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41.
Juan Carlos López-López Dr. Delia Bautista Dr. Pablo González-Herrero 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(49):11307-11315
A stereoselective synthetic route to homo- and heteroleptic facial tris-cyclometalated PtIV complexes is reported, involving the oxidative addition of 2-(2-pyridyl)- or 2-(1-isoquinolinyl)benzenediazonium salts to cis-[Pt(C^N)2] precursors, with C^N=cyclometalated 2-(p-tolyl)pyridine (tpy), 2-phenylquinoline (pq), 2-(2-thienyl)pyridine or 1-phenylisoquinoline (piq), to produce labile diazenide intermediates that undergo photochemical or thermal elimination of N2. The method allows the preparation of derivatives bearing cyclometalated ligands of low π–π* transition energies. The new complexes exhibit phosphorescence in fluid solution at room temperature arising from triplet ligand-centered (3LC) excited states, which, in the cases of the heteroleptic derivatives, involve the ligand with the lowest π–π* gap. The heteroleptic piq derivatives exhibit fluorescence and dual phosphorescence from different ligand-centered excited states in rigid media, demonstrating the potential of cyclometalated PtIV complexes as multi-emissive materials. 相似文献
42.
Antonio Jesús Martínez-Martínez María Teresa Chicote Delia Bautista 《Journal of chemical crystallography》2011,41(12):1961-1967
Abstract
The crystal structures of trans-[PdI{C=N(Xy)CH(R)NHC6H4-2}(CNXy)2]OTf (R = Me (1·CHCl3) space group P-1, a = 8.7665(4) ?, b = 15.5346(8) ?, c = 16.2415(8) ?, α = 72.698(2)o, β = 78.310(3)o, γ = 88.310(2)o, CH = CH2 (2·0.5Et2O) space group P21/c, a = 15.7868(6) ?, b = 14.5066(6) ?, c = 18.5814(7) ?, β = 106.707(2)o, C6H4Me-4 (Tol) (3) space group P-1, a = 11.96075(5) ?, b = 12.9452(51) ?, c = 13.1263(5) ?, α = 93.306o, β = 95.822(2)o, γ = 94.572(2)o) have been measured. The structural data suggest the existence of some electron delocalization over the heterocyclic ring, the extension of which seems to depend on the R substituent. The complex [PdI{C6H4(N=CHTol)-2}(bpy)] (Tol = C6H4Me-4, bpy = 2,2′-bipyridine, 4) is the fourth imino-substituted aryl palladium complex. Complex 4 crystallizes in triclinic P-1 with a = 8.7873(5) ?, b = 8.8936(5) ?, c = 13.8375(8) ?, α = 90.116(2)o, β = 92.760(2)o, γ = 106.243(2)o. 相似文献43.
Alajarín M Cabrera J Pastor A Sanchez-Andrada P Bautista D 《The Journal of organic chemistry》2006,71(14):5328-5339
The reaction of 2-(phenylamino)- and 2-(dimethylamino)thiazoles with dimethyl acetylenedicarboxylate led unexpectedly to dimethyl 6-(phenylamino)- and 6-(dimethylamino)-3,4-pyridinedicarboxylates. Those compounds reasonably result from a sequence of reactions initiated by a [2 + 2] cycloaddition of the alkyne to the formal C=C of the thiazole ring. These pyridines were obtained in nearly all the cases assayed as the exclusive reaction products under rather mild conditions and in fair to good yields. In contrast, the regioisomeric 2-amino-3,4-pyridinedicarboxylates, which would result from a [4 + 2] cycloaddition followed by sulfur extrusion, were only obtained in one particular case. The two reaction paths leading alternatively to both regioisomers were investigated computationally. The respective [2 + 2] and [4 + 2] cycloadducts were found to be formed stepwise from a common dipolar intermediate. Notably, the step following the [2 + 2] cycloaddition (i.e., the ring opening of the fused cyclobutene intermediate to give an all-cis 1,3-thiazepine) was found to take place in a disrotatory mode. Although geometric constraints and electronic factors may reduce the energy for the disrotation, the implication of the fused five-membered ring in the electronic reorganization leading to the 1,3-thiazepine is determinant. In this sense, this step could be regarded also as a thermally allowed six-electron five-center disrotatory electrocyclic ring opening. The proposed mechanism was experimentally supported by the isolation of several intermediates and other experimental facts. 相似文献
44.
Application of linear regression analysis for iron and copper removal process using natural zeolites
Mihaela-Ligia Ungure?an Andrada M?ic?neanu Francisc-Vasile Dulf Eva-Henrietta Dulf Delia Maria Gligor 《Journal of Thermal Analysis and Calorimetry》2012,110(3):1293-1297
Natural zeolites (zeolitic volcanic tuffs) cropped out from three regions of Transilvania, Vultureni (V), Pagli?a (P) and M?cica? (M), were evaluated in the process of iron (V, P, M) and copper (M) removal from wastewaters. Iron and copper removal process was studied using a fixed bed column, when equilibrium and kinetic data were acquired. Four isotherms, Langmuir, Freundlich, Langmuir?CFreundlich and Redlich?CPeterson, were used to fit the experimental data obtained for each natural zeolite sample. Parameters of the adsorption isotherms were estimated from the experimental equilibrium data using MATLAB. Using these data the best fit with one of the chosen isotherm can be found. Isotherm constants were determined by linear regression analysis of the experimental data. We concluded that the mathematical model based on Freundlich isotherm is the most appropriate to describe the iron and copper exchange on our natural zeolite samples. 相似文献
45.
Delia Ionescu 《PAMM》2006,6(1):813-814
A new approach to nonlinear RLC circuits, which is based on the geometric Birkhoffian formalism, is described in this note. The configuration space and a special Pfaffian form, called Birkhoffian, are obtained from the constitutive relations of the involved resistors, inductors and capacitors and from Kirchhoff's laws. No assumptions are placed upon the topology of the network. Properties of the corresponding Birkhoffian such as its regularity, or its dissipativeness, are discussed in this context. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
46.
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48.
The synthesis of derivatives of benzo[f]quinazoline, benzo[g]quinazoline and benzo[h]quinazoline is reviewed. Each class of compound is treated separately. The review covers ring formations as well as group modifications. 相似文献
49.
Dionisio Poveda ngela Vivancos Delia Bautista Pablo Gonzlez-Herrero 《Chemical science》2020,11(44):12095
Hydride complexes resulting from the oxidative addition of C–H bonds are intermediates in hydrocarbon activation and functionalization reactions. The discovery of metal systems that enable their direct formation through photoexcitation with visible light could lead to advantageous synthetic methodologies. In this study, easily accessible dimers [Pt2(μ-Cl)2(C^N)2] (C^N = cyclometalated 2-arylpyridine) are demonstrated as a very convenient source of Pt(C^N) subunits, which promote photooxidative C–H addition reactions with different 2-arylpyridines (N′^C′H) upon irradiation with blue light. The resulting [PtH(Cl)(C^N)(C′^N′)] complexes are the first isolable Pt(iv) hydrides arising from a cyclometalation reaction. A transcyclometalation process involving three photochemical steps is elucidated, which occurs when the C^N ligand is a monocyclometalated 2,6-diarylpyridine, and a detailed analysis of the photoreactivity associated with the Pt(C^N) moiety is provided. Alkyne insertions into the Pt–H bond of a photogenerated Pt(iv) hydride are also reported as a demonstration of the ability of this class of compounds to undergo subsequent organometallic reactions.The photochemical generation of isolable bis-cyclometalated Pt(iv) hydrides via photooxidative C–H addition reactions is demonstrated from easily accessible Pt(ii) precursors using visible light. 相似文献