Zur reaktion von metall-koordiniertem kohlenmonoxid mit yliden : VII. Trimethylphosphoranylidenmethyl(trimethylsiloxy)carben-komplexe von chrom,molybdän und wolfram: aufbau einer metallvinyl-einheit durch c(carbanion)c(carben)-π-wechselwirkung und photochemische e/z-isomerisierung

The treatment of the hexacarbonylmetal compounds M(CO)₆ (M = Cr. Mo, W) with two equivalents Me₃PCH₂ yields the phosphonium acylmetalphosphorus ylides Me₄P[(CO)₅MC(O)CHPMe₃] 1a–1c. Their reaction with Me₃SiOSO₂CF₃ leads via O-silylation to formation of the neutral “siloxy(ylidecarbene) complexes” (CO)₅MC(OSiMe₃)CHPMe₃2a–2c, which are protonated by HX (X = Cl, CF₃SO₃) to give the thermolabile carbene complexes [(CO)₅MC(OSiMe₃)H₂CPMe₃]X, 3a, 3b. ¹H, ¹³C NMR and IR data suggest, that delocalization of the ylidic charge to the carbene carbon generates a metal-coordinated vinyl group in the case of 2a–2c. In addition this fact is proved by the X-ray analysis of 2c, for which a C(ylide)C(carbene) bond distance of 133 pm is found. 2a–2c are obtained as pure E-isomers but can be converted to the Z-isomers 2a′–2c′ upon photolysis.     

Synthesis and x-ray structures of some homonuclear μ-alkylidenetungsten complexes

The complexes W₂{μ-CHCHC(CH₃)₂](CO)₁₀} and W₂{μ-CHCHC(CH₃)(CH₂)₃CH₃][(CO)₁₀} have been synthesized, and an X-ray diffraction study has revealed the presence of five CO groups on each metal center. The analogy between W₂{μ-CHCHC(CH₃)₂][(CO)₉]} anda complex of W(CO)₄ and a tungstabutadiene (CO)₅WCHCHC(CCH₃)₂ prompted the synthesis of the first heteroatom-substitued μ-alkylidene complexes of tungsten, starting from conjugated Fischer-typ carbene complexes (CO)₅WC(OR)CHCHR. The X-ray structure of the complex W₂{μ-C(OEt)CHCH(CH₃)][(CO)₉]} has also been determined. In the case of the simplest conjugated compelx (CO)₅WC(OR)CHCH₂, an interesting rearrangement initiated by addition of W(CO)₅ to the terminal CC double bond giving a dinuclear complex W(CO)₅[η²-CH₂CHC(OMe)W(CO)₅] in which the two metal centers are not directly linked, has been observed.     

1,4-dicyanobutene-bridged binuclear rhodium(I) complexes and their catalytic activities

Reactions of Rh(ClO₄)(CO)(PPh₃)₂ with dicyano olefins, cis-NCCHCH-CH₂CH₂CN (c-DC1B), rans-NCCHCHCH₂CH₂CN (t-DC1B), trans-NCCH₂CHCHCH₂CN (t-DC2B), and NCCH₂CH₂CH₂CN (DCB) produce the binuclear dicationic rhodium(I) complexes, [(CO)(PPh₃)₂RhNCACNRh-(PPh₃)₂(CO)](ClO₄)₂ (NCACN = c-DC1B 1), t-DC1B (2), t-DC2B (3), DCB (4). Complexes 1 and 2 are catalytically active for the hydrognation of c-DC1B and t-DC1B, respectively, to give DCB, while complex 3 catalyze the isomerization of t-DC2B to give c-DC1B and t-DC1B, and the hydrogenation of t-DC2B to DCB at 100°C.     

Synthèse de complexes du tungstène,du chrome et du rhénium contenant un ligand 1,4-bidenté carbéne-alcéne

A general synthesis of alkene-carbene complexes of tungsten, chromium and rhenium, containing a six-membered ring system, is outlined and the crystal structure of two new complexes of this type, (CO)₄WC(OEt)(CH)(η²-CH₂CHCH₂) (CH₂CHCH₂) and (CO)₉Re₂(OCH₂CH₃(CH₂(CH₂(CH₂CHCH₂), is described.     

1,3-Dichloro-2-butene: a useful precursor for the 2-butene-1,3-dianion and its corresponding 1,3-dipolar synthon

The reaction of 1,3-dicloro-2-butene (1; 5:1 Z:E-mixture) with lithium powder and a catalytic amount of 4,4′-di-tert-butylbiphenyl (DTBB, 1% molar) in the presence of different electrophiles [EtCHO, PrⁱCHO, Bu^tCHO, c-C₆H₁₁CHO, Me₂CO, Et₂CO, (CH₂)₄CO, (CH₂)₅CO, (c-C₃H₅)₂CO, Me₃SiCl] in THF at temperatures ranging between −78 and −50°C gives, after hydrolysis with water, the corresponding products 2 in different Z:E-ratios depending on the electrophile used. Treatment of some diols 2 with hydrochloric acid gives dienic alcohols 3 or substituted dihydropyrans 4, depending on the structure of the starting diol. Finally, the same dichlorinated starting material is transformed into the corresponding allylic amines derived from morpholine and benzyl methyl amine and submitted to the same DTBB-catalysed lithiation as above, so after reaction with different electrophiles [Bu^tCHO, c-C₆H₁₁CHO, Me₂CO, Et₂CO, (CH₂)₄CO, (CH₂)₅CO, Me₃SiCl] and final hydrolysis with water, compounds 7 are isolated having a Z-configuration. A mechanistic explanation for this behaviour is given.     

Reaktionen an komplexgebundenen liganden: XXIX. Ein einfacher weg zu azomethin-komplexen: Kondensation von chrom—, molybdän—, wolfram—, mangan— und eisen—ammoniak-komplexen und ketonen zu ketimin-komplexen

Treatment of transition-metal—ammonia complexes with ketones yields complexes with RR′CNH ligands. Of particular interest is the stabilization of dialkylketimines such as e.g. (CH₃)₂CNH and C₆H₁₀NH in [M(CO)₅{NHC(CH₃)₂}] or [M(CO)₅ {NHC₆H₁₀}] (M = Cr, Mo, W). The principle of synthesis may be applied to a wide range of different metals and types of complexes, as can be shown by the synthesis of [C₅H₅Mn(CO)₂ {NHC(CH₃)₂}], [C₅H₅Fe(CO)₂{NHC(CH₃)₂}]PF₆, [M(CO)₄L₂] (M = Cr, Mo, W; L = (CH₃)₂CNH, C₆H₁₀NH) and [W(CO)₃(diphos){NHC(CH₃)}₂]. Treatment of [Cr(CO)₅NH₃] with urotropine gives [Cr(CO)₅ {N₄(CH₂)₆}] which is also obtained from [Cr(CO)₅THF] and urotropine. The methods of preparation, reactions and spectroscopic properties of the complexes are reported.     

The chemistry of the transition metalcarbon σ-bond. Insertion reactions between stannous chloride and h1-allyl and h1-propargyl complexes of h5-cyclopentadienyldicarbonyliron

The reactions between h⁵-CpFe(CO)₂R (R = CH₂CHCH₂; CH₂CMe=CH₂; CH₂CHCHMe; CH₂CHCMe₂) and stannous chloride in tetrahydrofuran afford the insertion products h⁵-CpFe(CO)₂SnCl₂R. When treated with stannous chloride in methanol or with excess stannous chloride in tetrahydrofuran, h⁵-CpFe(CO)₂CH₂CMeCH₂ affords primarily h⁵-CpFe(CO)₂SnCl₃. The allenyl, 2-butynyl or cationic isobutylene complexes (R = CHCCH₂; CH₂ CCMe; CH₂CMe⁺₂) yield only h⁵-CpFe(CO)₂SnCl₃. Stannous iodide reacts with h⁵-CpFe(CO)₂CH₂CHCH₂ in benzene to form h⁵-CpFe(CO)₂I. Plumbous chloride in methanol fails to react with the above complexes.     

Heteronuclear (WFe) and homonuclear (FeFE) μ-alkylidene complexes of transition metals from mononuclear terminal carbene complexes. crystal structures of {WFe[μ-η1, η3-C(OCH2CH3)(CHCHCH3](CO)8} and [fe2{μ-η2,η3-C[OCH2CH3[CHC(OCH2CH3)(CH3]}(CO)6

The reactions of mononuclear carbene complexes of W and Fe of the type CO)_mMC(OR)(CH_2nCHCR′″ (M  = FE, W; m = 4 and 5; n = 0, 2, 3; R′, R″ = C, CH₃, OEt) with Fe(CO)₅ have been studied. In all cases the reaction leads to new hetero (WFe) or homo (FeFe) μ-alkylidene complexes, the position of the double bond depending strongly on n.     

The syntheses and coordination properties of M(CO)3X(DAB) (M = Mn,Re; X = Cl,Br, I; DAB = 1,4-diazabutadiene)

M(CO)₅X (M = Mn, Re; X = Cl, Br, I) reacts with DAB (1,4-diazabutadiene = R₁N=C(R₂)C(R₂)′=NR′₁) to give M(CO)₃X(DAB). The ¹H, ¹³C NMR and IR spectra indicate that the facial isomer is formed exclusively. A comparison of the ¹³C NMR spectra of M(CO)₃X(DAB) (M = Mn, Re; X = Cl, Br, I; DAB = glyoxalbis-t-butylimine, glyoxyalbisisopropylimine) and the related M(CO)₄DAB complexes (M = Cr, Mo, W) with Fe(CO)₃DAB complexes shows that the charge density on the ligands is comparable in both types of d⁶ metal complexes but is slightly different in the Fe-d⁸ complexes. The effect of the DAB substituents on the carbonyl stretching frequencies is in agreement with the A′(cis) > A″ (cis) > A′(trans) band ordering.Mn(CO)₃Cl(t-BuNCHCHNt-Bu) reacts with AgBF₄ under a CO atmosphere yielding [Mn(CO)₄(t-BuNCHCHN-t-Bu)]BF₄. The cationic complex is isoelectronic with M(CO)₄(t-BuNCHCHNt-Bu) (M = Cr, Mo, W).     

Protonation of Cp(CO)(PPh3) RuCCPh: Formation of cationnic phenylacetylene and phenylvinylidene complexes and subsequent reaction with ethylene oxide to form the net [2 + 3] cycloadduct [Cp(CO)(PPH3)Ru=CCH(Ph)CH2CH2O]+

Protonation of the alkynyl complex Cp(CO)(PPh₃)RuCCPh (1) at low temperature affords quantitatively the vinylidened complex [Cp(CO)(PPh₃)RuCCH(Ph)]⁺ (3), which upon warming to room temperature forms an equilibrium with the η²-phenylacetylene complex [Cp(CO)(PPh₃)Ru(η²-HCCPh)]⁺ (4), with the latter predominating. Subsequent reaction with ethylene oxide yields the cyclic oxacarbene complex [Cp(CO)(PPH₃)Ru=CCH(Ph)CH₂CH₂O]⁺ (5), which can be regarded as the result of a net [3+2] cycloaddition reaction between 3 and ethylene oxide. Depronation of 5 affords teh corresponding neutral cyclic vinyl complex [Cp(CO)(PPH₃)RuC=C(Ph)CH₂CH₂O]⁺ (6), which can in turn be protonated to regenerate 5 in a diastereoselective manner. The structures of complexes 5 and 6 were determined by X-ray crystallography.     

Preparation of siloxycarbenemanganese complexes including a chelated siloxycarbene-alkene complex

Reaction of Li{(η⁵-C₅H₄Me)Mn(CO)₂]C(O)Ph]} with one equivalent of RSiMe₂Cl yields (η⁵-C₅H₄Me)Mn(CO)₂[C(Ph)(OSiMe₂R)] for R  CH₃, CHCH₂, and CH₂CHCH₂ (1a–c, respectively). Low temperature photolysis of the vinyl derivative, 1b, results in formation of a chelated manganese siloxycarbene-alkene complex, (η⁵-C₅H₄Me)MN(CO)[C(Ph)(η²-OSiMe₂CHCH₂)]. (2). Photolysis of the allyl derivative, 1c, under similar conditions leads to uncharacterized decomposition products. Infrared, ¹H, ¹³C, and ²⁹Si NMR data are reported for these new siloxycarbenemanganese derivatives.     

Vinyliden-Übergangsmetallkomplexe: II. Die Protonierung der Vinyliden-Komplexe C5H5Rh(CCHR)(PPri3) und ihre stufenweise Umwandlung in Vinyl- und α-Halogenalkyl-Rhodiumverbindungen

The protonation ofC₅H₅Rh(CCH₂)(PPrⁱ₃) (I) by CF₃CO₂H, HCl and HI gives the vinylrhodium compounds C₅H₅Rh(CHCH₂)(PPrⁱ₃)X (II-IV). The reaction of III (X = Cl) and IV (X = I) with a second molecule of HCl leads to the formation of the α-chloroethyl complexes C₅H₅Rh(CHClCH₃)(PPrⁱ₃)X (VII, VIII). The stereochemistry of these products allows us to propose a mechanism for HCl addition to the CC double bond of the vinyl ligand. C₅H₅Rh(CCHPh)(PPrⁱ₃) (XII) reacts with CF₃CO₂H and HI to give the kinetically preferred compounds C₅H₅Rh(Z-CHCHPh)(PPrⁱ₃)X (XIVa, XVa) of which XIVa (X = CF₃CO₂) in4bpolar solvents rearranges smoothly to form the thermodynamically more stable E isomer C₅H₅Rh(E-CHCHPh)(PPrⁱ₃)OCOCF₃ (XIVb). C₅H₅Rh(E-CHCHPh)(PPrⁱ₃)I (XVb) is obtained from XIVb and NaI. The protonation reactions of C₅H₅Rh(CCHMe)(PPrⁱ₃) (XIII) with CF₃CO₂H, HCl and HI always produce mixtures of isomers of the complexes C₅H₅Rh(CHCHMe)(PPrⁱ₃)X (XVI-XVIII). The ratio of Z to E isomers (≈ 62/38) is not dependent on the anion X and is also not influenced by the polarity of the solvent.     

Übergangsmetall—methylen-komplexe: LIX. Ein neues darstellungsverfahren für vinyliden-komplexe

The diazo olefins N₂CCR₂ (R/R = CH₃/CH₃ and (CH₂)₅, respectively), generated in situ from the corresponding cyclic N-nitrosourethanes 2a, 2b, are suitable precursors for the corresponding vinylidene ligands 6CCR₂. Thus, treatment of the RhRh complex [(η⁵-C₅Me₅)Rh(μ-CO)]₂ (1) with 2a, 2b in the presence of lithium ethoxide yields the otherwise inaccessible μ-vinylidene complexes (μ-CCR₂)[(η⁵-C₅Me₅)Rh(CO)]₂ (3a, 3b). This procedure extends the well-documented diazoalkane method for synthesis of μ-alkylidene complexes to the less stable diazoalkenes*     

Cobalt metallocycles: XIII. Preparation and x-ray crystallography of cobaltacyclopentadiene and dinuclear cobalt complexes

(η-Cyclopentadienyl)(triphenylphosphine)cobaltacyclopentadienes having an electron withdrawing substituent on the cyclopentadienyl ring, (η-C₅H₄R)(PPh₃)($\text{CoCHCHC}$H) (1b: R = COOMe; 1c: R = COMe), were prepared in reasonable yields by treatment of a solution of (η-C₅H₄R)(PPh₃)₂Co with acetylene. A non-substituted cyclopentadienyl analog (1a: R = H) was also isolated in low yield according to a similar procedure. Novel dinuclear complexes were also formed as by-products and the structure of (η-C₅H₄R)Co(PPh₂$\text{C}{}_6\text{H}{}_4\text{)(μ-C}$Me)Co(η-C₅H₄R) (2b: R = COOMe), having a μ₂,η³-benzyl moiety, was determined by an X-ray crystallographic analysis. The X-ray analyses of 1a and 1b were also carried out. Crystals of 1a are monoclinic, space group Pa, a 8.529(3), b 16.010(6), c 8.028(4) Å, β 100.31(3)°, Z = 2; crystals of 1b are monoclinic, space group P2₁/a, a 8.327(2), b 36.468(7), c 8.021(1) Å, β 98.75(2)°, Z = 4; and crystals of 2b are monoclinic, space group P2₁/c, a 10.681(2), b 30.722(7), c 8.912(1) Å, β 93.55(1)°, Z = 4. They have been refined to R = 0.034, 0.047 and 0.050, respectively.     

Reaction of alkenyl carbonyl ruthenium(II) complexes with t-butyl isocyanide. Synthesis of η1-acylruthenium(II) complexes by intramolecular CO insertion

Reaction of Ru(CO)Cl(CHCHR)(PPh₃)₂ or Ru(CO)Cl(CHCHR)(PPh₃)₂L (L = py, Me₂Hpz) with 1 equivalent of t-butyl isocyanide gives the alkenyl derivatives Ru(CO)Cl(CHCHR)(PPh₃)₂(t-BuNC). When an excess of isocyanide is used, further reaction results in intramolecular CO insertion to yield η¹-acyl complexes [Ru(COCHCHR) (t-BuNC)₃(PPh₃)₂]Cl. Related complexes were obtained from [Ru(CO)(CHCHR)(MeCN)₂(PPh₃)₂]PF₆ and an excess of isocyanide.     

Allylstannation III. Synthesis of homoallylic alcohols and 4-chloro-2,6-dialkyl-3-methyltetrahydropyrans by reactions between (E/Z)-2-butenyldichloro-n-butyltin and aldehydes

2-Butenyldichloro-n-butyltin (in various cis/trans isomer ratios) reacts readily with neat RCHO (R = CH₃, C₂H₅, (CH₃)₂CH, and C₆H₅) at 25°C to give (a) linear alcohols, RCH(OH)CH₂CHCHCH₃ in the E and Z forms, (b) branched alcohols, RCH(OH)CH(CH₃)CHCH₂ in the threo and erythro forms, and (c) 2,3,4,6-tetra-substituted tetrahydropyrans (A) as a mixture of cis/trans isomers arising from the CH(CH₃)CHCl bond. The maximum yields of these tetrahydropyrans were obtained

by the use of 3–3.5 molar ratios RCHO/tin compound in the absence of solvent, whereas work-up after reactions in CH₂Cl₂ gave linear, alcohols as the main products. The formation of linear alcohols appears to be stereospecific, as the ratio of _E/_Z isomers obtained is the same as that in the organotin compound. Tetrahydropyrans are formed preferentially as the _trans isomers.     

A nonrigid mixed-chelate complex of iron(0)

The reaction of Fe(CO)(CH₂ CHCHCH₂)₂ with (Ph₂ PCH₂)₂ results in formation of a $\text{4}\text{1}$ mixture of two isomers of Fe(CO)(CH₂ CHCHCH₂)-(Ph₂ PCH₂ CH₂ PPh₂). NMR studies concerning the structures of these isomers and their dynamic behavior in solution are described.     

Übergangsmetall—methylen-komplexe: LXI. Übergangsmetall—vinyliden-komplexe: Neuartige synthese aus diazoalken-vorstufen

The diazoolefines of composition N₂CCR₂ (R/R = CH₃/CH₃ and(-CH₂-)₅) are suitable precursors of the corresponding vinylidene ligands CCR₂. Thus, treatment of the RhRh complex [(η⁵-C₅Me₅)Rh(μ-CO)]₂ (1) with the N-nitrosourethanes 2a and 2b, resp., in the presence of lithium t-butoxide yields the otherwise inaccessible μ-vinylidene complexes (μ-CCR₂)[(η⁵-C₅Me₅)Rh(CO)]₂ (R = CH₃ (3a), R,R = (-CH₂-)₅ (3b)). The analogous cobalt compound (μ-CCMe₂)[(η⁵-C₅Me₅)Co(CO)]₂ (5a) is obtained similarly. This procedure extends the well-documented diazoalkane method for the synthesis of μ-alkylidene complexes to the less stable diazoalkenes. A single-crystal X-ray diffraction study of the dimethylvinylidene derivative 3a shows the CMe₂ ligand to adopt an almost symmetrically metal-bridging position (d(RhC) 197.8(1) and 204.3(1) pm), with a rhodium-rhodium single bond completing a three-membered Rh₂C-metallacycle (d(RhRh) 268.4(0) pm) analogous with cyclopropane.     

Insertion d'une phosphine acétylénique dans un complexe μ-alkylidénique du tungstène suivie de la rupture d'une liaison CP

The diphosphinoalkyne Ph₂PCCPPh₂ (2) reacts with the μ-alkylidene complex (CO)₉W₂[CHCHC(CH₃)₂] (1) to give, upon insertion of the alkyne into one of the CW bonds of the bridging carbene followed by rupture of a CP bond, a phosphido complex (CO)₈W₂[C(PPh₂)CCHCHC(CH₃)₂] PPh₂ (3). An unexpected long-range ¹H³¹P coupling, through five bonds, is observed in complex 3.     

Hydrazinocarben-Metallkomplexe—synthese aus allenylidenkomplexen und hydrazinen, umlagerung und cyclisierung

The diarylallenylidene pentacarbonyl complexes (CO)₅M=C=C=C(C₆H₄NMe₂-p)₂ (M = W (1), Cr (2)) add 1,2,-disubstituted hydrazines RNH-HNR to form alkenyl hydrazino carbene complexes (CO)₅M=C(C(H)=C(C₆H₄NMe₂-p)₂) NR-N(H)R (M = W, R = Bn (3b), ⁱPr (3c), ^cHex (3d); M = Cr, R = Me (4a), ⁱPr (4b)) in good yield. 3c and 4b are formed selectively as E-conformers (E arrangement of N_βHR and (CO)₅M with respect to the C(carbene)-N_α bond). In contrast, all other derivatives of 3 and 4 are obtained as a mixture of E/Z-isomers. On heating, E-3a and E-3b rearrange to give the acrylamidine complexes (CO)₅W-NR=C(NHR)C(H)=C(C₆H₄NMe₂-p)₂ (R = Me (5a), Bn (5b). The structure of complex 5b was established by X-ray analysis. Acid-catalyzed, the alkenyl hydrazino carbene complexes E-3a, E-3b and 3c are transformed by intramolecular cyclization into the pyrazolidinylidene complexes

Full-size image

(R =Me (6a), Bn (6b), ⁱPr (6c)).

Zusammenfassung

Die Diarylallenyliden(pentacarbonyl)komplexe (CO)₅M=C=C=C(C₆H₄NMe₂-p)₂ (M = W (1), Cr (2)) addieren 1,2-disbustituierte Hydrazine RNH-HNR in guten Ausbeuten zu Alkenylhydrazinocarbenkomplexen (CO)₅M=C(C(H)=C(C₆H₄NMe₂p)₂) NR-N(H)R (M = W, R = Bn (3b), ⁱPr (3c), ^cHex (3d); M = Cr, R =Me(4a), ⁱPr (4b)). 3c und 4b entstehen hierbei selektiv in der E-Konformation (E-Anordnung von N_βHR und (CO)₅M bezülich der C(Carben)-N_α-Bindung). Alle anderen Derivate von 3 und 4 werden dagegen als E/Z-Isomerengemisch gebildet. E-3a und E-3b lagern sich beim Erwärmen in die Acrylamidinkomplexe (CO)₅W-NR=C(NHR)C(H)=C(C₆H₄NMe₂-p)₂ (R = Me (5a), Bn (5b)) um. Die Struktur von 5b wurde anhand einer Röntgenstrukturanalyse gesichert. Säurekatalysiert cyclisieren die Alkenylhydrazinocarbenkomplexe E-3a, E-3b und 3c zu den Pyrazolidinylidenkomplexen

Full-size image

(R = Me (6b), ⁱPr (6c)).