在负载铼催化剂上由CO2/H2合成甲醇的研究

CO加H₂合成甲醇的工作已应用于工业化生产,其中多采用锌、铬、铜基催化剂。而CO₂加H₂合成甲醇研究工作尚不很多,其催化剂多数是在CO/H₂制甲醇催化剂基础上发展而来。     

双核钼(Ⅴ)二乙基二硫代氨基甲酸络合物的歧化离解平衡及其离解常数

由于发生歧化离解,Mo₂O₃(S₂CNEt₂)₄的溶液不遵守Beer定律,我们测定了有关溶液的光吸收性质以及Mo₂O₃(S₂CNEt₂)₄的歧化离解常数,于15℃时数值为2.2×10^-4。     

Infrared laser magnetic resonance spectroscopy of OD at 118.8, 96.5 and 215.4μ m

Zeeman spectral data are presented for the ²Π_3/2: J = _7/2 → J= _9/2,²Π_3/2: J= _7/2→²Π_1/2:J= _5/2 and²Π_3/2 J= _3/2→ J = _5/2 transitions in OD. Data for the ²Π_3/2. J=3/2→ J= 5/2 and ²Π_3/2 J= _5/2 → ²Π_l/2 : J= _3/2 transitions in OH, taken under similar conditions, are included.     

O2/CO2气氛下CO2和H2O气化反应对煤及煤焦燃烧特性的影响

利用热天平对比研究了大同煤及煤焦在O₂/N₂、O₂/CO₂和O₂/H₂O/CO₂中的燃烧行为,探讨CO₂和H₂O气化反应对其富氧燃烧特性的影响。结果表明,在5%氧气浓度下,煤粉在O₂/N₂、O₂/CO₂和O₂/H₂O/CO₂中的燃烧速率按顺序依次降低。氧气浓度降低到2%,由于CO₂和H₂O气化反应的作用,煤粉在高温区的整体反应速率按顺序依次增大。当氧气浓度为5%时,煤焦在O₂/CO₂中的燃烧速率要低于O₂/N₂中的燃烧速率,但燃烧反应推迟后气化反应的参与使得煤焦在O₂/H₂O/CO₂中的整体反应速率显著升高。当氧气浓度降低到2%后,随着温度的升高,在CO₂气化反应的作用下,煤焦在O₂/CO₂中的整体反应速率逐渐高于O₂/N₂中的燃烧速率。在O₂/H₂O/CO₂中,由于H₂O在共气化中起主要作用,煤焦在O₂/H₂O/CO₂高温区的整体反应速率进一步升高。动力学分析表明,在5%氧浓度时,煤焦在O₂/N₂、O₂/CO₂和O₂/H₂O/CO₂中的表观活化能依次升高。随着氧气浓度的降低,在不同反应气氛中的表观活化能均有所下降。     

异质结型光催化膜的活性及其机理研究

采用浸渍提拉法制得TiO₂,ZnO,Fe₂O₃,ZnO/TiO₂,TiO₂/ZnO,Fe₂O₃/TiO₂和TiO₂/Fe₂O₃石英玻璃基底负载膜.光催化降解亚甲基蓝实验表明,TiO₂和ZnO具有良好的光催化活性,Fe₂O₃活性较差.但形成异质结后,TiO₂和Fe₂O₃的光催化降解能力发生明显的变化.用254nm紫外光光照后,TiO₂,ZnO和Fe₂O₃等3种氧化物膜与水的接触角均有不同程度的降低,TiO₂表现出超亲水性,ZnO/TiO₂和Fe₂O₃/TiO₂膜与水的接触角小于对应的单纯ZnO和Fe₂O₃膜与水的接触角,其中Fe₂O₃/TiO₂表面出现超亲水性.瞬态光电导谱的少数载流子寿命的测定表明,异质结势垒电场能有效地增强光生电子-空穴对的分离效率.根据能带理论建立的两组异质结能带模型可合理地解释实验结果.     

Binuclear methyplatinum and phenylplatinum complexes with bis(dimethylphosphino)methane ligands

Reaction of cis-[Ptph₂(SMe₂)₂] with Me₂PCH₂PMe₂ (dmpm) gave cis-[PtPh₂(dmpm-P)₂] (1) or cis,cis-[Pt₂Ph₄(μ-dmpm)₂] (2) and reaction of 1 with [Pt₂Me₄(μ-SMe₂)₂] gave cis,cis-[Ph₂Pt(μ-dmpm)₂PtMe₂] (3). Reaction of 1 with trans-[PtClR(SMe₂)₂] gave cis,trans-[Ph₂Pt(μ-dmpm)₂PtClR], R = Me (5) or Ph (6), and in polar solvents, these isomerized to give [Ph₂Pt(μ-dmpm)₂PtR]⁺Cl⁻. When R = Me, further isomerization via the phenyl group transfer gave [PhMePt(μ-dmpm)₂PtPh]⁺Cl⁻. Oxidative addition of methyl iodide occurred reversibly at the cis-[PtMe₂P₂ unit of 3 to give cis,fac-[Ph₂Pt(μ-dmpm)₂PtIMe₃] but complex 2 failed to react with MeI. A comparison with similar known complexes of Ph₂PCH₂PPh₂ (dppm) is made and differences are attributed primarily to the lower steric hindrance of dmpm.     

Group 14 chalcogenides featuring a bicyclo[3.3.0]octane skeleton

Reactions of mixtures of Cl₂MeSiSiMeCl₂ (1) and Me₂MCl₂ (M=Si, Ge, Sn) with either H₂S/NEt₃ or Li₂E (E=Se, Te) yielded the bicyclo[3.3.0]octanes Me₂M(E)₂Si₂Me₂(E)₂MMe₂. A carbon containing analog, (CH₂)₅C(S)₂Si₂Me₂(S)₂C(CH₂)₅, was prepared from 1 and (CH₂)₅C(SH)₂. Crystal structures of three of these compounds were determined and the observed conformations of the bicyclo[3.3.0]octane skeletons compared with results of density functional theory calculations. Another class of silchalcogenides featuring a bicyclo[3.3.0]octane skeleton, E(Me₂Si)₂Si₂Me₂(SiMe₂)₂E, was formed from the doubly branched hexasilane (ClMe₂Si)₂Si₂Me₂(SiMe₂Cl)₂ and H₂S/NEt₃ or Li₂E. All products were characterized by multinuclear NMR (¹H, ¹³C, ²⁹Si, ⁷⁷Se, ¹¹⁹Sn, and ¹²⁵Te).     

拉曼光谱法研究Na+, Mg2+//SO42-, Cl-, H2O四元体系中SO42-离子缔合结构特征及其变化规律

复杂水盐体系存在稳态和介稳固液相平衡以及复杂的成盐规律。为了解固液平衡状态下液相的结构特征,本文采用拉曼光谱技术并结合高斯-洛伦兹去卷积分峰拟合程序对Na⁺, Mg²⁺//SO₄^2-, Cl^-, H₂O四元体系及其二元和三元子体系中ν₁-SO₄^2-的离子缔合结构特征进行了分析。研究结果表明:SO₄^2-在Na₂SO₄-H₂O体系存在自由态SO₄^2-和SO₄^2-离子簇两种结构,在MgSO₄-H₂O, MgSO₄-MgCl₂-H₂O及Na⁺, Mg²⁺//SO₄^2-, Cl^-, H₂O等含镁体系中,还有Mg²⁺-H₂O-SO₄^2-和Mg²⁺-OSO₃^2-两种缔合结构。在二元和三元体系中ν₁-SO₄^2-的离子缔合结构以自由态SO₄^2-为主,随着SO₄^2-离子总浓度的变化,上述四种结构所占比例会发生规律性变化。Na⁺, Mg²⁺//SO₄^2-, Cl^-, H₂O四元体系在NaCl减少及等温蒸发过程中,自由态SO₄^2-结构比例逐步降低, Mg²⁺和SO₄^2-相结合形成Mg²⁺-H₂O-SO₄^2-或Mg²⁺-OSO₃^2-结构的机会增多,在复盐区还会形成SO₄^2-离子簇结构。由此判断溶液结构的适应性变化是导致介稳现象的重要原因。进一步的相关分析表明:SO₄^2-的浓度和耶涅克指数J与ν₁-SO₄^2-峰的峰强度和峰面积存在正相关关系, Mg²⁺浓度是影响ν₁-SO₄^2-峰中四种缔合结构的比例发生变化的主要因素。     

Reactions of the sterically hindered organosilicon diol (Me3Si)2C(SiMe2OH)2 and some of its derivatives

The diol R₂C(SiMe₂OH)₂ (R = Me₃Si) has been shown to react with: SO₂Cl₂ to give R₂ Me₂; SOCl₂ to give R₂C(SiMe₂Cl)₂; Me₃SiI or Me₃SiCl to give R₂C(SiMe₂OSiMe₃)₂; R′COCl; (R′ = Me or CF₃) to give R₂C(SiMe₂O₂CR′)-(SiMe₂Cl); (R′CO)₂O (R′ = Me or CF₃ to give R₂C(SiMe₂O₂CR′)₂; with MeOH containing acid to give R₂C(SiMe₂OMe)₂; with neutral MeOH to give R₂C-(SiMe₂OMe)₂ and probably R₂ Me₂; MeLi to give R₂C(SiMe₂OLi)₂ (and the latter to react with PhMeSiF₂ to give R₂ Me₂). The diacetate R₂C(SiMe₂O₂CMe)₂ reacts with CsF in MeCN to give R₂C(SiMe₂F)₂; it does not react with NaN₃ or KSCN in MeCN, but the bis(trifluoroacetate) reacts with these salts with KOCN to give R₂C(SiMe₂X)₂ (X = N₃, NCS, NCO).     

Preparation, properties, and reactions of metal-containing heterocycles: Part CV. Synthesis and structure of polyoxadiphosphaplatinaferrocenophanes

A series of novel heterobimetallic crown ether-like polyoxadiphosphaplatinaferrocenophanes cis-[1,1′-Fc(CH₂O(CH₂CH₂O)_nCH₂CH₂PPh₂)₂]PtCl₂ (n=1–3) (4a–c) was synthesized in good yield by cyclization of the bis(phosphine) ligands 1,1′-Fc(CH₂O(CH₂CH₂O)_nCH₂CH₂PPh₂)₂ (n=1–3) (3a–c) and (PhCN)₂PtCl₂ under high dilution conditions in CH₂Cl₂. The bisphosphines 3a–c are obtained by reaction of the corresponding diols 1,1′-Fc(CH₂O(CH₂CH₂O)_nCH₂CH₂OH)₂ (n=1–3) (1a–c) with: (i) CH₃SO₂Cl in CH₂Cl₂ and (ii) LiPPh₂ in THF. Although the X-ray crystal structure of 4a shows that the cavity is large enough for the encapsulation of small metal cations, inclusion experiments of 4a–c with Group 1 cations, and Mg²⁺, or NH₄⁺ in solution applying NMR titration and cyclovoltammetric methods reveal no evidence for the formation of host–guest complexes for 4a,b. In the case of 4c only the addition of Na⁺ or K⁺ leads to an insignificant effect.     

Dissociation reactions of the vinyl radical in the AA″ state

In the present theoretical work we have explored mechanisms of dissociation reactions of the vinyl radical in the A²A″ state (C₂H₃ (A²A″)) and examined possible pathways for nonadiabatic dissociation of C₂H₃ (A²A″) into C₂H₂ (X¹Σ_g⁺). In the calculations we used the complete active space self-consistent field (CASSCF) and multiconfiguration second-order perturbation theory (CASPT2) methods in conjunction with the cc-pVDZ and cc-pVTZ basis sets. Mechanisms for the following three dissociation channels of C₂H₃ in the A²A″ state were explored: (1) C₂H₃ (A²A″) → C₂H₂ (trans, ³A_u) + H, (2) C₂H₃ (A²A″) → C₂H₂ (cis, ³A₂) + H, and (3) C₂H₃ (A²A″) → H₂CC (³A₂) + H. The CASSCF and CASPT2 potential energy curve calculations for the C₂H₃ (A²A″) dissociation channels (1)–(3) indicate that there is neither transition state nor intermediate for each of the channels. At the CASPT2//CASSCF/cc-pVTZ level, the dissociation energies for channels (1)–(3) are predicted to be 84.3, 91.1, and 86.9 kcal/mol, respectively. For a recently observed nonadiabatic dissociation of C₂H₃ (A²A″) into C₂H₂ (X¹Σ_g⁺) + H [J. Chem. Phys. 111 (1999) 3783], two previously suggested internal conversion (IC) pathways were examined based on our CASSCF and CASPT2 calculations. Our preliminary CASSCF and CASPT2 calculations indicate that the assumed IC pathway via the twisted C₂H₃ (A²A^′) structure might be feasible. The CASSCF/cc-pVTZ geometry optimization and frequency analysis calculations were performed for the four C_2v bridge structures in the ²B₂, ²A₂, ²B₁, and ²A₁ states along the pathways of the 1²A^′ (X²A^′), 1²A″ (A²A″), 2²A″, and 2²A^′ states of C₂H₃, respectively, and the CASPT2//CASSCF/cc-pVTZ energetic results indicate that the assumed IC pathway, via a C_2v (²A₂) structure and then ²A₂/²A₁ surface crossing, be not feasible since at their excitation wavelengths (327.4 and 366.2 nm) the C_2v (²A₂) structure could not be accessed.     

Syntheses, X-ray structures, and reactions of ruthenium carbonyl complexes containing 1,1-dithiolates

Treatment of [Ru₂(CO)₄(MeCN)₆][BF₄]₂ or [Ru₂(CO)₄(μ-O₂CMe)₂(MeCN)₂] with uni-negative 1,1-dithiolate anions via potassium dimethyldithiocarbamate, sodium diethyldithiocarbamate, potassium tert-butylthioxanthate, and ammonium O,O′-diethylthiophosphate gives both monomeric and dimeric products of cis-[Ru(CO)₂(η²-(SS))₂] ((SS)⁻=Me₂NCS₂⁻ (1), Et₂NCS₂⁻ (2), ^tBuSCS₂⁻ (3), (EtO)₂PS₂⁻ (4)) and [Ru(CO)(η²-(Me₂NCS₂))(μ,η²-Me₂NCS₂)]₂ (5). The lightly stabilized MeCN ligands of [Ru₂(CO)₄(MeCN)₆][BF₄]₂ are replaced more readily than the bound acetate ligands of [Ru₂(CO)₄(μ-O₂CMe)₂(MeCN)₂] by thiolates to produce cis-[Ru(CO)₂(η²-(SS))₂] with less selectivity. Structures 1 and 5 were determined by X-ray crystallography. Although the two chelating dithiolates are cis to each other in 1, the dithiolates are trans to each other in each of the {Ru(CO)(η²-Me₂NCS₂)₂} fragment of 5. The dimeric product 5 can be prepared alternatively from the decarbonylation reaction of 1 with a suitable amount of Me₃NO in MeCN. However, the dimer [Ru(CO)(η²-Et₂NCS₂)(μ,η²-Et₂NCS₂)]₂ (6), prepared from the reaction of 2 with Me₃NO, has a structure different from 5. The spectral data of 6 probably indicate that the two chelating dithiolates are cis to each other in one {Ru(CO)(η²-Et₂NCS₂)₂}fragment but trans in the other. Both 5 and 6 react readily at ambient temperature with benzyl isocyanide to yield cis-[Ru(CO)(CNCH₂Ph)(η²-(SS))₂] ((SS)=Me₂NCS₂⁻ (7) and Et₂NCS₂⁻ (8)). A dimerization pathway for cis-[Ru(CO)₂(η²-(SS))₂] via decabonylation and isomerization is proposed.     

Intramolekulare Basenkoordination je nach Bedarf: Der 1-(Dimethylaminoethyl)-2,3,4,5-tetramethylcyclopentadienyl-Ligand in der Komplexchemie von s-, p-, d- und f-Block-Elementen

The synthesis of cyclopentadienyl complexes containing the polydentate C₅Me₄(CH₂CH₂NMe₂) ligand is described. The compounds (C₅Me₄CH₂CH₂NMe₂)₂M (M = Ca, Sm), (C₅Me₄CH₂CH₂ NMe₂)AIEt₂, [(C₅Me₄CH₂CH₂NMe₂)M(CO)₂]₂ (M = Mo, Fe) and [(C₅Me₄CH₂CH₂NMe₂)Fe(CO)₂]⁺BF₄^± are obtained by standard procedures. Except for the dimeric metal carbonyls, all cyclopentadienyl compounds are characterized by an additional intramolecular coordination of the nitrogen atom in the side chain.     

Synthesis and SpectroscOpic Charcterization of Di-and Triphenyltin Derivatives of Dithiocarbomatic Acid

A series of triphenyltin dithiocarbamates Ph₃SnS₂CNR₂, where NR₂=NMe₂,-NEt₂, N(pr-n)₂,-N(CH₂CH₂OH)₂, and diphenyltin derivatives of dithiocarbamatic acid Ph₂Sn(S₂CNR₂)₂,where NR₂=NMe₂,-NEt₂,-N(Pr-n)₂,N(Bu-n)₂, N(CH₂CH₂OH),were synthesiced by the action of the correspending phenyltin (Ⅳ) chlorides with dithiocarbamates in dichloromethane. Their structure were characterized by elemental analysis, IR, HNMR and MS.     

Surfactants having polyfluoroalkyl chains. II. Syntheses of anionic surfactants having two polyfluoroalkyl chains including a trifluoromethyl group at each tail and their flocculation-redispersion ability for dispersed magnetite particles in water

Anionic surfactants having two polyfluoroalkyl chains per molecule, i.e. the sodium salt of bis(1H, 1H, 2H,2H-heptadeca-fluorodecyl)-2-sulfosuccinate, CF₃(CF₂)₇(CH₂)₂OCOCH₂CH(SO₃Na)COO(CH₂)₂(CF₂)₇CF₃, the sodium salt of bis(1H, 1H, 2H, 2H-tridecafluoro-octyl)-2-sulfosuccinate, CF₃(CF₂)₅(CH₂)₂OCOCH₂CH(SO₃Na)COO(CH₂)₂(CF₂)₅CF₃, and the sodium salt of bis(1H, 1H, 2H, 2H-nonafluorohexyl)-2-sulfosuccinate, CF₃(CF₂)₃(CH₂)₂OCOCH₂CH(SO₃Na)COO(CH₂)₂(CF₂)₃CF₃, have been prepared from maleic anhydride, the corresponding alcohols possessing a polyfluoroalkyl chain and sodium hydrogen sulfite. The flocculation and redispersion abilities of these surfactants for dispersed magnetic particles in water have been examined to investigate the effect of the chain length. It was found that this ability was enhanced by an increase in the chain length. The contact angles for water for pelleted surface-modified magnetite have been measured. In order to compare this ability and the contact angles, data for other fluorinated surfactant have been obtained. The Kraff point, the surface tension and the pNa of the aqueous surfactant solutions have also been measured.     

Superoxometal-catalyzed co-oxidation of alcohols and nitrous acid with molecular oxygen

A superoxochromium(III) ion, Cr_aqOO²⁺, acts as a catalyst for the co-oxidation of alcohols and nitrous acid with molecular oxygen according to the stoichiometry: CH₃OH+HNO₂+O₂→CH₂O + NO₃⁻ + H₂O+H⁺. The kinetics are second order in [HNO₂] and independent of the concentrations of the superoxochromium catalyst, substrate, and O₂. The proposed mechanism features the disproportionation of HNO₂ to NO and NO₂, both of which react rapidly with Cr_aqOO²⁺. The Cr_aqOO²⁺/NO reaction generates another equivalent of NO₂ and a mole of Cr_aqO²⁺, the active oxidant. The two-electron oxidation of the alcohol by Cr_aqO²⁺ produces Cr_aq²⁺, which reacts rapidly with O₂ to regenerate the catalyst, Cr_aqOO²⁺. The NO₂/Cr_aqOO²⁺ reaction yields the peroxynitrato complex, Cr_aqOONO₂²⁺, in a dead-end equilibrium process that has no effect on the catalytic reaction. The disproportionation of NO₂ yields the final nitrogen-containing product, NO₃⁻, and regenerates an equivalent of HNO₂. Under a fixed set of conditions, the relative catalytic efficiency (CE) of Cr_aqOO²⁺ decreases as its concentration increases owing to the competition between O₂ and Cr_aqOO²⁺ for the intermediate Cr_aq²⁺.     

Mechanism of Lithium and Cobalt Recovery from Spent Lithium-ion Batteries by Sulfation Roasting Process

Different from the traditional pyrometallurgical recovery process of Li and Co from spent lithium-ion batteries, a new recovery method for Li and Co was established by converting LiCoO₂ into water-soluble metal sulfates by roasting a mixture of LiCoO₂ and NaHSO₄·H₂O. The evolution law of the mixture with increased roasting temperature was investigated by thermogravimetry-differential scanning calorimetry(TG-DSC), in situ X-ray diffraction(XRD), XRD, and X-ray photoelectron spectroscopy(XPS). The results show that the phase transition of LiCoO₂ mixed with NaHSO₄·H₂O with increased temperature proceeded as follows:LiCoO₂, NaHSO₄·H₂O→LiCoO₂, NaHSO₄→Li_1-xCoO₂, LiNaSO₄, Na₂S₂O₇, Na₂SO₄→Li_1-xCoO₂, Co₃O₄, LiNaSO₄, Na₂SO₄→Co₃O₄, LiNaSO₄. The reaction mechanism of this roasting process may be as follows:LiCoO₂+NaHSO₄·H₂O→1/2Li₂SO₄+ 1/2Na₂SO₄+1/3Co₃O₄+1/12O₂+3/2H₂O, Li₂SO₄+Na₂SO₄=2LiNaSO₄.     

Acetylen-Komplexe von Di(η-cyclopentadienyl)molybdän: Synthesen und Protonierung. Struktur von [Cp2MoH{η-C2(SiMe3)2}]PF6

Cp₂MoH₂ reacts with methyl acrylate in the presence of acetylenes (L = C₂H₂, C₂Me₂, HCC^tBu, HCCSiMe₃, C₂(SiMe₃)₂, HCCCH₂OMe, HCCCH₂NMe₂) to form acetylene complexes Cp₂Mo(L) 5. Protonation takes place with CF₃CO₂H at −80°C to give short-lived cations [Cp₂MoH(L)⁺ (8) (L = C₂Me₂, HCCSiMe₃, C₂(SiMe₃)₂). The structure of [Cp₂MoH{η²-C₂(SiMe₃)₂}]PF₆(9) was determined by an X-ray diffraction study.     

Synthesis and low temperature fluorination of the alkaline-earth palladates Ba2−xSrxPdO3 (x = 0–2)

Since the discovery of superconductivity in Sr₂CuO₂F_2+δ there has been an increased interest in ternary oxide-fluorides. Sr₂CuO₂F_2+δ is prepared via low temperature (T = 220 °C) reaction routes. Low temperature fluorination induces an interesting structural rearrangement in the parent compound Sr₂CuO₃, which is a one-dimensional material containing linear chains of vertex sharing CuO₄ squares along the crystallographic b axis. Upon fluorination, one oxide is substituted by two fluorides and Cu²⁺ becomes octahedrally coordinated by four oxides and two fluorides. The fluorinated compound Sr₂CuO₂F_2+δ displays the T-type structure (La₂CuO₄). Insertion of excess fluorine, δ, also takes place and this fluorine occupies interstitial sites in the T structure. Although the starting material Ca₂CuO₃ is isostructural to Sr₂CuO₃, Ca₂CuO₂F_2+δ displays the T′ (Nd₂CuO₄) structure due to the smaller radius of Ca²⁺ compared to that of Sr²⁺.

The alkaline-earth palladates with the general formula A₂PdO₃ (A = Ba, Sr) are isostructural with the A₂CuO₃(A = Ca, Sr) materials. We prepared the Ba_2−xSr_xPdO₃ (x = 0–2) series and performed low temperature fluorination, which led to the synthesis of the series Ba_2−xSr_xPdO₂F_2+δ (0 ≤ x ≤ 1.5). All the compounds in the Ba_2−xSr_xPdO₂F_2+δ series show T′ structure (Ca₂CuO₂F_2+δ). Similarities and differences with Sr₂CuO₂F_2+δ and Ca₂CuO₂F_2+δ will be discussed.     

Protonated ethanol and its neutral counterparts

Collisionally activated dissociation and neutralization-reionization experiments reveal that protonation of ethanol leads to two distinct isomers, the classical ion CH₃CH₂OH⁺₂ and the proton-bound complex C₂H₄…H⁺…OH₂. The neutral counterpart of the latter is unstable, whereas that of the former can be produced in a bound state if the CH₃CH₂OH⁺₂ precursor ion is formed under low ion source pressure conditions and, thus, with higher internal energies. This suggests that there are substantial differences in the geometries of CH₃CH₂OH⁺₂ and the hypervalent CH₃CH₂OH₂ ·. This provides only a partial explanation for unusual isotope effects; C₂H₅OD₂ ·, CH₃CD₂OD₂ ·, and CD₃CH₂OD₂ · are substantially more stable than C₂D₅OD₂ · and C₂H₅OH₂ ·.