HALIDE EXCHANGE REACTIONS BETWEEN CpW(CO)3 − AND CpMo(CO)3X

Abstract

Halogen atom transfer from CpMo(CO)₃X (X = Cl, Br and I) to CpW(CO)₃ ^? forming CpMo(CO)₃ ^? and CpW(CO)₃X occurs with a first-order dependence on the oxidant and the reductant. The rate constants show a very small dependence on the identity of X, suggesting a mechanism involving nucleophilic attack by CpW(CO)₃ ^? on a carbonyl of CpMo(CO)₃X.     

SYNTHESIS,LASER-RAMAN,INFRARED AND PROTON MAGNETIC RESONANCE SPECTRA OF (CH3)3PtX2- 3 IONS (X = Cl−, Br−) AND (CH3)3Ptiv ISOCYANIDE COMPLEXES

Abstract

The novel ionic complexes [(C₆H₅)₄As]₂ [(CH₃)₃PtX₃](X = Cl^? and Br^?) and [(CH₃)₃Pt(bipy)L]⁺[B(C₆H₅)₄]^? (bipy = 2,2′-bipyridine, L = aliphatic and aromatic isocyanide) have been prepared. The structure of the complex ions has been inferred from Laser-Raman and infrared spectra in the solid state and ¹H NMR in solution. These data are consistent with a facial configuration of the organometallic moiety. Trends in vibrational frequencies ν(Pt-C) and ν(Pt-X) indicate a “trans” influence sequence for the ligands, which in the case of (CH₃)₃PtX^2- ₃ is related with that found for (CH₃)₂AuX^? ₂ ions.     

SYTHESE AND REACTIONS OF HETEROBINUCLEAR COMPLEXES [PhCl_2SnM(Cl)(CO)_3(CH_3CN)_2] (M = Mo, W)

Abstract The complexes [M(CO)_3(CH_3CN)_3](M=Mo, W)react with an equimolar quantity ofPhSnCl_3 in dichloromethane at room tempreture to afford new heterobinuclearcomplexes [PhCl_2SnM(Cl)(CO)_3(CH_3CN)_2] [M=Mo(1); W(2)]. The complexes reactwith two equivalents of PR_2R'(R=Ph, R'=Ph, Me; R=Cy, R'=H) to yield stablecomplexes [PhCl_2SnM(Cl)(CO)_3(PR_2R')_2]. Reaction of[PhCl_2SnM(Cl)(CO)_3(CH_3CN)_2]with one equivalent of PPh_2(CH_2)nPPh_2(n=I,2) or bulky phosphine ligands PBu_2~tClin dichloromethane at room tempreture to give [PhCl_2SnMo(Cl)(CO)_3{PPh_2(CH_2)n-PPh_2}] .CH_2Cl_2, [PhCl_2SnMo(Cl)(CO)_3PBu_2~tCl]. CH_2Cl_2, respectively. The complexes1 and 2 react with phosphite donor ligands P(OMe)_3 to give [PhCl_2SnM(Cl)(CO)_2-{P(OMe)_3}_3]. All complexes have been characterized by elemental analysis, IRand ~1HNMR spectroscopies. Here we report the preliminary results of this work.     

[3+2]-CYCLOADDITION REACTIONS OF THIOISATIN WITH L-PROLINE AND (R)-(−)-THIAPROLINE

The [3+2]-cycloaddition reactions of cyclic secondary α-amino acids viz L-proline and (R)-(?)-thiaproline with 5-methylthioisatin via azomethine ylide in the presence of dipolarophiles afford azabicyclooctane derivatives in moderate-to-good yields. The cycloadducts have been characterized by elemental analysis and spectral techniques viz IR, ¹H NMR, ¹³C NMR, MASS. In addition, stereochemical aspects of the cycloaddition have been ascertained by MOPAC-6 calculations using AM1 hamiltonians.     

REACTIONS OF [η5−RC5H4 (CO)2Mo]2 (Mo≡Mo) WITH (μ-PhSe)2Fe2 (CO)6. SYNTHESIS AND CHARACTERIZATION OF SELENOLATO-BRIDGED TRANSITION METAL COMPLEXES [η5−RC5H4Mo (CO) (μ-SePh)]2 (R ˭ MeCO,MeO2C) AND η5−RC5H4MoFe2 (CO)4 (μ3-Se) [μ,η1: η2−C(0)Ph] (μ-SePh)2 (R ˭ H,MeCO, EtO2C)

Abstract

Mo≡Mo triply bonded dimers [η⁵?RC₅H₄ —react with (μ,-PhSe)₂Fe₂ (CO)₆ in boiling xylene to give selenolato-bridged bimetallic complexes [η⁵?RC5H₄Mo(CO) (μ-SePh)]₂ (R ? MeCO, MeO₂C). However, irradiation of a benzene solution of —(R ? H, MeCO, EtO₂C) and (μ-PhSe)₂Fe₂ (CO)₆ with a 400W high pressure mercury lamp gave rise to selenolato-bridged trimetallic clusters η⁵?RC₅H₄MoFe₂(CO)₂ (μ₃-Se) [μ,η:η²?C (O) Ph] (μ-SePh)₂ (R ? H, MeCO, EtO₂C). All products were characterized by elemental analysis and spectroscopic methods, as well as by an X-ray diffraction analysis of the product η⁵?MeCOC₅H₄MoFe₂(CO)₄ (μ-Se)[μ;η¹:η²?C(O)Ph](μ-SePh)₂.     

CLEAVAGE OF cyclo-( t BuSb)4 WITH Li,Na OR K AND FORMATION OF Sb7 3 − BY REACTIONS OF PRIMARY STIBINES WITH BuLi OR K

Novel reactions of cyclo-(^tBuSb) ₄ and RSbH₂ (R═C₆ H ₅ , 2,4,6-(CH₃)₃ C₆ H₂ or [(CH₃)₃Si]₂CH) with alkali metals or n-BuLi are described.     

CH3SOCH3与XO(X=Cl,Br)自由基反应的理论研究

采用密度泛函理论B3LYP方法,在6-311 G(d,p)基组水平上研究了二甲亚砜(DMSO)与XO(X=Cl,Br)自由基反应的微观动力学机理,并利用经过wigner校正的传统过渡态理论计算了标题反应在200~2000 K温度范围内的反应速率常数。研究结果表明,DMSO与XO(X=Cl,Br)自由基反应主要有氧转移和抽氢两种反应机理,氧转移反应的能垒显著低于抽氢反应,且前者为放热反应后者为吸热反应;低温时氧转移反应占绝对优势,298 K时DMSO与XO(X=Cl,Br)两个反应体系的总速率常数分别为2.09×10-15和1.75×10-14cm3.molecu le-1.s-1,氧转移反应分支比均为100%。高温时抽氢反应上升为主通道。2000 K时其总速率常数分别为6.32×10-12和8.41×10-12cm3.molecule-1.s-1,抽氢反应分支比分别为91.8%和79.4%。     

A STUDY OF THE XBS~+CATIONS(X=H,F,Cl)BY IMPROVED MS-X_α METHOD

By means of improved overlapping Muffin-Tin X_a method recently developed theground state ~2(?)and the first excited state ~2Σ~+ of the XBS~+(X=H,F,Cl)cations are studied.Thecalculated energies are in good agreement with experiment.The ionization potentials of sulphi-doborons,XBS(X=H,F,Cl,Br)are also computed and compared with photoelectron spectra re-sults.     

SYNTHESIS AND CARBON TRANSFER REACTIONS OF 12-DIMETHYL-3-ARYLSULFONYL (ARYL=p-TOLYL PHENYL)-△~2-IMIDAZOLINIUM IODIDE

As models of 5, 10-methenyl-tetrahydrofolate coenaymes imidazolinium salts 6a. b were synthesized and their carbontransfer reactions with several types of nucleophiles were studied.     

CRYSTAL AND MOLECULAR STRUCTURE OF (μ-PhS) (μ-σ,π-CH_3CH = CH)Fe_2(CO)_6

<正> The crystal and molecular structure of (μ-PhS) (μ-σ, n-CH3CH = CH)-Fe2(CO)6 has been determined by X - ray diffraction technique. The complex has chemical formula of C15H10O6SFe2 and Mr=129. 99. The crystals are monoclinic,space group P21/c,with α=11. 789(2),b= 7. 159(1),c = 20. 890(4) A ;β = 100. 89(2);V = 1731. 32 A3;Z=4,Dc=1. 65g·cm-3;F(000) = 863. 86. The final R and Rw equal 0. 0315 and 0. 0405 respectively for 2527 observed unique reflections.     

Some Aryl Substituted Metal Phosphorus Double Bonded Complexes C5R5 (CO)2 M=PR′2 (R=H,CH3; M=Mo,W)

Abstract

The attempt to generate the metal-phosphorus double bonded system Cp(CO)₂M=PPh₂ (M=Mo, W) (4a,b) via thermal or photochemical decarbonylation of Cp(CO)₃M-PPh₂ (la,b) leads to the formation of hydrido-phosphido-bridged complexes (μ2-H) (μ2-PPh₂)[M(CO)₂Cp]₂ (2a,b).     

Comparative mass spectrometric investigation of transition metal polymethylcyclopentadienylcarbonyl complexes: I. Mass spectra of RnC5H5−nRe(CO)3 (R = CH3, n = 0-5; R = t-C(CH3)3, n = 1)

Mass spectra of π-(CH₃)_nC₅H_5−nRe(CO)₃ Me_nCpReT) (n = 0–5) and t-BuCpReT were recorded, from which it was found that molecular ion (M⁺) fragmentation for Me_nCpReT (_n = 0, 1) differs from that for Me_nCpReT (_n = 2–5). The (M – 2CO)⁺ ions have maximum intensity in n = 0, 1 complexes, and the (M – 2CO – H₂)⁺ ions, in _n = 2–5 complexes. H₂ elimination from (M – 2CO)⁺ is typical of rhenium π-cyclopentadienyl complex fragmentation, where the number of methyl groups in the Cp ring is > 1, and seems to occur with participation of the Re atom.     

Study of allylic rearrangement in (μ-H)Os3(μ-O=CNRCH2CH=CH2)(CO)10 (R=H or CH3) clusters

The migration of the double bond in the allylcarboxamide ligands of (μ-H)Os₃(μ-O=CN RCH₂CH=CH₂) (CO)₁₀ (R=H (1) or CH₃ (2)), (μ-D)Os₃(μ-O=CNDCH₂CH=CH₂) (CO)₁₀, and (μ-H)Os₃(μ-O=CNHCD₂CH=CH₂)(CO)₁₀ clusters was studied by¹H,²H, and¹³C NMR spectroscopy. Neither μ-D nor ND groups in the deuterated complexes are directly involved in prototropic processes of allylic rearrangement. Initially, the deuterium atom of the CD₂ group migrates to the ψ-carbon atom of the allyl fragment to form the −CD=CH-CH₂D propenyl moiety, in which the deuterium and hydrogen atoms are gradually redistributed between the ψ-and β-carbon atoms. The triosmium cluster complexes containing the bridging carboxamide ligands O=CNRR' catalyze the allylic rearrangement ofN-allylacetamide. Based on the data obtained, the probable scheme of the allylic rearrangements in clusters1 and2 was proposed. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2182–2186, November, 1999.     

STEREOSELECTIVITY OF ELECTRON TRANSFER REACTIONS (II); REACTION OF Λ-[Co(EDDS)]− AND Co(II) COMPLEXES WITH STEREOSPECIFIC DIAMINE LIGANDS

Abstract

Stereoselective electron-transfer between optically active Λ-[Co(EDDS)]^? and [Co(diamine)₃]²⁺ (diamine = racemic-1,2-diaminopropane (pn); R-1,2-diaminopropane (R-pn)) have been investigated in aqueous and in DMSO solutions. In aqueous solution, the reaction between Λ-[Co(EEDS)]^? and [Co(pn)₃]²⁺ produces four conformational isomers of the [Co(pn)₃]³⁺ complex which have the Λ-forms in excess. Their optical purities are increased ob₃>lelob₂> lel₂ob> lel₃ . In contrast, the reaction in DMSO results in more δ isomers than Λ and the sequence of optical purities are in reversed order.

The reaction between Λ-[Co(EDDS)]^? and [Co(R-pn)₃]²⁺ in aqueous solution produces two conformational isomers of [Co(R-pn)₃]³⁺; their absolute configurations are identified as δ-lel₂ob and Λ-ob₃ . In DMSO, in contrast, the reaction produces only one isomer which is identified as δ-lel₂ob.     

Koordinationschemie tripodaler Triisocyanid-Liganden: Synthese von Komplexen des Typs CH3C[CH2NC-M(CO)x]3 (M = Cr,W, χ = 5; M = Fe, χ = 4) und Kristallstruktur von CH3C[CH2NC-W(CO)5]3

The triisocyanide ligand CH₃C(CH₂NC)₃, time, reacts with metal carbonyls M(CO)_x (M = Cr, W, χ = 6; M = Fe, χ = 5) to give the triply metal carbonyl substituted complexes CH₃C[CH₂NCM(CO)_x]₃ (M = Cr, W, χ = 5; M = Fe, χ = 4). CH₃C[CH₂NCW(CO)₅]₃ was characterized by an X-ray structure determination.     

(CH3NH3)AuX4⋅H2O (X=Cl,Br) and (CH3NH3)AuCl4: Low-Band Gap Lead-Free Layered Gold Halide Perovskite Materials

Perovskite solar cells have recently enabled power conversion efficiency comparable to established technologies such as silicon and cadmium telluride. Ongoing efforts to improve the stability of halide perovskites in ambient air has yielded promising results. However, the presence of toxic heavy element lead (Pb) remains a major concern requiring further attention. Herein, we report three new Pb-free hybrid organic–inorganic perovskite-type halides based on gold (Au), (CH₃NH₃)AuBr₄⋅H₂O ( 1 ), (CH₃NH₃)AuCl₄⋅H₂O ( 2 ), and (CH₃NH₃)AuCl₄ ( 3 ). Hydrated compounds 1 and 2 crystallize in a brand-new structure type featuring perovskite-derived 2D layers and 1D chains based on pseudo-octahedral AuX₆ building blocks. In contrast, the novel crystal structure of the solvent-free compound 3 shows an exotic non-perovskite quasi-2D layered structure containing edge- and corner-shared AuCl₆ octahedra. The use of Au metal instead of Pb results in unprecedented low band gaps below 2.5 eV for single-layered metal chlorides and bromides. Moreover, at room temperature the three compounds show a weak blue emission due to the electronic transition between Au-6s and Au-5d, in agreement with the density function theory (DFT) calculation results. These findings are discussed in the context of viability of Au-based halides as alternatives for Pb-based halides for optoelectronic applications.     

1H, 13C and 31P NMR studies of some (C6H5)3−nPRn and (C6H5)3−nPRn Cr(CO)5 (n = 0–3; R  H,CH3, C2H5, i-C3H7, t-C4H9) derivatives

The ³¹P chemical shift of the (C₆H₅)_3−nPR_n and (C₆H₅)_3−nPR_nCr(CO)₅ (n = 0–3; R  H, CH₃, C₂H₅, i-C₃H₇, t-C₄H₉) derivatives is dominated by the steric effect. A small inductive effect is also operative but there are no indications of notable (d_Cr→d_P)π back-bonding. The ¹³C chemical shift of the phenyl carbon atoms indicates that (p_ring-d_P)π electron delocalization is unimportant.The ¹³C chemical shift of the carbonyl carbon atoms, which is mainly governed by the mean excitation energy, confirms the conclusion that there are no notable changes in (d_Cr→d_P)π back-bonding in this series of compounds.     

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⁺.     

Oxidative addition reactions TO Cp′Co(CO)L (Cp′ = C5H4CH3; L = CO,PPh3 and tetracyanoethylene) with XCN (X = Br,I)

Oxidative addition of XCN (X = Br, I) to Cp′Co(CO)L (L = CO, PPh₃) leads to the formation of Cp′CoL(CN)X. The complexes C′_pCoTCNE(L) do not react with XCN.