electrochemical properties, and avidin-binding studies

Two luminescent ruthenium(II) polypyridine complexes containing a biotin moiety [Ru(bpy)(2)(L1)](PF(6))(2) (1) and [Ru(bpy)(2)(L2)](PF(6))(2) (2) (bpy = 2,2'-bipyridine; L1 = 4-(N-((2-biotinamido)ethyl)amido)-4'-methyl-2,2'-bipyridine; L2 = 4-(N-((6-biotinamido)hexyl)amido)-4'-methyl-2,2'-bipyridine) have been synthesized and characterized, and their photophysical and electrochemical properties have been studied. Upon photoexcitation, complexes 1 and 2 display intense and long-lived triplet metal-to-ligand charge-transfer ((3)MLCT) (dpi(Ru) --> pi*(L1 or L2)) emission in fluid solutions at 298 K and in low-temperature glass. We have studied the binding of these ruthenium(II) biotin complexes to avidin by 4'-hydroxyazobenzene-2-carboxylic acid (HABA) assays, luminescence titrations, competitive assays using native biotin, and quenching experiments using methyl viologen. On the basis of the results of these experiments, a homogeneous competitive assay for biotin has been investigated.     

Imidotungsten(VI) complexes with chelating amino and imino phenolates

The reaction of WOCl(4) with 2,4-di-tert-butyl-6-((isopropylamino)methyl)phenol followed by the reaction with phenyl isocyanate leads to the formation of imidotungsten(VI) complex [W(NPh)Cl(3)(OC(6)H(3)(CH(2)NH-i-Pr)-2-t-Bu(2)-4,6)] 4 with a chelating aminophenolate ligand. When the same procedure was applied using aminophenols with bulkier substituents in the amino group, the final product was an unexpected Schiff-base complex [W(NPh)Cl(3)(OC(6)H(3)(CH=NPh)-2-t-Bu(2)-4,6)] 5, where the ligand is derived from 2,4-di-tert-butyl-6-((phenylimino)methyl)phenol. Complex 5 is also formed in the thermal degradation of 4. On the whole, 5 appears to be formed by a disproportionation of intermediate compounds, which are analogous to complex 4. The solid-state structures of 4 and 5 have been determined by X-ray crystallography whereas the solution structures were studied by (1)H and (13)C NMR.     

Biomimetic iron(III) complexes of N3O and N3O2 donor ligands: protonation of coordinated ethanolate donor enhances dioxygenase activity

A series of iron(III) complexes 1-4 of the tripodal tetradentate ligands N,N-bis(pyrid-2-ylmethyl)-N-(2-hydroxyethyl)amine H(L1), N,N-bis(pyrid-2-ylmethyl)-N-(2-hydroxy- propyl)amine H(L2), N,N-bis(pyrid-2-ylmethyl)-N-ethoxyethanolamine H(L3), and N-((pyrid-2-ylmethyl)(1-methylimidazol-2-ylmethyl))-N-(2-hydroxyethyl)amine H(L4), have been isolated, characterized and studied as functional models for intradiol-cleaving catechol dioxygenases. In the X-ray crystal structure of [Fe(L1)Cl(2)] 1, the tertiary amine nitrogen and two pyridine nitrogen atoms of H(L1) are coordinated meridionally to iron(III) and the deprotonated ethanolate oxygen is coordinated axially. In contrast, [Fe(HL3)Cl(3)] 3 contains the tertiary amine nitrogen and two pyridine nitrogen atoms coordinated facially to iron(III) with the ligand ethoxyethanol moiety remaining uncoordinated. The X-ray structure of the bis(μ-alkoxo) dimer [{Fe(L5)Cl}(2)](ClO(4))(2)5, where HL is the tetradentate N(3)O donor ligand N,N-bis(1-methylimidazol-2-ylmethyl)-N-(2-hydroxyethyl)amine H(L5), contains the ethanolate oxygen donors coordinated to iron(III). Interestingly, the [Fe(HL)(DBC)](+) and [Fe(HL3)(HDBC)X] adducts, generated by adding ～1 equivalent of piperidine to solutions containing equimolar quantities of iron(III) complexes 1-5 and H(2)DBC (3,5-di-tert-butylcatechol), display two DBC(2-)→ iron(III) LMCT bands (λ(max): 1, 577, 905; 2, 575,915; 3, 586, 920; 4, 563, 870; 5, 557, 856 nm; Δλ(max), 299-340 nm); however, the bands are blue-shifted (λ(max): 1, 443, 700; 2, 425, 702; 3, 424, 684; 4, 431, 687; 5, 434, 685 nm; Δλ(max), 251-277 nm) on adding 1 more equivalent of piperidine to form the adducts [Fe(L)(DBC)] and [Fe(HL3)(HDBC)X]. Electronic spectral and pH-metric titration studies in methanol disclose that the ligand in [Fe(HL)(DBC)](+) is protonated. The [Fe(L)(DBC)] adducts of iron(III) complexes of bis(pyridyl)-based ligands (1,2) afford higher amounts of intradiol-cleavage products, whereas those of mono/bis(imidazole)-based ligands (4,5) yield mainly the auto-oxidation product benzoquinone. It is remarkable that the adducts [Fe(HL)(DBC)](+)/[Fe(HL3)(DBC)X] exhibit higher rates of oxygenation affording larger amounts of intradiol-cleavage products and lower amounts of benzoquinone.