Synthesis of molecular ferromagnetics [R3R′X]MCr(C2O4)3 (X = N,R = Bun,R′ = Prn,Et, Me; X = P,R = Ph,R′ = Bun; M = Mn,Fe, Co,Ni, Cu)

The synthesis, IR spectra, and the temperatures of the transition into a ferromagnetic state (T _c) of layered ferromagnetics [R₃RX[MCr(C₂O₄)₃ (M = Mn, Fe, Co, Cu, and Ni) with the [Ph₃BuP]⁺, [Bu₃RN]⁺ (R = Pr, Et, and Me) cations capable of subsequently changing the distances between metallooxalate layers have been considered. The temperatureT _c has been found to be independent of the size of the organic cation. It is believed that the determining factors in the transition to a ferromagnetic state are exchange interactions inside the metallooxalate layer.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2327–2330, September, 1996.     

Cétonisation catalytique du méthyl-2-butène-3-ol-2 par des complexes du rhodium(III) ou du palladium(II)

A number of efficient catalytic procedures for the oxidation of acid-sensitive substrate such as 2-methyl-3-buten-2-ol to the corresponding ketone (2-methylbutan-2-ol-3-one) are compared. Reaction with dioxygen (or quinone) and a palladium precursor (PdCl₂ or [PdCl(NO₂)(CH₃CN)₂]) under mild conditions (⋍ 35°C), gave good conversions (⋍ 98%) and good selectivities (⋍ 90%).     

Synthesis and structures of the six-coordinate donor-acceptor complexes R3(C6H4O2)Sb…L (R=Ph, L=OSMe2 or ONC5H5; R=Me, L=ONC5H5 or NC5H5) and R3(C2H4O2)Sb…L (R=Ph, L=ONC5H5; R=Cl or C6F5, L=OPPh3)

One-pot oxidation of R₃Sb (R=Ph, Me, Cl, or C₆F₅) withtert-butyl hydroperoxide in the presence of 1,2-diols and monodentate donor compounds was studied. The structures of the resulting neutral organic donor-acceptor Sb^V complexes, Ph₃(C₆H₄O₂)Sb…OSMe₂, Ph₃(C₆H₄O₂)Sb…ONC₅H₅, Me₃(C₆H₄O₂)Sb…ONC₅H₅, Me₃(C₆H₄O₂)Sb…NC₅H₅, Ph₃(C₂H₄O₂)Sb…ONC₅H₅, and Cl(C₆F₅)₂(C₂H₄O₂)Sb…OPPh₃, were established by X-ray diffraction analysis. In these complexes, the coordination environment about the Sb atoms is a distorted octahedron. The Sb?O(N) distances and the Sb?O?E angles (E=S, N, or P) vary over wide ranges.     

Synthesis,crystal and molecular structure of the “slipped” sandwich complex [Ni(η5-P3C2R2)(η3-P2C3R3)] (R = But)

The synthesis of the novel “slipped” sandwich compound [Ni(η⁵-P₃C₂R₂)(η³-P₂C₃R₃)] (R = Bu^t) is described. The mode of attachment of the P₃C₂R₂ and P₂C₃R₃ rings has been determined by NMR spectroscopy and a single crystal X-ray diffraction study.     

三核过渡金属配合物[M3ⅢO(OOCR)6L3]+(M=Cr,Fe,Mn;R=CH3,C2H5,CH2NH2;L=C5H5N,H2O)的1H NMR性质

采用1H NMR谱研究了通式为[M3ⅢO(OOCR)6L3]+(M=Cr,Fe,Mn;R=CH3,C2H5,CH2NH2;L=C5H5N,H2O)的一系列氧心三核过渡金属配合物,主要考察其1H化学位移随金属、配体、温度、溶剂等因素变化而变化的规律.结果表明,骨架金属对化学位移的影响最大,M3O中的3个金属离子间存在反铁磁交换相互作用.对Mn配合物中顺磁中心对化学位移和线宽的影响机制的研究表明,其1H各向同性位移主要由接触作用贡献.     

Synthesis,Crystal Structures,and Properties of (4,4'-Hbipy)2[Sn2(C2O4)3] and (4,4'-Hmbipy)[SnX2] (X = C2O42–, m = 2; X = Cl,m = 0; bipy = bipyridine)

Three new tin coordination compounds (4,4'-Hbipy)₂[Sn₂(C₂O₄)₃] ( 1 ), (4,4'-H₂bipy)[Sn(C₂O₄)₂] ( 2 ), and SnCl₂(4,4'-bipy) ( 3 ) were synthesized under hydro-(solvo-)thermal conditions and their crystal structures were determined by single-crystal X-ray diffraction. Compound 1 exhibits a ionic structure based on discrete [4,4'-Hbipy]⁺ cations and [Sn₂(C₂O₄)₃]^2– anions. These two units are linked via N–H ··· O hydrogen bonds to form a pseudo-one-dimensional zigzag hydrogen-bonded chain. In compound 2 , four-coordinate Sn atoms form monomeric tin dioxalato complexes, which are connected to the doubly protonated [4,4'-H₂bipy]²⁺ cations through N–H ··· O hydrogen bonded to give a one-dimensional zigzag hydrogen-bonded chain. Compound 3 forms a three-dimensional hydrogen-bonded network, in which ¹_∞[SnCl₂(4,4'-bipy)] linear chains are interconnected to each other by C–H ··· Cl hydrogen bonding. The solid-state UV/Vis/NIR diffuse reflectance spectroscopy shows that three compounds are broadband semiconductors. The thermogravimetric analysis evidences the thermal stability of the three compounds up to 175, 201, and 246 °C, respectively.     

Phosphonates α-silylés (RO)2P(O)CR1R2SiR3R4R5 et α,α-disilylés (RO)2P(O)CR1[Si(CH3)3]2; preparation et propriétés

Phosphonoalkylation of trisubstituted chlorosilanes in the presence of excess i-Pr₂NLi has been examined to establish the steric acid and electrophilic properties of each silane. A similar sequence has been developed for the introduction of two Si(CH₃)₃ groups. The SiC bond cleavage clearly demonstrates the protecting effect of trisubstituted silyl groups; but the silyl groups do not influence the formation of vinylphosphonates in the Peterson reaction.     

Syntheése d′Imines Polyfluorées (R) (RF) C = NR′

Primary amines R′eNH₂ react with hemifluorinated ketones R-CO-R_F to give the corresponding polyfluorinated imines (R) (RF) C - NR′ in good yields. By means of ¹⁹F NMR, it is shown that the imine formation involves a gem-aminoalcohol intermediate, which spontaneously dehydrates without any catalyst.     

Kinetics of Intramolecular Hydrogen Atom Transfer in the Radicals >Si(O·)(R) (R = H,D, CH3, CD3, and C2H5)

Methods are developed for obtaining oxy radicals by the photodecomposition and thermal decomposition of precursors (Si–O)₂Si(N=N–O^·)(R) and (Si–O)₂Si(O–C^·=O)(R). The mechanism of these processes is established. Kinetic data are obtained for the reaction of hydrogen atom transfer in oxy radicals (Si–O)₂Si(O^·)(R) (R = H, D, CH₃, CD₃, and C₂H₅). The activation energies of hydrogen atom transfer are found for three-, four-, and five-membered transition states: 13.5 ± 1, 18 ± 1, and <10 kcal/mol, respectively. For the reaction of H(D) atom transfer in the (Si–O)₂Si(O^·)(H(D)) radical, the kinetic isotope effect is found. Quantum-chemical calculations were used to determine the structures of transition states in the studied processes. Experimental studies were carried out using ESR spectroscopy.     

MO-RE2O3-B2O3(M=Mg,Ca,Sr,Ba;RE=La,Eu,Gd)玻璃的发光性质

在空气中采用高温固相反应方法合成的17MO－（8-x-y)-75B2O3-xGd2O3(MLBEG,M-Mg,Ca,Sr,Ba)玻璃，在紫外光（λex=350nm)激发下发射蓝光和红光，在绿色光（λex=532nm)激发下发射红光，电子自旋共振谱研究表明玻璃体系中有Eu^2 离子存在，蓝色区的宽带发射是Eu^2 离子的5d-4f跃迁发射：红色区的窄带发射是Eu^3 离子的5Do-7FJ(J=1,2,3,4)跃迁发射，发现玻璃中的碱土金属离子对Eu^3 /Eu^2 离子的比例有很大影响，选择不同的碱土金属离子可以调节玻璃蓝色光和红色光的相对发射强度，MLBEG玻璃的发光性质可用于转换太阳能，增强植物的光合作用。     

Synthesis and Structure of Tetraphenylantimony Oximates Ph4SbON=CRR′ (CRR′ = C6H9−C6H9-2 and R = Ph,R′ = C(O)Ph)

The reaction of pentaphenylantimony and the oxime HON=CRR taken in 1 : 1 molar ratio in toluene gave tetraphenylantimony oximates Ph₄SbON=CRR (CRR = C₆H₉–C₆H₉-2 (I) and R = Ph, R = C(O)Ph (II)). According to X-ray diffraction data, the Sb atoms in I and II have a distorted trigonal-bipyramidal coordination with oximate ligands in the axial positions. The C_axSbO angles are 177.6(1)° in I and 176.58(6)° in II. The Sb–C bond lengths lie in the ranges of 2.120(4)–2.203(4) Å for I and 2.122(2)–2.181(2) Å for II. The Sb–O bond lengths are 2.120(2) Å (I) and 2.166(1) Å (II). The lengths of the intramolecular Sb···N contacts are 2.806(3) and 2.918(2) Å in I and II, respectively.     

Chalcogen–acetylide interaction and unusual reactivity of coordinated acetylide with water: synthesis and characterisation of [(η5-C5R5)Fe3(CO)6(μ3-E)(μ3-ECCH2RI)] (R=H,Me; RI=Ph,Fc; E=S,Se) and [(η5-C5R5)MoFe2(CO)6(μ3-S)(μ-SCCH2Ph)] (R=H,Me)

Photolysis of a benzene solution containing [Fe₃(CO)₉(μ₃-E)₂] (E=S, Se), [(η⁵-C₅R₅)Fe(CO)₂(CCR^I)] (R=H, Me; R^I=Ph, Fc), H₂O and Et₃N results in formation of new metal clusters [(η⁵-C₅R₅)Fe₃(CO)₆(μ₃-E)(μ₃-ECCH₂R^I)] (R=H, R^I=Ph, E=S 1 or Se 2; R=Me, R^I=Ph, E=S 3 or Se 4; R=H, R^I=Fc, E=S 5; R=Me, R^I=Fc, E=S 6 or Se 7). Reaction of [Fe₃(CO)₉(μ₃-S)₂]with [(η⁵-C₅R₅)Mo(CO)₃(CCPh)] (R=H, Me), under same conditions, produces mixed-metal clusters [(η⁵-C₅R₅)MoFe₂(CO)₆(μ₃-S)(μ-SCCH₂Ph)] (R=H 8; R=Me 9). Compounds 1–9 have been characterised by IR and ¹H and ¹³C-NMR spectroscopy. Structures of 1, 5 and 9 have been established crystallographically. A common feature in all these products is the formation of new C-chalcogen bond to give rise to a (ECCH₂R^I) ligand.     

Organophosphoryl polyoxotungstates α-[R2PW9O34]5− [R = PhP(S), C6H11P(O), H2NCH(n-Pr)P(O)]

Tetrabutylammonium salts of organophosphoryl derivatives of tungstophosphate of formula α-[R₂PW₉O₃₄]⁵⁻ [R = PhP(S), C₆H₁₁P(O), H₂NCH(n-Pr)P(O)] have been prepared, purified and characterized by elemental analysis, i.r., ³¹P- and ¹⁸³W-n.m.r. spectroscopy. These anions consist of an α-[PW₉O₃₄]⁹⁻ framework on to which are grafted two equivalent organophosphoryl groups through P–O–W bridges; these new species still retain the ‘unsaturated’ Keggin structure. The five-line ¹⁸³W spectra indicates that the hybrid anions possess C _s symmetry in acetonitrile. This revised version was published online in June 2006 with corrections to the Cover Date.     

Nature of bonding in terminal borylene, alylene, and gallylene complexes of vanadium and niobium [(η(5)-C5H5)(CO)3M(ENR2)] (M = V, Nb; E = B, Al, Ga; R = CH3, SiH3, CMe3, SiMe3): a DFT study

Density functional theory calculations have been performed for the terminal borylene, alylene, and gallylene complexes [(η(5)-C(5)H(5))(CO)(3)M(ENR(2))] (M = V, Nb; E = B, Al, Ga; R = CH(3), SiH(3), CMe(3), SiMe(3)) using the exchange correlation functional BP86. The calculated geometry parameters of vanadium borylene complex [(η(5)-C(5)H(5))(CO)(3)V{BN(SiMe(3))(2)}] are in excellent agreement with their available experimental values. The M-B bonds in the borylene complexes have partial M-B double-bond character, and the B-N bonds are nearly B═N double bonds. On the other hand, the M-E bonds in the studied metal alylene and gallylene complexes represent M-E single bonds with a very small M-E π-orbital contribution, and the Al-N and Ga-N bonds in the complexes have partial double-bond character. The orbital interactions between metal and ENR(2) in [(η(5)-C(5)H(5))(CO)(3)M(ENR(2))] arise mainly from M ← ENR(2) σ donation. The π-bonding contribution is, in all complexes, much smaller. The contributions of the electrostatic interactions ΔE(elstat) are significantly larger in all borylene, alylene, and gallylene complexes than the covalent bonding ΔE(orb); that is, the M-ENR(2) bonding in the complexes has a greater degree of ionic character.     

Synthesis,spectral, thermal and structural characterization of {[Cu(H2O)3][Cu(MAL)2] · 2H2O}∞ and [Cu(MAL)(TEA)] · H2O (MAL = malonate and TEA = triethanolamine)

A polymeric malonato-bridged copper(II) complex, {[Cu(H₂O)₃][Cu(MAL)₂]· 2H₂O}, and a mononuclear malonato-copper(II) complex with triethanolamine, [Cu(MAL)(TEA)]·H₂O, have been prepared and characterized by elemental analyses, i.r., u.v.–vis, magnetic measurements and single crystal X-ray diffraction. The polymeric complex consists of one-dimensional chains containing the MAL bridged [Cu(H₂O)₃]²⁺ and [Cu(MAL)₂]^2– ions and each MAL ligand simultaneously exhibits chelating bidentate (at one copper atom) and bridging (at the adjacent copper atom) coordination modes. The intrachain Cu1...Cu2 separation is 4.963 Å and the polymeric complex exhibits antiferromagnetic behaviour. In the mononuclear complex, the copper(II) ion is octahedrally coordinated by one bidentate MAL and one tetradentate neutral TEA ligands. The i.r. spectra and thermal decompositions of both complexes are described.     

Synthesis, Characterization, and Physical Properties of Two Trinuclear, Mixed-Valence Species of Type [μ3-OMnIIMnIII 2(O2CCF3)6(R)3] (R=H2O, CH3COOH)

The preparation and characterization of two new mixed-valence, trinuclear species, [Mn₃O(O₂CCF₃)₆(H₂O)₃]CF₃COOH4/3H₂O (1) and [Mn₃O(O₂CCF₃)₆(CH₃COOH)₃] (2), is reported. Compound 1 crystallizes in the triclinic space group, P¯1 (No. 2), with the parameters, a=12.3131(9) Å, b=12.4427(9) Å, c=12.965(1) Å, =72.593(4)°, =73.453(5)°, =68.345(4)°, V=1727.2(2) ų, and Z=2. A total of 14060 reflections were collected in the range 1.6827.52°. The final weighted and non-weighted agreement indices, R1=0.0589 and wR2=0.1445 were based on a total of 6953 unique reflections with an R _int value of 0.0542. Compound 2 crystallizes in the monoclinic space group, P2₁/n (No. 14), with the parameters, a=12.876(3) Å, b=12.212(4) Å, c=17.732(4) Å, =100.40(3)°, V=3640.4(1) ų, and Z=4. A total of 32197 reflections were collected in the range 1.7227.13°. The final weighted and non-weighted agreement factors, R1=0.0647 and wR2=0.1609 were based on a total of 8018 unique reflections with an R _int value of 0.0462. An investigation of the physical properties revealed that both compounds display an intermediate ground state of S=3/2 as a consequence of intramolecular antiferromagnetic coupling. The magnetic data for compound 1 was best fit to the parameters g=2.09, J=–5.5 cm^–1, J=–3.4 cm^–1, and D _Mn(III)=–4.5 cm^–1; the data for compound 2 was best fit to the parameters g=2.10, J=–2.9 cm^–1, J=–5.5 cm^–1, and D _Mn(III)=–4.5 cm^–1.     

Préparation du complexe endoédrique hydrogène moléculaire fullerène C60, associé à du C60 hydrogéné

Preparation of endohedral complexes of molecular hydrogen-fullerene C_60, together with hydrogenated C₆₀. Using our new method described elsewhere, we have obtained the preparation of endohedral complexes H₂@C₆₀, together with hydrogenated C₆₀. Analyses by ¹H NMR, and by infrared and vacuum ultraviolet spectroscopies have been carried out, which proved the existence of these two kinds of compounds in our samples. A quantitative measurement has been done, giving values for the endohedral complexes of about 18%, and for the hydrogenated C₆₀ of about 35%. To cite this article: B. Oksengorn, C. R. Chimie 6 (2003).     

NbX(X=C,N,O)的能带结构研究

本文采用EHT近似下的紧束缚能带方法,计算了NbX(X=C,N,O)的能带结构。结果表明,它们的能带结构相近,Nb—X间存在较强的成键作用,传导电子主要具有Nb的4d特征,Nb—Nb键与超导电性相关,从C到N,Nb—Nb键共价性削弱,Tc提高。尽管计算所得NbO中Nb—Nb键强度介于NbC和NbN之间,但其实际Tc却比NbC和NbN的都低,这是NbO的空位效应所致,这一结果可从我们对有序缺陷的Nb_(0.75)O_(0.75)晶体能带结构的计算得到验证。     

Comparative mass spectrometric investigation of transition metal polymethylcyclopentadienylcarbonyl complexes: II mass spectra of RnC5H5–nMN(CO)3 (R = CH3, n = 0–5; R = t-C(CH3)3, n = 1)

Investigation of π-(CH_3nC₅H_5–nMn(CO)₃ (Me_n-CpMnT) n = 0−5 and t-butyl CpMnT mass spectra showed that Me_nCpMnT molecular ion (M⁺) fragmentation occurs by a simpler scheme than that for Me_nCpReT M⁺ molecular ions. The reason is that MnCp and MnCO bonds are not as strong as the ReCp and ReCO bonds, and the relative “inertness” (compared to Re) of the Mn atom (ion), coordinated to the methylcyclopentadienyl ligand. Variations of M⁺ molecular ion intensity with different values of n are probably due to a complexity of electronic and spatial methyl-carbonyl group interactions in M⁺.