Herbert Blau

Chemische und strukturelle Charakterisierung eines Eisenacylphosphorylids

Zusammenfassung [Cp(CO)3Fe]BF4 reacts with Me3PCHSiMe3 to give Cp(CO)2FeC(O)CHPMe3 (III), [Me3PCH2SiMe3]BF4 and Me3PC(SiMe3)2 via ylidic attack at the carbonyl carbon, transylidation and H/SiMe3-exchange. III is converted with HCl, MeI and Me3SiCl to the ironacyl-phosphonium salts [Cp(CO)2FeC(O)-CHRPMe3]X (IVa–IVc). The X-ray structure analysis of III reveals an extensive electronic transfer of the ylidic charge to the acyl carbon. This transfer is reduced in favor of a metalcarbon (d→p)π interaction in the thermolabile ylide Cp(CO)(PPhMe2)FeC(O)CHPMe3 (V).

Zur reaktion von metall-koordiniertem kohlenmonoxid mit yliden

Abstract The addition of MeI to the ironacyl phosphorusylide Cp(CO) 2 FeC(O)CH PMe 3 (I) gives the phosphonium salt [Cp(CO) 2 FeC(O)(Me)CHPMe 3 ]I (II), which can be dehydrohalogenated with Me 3 PCH 2 to the corresponding ylide Cp(CO) 2 FeC(O)(Me)CPPMe 3 (III). III is thermally stable in the pure state, but rearranges irreversibly with the addition of a trace of Me 3 PCH 2 to the thermodynamically favored isomer Cp(CO) 2 FeC(O)HCPEtMe 2 (IV). A plausible mechanism for the rearrangement is established, involving the intermolecular transfer of the Cp(CO) 2 FeC(O)-group between the tautomeric ylides Me 3 PCHMe and EtMe 2 PCH 2 . It is proved by the simple reaction of Cp(CO) 2 FeC(O)(Me)CPEt 3 (V) with Me 3 PCH 2 to give quantitatively I and Et 3 PCHMe. The first ylide rearrangement involving the shift of a transition metal group is mainly induced by the better electronic stabilization of the ylidic function, when the Cp(CO) 2 FeC(O) moiety is combined with a hydrogen atom.

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

Summary The treatment of the hexacarbonylmetal compounds M(CO) 6 (M = Cr. Mo, W) with two equivalents Me 3 P=CH 2 yields the phosphonium acylmetal—phosphorus ylides Me 4 P[(CO) 5 M=C(O)CH==PMe 3 ] 1a–1c . Their reaction with Me 3 SiOS0 2 CF 3 leads via O-silylation to formation of the neutral “siloxy-(ylidecarbene) complexes” (CO) 5 M=C(OSiMe 3 )-CH=PMe 3 2a–2c , which are protonated by HX (X = CI, CF 3 SO 3 ) to give the thermolabile carbene complexes [(CO) 5 M=C(OSiMe 3 )H 2 CPMe 3 ]X 3a, 3b . 1 H, 13 C NMR and IR data suggest, that derealization 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) bona 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.

Zur reaktion von metall-koordiniertem kohlenmonoxid mit yliden: XV. Neuartige spaltung von kohlenmonoxid via β-trimethylphosphonio(α-trimethylsiloxy)vinyl-komplexe: Einbau des carbonylkohlenstoffs in einen β-trimethylphosphonioacetylid-liganden☆

Abstract The manganese complexes RC5H4Mn(CO)3 (R = H (1a), Me (1b)) react with Me3P=CHSiMe3 only under photochemical conditions to yield the ylide complexes RC5H4(CO)2MnCH(SiMe3)PMe3 (2a,2b). Treatment of the phosphonium or lithium manganeseacylates R4P(Li)[MeC5H4(CO)2MnC(O)C(R′)=PR3] (R = Me, Et; R′ = H, Me) (3a,3b,5) with Me3SiOSO2CF3 leads to the formation of the vinyl complexes MeC5H4(CO)2MnC(OSiMe3)=C(R′)- P + R3 (4a,4b). Pure 4a slowly eliminates Me3SiOH at room temperature to produce the β-trimethylphosphonio-acetylide complex MeC5H4(CO)2M n - CCPMe3 (6). In the presence of a catalytic amount of Me3P=CH2 4a is rapidly cleaved to 1b and Me3P=CHSiMe3.

Zur reaktion von metall-koordiniertem kohlenmonoxid mit yliden: XXI. Ambidentes verhalten von eisenacyl-phosphor-yliden gegenüber methylfluorsulfonsäureester: Umwandlung in eisenacyl-phosphoniumsalze oder β-phosphoniovinyl- eisenkomplexe☆☆☆★

Abstract ]The reaction of the acyliron phosphorus ylide Cp(CO) 2 FeC(O)CHPMe 3 with MeOSO 2 F yields the acyliron phosphonium salt [Cp(CO) 2 FeC(O)C(Me)- HPMe 3 ]SO 3 F, while Cp(CO) 2 FeC(O)C(Me)PEt 3 undergoes exclusively O -alkylation to the complex salt [Cp(CO) 2 FeC(OMe)C(Me)PEt 3 ]SO 3 F, (A). The acyliron ylides Cp(CO) 2 FeC(O)C(R)PR 3 (R  R′  Me; or R  H, R′  Et) are converted to a mixture of the O - and C -methylated products. According to spectroscopic data and X-ray diffraction analysis of A the O - alkylation products have to be described as phosphoniovinyliron complexes.

Reaktionen von metall-koordiniertem kohlenmonoxid mit yliden: XVII. Darstellung eines molybdän- und wolframkomplexes mit η3-gebundenem trimethylsiloxybutenon-liganden durch silylierung der phosphonium-metall-enolat-vorstufe☆

The reaction of the phosphonium metallates Me4P[C5R5(CO)(Me3P)MC(O)=CHC(O)R′] (M = W, R = H, R′ = Et (1a); M = Mo, R = Me, R′ = Me (1b)) with the silylating reagent Me3SiOSO2CF3 yields the neutral complexes C5R5(CO)(Me3P)MC(OSiMe3)=CHC(O)R (2a, 2b) bearing a chelating O(2), C(4)-trimethylsiloxybutenone ligand. The structure of the new compounds is established by the IR, 1H and 31P NMR spectra.

Zur reaktion von metall-koordiniertem kohlenmonoxid mit yliden: XVI. Reversibler einbau von kohlenmonoxid in eine trimethylphosphonio (trimethylsiloxy) vinyl-einheit; Darstellung des zwitteriqnischen vinyl-chromkomplexes Cp(CO)(NO) CrC(OSiMe3)CHPMe3 und solvolytischer abbau sowie spaltung mit Me3P=CH2 oder MeX (X = I, SO3F)

Abstract The β-trimethylphosphonio(α-trimethylsiloxy)vinylchromium complex Cp(CO)(NO) C rC(OSiMe3)=CHPMe3 (2) can be isolated from a concentrated solution of Cp(CO)2(NO)Cr (1) and Me3P=CHSiMe3 in benzene. 2 is obtained in better yield via O-silylation of the tetramethylphosphonium chromium acylate Me4P[Cp(CO)(NO)CrC(O)CH=PMe3] (3) with Me3SiOSO2CF3. 2 decomposes readily by treatment with benzene to 1 and Me3P=CHSiMe3, which forms the ylide complex Cp(CO)(NO)CrCH(SiMe3)PMe3 (4) on photolysis. Degradation of 2 can be accelerated extraordinarily by traces of Me3P=CH2. With Me3P= CH2 (2 mol) controlled conversion of 2 to 3 and Me3P=CHSiMe3 occurs. MeX (X = I, SO3F) cleaves 2 to 1 and the phosphonium salt [Me3PCH(SiMe3)]X (5a,5b).