Übergangsmetall-heteroallen-komplexe: XIII. Reaktionen der cobalt-thioketen-komplexe [Co(R2CCS)(C5H5)] mit elektrophilen

Reaction of the η²(C,S)-coordinated thioketene cobalt complex [Co(C₁₁H₁₈S)-(PMe₃(C₅H₅)] (2a) with the electrophils [Mn(CO)₂(THF)(C₅H₅] and [Cr(CO)₅(THF)] gives the dinuclear thioketene complexes (4) with two different metal atoms in the molecule. The structure of the cobalt manganese compound was determined by X-ray diffraction. Protonation of the mononuclear thioketene complexes 2 give novel cationic η²-bonded thioacyl compounds [Co(η²-RCS)-(PMe₃(C₅H₅)]⁺ (9), as confirmed by X-ray analysis.     

Vinylidene transition-metal complexes: I. Novel rhodium(I) and rhodium(III) complexes containing alkynes,alkynyls, and vinylidenes as ligands.Crystal structure of IC5H5Rh(CCHPh)(PPri3)

The syntheses of the novel cyclopentadienylphosphinevinylidenerhodium complexes C₅H₅Rh(CCHR)(PPrⁱ₃) (R = Ph, Me, H) and, for R = Ph, of the isomeric alkynyl hydrido compound C₅H₅ RhH(C₂Ph)(PPrⁱ₃) are reported. The square-planar complexes trans-[RhCl(RC₂H)(PPrⁱ₃)₂] (IIa, IIb), which in solution are in equi-librium with the five-coordinated pyridine to give the octahedral compounds RhHCl(C₂R)(PRrⁱ₃)₂(py) (VIa, VIb). Treatment of Via, VIb with NaC₅H₅ gives the vinylidene complexes IVa, IVb in good yield. C₅H₅Rh(CCH₂)(PPrⁱ₃) (IVc) is directly obtained from trans-[RhCl(C₂H₂)(PPrⁱ₃)₂] (IIc) and NaC₅H₅. Mechanistic studies confirm that the reaction of VIa, VIb with the cyclopentadienide anion primarily gives, by elimination of HCl, the rhodium(I) compounds trans-[Rh(C₂R)(py)(PPrⁱ₃)₂] (VIIIa, VIIIb), which react with cyclopentadiene, possibly via trans-[Rh(C₂R)(η²-C₅H₆)(PPrⁱ₃)₂](X) as an intermediate, to give C₅ VIIIa with cyclopentadiene in presence of water gives the complex C₅H₅RhH(C₂Ph)(PPrⁱ₃), which isomerizes only slowly to form IVa and, therefore, is not an intermediate in the reaction of VIIIa and C₅H₆ to give IVa. The crystal structure of IVa has been determined. The RhCC arrangement is almost linear. The RhC distance is significantly shorter than in carbenerhodium complexes, which, in agreement with ¹³C NMR data and MO calculations, indicates a high degree of multiple bonding.     

Über Umlagerungen: Die Umwandlung des Cinchonins in α-Isocinchonin

Ohne Zusammenfassung     

The addition of small molecules to (η-C5H5)2Rh2(CO)(CF3C2CF3): IV. The sunlight assisted making and breaking of alkene CH bonds on the dirhodium centre; the crystal and molecular structures of (η-C5H5)2Rh2(CHCHCN){C(CF3)CF3)H} · H2O and (η-C5H5)2Rh2(CHCF2){C(CF3)C(CF3)H}

Bis-alkenyl complexes of the type (η-C₅H₅)₂RH₂(alkene − H)(alkyne + H) are obtained when the alkyne complex (η-C₅H₅)₂Rh₂(CO)(CF₃C₂CF₃) is treated with the following alkenes: H₂CCH₂, H₂CCHR (R = Me, Bu^t, Ph, CN), H₂CCF₂, RHCCHR′ (R = R′ = Me, Ph, Cl; R = Me, R′ = Et), cyclooctene and norbornene. An approximately equimolar amount of (η-C₅H₅)₂Rh₂(CO)₂(CF₃C₂CF₃) is also formed. The reactions are greatly accelerated when the reaction mixtures are exposed to sunlight. There is some regioselectivity in the reactions with H₂CCHR and MeHCCHet, with a preference for CH bond cleavage at the least crowded alkene-carbon. When the reaction with acrylonitrile is performed in the absence of sunlight, the complex (η-C₅H₅)₂(CO){(H₂CCHCN)(CF₃C₂CF₃)} can be isolated; upon exposure to sunlight, there is loss of CO and H-transfer to form two isomers of the appropriate bis-alkenyl complex.The molecular geometries of (η-C₅H₅)₂Rh₂(CHCHCN){C(CF₃)C(CF₃)H} and (η-C₅H₅)₂Rh₂(CHCF₂){C(CF₃)C(CF₃)H} have been ascertained by X-ray structure determination. Each molecule has two bridging alkenyl units spanning a RhRh single bond; the dihedral angle between the two RhRhCC planes is just above 90°. There is a cyclopentadienyl ring η⁵-attached to each metal. Crystal data: C₁₇H₁₃F₆NRh₂·H₂O, M 569.1, monoclinic, P2₁/n, a 15.014(7), b 14.882(7), c 8.590(5) Å, β 94.57(9)°, Z = 4, final R 0.056 for 2493 observed reflections; C₁₆H₁₂F₈Rh₂, M 562.1, monoclinic, P2₁/c, a 13.037(6), b 8.765(2), c 14.873(3) Å, β 103.16(3)°, Z = 4, final R 0.062 for 1820 observed reflections.     

Konkurrierende bildung von heterometall-zweikern-komplexen mit μ-CCHPh und μ-ηPsu1,η3-CHCPhCO-brückenliganden bei der reaktion von C5H5Rh(PhCCH)PPri3 MIT Fe2(CO)9

The alkyne complex C₅H₅Rh(PhCCH)PPrⁱ₃ reacts wit Fe₂(CO)₉ to form two isomeric dinuclear products, C₅H₅(PPrⁱ₃)Rh(μ-CCHPh)(μ-CO)Fe(CO)₃ and C₅H₅(PPrⁱ₃)Rh(μ-η¹,η³-CHCPhCO)Fe(CO)₃. The X-ray crystal structure of the latter has been determined.     

Chiral dienolates : Stereoselective formation and α-alkylation of the lithium dienolates derived from (RS)-Z-[(n5-C5H5)Fe(CO)(PPh3)COCHCHCH2R] (RMe,Et,n-pr) and (RS)-[(n5-C5H5)Fe(CO)(PPh3)(COCHCMme2)]

The acyl ligands Z-(COCHCHCH₂-R)(RMe,Et,$\text{n}$-Pr) and (COCH-CMe₂) bound to the chiral auxiliary [(n⁵ -C₅H₅)Fe(CO)(PPh₃)] undergo exclusive γ-deprotonation to form the corresponding dienolates which react with electrophiles regio- and stereoselectively at the α-position to give in most cases single diastereoisomers of the corresponding α-substituted-βγ-unsaturated acyl complexes, together with in the former cases complete control over the β,γ-double bond geometry (E).     

Hydrido-silyl-komplexe: VII. Strukturchemische und 29Si-NMR-spektroskopische untersuchungen an C5R′5(CO)(L)Mn(H)SiR3. Einfluss der substituenten R und R′ sowie des liganden L auf die Mn,H,Si-dreizentrenbindung

In C₅R′₅(CO)(L)Mn(H)SiR₃ complexes the oxidative addition reaction of the silane HSiR₃ with the C₅R′₅(CO)(L)Mn fragment (L = CO, PR₃, P(OR)₃, CNR) is incomplete. These compounds contain Mn,H,Si two-electron three-center bonds in their ground states, which are strongly influenced by electronic and steric properties of both the metal complexes moiety and the silyl group. ²⁹Si NMR spectroscopic investigation of complexes with different ligands L or substituents R and R′, and structure analyses reveal, that the coupling constant J(SiMnH) and the MnSi distance are especially good indicators for changes in the bonding situation. Electron-donating ligands and/or electronegative substituents R favour addition of SiR₃, as indicated by small J(SiMnH) values and short MnSi distances in the particular complexes. By means of a neutron diffraction study of MeCp(CO)₂Mn(H)SiFPh₂ (1) (MnSi 235.2(4), MnH 156.9(4), SiH 180.2(5) pm) and X-ray structure analyses of MeCp(CO)(PMe₃)Mn(H)SiHPh₂ (2) (MnSi 232.7(1) pm) and C₅Me₅(CO)₂Mn(H)SiHPh₂ (3) (MnSi 239.5(1) pm) structural parameters which are typical for the three-center bonds, are discussed. By comparison of known structures the reaction pathway for the oxidative addition (reductive elimination) of silanes can be derived.     

Synthesis of some bis(triphenylphosphine)(ethynylferrocenyl) platinum(II) complexes; molecular structure of [PtH(CC-C5H4FeC5H5)(PPh3)2]

Substituted acetylidoplatinum(II) complexes trans-[PtX(CC-C₅H₄FeC₅H₅)(PPh₃) ₂] (X  H, Cl, CCPh or CC-C₅H₄FeC₅H₅) have been prepared. Controlled basicity of the reaction solutions yields the different complexes. A single-crystal X-ray diffraction study of trans-[PtH(CC-C₅H₄FeC₅H₅)(PPh₃)₂] indicates an alternating alignment of the ethynyl ligands between two centrosymmetric platinum atoms, resulting in the formation of a pseudo- polymeric structure.     

Metallkomplexe mit verbrückenden dimethylphosphidoliganden: VI. Zweikernkomplexe mit substituierten vinyldimethylphosphan-brückenliganden durch templatsynthese aus [(C5H5Co)2(μ-PMe2)2(μ-H)]+ und alkinen. Die kristallstruktur von [(C5H5Co)2(μ-PMe2)(μ-η4-Me2PC(CO2Me)CHC(OMe)O)]BF4

The hydrido-bridged dinuclear complex [(C₅H₅CO)₂(μ-PMe₂)₂(μ-H)]BF₄ (I) reacts with C₂(CO₂Me)₂ to produce a mixture of (C₅H₅Co)₂[μ-η⁴-Me₂PC(CO₂Me)C(CO₂Me)PMe₂] (II) and [(C₅H₅Co)₂(μ-PMe₂)(μ-η⁴-Me₂PC(CO₂Me)-CHC(OMe)O)]BF₄ (III). The X-ray structural analysis of III reveals that besides a dimethylphosphido bridge the cation contains a substituted vinyldimethylphosphine ligand which behaves as a 6-electron donor group and is coordinated via phosphorus and oxygen to the first cobalt and via the CC bond the second cobalt atom. The reactions of I with HC₂CO₂Me and CH₃C₂CO₂Me also give mixtures of products which contain the neutral component, (C₅H₅Co)₂[μ-η⁴-Me₂PCRC(CO₂Me)PMe₂] (IV: R  H; VII: R  CH₃), i.e., the structural analogue of II. The ionic products V, VI (obtained from HC₂CO₂Me) and VIII, IX (obtained from CH₃C₂CO₂Me) have been characterized by IR and NMR spectroscopy. {(C₅H₅Co)₂[μ-η⁴-PMe₂C(CH₃)C(CO₂Me)PMe₂](μ-H)}BF₄ (VIII) has independently been prepared by treatment of VII with HBF₄.     

Komplexchemie perhalogenierter Cyclopentadiene und Alkine: III. Reaktion von Pt(PPh3)2(C2H4) mit Monofluoracetylen und Dichloracetylen. Kristallstruktur von Pt(PPh3)2(Cl)(CCCl)

Pt(PPh₃)₂(C₂H₄) reacts with monofluoroacetylene to give the π-complex Pt(PPh₃)₂(FCCH), and with dichloroacetylene under oxidative addition to yield Pt(PPh₃)₂(Cl)(ClCCl), the structure of which was determined by X-ray crystallography.     

Metallorganische lewis-säuren: XXX. Kationische benzaldehyd- und acetophenon-komplexe durch hydrid- bzw. Methylabstraktion aus (η5-C5H5)(OC)3MH (M = Mo,W) und (OC)5ReCH3 mit benzyliumhexafluoroantimonat

Hydride or methyl abstraction from (η⁵-C₅H₅)(OC)₃MH (M = Mo, W), (OC)₅ReCH₃ with benzyliumhexafluoroantimonate gives the complexes [(η⁵-C₅H₅)(OC)₃M(OCPhH)]⁺SbF₆⁻ and [(OC)₅Re(OCPhMe)]⁺SbF₆⁻, respectively. The acetaldehyde and benzaldehyde complexes [(η⁵-C₅H₅)(OC)₃M(OCRH)]⁺BF₄⁻ (M = Mo, W; R = Me, Ph), [(OC)₅Re(OCMeH)]⁺Bf₄⁻ can also be formed by treating (η⁵-C₅H₅)(OC)₃MFBF₃ or (OC)₅ReFBF₃ with aldehyde.     

Synthesis and reactivity of functionalized rhenium germyl complexes (η5-C5H5)Re(NO)(PPh3)(GePh2X); dynamic equilibria with germylene complex [(η5-C5H5)Re(NO)(PPh3)(GePh2)]+X−

Reaction of Li⁺[(η⁵-C₅H₅)Re(NO)(PPh₃)]⁻ with Ph₃GeCl and Ph₂GeCl₂ (THF, −75°C) gives germyl complexes (η⁵-C₅H₅)Re(NO)(PPh₃)(GePh₃) (84%) and (η⁵-C₅H₅) Re(NO)(PPh₃)(GePh₂Cl) (3, 82%), respectively. Reaction of 3 and (CH₃)₃SiOTf gives (η⁵-C₅H₅)Re(NO)(PPh₃)(GePh₂OTf) (4, 82%). Several properties show the triflate substituent in 4 to be extremely labile. First, reaction of 4 and pyridine to give [(η⁵- C₅H₅)Re(NO)(PPh₃)(GePh₂NC₅H₅)]⁺TfO⁻ (5) is complete in < 5 min at −78°C; the pyridine in 5 rapidly exchanges with pyridine-d₅ (CD₂Cl₂, −80°C). Second, the ¹³C NMR resonances of the diastereotopic germanium phenyl substituents in 4 coalesce upon warming (ΔG3_268K (CD₂Cl₂) = 12.6±0.2 kcal mol⁻¹). The most likely mechanisms for this dynamic behaviour entail initial triflate dissociation to give the germylene complex [(η⁵-C₅H₅)Re(NO)(PPh₃)( GePh₂)]⁺TfO⁻.     

Reactions of transition metal σ-acetylides: VII. Synthesis and properties of complexes containing halovinylidene ligands. X-ray structure of [Ru(CCIPh)(PPh3)2(η-C5H5)][I3]

Addition of halogen (Cl₂, Br₂ or I₂) to ruthenium or osmium acetylide complexes has afforded cationic halovinylidene derivatives; in one case, halogenation of the phenyl group of a phenylacetylide ligand also occurred. The structure of [Ru(CCIPh)(PPh₃)₂(η-C₅H₅)][I₃] has been determined; crystals are monoclinic, space group P2₁/c, with a 18.693(5), b 15.460(5), c 15.679(5) Å, β 101.49(2)° and Z 4; 5180 data with I > 2σ(I) were refined to R 0.045, R_w 0.051. Significant distances are RuC 1.839(7), CC 1.31(1) Å; angle RuCC is 171.0(7)°.