Synthesis of catalytically active diene and cyclopentadienyl rhodium halide complexes

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Unexpected reactions of (Me2C)(Me2Si)[(η-C5H3)Mo(CO)3]2 with diazoalkane and carbon disulfide: Activation and cleavage of the NN bond and disproportionation of carbon disulfide

The N-N bond cleavage of diazoalkane Ar₂CN₂ following a orthometalation of the aryl occurred in the thermal reactions with (Me₂C)(Me₂Si)[(η⁵-C₅H₃)Mo(CO)₃]₂ (1), which led to (Me₂C)(Me₂Si)[(η⁵-C₅H₃)₂Mo₂(CO)₂(O){μ-η¹:η²-NC(RC₆H₃)(RC₆H₄)}] [R = H (2), p-Me (3)]. Two products (Me₂C)(Me₂Si)[(η⁵-C₅H₃)₂Mo₂(CO)₄(μ-η¹:η²-CS)] (4) and (Me₂C)(Me₂Si)[(η⁵-C₅H₃)₂Mo₂(CO)₄(μ-η²:η²-CS₃)] (5) were isolated in the reaction of complex 1 with CS₂ with the disproportionation of carbon disulfide. The molecular structures of 2-5 have been determined by X-ray diffraction analysis. The proposed mechanism was discussed.     

Hydrogen bonds and protonation of carbonyl-containing polynuclear rhodium complexes

According to IR spectroscopy data, the interaction of bi-, tri-, and tetranuclear cyclopentadienylcarbonyl rhodium complexes with rather weak protic acids (phenols, fluoroalcohols) in low-polarity media results in the formation of hydrogen bonds of the OH...O=C type with bridged carbonyl groups. According to¹H NMR data, protonation of these complexes with strong acids (CF₃COOH and HBF₄) occurs at the the Rh-Rh bond to give the symmetrical bridge.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 386–388, February, 1995.This work was carried out with the financial support of the Russian Foundation for Basic Research (Project No. 93-03-0461).     

Protonation Switching to the Least‐Basic Heteroatom of Carbamate through Cationic Hydrogen Bonding Promotes the Formation of Isocyanate Cations

We found that phenethylcarbamates that bear ortho‐salicylate as an ether group (carbamoyl salicylates) dramatically accelerate O?C bond dissociation in strong acid to facilitate generation of isocyanate cation (N‐protonated isocyanates), which undergo subsequent intramolecular aromatic electrophilic cyclization to give dihydroisoquinolones. To generate isocyanate cations from carbamates in acidic media as electrophiles for aromatic substitution, protonation at the ether oxygen, the least basic heteroatom, is essential to promote C?O bond cleavage. However, the carbonyl oxygen of carbamates, the most basic site, is protonated exclusively in strong acids. We found that the protonation site can be shifted to an alternative basic atom by linking methyl salicylate to the ether oxygen of carbamate. The methyl ester oxygen ortho to the phenolic (ether) oxygen of salicylate is as basic as the carbamate carbonyl oxygen, and we found that monoprotonation at the methyl ester oxygen in strong acid resulted in the formation of an intramolecular cationic hydrogen bond (>C?O⁺?H???O<) with the phenolic ether oxygen. This facilitates O?C bond dissociation of phenethylcarbamates, thereby promoting isocyanate cation formation. In contrast, superacid‐mediated diprotonation at the methyl ester oxygen of the salicylate and the carbonyl oxygen of the carbamate afforded a rather stable dication, which did not readily undergo C?O bond dissociation. This is an unprecedented and unknown case in which the monocation has greater reactivity than the dication.     

基于3，6-二(2-(4-氧化苯并吡嗪基))-4，5-二氮杂-3，5-辛二烯配体的两个离散型Ag(Ⅰ)配合物的合成与晶体结构

3,6-二（2-（4-氧化苯并吡嗪基））-4,5-二氮杂-3,5-辛二烯配体（L）与银盐室温下反应得到了2个结构新颖的离散型配位化合物[Ag₈（L）₈]（BF₄）₈·CH₂Cl₂·3CH₃OH（1）和[Ag₄（L）₄]（PF₆）₄·CH₂Cl₂（2）。通过红外、元素分析、X射线单晶衍射等检测手段对所得配合物进行了表征。结果表明,2个配合物皆以二聚体的形式存在。未配位的平衡阴离子与二聚体通过氢键连接成一维或二维结构。     

N-tosyloxycarbamates as reagents in rhodium-catalyzed C-H amination reactions

Metal nitrenes for use in C-H insertion reactions were obtained from N-tosyloxycarbamates in the presence of an inorganic base and a rhodium(II) dimer complex catalyst. The C-H amination reaction proceeds smoothly, and the potassium tosylate that forms as a byproduct is easily removed by filtration or an aqueous workup. This new methodology allows the amination of ethereal, benzylic, tertiary, secondary, and even primary C-H bonds. The intramolecular reaction provides an interesting route to various substituted oxazolidinones, whereas the intermolecular reaction gives trichloroethoxycarbonyl-protected amines that can be isolated with moderate to excellent yields and that cleave easily to produce the corresponding free amine. The development, scope, and limitations of the reactions are discussed herein. Isotopic effects and the electronic nature of the transition state are used to discuss the mechanism of the reaction.     

一种新型羧酸-磺酸双功能配体的钴配合物的合成与三维氢键网络结构

Using the ligand 4-sulfonyl-2,6-naphthalenedicarboxylate (SNDC), a coordination compound [Co(H₂O)₆]₂[Co(SNDC)₂(H₂O)₄]·4H₂O(1) was synthesized and characterized by elemental analysis, thermal analysis, IR and single crystal X-ray diffraction structure analysis. The complex crystallizes in the triclinic P1 space group. The crystallographic data are: a=0.722 4(3) nm, b=1.181 2(4) nm, c=1.353 4(5) nm, V=1.039 47(7) nm³, Z=1, D_c=1.795 g·cm^-3, R₁=0.055 8, wR₂=0.148 7. In the complex, the cobalt(Ⅱ) mononuclear anion ([Co(SNDC)₂(H₂O)₄]^4-) adopts the six-coordinated octahedral geometry furnished by two carboxylate oxygen atoms from the SNDC ligands and four water oxygen atoms. The cobalt(Ⅱ) mononuclear anions are self-assembled into two-dimensional sheets through hydrogen bonding between coordinated water molecules and carboxylate oxygens and π-π stacking of the aromatic naphthalene moieties. The [Co(H₂O)₆]²⁺ cations are intercalated between the layers through additional hydrogen bonds involving coordinated water molecules and sulfonate/carboxylate oxygen atoms. CCDC: 694556.     

氯化六咪唑合铁四水分子的结构表征和电化学性能研究(英)

The crystal structure of the title compound, [Fe(Im)₆]Cl₂·4H₂O, (Im=imidazole) was determined by X-ray analysis. The crystal structure consists of Fe(Im)₆²⁺ cation, two Cl^- anions and four non-coordinated water molecules. It crystallizes in the triclinic system, space group P1, with lattice parameters a=0.879 7(2) nm, b=0.906 8(2) nm, c=1.058 1(2) nm, α=75.35(3)°, β=83.20(3)°, γ=61.85(3)°, and Z=1; The Fe(Ⅱ) ion assumes centrosymmetric octahedron geometry with the FeN₆ core. Six imidazole molecules are coordinated to each iron(Ⅱ) ion through its tertiary nitrogen atom. The bond distances of Fe-N are in range of 0.212 8(1) nm to 0.220 4(1) nm. In the solid state, [Fe(Im)₆]²⁺, H₂O molecules and chlorine anions form three dimensional hydrogen bonds network which stabilized the crystal structure. Elemental analysis and electronic spectrum are in agreement with the structural data. The thermal gravity (TG) data indicate that thermal decomposition of the title compound takes place in five steps. In these cases, the residue may be Fe. From the cyclic voltammogram measurement in EtOH/H₂O, we know that electrode reaction was a quasi-reversible process. CCDC: 215335.     

Synthesis and Characterization of Two Chiral Cadmium Coordination Compounds Constructed from (1S,1′S)-1,1′-(4-amino-4H-1,2,4-triazole-3,5-diyl)diethanol

Two chiral cadmium coordination compounds,(S)-[Cd(deoatrz)2 Cl2](1)and(S)[Cd(deoatrz)2 (NO3)2](2)(deoatrz=(1S,1 S)-1,1-(4-amino-4H-1,2,4-triazole-3,5-diyl)diethanol),are reported.Both 1 and 2 are mononuclear,crystallizing in tetragonal P41212 chiral space group with Z=2.For1,a=11.520(3),b=11.520(3),c=15.175(1),V=2013.6(1)3,Mr=527.7,Dc =1.741 g/cm 3,μ=1.386mm-1,F(000)=1064,the final GOF=1.05,R=0.0147 and wR=0.0433 for1932 observed reflections with I>2σ(I).For 2,a=12.201(3),b=12.201(3),c=15.027(4),V=2237.1(1)3,Mr=580.8,Dc=1.725 g/cm 3,μ=1.047mm-1,F(000)=1176,the final GOF=1.00,R=0.0201 and wR=0.0415 for 2408 observed reflections with I>2σ(I).Compounds 1 and 2 are connected into three-dimensional supramolecular networks through hydrogen bonding interactions.     

[ZnN(CH2CH2NH2)2(CH2CH2N=CHC6H4O)]·Pic的合成与晶体结构

在不加任何碱的条件下,三[2-(亚水杨基胺)乙基]胺与苦味酸锌[Zn(Pic)26H2O]在乙醇中反应,得到了较为少见的多胺单缩合西夫碱配体的配合物[ZnN(CH2CH2NH2)2(CH2CH2N=CH-C6H4O)]Pic。化学式为C19H23N7O8Zn,Mr=542.81,晶体属三斜晶系,空间群为P,晶胞参数为a=0.7494(3),b=1.1917(5),c=1.3142(6)nm,a=78.111(7),b=79.093(7),g=78.577(7),V=1.1121(8)nm3,Dc=1.621g/cm3,m(MoKa)=1.167mm-1,Z=2,F(000)=560,在1.602s(I)的可观测点为2433个,最终偏离因子R=0.0555,wR=0.1139。配合物中Zn(II)与配体的4个N原子和1个O原子配位形成变形的三角双锥结构,桥头N和O为锥顶,4个配位N中桥头N与金属离子的配位作用最弱。晶体通过p-p堆积和分子内、分子间的氢键作用形成二维层状超分子结构。     

二(三苯基膦)水杨酸铜(Ⅰ)乙醇溶剂配合物的晶体结构

0IntroductionThestudyofcopper?complexesisinvestigatedinmanylaboratories.Amongthereasonsforcarryingouttheinvestigationofsuchspeciesaretheirstructuralfeatures犤1犦,theusefulnessofcopper?compoundsinorganicsyntheses犤2犦andthewell-documentedimpor-tanceofcopper?centersattheactivesitesofanumberofprotein犤3犦.Concerningcopper?carboxy-latesafurtherinterestexists,stemmingfromtheiruseinhomogeheouscatalysedhydrogenation犤4犦.Thecopper?bis(triphenylphosphine)cationisasoft,butflexi-bleacceptorionthatcanacc…     

Computational study of bond dissociation enthalpies for substituted β-O-4 lignin model compounds

The biopolymer lignin is a potential source of valuable chemicals. Phenethyl phenyl ether (PPE) is representative of the dominant β-O-4 ether linkage. DFT is used to calculate the Boltzmann-weighted carbon-oxygen and carbon-carbon bond dissociation enthalpies (BDEs) of substituted PPE. These values are important for understanding lignin decomposition. Exclusion of all conformers that have distributions of less than 5% at 298 K impacts the BDE by less than 1 kcal mol(-1). We find that aliphatic hydroxyl/methylhydroxyl substituents introduce only small changes to the BDEs (0-3 kcal mol(-1)). Substitution on the phenyl ring at the ortho position substantially lowers the C-O BDE, except in combination with the hydroxyl/methylhydroxyl substituents, for which the effect of methoxy substitution is reduced by hydrogen bonding. Hydrogen bonding between the aliphatic substituents and the ether oxygen in the PPE derivatives has a significant influence on the BDE. CCSD(T)-calculated BDEs and hydrogen-bond strengths of ortho-substituted anisoles, when compared with M06-2X values, confirm that the latter method is sufficient to describe the molecules studied and provide an important benchmark for lignin model compounds.     

二维网状配合物[Co(dimb)2(MeOH)2](ClO4)2的合成及晶体结构

设计并合成了一个含咪唑基团的柔性双齿配体:1,3-二(咪唑基-1′-甲基)-5-甲基苯(dimb)(1),并进行了 ¹H NMR和结构表征。通过dimb与高氯酸钴的反应,得到了一个新型的具有二维网状结构的配合物:[Co(dimb)₂(MeOH)₂](ClO₄)₂(2)。X-射线晶体结构测定表明,这两个化合物的晶体学参数分别为:配体(1)属单斜晶系, 空间群     

Structure of Hexakis(imidazole)nickel(II) Nitrate Water Solvate:[Ni(Im)_6] (NO_3)_2·4H_2O

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Isolation of New Disilanylene-bridged Bis（cyclopentadienyl）tetracarbonyldiiron Complexes and Molecular Structure of [η^5, η^5-C5H4SiMe（SiMePh2）C5H4]Fe2（CO）2（μ-CO）2

1,2-Diphenyl-1,2-dimethyldisilanylene-bridged bis-cyclopentadienyl complex[η~5,η~5-C_5H_4PhMeSiSiMePh-C_5H_4]Fe_2(CO)_2(μ-CO)_2(1)was synthesized by a modified procedure,from which the trans-isomer 1b that was pre-viously difficult to obtain has been isolated for the first time.More interestingly,two new regio-isomers[η~5,η~5C_5H_4SiMe(SiMePh_2)C_5H_4]Fe_2(CO)_2(μ-CO)_2(2)and [η~5,η~5-C_5H_4Me_2SiSiPh_2C_5H_4]Fe_2(CO)_2(μ-CO)_2(3)were occa-sionally obtained during above process,the novel structures of which opened up new options for further study ofthis type of Si—Si bond-containing transition metal complexes.The molecular structure of 2 has been determinedby the X-ray diffraction method.     

The reactivity of cyclopentadienyl dicarbonyl complexes of iron, η5-C5H5(CO)2Fe-η1-R (R = alkyl or aryl). Synthesis of novel derivatives substituted in the cyclopentadienyl ring

The results of the study of the reactivity of the cyclopentadienyl ligand in Cp(CO)₂Fe-¹-R (R=Alk or Ar) iron complexes have been summarized. The methods for preparation of mono-, bi-, and trinuclear homo- and heterometallic complexes containing a Cp(CO)₂Fe moiety are presented.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1367–1373, August, 1994.     

Molecular and Supramolecular Structures of Manganese(Ⅱ) and Cobalt(Ⅱ) Complexes with 1-Carboxymethylpyridinium-4-carboxylate

Two complexes with a zwitterionic dicarboxylate ligand,Mn(L)2(H2O)4 1 and Co(L)2(H2O)4 2(L = 1-carboxymethylpyridinium-4-carboxylate),were synthesized and structurally characterized.Complex 1 crystallizes in monoclinic,space group P21 with a = 6.490(2),b = 19.210(7),c = 7.813(3) ,β = 92.716(5)o,V = 972.9(6) 3,Z = 2,Mr = 487.28,Dc = 1.663 g/cm3,F(000) = 502,μ = 0.749 mm-1,S = 1.060,the final R = 0.0377 and wR = 0.0893 for 3292 observed reflections with I 2σ(I).Complex 2 is isomorphous with 1,with a = 6.478(2),b = 19.052(7),c = 7.742(3) ,β = 92.690(4)o,V = 954.6(6) 3,Z = 2,Mr = 491.28,Dc = 1.709 g/cm3,F(000) = 506,μ = 0.971 mm-1,S = 1.035,the final R = 0.0425 and wR = 0.0809 for 3289 observed reflections with I 2σ(I).In the compounds,the mononuclear [M(L)2(H2O)4] units with trans-octahedral coordination geometry are linked into 3D architectures via hydrogen bonding(or second-sphere coordination) involving carboxylate groups and coordinated water molecules.The 3D networks illustrate a 3,8-connected net with Schlfli symbol(4·62)2(42·623·83).     

Cyclopentadienyl rhodium(III) complexes as catalysts for the insertion of phenyldiazoacetate into E−H bonds

Rhodium(III) complexes catalyze the insertion of carbenoids generated from diazo compounds into E?H bonds (E = B, Si, N, but not C), although less efficiently than classical rhodium(II) carboxylates, despite formally higher oxidation state of the metal.