The tris(2-thienyl)methyl cation problem. NMR spectroscopic study
摘要:
A series of homologues of the trityl cation obtained by total or partial substitution of the phenyl rings for 2- or 3-thienyl groups has been studied by H-1 and C-13 NMR. In general, the spectral parameters found follow the expected trends. However, a most unexpected effect is found in the transformation of tris(2-thienyl)carbinol (1d) into tris(2-thienyl)methyl cation (2d), since the increase of the total chemical shift (DELTA-SIGMA-delta) associated with the ionization is as low as 105 ppm. To account for this observation, several hypotheses are discussed including the possibility of through-space charge delocalization by the three sulfur atoms and the interaction of the thiophene rings in an alternate conformation.
The reaction of organolithium compounds with oxalyl derivatives and cyclic 1,2-dicarbonyl compounds leads to pinacols or ketones derivedfrom homolyttc C-C bond cleavage of the intermediate O,O-centered pinacol dianions depending on the ability of the substituents for the stabilisation of the resulting radical amon The homolysis is induced by electrostatic repulsion of the negatively charged oxygen
Syntheses, Crystal Structures, and Physico-Chemical Studies of Sodium and Potassium Alcoholates Bearing Thienyl Substituents and their Derived Luminescent Samarium(III) Alkoxides
The synthesis, structural characterisation, electrochemistry, and luminescence properties of a series of alkali metal alcoholates and samarium(III) alkoxides with thiophene-based OR substituents are presented. The alkali metal alcoholates 7–15 were obtained by deprotonation of the carbinol with NaH or KH. Their molecularstructures consist of tetranuclear alkali metal alcoholates with a distorted cubane-like
介绍了一系列具有噻吩基 OR 取代基的碱金属醇化物和钐 (III) 醇盐的合成、结构表征、电化学和发光特性。碱金属醇化物 7-15 是通过甲醇与 NaH 或 KH 的去质子化获得的。它们的分子结构由四核碱金属醇化物和扭曲的立方烷状 M4O4 核心组成(X 射线结构分析)。每个碱金属都被三个羧酸盐配体和(取决于衍生物)额外的四氢呋喃分子包围。通过盐复分解合成了单核钐醇盐Sm[OC(C4H3S)3]3(thf)3}·thf(16)和Sm[OC(C16H13S)]3(thf)3}·thf(17) [KOC(C4H3S)3]4(thf)2}·thf(7)、[NaOC(C4H3S)3]4(thf)2(8)或[KOC(C16H13S)]4(thf)3之间的反应}·1/2thf (11), 分别为 thf 溶液中的 SmCl3。这些对空气敏感的碱加合物的分子结构已通过单晶 X 射线晶体学确定,并
Influence of the Solvent on the Formation of New Tin(II) Methoxides Containing Thienyl Substituents: Crystal Structure and NMR Investigations
The synthesis, structural characterization, and NMR studies of new tin(II) alkoxides with thiophene-based substituents are presented. The reaction of ligand HO–C(C4H3S)3 (1) with bis(hexamethyldisilazyl)tin Sn[N(SiMe3)2]2} in the ratio 2:1 in toluene yields the dinuclear compound Sn[OC(C4H3S)3]2}2·2 toluene (2). The same reaction in tetrahydrofuran allows the isolation of two compounds: a dinuclear
介绍了具有噻吩基取代基的新型锡 (II) 醇盐的合成、结构表征和 NMR 研究。配体 HO–C(C4H3S)3 (1) 与双(六甲基二硅基)锡 Sn[N(SiMe3)2]2} 以 2:1 的比例在甲苯中反应生成双核化合物 Sn[OC(C4H3S) 3]2}2·2甲苯(2)。在四氢呋喃中的相同反应可以分离两种化合物:双核 Sn[OC(C4H3S)3]2}2·2 thf (3) 和单核 Sn[OC(C4H3S)3]2(thf) (4)分子。通过单晶 X 射线晶体学研究了这些含有噻吩基取代基 2-4 的甲醇锡 (II) 的分子结构。Sn[OC(C4H3S)3]2}2·2甲苯(2)或Sn[OC(C4H3S)3]2}2·2 thf(3)和Sn[OC(C4H3S)溶液的NMR谱图3]2(thf) (4) 几乎相同,
New Yttrium and Europium(+3) Alkoxides Bearing Thiophene Units: Syntheses, Crystal Structure Determinations and Physico‐Chemical Properties
作者:Michael Veith、Céline Belot、Volker Huch
DOI:10.1002/ejic.201101089
日期:2012.3
spectroscopy. In addition, a novel europium(+3) alkoxide Eu[OC(C4H3S)3]3(thf)3}·thf (15) was synthesized by the reaction between Eu[N(SiMe3)2]3 and the tertiary alcohol HO–C(C4H3S)3 (1) in thf. The molecularstructure of this compound reveals an approximately octahedral coordination sphere around the europium(+3) metal centre with three methoxido ligands and three facially arranged tetrahydrofuran molecules
(3a), Y[OC(C4H3S)3]3(thf) 2 }. toluene (3b), Y[OC(C 4 H 3 S) 3 ] 3 (py) 2 (4a), Y[OC(C 4 H 3 S) 3 ] 3 -(py) 2 }·toluene (4b) and Y[OC(C 8 H 5 S 2 )3]3(thf)2 (5). An almost tetrahedral geometry has been detected for Er[OC(C 8 H 5 -S 2 ) 3 ] 3 (thf) (9), whereas an approximately octahedral geometry was found for (Nd[OC(C4H3S)3]3(thf)3).thf (6), Nd-[OC(C 8 H 5 S 2 ) 3 ] 3 (thf) 3 }·4thf (7) and Er[OC(C4H3S)3]3(thf)3
介绍了具有噻吩基取代基的稀土醇盐的合成和结构表征。通过 M[N(SiMe 3 ) 2 ] 3 (M = Y 3+ , Nd 3+ , Er 3+ ) 和结构表征的叔醇 HO-C(C 4 H 3 S) 之间的氨解反应制备了单体金属噻吩基甲醇盐) 3 (1) 或 HO-C(C 8 H 5 S 2 ) 3 (2)。这些噻吩取代的醇的金属醇盐衍生物已被分离为对空气敏感的碱加合物,它们的分子结构正在通过单晶 X 射线晶体学进行研究。对于噻吩基甲醇钇 Y[OC(C 4 H 3 S) 3 ] 3 (thf) 2 (3a), Y[OC(C4H3S)3]3(thf),金属中心周围的配位球是扭曲的三角双锥2}。甲苯(3b),Y[OC(C 4 H 3 S) 3 ] 3 (py) 2 (4a),Y[OC(C 4 H 3 S) 3 ] 3 -(py) 2 }·甲苯(4b)和Y[OC(C 8 H 5 S 2 )3]3(thf)2