Carbon-13-nuclear magnetic resonance spectra of 5-coordinate tris-olefin complexes of rhodium(I)

Studies of the ¹³C N.M.R. spectra of the series RhX[P(Ch₂CH₂CHCH₂)₃] and RhX[P(CH₂CH₂CH₂CHCH₂)₃] where x  Cl or Br have revealed that (a) the J(¹⁰³Rh-¹³C) (olefin) for the complexes studied is only $\text{1}\text{2}$ ? $\text{1}\text{3}$ that found for square-planar complexes, and (b) the fluxional character in the olefinic carbons observed for the compounds RhX[P(CH₂CH₂CHCH₂)₃] is related to the partial rotation of the olefin about the rhodium-olefin bond.     

Chiral discrimination in the reactions of the enolate E-[(η5-C5H5)Fe(CO)(PPh3)COCHMe]−Li+ with cis and trans but-2-ene oxides in the presence of BF3·OEt3

$\text{cis}$ and $\text{trans}$-but-2-ene oxides undergo S_N2 opening with the lithium enolate derived from [(η⁵-C₅H₅)Fe(CO)(PPh₃)COCH₂CH₃] in the presence of BF₃·OEt₂; preferential opening occurs where the enolate configuration at iron matches that of the epoxide carbon being attacked.     

Cleavage of iron2-alkenyl and iron2-alkynyl bonds by mercury(II) chloride

Reactions of HgCl₂ with η⁵-C₅H₅Fe(CO)₂R (R  CH₂CHCH₂ and CH₂C(CH₃)CH₂) in THF at 25°C rapidly afford $\text{1}\text{1}$ adducts of the two reactants. These adducts were converted to the corresponding PF₆^? salts, [η⁵-C₅H₅Fe(CO)₂(η²-CH₂C(R)CH₂HgCl)]⁺ PF₆^? (R  H and CH₃), for characterization. Slower reactions with cleavage of the ironcarbon σ bond and elimination of the R group from η⁵-C₅H₅Fe(CO)₂R occur for R  CH₂CHC(CH₃)₂, CH₂CHCHC₆H₅, and CH₂CCC₆H₅. Both elimination and $\text{1}\text{1}$ adduct formation are observed when R  CH₂CHCHCH₃. The kinetics of the cleavage reactions are presented and possible mechanisms for both cleavage and $\text{1}\text{1}$ adduct formation are discussed.     

Synthesis,Reactions and Catalytic Activities of a Cationic Acrylonitrile-Rhodium(I) Complex

Reaction of RhCl (CO)(Ph₃P)₂(Ph₃P = triphenylphosphine) with AgClO₄ in acrylonitrile at 30°C produces a new cationic rhodium(I) complex, [Rh(CH₂CHCN)(CO) (Ph₃P)₂]ClO₄ ($\text{1}$) and AgCl. The ¹H-NMR and IR spectra of $\text{1}$ suggest that acrylonitrile is coordinated to rhodium through the π-system of the vinyl group. The complex $\text{1}$ reacts with molecular hydrogen to give a propionitrile-rhodium(I) complex, [Rh(CH₃ CH₂CN) (CO)(Ph₃P)₂ClO₄($\text{2}$) where the coordination of propionitrile through nitrogen is suggested by the ¹H-NMR and IR spectral data. The coordinated acrylonitrile in $\text{1}$ is readily replaced with triphenylphosphine and propionitrile to give [Rh(CO)(Ph₃P)₃] ClO₄ and $\text{2}$, respectively. The complex $\text{1}$ is catalytically active for the hydrogenation and polymerization of acrylonitrile at 25°C under the atmospheric pressure of hydrogen.     

A practical synthesis of fluoromethyltriphenylphosphonium salts

A practical synthesis of [Ph₃$\text{P}\text{+}$CH₂F]BF₄^? is reported $\text{via}$ two routes, $\text{via}$ fluorination of [Ph₃$\text{P}\text{+}$CH₂OH]BF₄^? with DAST or $\text{via}$ hydrolysis of the phosphoranium salt, [Ph₃$\text{P}\text{+}$$\text{C}$F$\text{P}\text{+}$Ph₃]Br^?.     

Synthesis of 3,3,3-trifluoropropene from vinylidene fluoride

3,3,3-Trifluoropropene is obtained under mild conditions via 3,3,3-trifluoropropyl acetate or 3,3,3-trifluoropropyl methyl ether as key intermediates. The intermediates were prepared by conjugate addition of FCH₂OR (R = COCH₃, CH₃) generated $\text{in situ}$ from HF, paraformaldehyde and HOR to vinylidene fluoride.     

Synthesis of cationic dialkylgold(III) complexes: nature of the facile reductive elimination of alkane

A series of gold(III) cations of the type cis-[CH₃)₂AuL₂]⁺ X^? where L  Ph₃, PMePh₂, PMe₂Ph, PMe₃, AsPh₃, AsPh₃, SbPh₃, $\text{1}\text{2}$H₂NCH₂CH₂NH₂, $\text{1}\text{2}$ Ph₂PCH₂CH₂-PPh₂, $\text{1}\text{2}$ Ph₂AsCH₂CH₂AsPh₂, and $\text{1}\text{2}$o-C₆H₄(AsMe₂)₂ and X  BF₄^?, PF₆^?, ClO₄^?, and F₃CSO₃^? has been prepared. In addition, the cis complexes [(CH₃)(CD₃)-Au(PPh₃)₂]F₃CSO₃, [(C₂H₅)₂Au(PPh₃)₂]F₃CSO and [(n-C₄H₉)₂Au(PPh₃)₂]F₃-CSO₃ have been synthesized. All have been characterized by PMR, Raman and infrared spectroscopy. These [R₂AuL₂]X compounds yield only ethane, butane, or octane via reductive elimination, and no disproportionation is observed. The alkane eliminations have been studied in CHCl₃, CH₃Cl₂, and CH₃COCH₃ solution as a function of temperature, concentration of the complex, and concentration of added ligand L. Elimination is fastest when L is bulky (PPh₃ > PMePh₂ > PMe₂Ph > PMe₃), decreases in the sequence SbPh₃ > AsPh₃ > PPh₃, is slow with chelating ligands, is inhibited by excess ligand, and there is small anion effect as X is varied. As R is varied, the rate of elimination decreases Bu ? Et > Me. An intramolecular dissociative mechanism is proposed which involves rapid elimination of alkane from an electron deficient dialkylgold(III) complex with nonequivalent gold—carbon bonds and produces the corresponding [AuL₂]X complex.     

The chemical oxidation and electronic spectra of the complexes trans-[M(CNR)2(Ph2PCH2CH2PPh2)2] (M = Mo or W)

Oxidation of the complexes $\text{trans}$-[M(CNR)₂(dppe)₂] (A) (M = Mo or W; R = Me, Bu^t or CH₃C₆H₄-$\text{4}$; dppe = Ph₂PCH₂CH₂PPh₂) with diiodine or silver (I) salts gives the paramagnetic cations $\text{trans}$-[M(CNR)₂(dppe)₂]⁺, (M = Mo, R = CH₃C₆H₄-$\text{4}$; M = W, R = Bu^t) and $\text{trans}$-[M(CNR)₂(dppe)₂]²⁺ (M = Mo, R = Me or CH₃C₆H₄-$\text{4}$; M = W, R = Me or Bu^t). Mixtures of products are generally produced when dichlorine or dibromine are the oxidising agents, however pure salts, the seven-coordinate complex cations [MX(CNC₆H₄CH₃-$\text{4}$)₂(dppe)₂]⁺ (B, X = Cl or Br) have been isolated. A simple molecular orbital scheme is proposed for complexes (A) and used to discuss their electronic spectra and their oxidation.     

Reaction des p-phenylphospholes avec le dicyclopentadienyl-difer-tetracarbonyle,synthese et etude spectrochimique des phosphaferrocenes

In boiling benzene, 1-phenyl-3,4-dimethylphosphole (L) with [(C₅H₅)Fe(CO)₂]₂ gives mainly a classical σ-complex in which L relaces one terminal CO. In boiling xylene, however, L also gives 3,4-dimethylphosphaferrocene and 2-phenyl-3,4-dimethylphosphaferrocene resulting from a P—Ph bond cleavage followed by a C-phenylation of the phospholyl nucleus in the second case. The same reaction with 1-phenylphosphole yields phosphaferrocene itself and a mixture of 2- and 3-phenylphosphaferrocene. The phosphaferrocenes thus prepared are exclusively acetylated at the phospholyl nucleus by the CH₃CGClAlCl₃ complex in CH₂Cl₂.With the unsubstituted phosphaferrocene, the acetylation takes place at the 2 and 3 positions (ratio $\text{2}\text{3}$ ～ $\text{85}\text{15}$) ¹H, ¹³C, ¹³P NMR and mass spectral data are given. The phosphaferrocene system is characterized by a very large ¹J(P—C) coupling (～60 Hz) and a very shielded phosphorus atom.     

Biosynthesis of highly modified meroterpenoids in aspergillus variecolor. Incorporation of 13C-labelled acetates and methionine into anditomin and andilesin C

Incorporations of [1-¹³C]?, [2-¹³C]?, [1,2-¹³C₂]-acetates and [¹³C]-methionine into anditomin, a metabolite of $\text{Aspergillus variecolor}$, indicate its formation by a mixed polyketide-terpenoid biosynthetic pathway similar to that elucidated for andibenin; observations are made on the possible biosynthetic relationship of the $\text{A. variecolor}$ metabolites with austin and terretonin, mycotoxins recently isolated from $\text{A. ustus}$ and $\text{A. terreus}$ respectively.     

On the possibility of a carbenium ion structure for the complexes [Os3H3(CO)9CCR2]+. Further application of the 187Os nucleus

In the ¹H NMR spectrum of the complex [Os₃H₃(CO)₉C$\text{C(CH}{}_2\text{C}$H₂]⁺ at 30°C, under conditions of rapid exchange, the single hydride resonance has two sets of satellites of equal intensity (separated by 32.0 and 28.8 Hz) caused by ¹⁸⁷Os¹H spin—spin coupling. The spectral data rule out the upright carbenium ion structure for the complex, and are consistent with the fluxional process involving hydrocarbon ligand rotation about the C$\text{C(CH}{}_2\text{)}{}_2\text{C}$H₂ axis in a tilted structure, with concomitant rotation of the Os₃H₃(CO)₉ moiety.     

Darstellung und eigenschaften von und reaktionen mit metallhaltigen heterocyclen: XXV. Synthese und eigenschaften neuer platina- und rhodacycloalkane durch substitution und oxidative addition einer CCl-bindung

The platinacyclopentane derivative [Cl(CH₂)₃R₂P](Cl)$\text{PtPR}{}_2\text{CH}{}_2\text{CH}{}_2\text{CH}{}_2$ is formed by action of Cl(CH₂)₃PR₂ on Pt(COD)₂ in n-hexane via the not isolable Pt[PR₂(CH₂)₃Cl]₂ (R  C₆H₁₁) by oxidative addition of a CCl bond to platinum. [μ-CIRh(CO)₂]₂ reacts in benzene with Cl(CH₂)₃PR₂ under partially CO substitution to give the stable intermediate Cl(OC)Rh[PR₂(CH₂)₃Cl]₂. In boiling toluene oxidative addition of a CCl bond to rhodium occurs under formation of the phospharhodacyclopentane [CI(CH₂)₃R₂P] Cl₂(OC)-$\text{RhPR}{}_2\text{CH}{}_2\text{CH}{}_2\text{CH}{}_2$ (R  C₆H₅). The ³¹P{¹H}-NMR spectra of the rhodium compound is characterized by an ABX system, that of the platinum by superposition of an ABX pattern with an AB spectrum.     

Proton and carbon nuclear magnetic resonance study on some n- and o-acyl derivatives of monohydroxypyridines

Comparative study on the proton and carbon NMR spectra for a series of $\text{N}$- and $\text{O}$-acyl substituted monohydroxypyridines (C₅H₄NO$\text{R}$: $\text{R}$=-H, -CHO, -COCH₃, -COC(CH₃)₃, -COCF₃, -COC₆H₅, -SO₂CH₃, -SO₂C₆H₄CH₃ is reported. p]Characteristic ¹H, ¹³ NMR and IR spectral features allow simple and unambiguous distinction between the isomeric $\text{N}$- and/or $\text{O}$-acyl-derivatives of 2-, 3- and 4-hydroxypyridines, so that both forms can clearly be identified when tautomeric equilibria occur, since the tautomerism rate is slow on the NMR time scale     

Oxidation of coordinated olefins: the reactions of Cl2 with trichloro(ehtylene)platinate(II)

The oxidation of [PtCl₃(C₂H₄)]- by Cl₂ in aqueous solution, to yield CH₂ClCH₂OH and [PtCl₄]^2-, has been shown to proceed through the following sequence of steps: [PtCl₃(C₂H₄)] Cl₂Cl [PtCl₅(CH₂CH₂Cl)]^2-$\text{H}{}_2\text{O}\text{(HCl)}$ [PtCl₅(CH₂CH₂OH)]^2- → [PtCl₄^2- + CH₂ClCH₂OHEach of the steps and intermediates in this mechanistic sequence has been identified and characterized.     

Action of tert-butyl azidoformate on the conjugate bases of 1,2,3,4-tetrahydro-9H-carbazole and other indole derivatives

tert-Butyl azidoformate ($\text{2}$) reacts with the conjugate bases of $\text{3a}$, $\text{7a}$, $\text{9}$ (R¹ = R² = CH₃), and $\text{9}$ (R¹ = CH₃, R² = H) to give products [$\text{4}$, $\text{8}$, $\text{12}$, and $\text{14}$, respectively] in addition to the expected N-(tert-butoxycarbonyl)indole derivatives.     

Photofragmentation of CH3Br in the A band

CH₃Br is photodissociated in the first continuum. Dissociation takes place into ground state CH₃ and Br [ = Br(²P_{$\text{3}\text{2}$}] or Br* [ = Br(*P_{$\text{1}\text{2}$})]. Time of flight and angular distributions of the CH₃ fragments are measured. The Br*/Br ratios upon excitation at 222 and 193 nm are found to be 1.00 and 0.20 respectively. The anisotropy parameters at these wavelengths are β = 0.28±0.04 and β = ?0.23±0.02, respectively. The total absorption cross section is decomposed into partial absorption cross sections of the ¹Q, ³Q₀ and ³Q₁ states. It appears that excitation at 222 nm takes place to the ³Q₀ and ³Q ₁ states whereas at 193 nm the ¹Q and ³Q₀ states are excited. Contrary to CH₃I, the adiabatic curve crossing between the ³Q₀ and the ¹Q states in Ch₃Br is not important. The dissociation energy of the CBr bond is determined to be D₀(CH₃Br) = 2.87±0.02 eV.     

Metallorganische verbindungen des iridiums und rhodiums: XXVI. CH-metallierung und hydridbildung im system Ir2Cl2(C8H14)4/PR3(PR3 = P(CH2CMe3)3, t-BuP(CH2CMe3)2, t-Bu2PCH2CMe3; i-Pr3P

Treatment of Ir₂Cl₂(C₈H₁₄)₄ with the phosphines t-Bu_3?nP(CH₂CMe₃)_n (n = 3,2,1) in hot toluene followed by crystallization of the products from C₇H₈/ EtOH mixtures gave the cyclometallated hydrides (C₈H₁₄)₂Ir-μ-Cl₂$\text{IrH[CH}{}_2\text{CMe}{}_2\text{CH}{}_2\text{P}$(CH₂CMe₃)₂][P(CH₂ (I) [t-BuP(CH₂CMe₃)₂]₂H₂Ir-μ-Cl₂$\text{IrH[CH}{}_2\text{CMe}{}_2\text{CH}{}_2\text{P}$Bu^t(CH₂CMe₃)][t-BuP(CH₂CMe₃)₂] (II), and [(t-Bu₂$\text{PCH}{}_2\text{CMe}{}_2\text{CH}{}_2\text{)HI}$rCl]₂ (III). The dihydrides IrH₂Cl[t-BuP(CH₂CMe₃)₂]₂ (IIa) and IrH₂Cl(t-Bu₂PCH₂CMe₃)₂ (IIIa) were also isolated; these species were, however, more conveniently obtained by bubbling hydrogen through the solution of Ir₂Cl₂ (C₈H₁₄)₄ and the respective phosphine in toluene. i-Pr₃ reacted with the olefiniridium(I) precursor in C₇H₈/EtOH to yield the carbonyl complexes (i-Pr₃P)₂H₂Ir-μ-Cl₂Ir(CO)(PPrⁱ₃)₂ (IV) and IrCl(CO)(PPⁱ₃)₂ (IVa), no cyclometallated product being detected. The stereochemistries of the complexes were deduced from IR, ¹H, ³¹P, and ¹³C NMR data. The crystal structures of IIIa and IVa were also determined.     

Micellar alkylation: a methylating surfactant

Micellar $\text{n}$-C₁₆H₃₃$\text{N}\text{+}$(CH₃)₂CH₂$\text{S}\text{+}$(CH₃)₂, 2CF₃SO₃^? rapidly methylates bound thiophenoxide ions.     

Biosynthesis of psilotin from [2′,3′-13C2,1′-14C,4-3H]phenylalanine studied with 13C-NMR

The 6-phenyl-dihydro-α-pyrone moiety of psilotin is formed from [2′,3′-¹³C₂,1′-¹⁴C,-4-³H]phenylalanine in the plant $\text{Psilotum}$$\text{nudum}$ with retention of all the isotopes.     

A novel synthesis of carbene complexes of manganese and molybdenum containing the trichlorogermyl group

A number of carbene complexes of formulas Cl₃GeMn(CO)₄C(OR′)R and C₅H₅Mo(CO)₂(GeCl₃)C(OR′)CH₃ (R = CH₃, C₆H₅; R′ = CH₃, C₂H₅) have been prepared by the reaction of [N(C₂H₅)₄]GeCl₃ with CH₃Mn(CO)₅, C₆H₅Mn(CO)₅, or C₅H₅Mo(CO)₃CH₃ followed by alkylation of the resulting trichlorogermylacylcarbonylmetallate ion. The compound C₅H₅Mo(CO)₂(GeCl₃)$\text{COCH}{}_2\text{CH}{}_2\text{C}$H₂ has been prepared directly by the reaction of [N(C₂H₅)₄]GeCl₃ with C₅H₅Mo(CO)₃(CH₂)₃Br.