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.     

Insertion reactions of [Pt(PPh3)2] fragments into the four-membered ring complex [W(CO)5PPhC(OEt)CPhCHPh]. Crystal and molecular structures of [Pt(dppe)PPh(W(CO)5)C(OEt)CPhCHPh] and [Pt(PPh3)2((W(CO)5)PhPC(OEt)CPhCHPh)(η2-PC))]

Insertion of platinum bis(phosphane) fragments into a 1,2-dihydrophosphete ring lead to complexes derived from a 1-phosphabuta-1,3-diene species.     

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.     

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.     

Charakterisierung und photochemie von (dihalogenmethylen)sulfoxiden,XYCSO

Dihalogenomethylene sulfoxides (dihalogenosulfines) 2a–c were generated by flash vacuum pyrolysis of 2,2,4,4-tetrahalogeno-1,3-dithietane 1,3-dioxides 1a–c and trapping the pyrolysis products in argon at 10 K. At room temperature unstable difluorosulfine (2a) and chlorofluorosulfine (2b) were identified by i.r. spectroscopy, and the photochemistry of the sulfines was investigated. Chlorofluorosulfine (2b) exists in two geometrical isomers. Photolysis of 2a leads to fragmentation to give CF₂ and SO, photolysis of the chlorine containing sulfines 2b and 2c to rearrangement to give the sulfenyl chlorides 6 and 8. This is explained by different migratory tendencies of fluorine and chlorine and the stability of the CF bond.     

Reaction of a bridged ethenylidene diiron complex with tetracyanoethylene. Synthesis and crystal structure of the μ-3,4,4-tricyanobuta-1,3-dienylidene complex [(C5H5)Fe(CO)]2(μ-CO)[μ-CCH(NC)CC(CN)2]

The reaction of μ-ethenylidene [(C₅H₅)Fe(CO)]₂(μ-CO)(μ-CCh₂) 1 with tetracyanoethylene gives the μ-3,4,4-tricyanobuta-1,3-dienylidene complex [(C₅H₅)Fe(CO)]₂(μ-CO)[μ-CCH(NC)CC(CN)₂] (2), whose crystal structure has been determined ESR studies suggests that a radical process may be involved.     

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.     

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).     

Regioselective anion generation and alkylation at carbon α to nitrogen in (CO)5WC[N(CH3)2]C6H4-p-CH3

Treatment of (CO)₅WC[N(CH₃)₂]C₆H₄-p-CH₃ (1) with lithium diisopropylamide (LDA) in THF at −78°C followed by quenching with D₂O leads to incorporation of deuterium into the (E)-N-methyl group only. Reaction of the anion of 1 with benzyl bromide at −78°C followed by quenching with water gave the E-isomer of (CO)₅WC[N(CH₃)CH₂CH₂C₆H₅]C₆H₄-p-CH₃ (2E, 26%) and recovered 1. When a mixture of the anion of 1 and benzyl bromide was warmed from −78°C to ambient temperature, a mixture of the E-isomer of the dibenzylated product (CO)₅WC[N(CH₃)CH(CH₂C₆H₅)₂]C₆H₄-p-CH was obtained. Reaction of the anion of 1 with allyl bromide gave (CO)₅WC[N(CH₃)CH₂CH₂CHCH₂]C₆H₄-p-CH₃ (5, 38%) and with methyl iodide gave a mixture of (CO)₅WC[N(CH₃)CH₂CH₃]C₆H₄-p-CH₃ (6, 7%) and (CO)₅W C[N(CH₃)CH(CH₃)₂]C₆H₄-p-CH₃ (7, 16%).     

Different modes of hydrogen migration in reactions of diphosphaallene,ArPCPAr (Ar = 2,4,6-But3C6H2) with [W(CO)5(THF)] and [Fe3(CO)12]. Crystal and molecular structure of [Fe2(CO)6(ArPCHPCH2(CMe2)C6H2But2)]

Rearrangement of ArPCPAr (Ar = 2,4,6-Bu^t₃C₆H₂) involving hydrogen migration from carbon to phosphorus occurs on heating with [W(CO)₅(THF)], but with [Fe₃(CO)₁₂] an unusual carbon to carbon hydrogen migration results.     

Preparation of η2-acetylene- and η1-vinylidene-manganese complexes from p-diethynylbenzene and cymantrene. X-ray crystal and molecular structure of Cp(OC)2MnCCHC6H4CBrCH2

Cp(OC)₂Mn(THF) reacts with p-diethynylbenzene (Deb), yielding Cp(OC)₂Mn(Deb) (I) and [Cp(OC)₂Mn]₂(Deb) (II) with the η²-acetylene coordination of Deb (to both Mn atoms in II). Under the action of PhLi, I and II are isomerized into Cp(OC)₂MnCCHC₆H₄CCH (III) and [Cp(OC)₂MnCCH]₂C₆H₄ (VI). Treatment of I with PhLi, LiBr and an excess of HCl in ether, as well as direct interaction of III with LiBr and HCl/Et₂O, gives Cp(OC)₂MnCCHC₆H₄CBrCH₂ (IV), which has been characterized by an X-ray single-crystal diffraction study. III adds PPh₃, yielding a zwitterionic complex, Cp(OC)₂Mn⁻C(P⁺Ph₃)CHC₆H₄CCH (V).     

Formation of the triosmium μ-carbyne complex in the reaction of with dimethylphenylphosphine. X-ray structure of HOs3(CO)10{μ-CC(Ph)CC(Ph)Re(CO)4PMe2Ph}

The μ-acyl complex B″O

(I) reacts with PMe₂Ph to yield the allenyl-substituted μ-carbyne complex HOs₃(CO)₁₀{μ-CC(Ph)CC(Ph)Re(CO)₄PMe₂Ph} (II). Complex II has been characterized by an X-ray structural study.     

Synthese und kristallstrukturuntersuchung von bis[dicarbonyl(μ-trifluormethylisocyanid)-(η-pentamethylcyclopentadienyl)molybdän)], [Mo(CO)2(μ-CNCF3)(η-Cp)]2 und dessen isomerisierung zu Cp(CO)2Mo(μ-F3CNCCNCF3)Mo(CO)2Cp

Trifluoromethyl isocyanide adds to the metal—metal triple bond of bis[dicarbonyl(η-pentamethylcyclopentadienyl)molybdenum] forming Mo₂Cp₂(CO)₄(η²-μ-CNCF₃) as the first isolated product. Further addition of trifluoromethyl isocyanide at 0°C leads to the formation of [Mo(CO)₂(μ-CNCF₃)(η-Cp)]₂, which according to crystal structure analysis contains two bridging CF₃NC ligands. During the isomerization of this compound in dichloromethane solution at room temperature or in the solid state above 110°C molybdenum—molybdenum bond cleavage and carbon—carbon bond formation occurs, leading to Cp(CO)₂Mo(μ-F₃CNCCNCF₃)Mo(CO)₂Cp, which contains 1,1,1,6,6,6-hexafluoro-2,5-diaza-2,3,4-hexatriene as bridging ligand.     

Microwave spectrum,dipole moment and AB initio structure of iminopyruvonitrile (CH3C(CN)NH)

The microwave spectrum of iminopyruvonitrile has been investigated from 19 to 51 GHz. Rotational transitions have been assigned for the vibrational ground state and the rotational and centrifugal distortion constants have been adjusted. The electric dipole components μ_a = 1.806(6), μ_b = 0.759(21) and μ_total = 1.958(10) D have been deduced from Stark splittings. Some rotational transitions showed splittings arising from the internal rotation of the methyl group, the barrier to which has been determined to be V₃ = 593.5(89) cm⁻¹. Different conformations have been predicted via ab initio calculations and are compared to the microwave results.     

[(CO)2(C5H5)Fe]2C60的合成与表征

有关 C6 0 取代的金属羰基化合物的研究方兴未艾 .C6 0 作为一个特殊的烯烃 ,以六元环间的碳碳双键提供电子对 ,与过渡金属羰基化合物形成诸如 η2 ,η4 ,η6等结构新颖的化合物约有 40多例 [1～ 5] ,但只有一例是以 Fe为中心原子的 C6 0 取代的金属羰基化合物 ( η2 - C6 0 ) Fe( CO) 4 [1] .本文报道了第一例 C6 0配位的 Fe的双核金属羰基化合物 [( CO) 2 ( C5H5) Fe]2 (η2 - C6 0 ) ,并通过元素分析 ,IR,1H NMR,13CNMR和 XPS进行表征 .1　实验部分[Fe( CO) 2 ( C5H5) ]2 购自 Aldrich公司 .C6 0 纯度为 99% .其余试剂均…     

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.