Use of the Cationic Fragments [Ru(η5-C5H5) (MeCN)3]+ and [M(η6-C6H5R)(MeCN)3]+ (M=Os, Ru; R=H, Me) as Ionic Coupling Reagents in the Synthesis of the Clusters [Os4M2(CO)12(η6-C6H5R)], [Os4M(CO)12(η6-C6H6)(Au2dppm)] and [Os5Ru(CO)15(η5-C5H5)(AuPPh3)]*

The clusters [H₂Os₄M(CO)₁₂eta⁶-C₆H₆)] (M=Os, Ru) may be deprotonated to generate anions [Os₄M(CO)₁₂eta⁶-C₆H₆)]^2- which react with [M′eta⁶-C₆H₅R) (MeCN)₃]²⁺(M^′=Os, Ru; R=H, Me) to give the bicapped tetrahedral clusters [Os₄(CO)₁₂MM′eta⁶-C₆H₅R)₂]. Whereas [Os₄(CO)₁₂M₂eta⁶-C₆H₆)₂] (M=Os, Ru) have one Meta⁶-C₆H₆) unit in a site connected to three other metals, {3}, and one in a site connected to four other metals, {4}, [Os₄(CO)₁₂OsRueta⁶-C₆H₆)₂] has the Rueta⁶-C₆H₆) unit in the {3} site irrespective of whether the Os or Ru anion is capped. Coupling of these anions with Au₂dppm yields [Os₄M(CO)₁₂eta⁶-C₆H₆)(Au₂dppm)] (M=Os, Ru), which have the arene ligand in the axial site of a trigonal bipyramid and the digold unit capping two faces. Reduction of [H₂Os₅(CO)₁₅] with K/Ph₂CO and coupling with [Rueta⁵-C₅H₅)(MeCN)₃]²⁺yields the monoanion [Os₅(CO)₁₅Rueta⁵-C₅H₅)]^? which reacts with [AuPPh₃]⁺ generating [Os₅(CO)₁₅Rueta⁵-C₅H₅)(AuPPh₃)] with the “Ru(C₅H₅)” unit in the terminal {3} site.     

Dihalogen(pentafluorphenyl)sulfonium(IV)-hexafluoroarsenat C6F5SX2+AsF6− (X = Cl,Br) und Kristallstruktur von Di(pentafluorphenyl)sulfan (C6F5)2S

Dihalogen(Pentafluorophenyl)sulfonium(IV) Hexafluoroarsenate C₆F₅SX₂⁺AsF₆^? (X = Cl, Br) and Crystal Structure of Di(pentafluorophenyl)sulfane (C₆F₅)₂S The preparation and spectroscopic characterisation of the halogensulfonium salts C₆F₅SCl₂⁺AsF₆^? and C₆F₅SBr₂⁺AsF₆^? is reported. The new salts are much more stable than their trifluoromethyl derivatives. In addition the crystal structure of (C₆F₅)₂S is reported. Space group P4₃2₁2, Z = 4, 478 unique observed diffractometer data, R_int. = 0.07, lattice constants: a = 569.0(5) pm, c = 3785.8(22) pm, V = 1225 times; 10^?30 m³.     

Synthesis of (5R,8S,10R)-6-(Allyloxy)- and (5R,8S,10R)-6-(Propyloxy)ergolines from the 6-Methyl Precursors

Novel (5R,8S,10R)-6-(allyloxy)- and (5R,8S,10R)-6-(propyloxy)ergolines have been synthesized by use of a Meisenheimer [2,3]-sigmatropic rearrangement of a (5R,8S,10R)-6-allyl-ergoline N⁶-oxide as key step.     

Wolfram(VI)-fluorid-pentafluorotellurate(VI): WFn(OTeF5)6-n

Tungsten(VI) Fluoride Pentafluorotellurates(VI): WF_n(OTeF₅)_6-n In WF₆ fluorine can be replaced by F₅TeO groups by means of B(OTeF₅)₃ to form WF_n(OTeF₅)_6-n. Isolation was achieved for WF₅OTeF₅ and cis-WF₄ (OTeF₅)₂. Compounds with n > 2 have been identified by ¹⁹F-nmr spectroscopy. The ligand behaviour of the F₅TeO group is compared to OMe and OPh.     

Le ligande isocyanure de benzoyle CNCOR: II. Spectres de vibrations du (η6-benzoate de methyle) chrome(0) dicarbonyle (isocyanure de benzoyle): (η6-C6H5CO2CH3)Cr(CO)2(CNCOC6H5)

Infrared and Raman spectra (4000-40 cm^?1 of (η⁶-C₆H₅CO₂CH₃)Cr(CO)₂(CNCOC₆H₅) are recorded and interpreted with the aid of isotopic derivatives. Vibration modes and modification of the aromatic ring bonds by coordination are discussed.     

Synthesis and structure of the s-methylsulfenator bridged cation [η6-MeC6H5)Mo(μ-S(O)Me)(μ-SMe)3Mo(η6-MeC6H5)]2+

The novel S-methylsulfenato bridged cation [(η⁶-MeC₆H₅Mo(μ-S(O)Me)-(μ-SMe)₃Mo(η⁶-MeC₆H₅]²⁺ has been synthesized by KMnO₄ oxidation of the cation [(η⁶MeC₆H₅Mo(μ-SMe)₄Mo(η⁶-MeC₆H₅)]²⁺ and characterized by IR, and ¹H NMR spectroscopy.     

The preparation,characterization and reactivity of the cyclometallosilane,cyclo-1,1-di-h5-cyclopentadienyltitana-2,2,3,3,4,4,5,5,-octaphenylpentasilane, (h5-C5H5)2TiSi(C6H5)2[Si(C6H5)2]2Si(C6H5)2

Titanium has been incorporated into a catenated silicon ring by means of the salt elimination reaction of dichlorodi-h⁵-cyclopentadienyltitanium(IV), (I), with 1,4-dilithiooctaphenyltetrasilane, Li₂Si₄(C₆H₅)₈, to yield the title compound (II). II was characterized as a cyclometallopolysilane by means of elemental analyses, base catalyzed hydrolyses, molecular weight determination, infrared and ¹H NMR spectroscopy. Electronic spectral data and electrochemical data are also discussed and support the formulation of II as a disubstituted (h⁵-C₅H₅)₂Ti^IV derivative. The reactivity of II, with CHCl₃, is described in terms of a radical decomposition pathway.     

Oxidation of (η5-6-exo-cyclopentadienylcyclohexadienyl)- (η5-cyclopentadienyl) iron by trityl hexafluorophosphateby trityl hexafluorophosphate

Oxidation of the cyclohexadienyl complex Fe(η⁵-C₅H₅)(1-5-7⁵-6-exo-C₅H₅-C₆H₆) (2) by (Ph₃C)PF₆ (CH₂Cl₂, from −30 to +20 °C) occurs as two concurrent processes: elimination of an H atom from the cyclohexadienyl ligand and replacement of an H atom in the cyclopentadienyl ring by a CPh₃ fragment. A mixture of cationic complexes [Fe(η⁵-C₅H₅) (η⁶-Ph-C₅H₅]⁺ (1⁺) and [Fe(η⁵-C₅H₄CPh₃) (η⁶-Ph-C₅H₅]⁺ (4⁺) (4 ⁺) with PF₆ ⁻ anions is obtained. Deprotonation of the mixture of 1⁺ and 4⁺ complexes under the action of Bu ^t OK inm-xylene followed by boiling of the reaction mixture gives phenylferrocene (7) as the product of η⁶:η⁶ haptotropic rearrangement. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, NO. 5, pp. 1045–1047, May, 1997.     

Beiträge zur Chemie des Phosphors. 67. Zur Kenntnis der Cyclotriphosphane (PC6H5)3, (PC6H5)2(PC2H5) und (PC6H5)2(PCH3)

Contributions to the Chemistry of Phosphorus. 67. About the Cyclotriphosphanes (PC₆H₅)₃, (PC₆H₅)₂(PC₂H₅), and (PC₆H₅)₂(PCH₃) The reaction of (CH₃)₃Si(C₆H₅)P? P(C₆H₅)Si(CH₃)₃ with RPCl₂ (R = C₆H₅, C₂H₅, CH₃) yields the cyclotriphosphanes (PC₆H₅)₃ 1 , (PC₆H₅)₂(PC₂H₅) 3 , and (PC₆H₅)₂(PCH₃) 4 , respectively. Besides, the corresponding homo- and mixed-substituted cyclotetraphosphanes, cyclopentaphosphanes, and cyclohexaphosphanes are formed. The relative concentrations of the cyclotriphosphanes in the reaction mixtures decrease continuously, whereas those of the cyclopentaphosphanes increase. The reasons for these ring-interconversion reactions of the cyclophosphanes (PR)_n are discussed. The cyclotriphosphanes 1, 3 , and 4 are characterized by ³¹P chemical shifts between +130 and +160 ppm that are at considerable high field compared to open-chain triphosphanes and cyclophosphanes of different ring-size. The substituents R are situated on both sides of the P₃-ring plane, thus giving rise to two diastereomers of 3 that are observed simultaneously in the statistically expected ratio. The ³¹P n.m.r. parameters of 1 and 3 are reported and discussed.     

Synthese von (C6F5)2SF+MF6− (M  As,Sb) und Kristallstruktur von (C6F5)2SF+SbF6− [1]

Preparation of (C₆F₅)₂SF⁺MF₆^? (M ? As, Sb) and Crystal Structure of (C₆F₅)₂SF⁺SbF₆^? XeF⁺MF₆^? (M ? As, Sb) reacts with (C₆F₅)₂S in HF to form (C₆F₅)₂SF⁺MF₆^?. The deeply violet sulfonium salts can be kept without decomposition up to 24 h at room temperature. The hexafluoroantimonate salt crystallizes in the monoclinic space group P2₁/n with a = 1056.4(7) pm, b = 1446.3(10) pm, c = 1102.9(8) pm, β = 91.29(6)° und Z = 4. The SF-bond distance with 158.4(3) pm is of unusual length. Cations and anions are connected via interionic fluorine contacts to an infinite chain, in which cations and anions form to ABAB sequence along the chain.     

Synthese d'une phosphine contenant du titane(II), (η5-C5H5)[η7-C7H6P(C6H5)2]Ti,ET DEcomplexes heterobimetalliques

Reaction of chlorodiphenylphosphine with (η⁵-C₅H₅)(η⁷-C₇H₆Li)Ti gave (η⁵-C₅H₅)[η⁷-C₇H₆P(C₆H₅)₂]Ti in good yields. This novel phosphinetitanium (II) derivative displaced one carbonyl of metal carbonyl complexes [Ni(CO)₄, Fe(CO)₅ and Mo(CO)₆] to afford heterobimetallic complexes containing low valent titanium, and behaved as a poor electron-donating phosphine.     

Chloroselenate(IV): Darstellung,Struktur und Eigenschaften von [As(C6H5)4]2Se2Cl10 und [As(C6H5)4]Se2Cl9

Chloroselenates(IV): Synthesis, Structure, and Properties of [As(C₆H₅)₄]₂Se₂Cl₁₀ and [As(C₆H₅)₄]Se₂Cl₉ The Se₂Cl₁₀^2? and Se₂Cl₉^? anions were prepared, as the first dinuclear haloselenates(IV), from the reaction of (SeCl₄)₄ with stoichiometric quantities of chloride ions in POCl₃ solutions; they were isolated as yellow crystalline As(C₆H₅)₄⁺ salts. Complete X-ray structural analyses at ?130°C of [As(C₆H₅)₄]₂Se₂Cl₁₀ ( 1 ) (space group P1 , a = 10.296(7), b = 11.271(6), c = 12.375(8) Å, = 74.17(5)°, α = 81.38(5)°, β = 67.69(4)°, V = 1276 ų) and of [As(C₆H₅)₄]Se₂Cl₉ ( 2 ) (space group P2₁/n, a = 12.397(5), b = 17.492(6), c = 14.235(4) Å, α 93.25(3)°, V = 3082 ų) show in both cases two distorted octahedral SeCl₆ groups connected through a common edge in 1 and a common face in 2 . The terminal Se? Cl bonds (average 2.317 Å in 1 , 2.223 Å in 2 ) are much shorter than the Se? Cl bridges (av. 2.661 Å in 1 , 2.652 Å in 2 ). The stereochemical activity of the Se^IV lone electron pair causes severe distortion of the central Se₂Cl₂ ring in the centrosymmetric Se₂Cl₁₀^2? ion. The vibrational spectra of the anions are reported.     

Pentaazadienido-Komplexe von Zink,Cadmium und Quecksilber Die Kristallstruktur von [Cd(EtOC6H4-N5-C6H4OEt)2(py)2] und [Hg(tol-N5-tol)2(py)]

Pentaazadienido Complexes of Zinc, Cadmium, and Mercury. The Crystal Structure of [Cd(EtOC₆H₄-N₅-C₆H₄OEt)₂(py)₂] and [Hg(tol-N₅-tol)₂(py)] The pentaazadienido complexes [M(EtOC₆H₄N₅C₆H₄OEt)₂] (M = Zn ( 1 ), Cd ( 2 )) are formed by the reaction of [M(NH₃)₄]²⁺ with [EtOC₆H₄N₅C₆H₄OEt]^? in aqueous ammonia. 2 crystallizes from pyridine as [Cd(EtOC₆H₄N₅C₆H₄OEt)₂py₂] ( 3 ) with the triclinic space group P1 and a = 937.2(2); b = 1422.7(2); c = 2085.5(2) pm; α = 75.28(1)°; β = 94.74(1)°; γ = 99.75(1)°; Z = 2. The central Cd²⁺ ion of 3 exhibits an octahedral coordination by two pyridine ligands in cis arrangement and two (N1, N3)-²⁺ chelating pentaazadienide ions. The reaction of [HgI₄]² with the 1,5-di(tolyl)pentaazadienide anion in aqueous ammonia affords [Hg(p-tol-N₅-tol)₂] ( 4 ), which crystallizes from pyridine in form of [Hg(tol-N₅-tol)₂py] ( 5 ) with the space group P1 and a = 1176.2(4); b = 1203.1(3); c = 1295.6(5) pm; α = 100.77(3)°; β = 110.08(3)°; γ = 94.29(2)°; Z = 2. In 5 the Hg²⁺ cation is threefold coordinated by two monodentate (N3)-η¹ pentaazadienid anions and one pyridine ligand. Within the N₅ chains of the pentaazadienid anions of 3 and 5 localized N? N double bonds are found in the positions N1? N2 and N4? N5 with distances between 125 and 129 pm.     

Antimonypentafluoroorthotellurates: Sb(OTeF5)3, Sb(OTeF5)5 and salts of Sb(OTeF5)6−

Antimony(III)pentafluoroorthotellurate has been synthesized from SbF₃ and B(OTeF₅)₃. Contrary to a previous report it is a low melting, sublimable solid (mp = 28°, bp (0.1 torr) = 68°, ¹⁹F - NMR: AB₄ spinsystem δ (A) = ?42.7, δ (B) = ?38.1, J (AB) = 186 Hz). It reacts with F₂, Cl₂ and Br₂ to give SbF₂(OTeF₅)₃, SbCl₄⁺Sb(OTeF₅)₆^? and SbBr₄⁺ Sb(OTeF₅)₆^? respectively. Interaction of Xe(OTeF₅)₂ and Sb(OTeF₅)₃ yields Sb(OTeF₅)₅, which is unstable at room temperature. Salts containing the new anion Sb(OTeF₅)₆^? have been synthesized either from Sb(OTeF₅)₅ and a corresponding pentafluoroorthotellurate e.g. Sb(OTeF₅)₅ + NMe₄⁺ OTeF₅^? = NMe₄⁺ Sb(OTeF₅)₆^?, or from SbCl₄ Sb(OTeF₅)₆^? and an appropriate chloride SbCl₄⁺ Sb(OTeF₅)₆^? + NOCl = SbCl₅ + NO⁺ Sb(OTeF₅)₆^?, or oxidatively, using a mixture of Xe(OTeF₅)₂ and Sb(OTeF₅)₅, e.g. C₆F₆ + $\text{1}\text{2}$ Xe(OTeF₅)₂ + Sb(OTeF₅)₅ = C₆F₆⁺ Sb(OTeF₅)₆^? + $\text{1}\text{2}$ Xe.     

Ansa‐Complexes of [Mn(η5‐C5H5)(η6‐C6H6)]: Preparation,Characterization, and Reactivity of [n]Manganoarenophanes (n=1, 2, 3)

We report the synthesis of [n]manganoarenophanes (n=1, 2) featuring boron, silicon, germanium, and tin as ansa‐bridging elements. Their preparation was achieved by salt‐elimination reactions of the dilithiated precursor [Mn(η⁵‐C₅H₄Li)(η⁶‐C₆H₅Li)]?pmdta (pmdta=N,N,N′,N′,N′′‐pentamethyldiethylenetriamine) with corresponding element dichlorides. Besides characterization by multinuclear NMR spectroscopy and elemental analysis, the identity of two single‐atom‐bridged derivatives, [Mn(η⁵‐C₅H₄)(η⁶‐C₆H₅)SntBu₂] and [Mn(η⁵‐C₅H₄)(η⁶‐C₆H₅)SiPh₂], could also be determined by X‐ray structural analysis. We investigated for the first time the reactivity of these ansa‐cyclopentadienyl–benzene manganese compounds. The reaction of the distannyl‐bridged complex [Mn(η⁵‐C₅H₄)(η⁶‐C₆H₅)Sn₂tBu₄] with elemental sulfur was shown to proceed through the expected oxidative addition of the Sn?Sn bond to give a triatomic ansa‐bridge. The investigation of the ring‐opening polymerization (ROP) capability of [Mn(η⁵‐C₅H₄)(η⁶‐C₆H₅)SntBu₂] with [Pt(PEt₃)₃] showed that an unexpected, unselective insertion into the C_ipso?Sn bonds of [Mn(η⁵‐C₅H₄)(η⁶‐C₆H₅)SntBu₂] had occurred.     

Heterometallische Clusterkomplexe der Typen Re2(μ-PR2)(CO)8(HgY) und ReMo(μ-PR2)(η5-C5H5)(CO)6(HgY) (R = Ph,Cy; Y = Cl,W(η5-C5H5)(CO)3)

Heterometallic Cluster Complexes of the Types Re₂(μ-PR₂)(CO)₈(HgY) and ReMo(μ-PR₂)(η⁵-C₅H₅)(CO)₆(HgY) (R = Ph, Cy; Y = Cl, W(η⁵-C₅H₅)(CO)₃) Dinuclear complexes Re₂(μ-H)(μ-PR₂)(CO)₈ and ReMo(μ-H)(μ-PR₂)(η⁵-C₅H₅)(CO)₆ (R = phenyl, cyclohexyl) were deprotonated and reacted as anions with HgCl₂ to compounds of the both types Re₂(μ-PR₂)(CO)₈HgCl) and ReMo(μ-PR₂)(η⁵-C₅H₅)(CO)₆(HgCl). The heterometallic three-membered cluster complexes correspond to an isolobal exchange of a proton against a cationic HgCl⁺ group. For one of the products ReMo(μ-PCy₂)(η⁵-C₅H₅)(CO)₆(HgCl) has been shown its conversion with NaW(η⁵-C₅H₅)(CO)₃ to ReMo(μ-PCy₂)(η⁵-C₅H₅)(HgW(η⁵-C₅H₅)(CO)₃) under substitution of the chloro ligand, par example. The newly prepared compounds were characterized by means of IR, UV/VIS and ³¹P NMR data. A complete determination of the molecular structure by single crystal analyses was done in the case of Re₂(μ-PCy₂)(CO)₈(HgCl) and of ReMo(μ-PCy₂)(η⁵-C₅H₅)(CO)₆(HgCl) which both are dimer because of the presence of an asymmetric dichloro bridge, and of ReMo(μ-PCy₂)(η⁵-C₅H₅)(CO)₆(HgW(η⁵-C₅H₅)(CO)₃). The structural study illustrates through comparison the influence of various metal types on an interaction between centric and edge-bridged frontier orbitals in three-membered metal rings.     

Elektronenreiche Phenylkomplexe der Übergangsmetalle. II. Li4Co2(C6H5)4 · 4THF,Li4Co2(C6H5)4 · 3 Dioxan und Li3Co(C6H5)2(LiC6H5) · 5THF,die ersten Komplexe mit einer Bis(phenyl)cobalt(0)- und -cobalt(-I)-Einheit

Electron-rich Phenyl Complexes of Transition Metals. II. Li₄Co₂(C₆H₅)₄ · 4THF, Li₄Co₂(C₆H₅)₄ · 3 Dioxan and Li₃Co(C₆H₅)₂(LiC₆H₅) · 5THF, the First Complexes with a Bis(phenyl)-cobalt(0)- and -cobalt(-I) Unity . Li₂Co^II(C₆H₅)₄ · 4THF reacts spontaneously in benzene by splitting off of two phenyl radicals to a dimeric bis(phenyl) cobalt(0) complex which has been isolated as a THF and a dioxan adduct Li₄Co₂(C₆H₅)₄ · 4THF and Li₄Co₂(C₆H₅)₄ · 3 Dioxan, respectively. Reduction with lithiumphenyl in ether gives a phenyl cobalt(-I) complex Li₄Co(C₆H₅)₃ · 5THF containing besides σ-bonded phenyl anions lithium phenyl coordinated to cobalt in a π-complex like manner, proved by means of ¹³C? NMR-spectroscopy. The stabilization of the low oxidation states is explained by coordination of the lithium ions to cobalt by multiple center bonds, and for each compound a plausible structure is derived.     

Pseudohalogeno-Metallverbindungen. LXXV. Pentacarbonylrhenium-und Triphenylphosphangold-Komplexe mit Pseudohalogeniden: (OC)5ReX,Ph3PAuX (X = ONC(CN)2, o-MeC6H4SO2C(CN)2,o-MeC6H4SO2NCN,Ph2(S)PNCN)

Pseudohalogeno Metal Compounds. LXXV. Pentacarbonylrhenium and Triphenylphosphinegold Complexes of Pseudohalide Anions: (OC)₅ReX, Ph₃PAuX (x = ONC(CN)₂, o-MeC₆H₄SO₂C(CN)₂, o-MeC₆H₄SO₂NCN, Ph₂(S)PNCN) The pseudohalides (X^?) nitrosodicyanmethanide, o-tosyldicyanmethanide, o-tosylcyanamide and diphenylthiophosphinylcyanamide react with the Organometallic Lewis Acids (OC)₅Re⁺ (as (OC)₅ReFBF₃) and Ph₃PAu⁺ (as Ph₃PAuNO₃) to give the neutral title complexes (OC)₅Re—X and Ph₃PAu? X, respectively. X-ray diffraction shows that nitroso-dicyanmethanide is coordinated through the nitroso N-atom to the Re(CO)₅ fragment. Cyanide-N-coordination is observed for the complexes with o-tosyldicyanmethanide and o-tosylcyanamide whereas diphenylthiophosphinylcyanamide is S-coordinated to the gold atom. Spectroscopic data (IR, NMR) of 1–6 are described.     

Pentafluorphenyliod(III)-Verbindungen. 2. Fluor-Aryl Substitution an Iodtrifluorid: Synthese von Pentafluorphenylioddifluorid C6F5IF2 und Bis(pentafluorphenyl)iodonium Pentafluorphenylfluoroboraten [(C6F5)2I]+[(C6F5)nBF4−n]−

Pentafluorophenyliodine(III) Compounds. 2. Fluorine-Aryl Substitution Reactions on Iodinetrifluoride: Synthesis of Pentafluorophenyliodinedifluoride C₆F₅IF₂ and Bis(pentafluorophenyl)iodonium Pentafluorophenylfluoroborates[(C₆F₅)₂I]⁺[(C₆F₅)_nBF_4?n]^? Mono- and disubstitution can be achieved in the fluorine-aryl substitution reaction on the low-temperature phase IF₃ in CH₂Cl₂ at ?78°C depending on the aryl transfer reagent. With B(C₆F₅)₃ [(C₆F₅)₂I]⁺ [(C₆F₅)_nBF_4?n]^? (68% yield) and with Cd(C₆F₅)₂ C₆F₅IF₂ (97% yield) is obtained whereas with C₆F₅SiMe₃ no fluorine-aryl substitution takes place on IF₃ even under basic conditions (EtCN or F^? addition). At ?78°C in EtCN solution IF₃ does not disproportionate but attacks the solvent under formation of HF.     

Stereospecific and chemospecific interconversions of the rhenium alkylidene [(η-C5H5)Re(NO)(PPh3)(CHC6H5)]+PF6− and the alkylrhenium (η-C5H5)Re(NO)(PPh3)(CH(OCH3)C6H5)

Addition of methoxide to either geometric isomer of the benzylidene complex [(η-C₅H₅)Re(NO)(PPh₃)(CHC₆H₅)]⁺PF₆^? (1t, 1k) affords (η-C₅H₅)Re(NO)(PPh₃)(CH(OCH₃)C₆H₅ (2t, 2k) in which a new chiral center has been generated stereospecifically or with high stereoselectivity. Reaction of 2t and 2k with Ph₃C⁺PF₆^? results in the chemospecific abstraction of a methoxy group and the stereospecific regeneration of 1t and 1k, respectively.