Synthese,Struktur und Reaktivität von η1und η3‐Allyl‐Rhenium‐Carbonylen

Synthesis, Structure, and Reactivity of η¹‐ and η³‐Allyl Rhenium Carbonyls In (η³‐C₃H₅)Re(CO)₄ one CO ligand can be substituted by PPh₃, pyridine, isocyanide and benzonitrile. With 1,2‐bis(diphenylphosphino)ethylene, 1,1′‐bis(diphenylphosphino)ferrocene and 1,2‐bis(4‐pyridyl)ethane dinuclear ligand bridged complexes are obtained. The η³‐η¹ conversion of the allyl ligand occurs on reaction of (η³‐C₃H₅)Re(CO)₄ with the bidendate ligands 1,2‐bis(diphenylphosphino)ethane and 1,3‐bis(diphenylphosphino)propane and with 2,2′‐bipyridine (L–L) which gives the complexes (η¹‐C₃H₅)Re(CO)₃(L–L). By reaction of (η³‐C₃H₅)Re(CO)₄ with bis(diphenylphosphino)methane the allyl group is protonated and under elemination of propene the complex (OC)₃Re(Ph₂PCHPPh₂)(η¹‐Ph₂PCH₂PPh₂) ( 19 ) with a diphosphinomethanide ligand is formed. On heating solutions of (η³‐C₃H₅)Re(CO)₄ and (η³‐C₃H₅)Re(CO)₃(CN‐2,5‐Me₂C₆H₃) ( 5 ) in methanol the methoxy bridged compounds Re₄(CO)₁₂(OH)(OMe)₃ and Re₂(CO)₄(CN‐2,5‐Me₂C₆H₃)₄(μ‐OMe)₂ ( 20 ) were isolated. The crystal structures of (η³‐C₃H₅)Re(CO)₃(CNCH₂SiMe₃) ( 4 ), [(η³‐C₃H₅)(OC)₃Re]₂‐ (μ‐bis‐(diphenylphosphino)ferrocene) ( 8 ), (η¹‐C₃H₅)Re(CO)₃‐ (bpy) ( 14 ), of 19 , 20 and of (OC)₃Re‐[Ph₂P(CH₂)₃PPh₂]Cl ( 16 ) were determined by X‐ray diffraction.     

Reactive Dimerization of an N‐Heterocyclic Plumbylene: C−H Activation with PbII

The N‐heterocyclic plumbylene [Fe{(η⁵‐C₅H₄)NSiMe₃}₂Pb:] is in equilibrium with an unprecedented dimer in solution, whose formation involves the cleavage of a strong C?H bond and concomitant formation of a Pb?C and an N?H bond. According to a mechanistic DFT assessment, dimer formation does not involve direct Pb^II insertion into a cyclopentadienyl C?H bond, but is best described as an electrophilic substitution. The bulkier plumbylene [Fe{(η⁵‐C₅H₄)NSitBuMe₂}₂Pb:] shows no dimerization, but compensates its electrophilicity by the formation of an intramolecular Fe?Pb bond.     

η5:η5-Bicyclopentadienylmolybdenum chemistry: Some alkyl,halo and thiol derivatives

The preparation of the compounds {(η-C₅H₅)MoX}₂{μ-(η⁵-C₅H₄-η⁵-C₅H₄)} (X = Me, PhCH₂, Me₃SiCH₂, Br) and {(η-C₅H₅)MoY₂}₂{μ-(η⁵-C₅H₄-η⁵-C₅H₄)}, (Y = H, I, SMe, S-n-Bu) is described. Photolysis of {(η-C₅H₅)MoH}₂ {μ-(η¹:η⁵ -C₅H₄)}₂ and {(η-C₅H₅)MoH}₂{(η⁵-C₅H₄-η⁵-C₅H₄)} in benzene leads to a compound of stoichiometry C₂₀H₁₈Mo₂.     

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⁻.     

(n-C5H5) (CO)2W{n3-C5H5[(n-C5H4)2Fe]} - ein neuer Fe und N enthaltender Zweikernkomplex

(η-C₅H₅)(CO)₂W[(η³-C₅H₅)(C₅H₅)₂], I, containing two tilted five-membered rings, is converted into the bridged ferrocene derivative (η-C₅H₅)(CO)₂W{(η³-C₅H₅)}[(η-C₅ H₄)₂Fe]} II by successive reaction with Na and FeCl₂.     

Einführung eines terminalen Halogenoliganden in diorgano-verbrücke Dirhenium- und Molybdän-Rhenium-Komplexanionen in Gegenwart eines Amidinkations

Insertion of a Terminal Halogeno Ligand into Diorgano-bridged Dirhenium and Rhenium-Molybdenum Complex Anions in the Presence of an Amidin Cation and the Isomerization Processes The equimolar reaction of in situ generated anion Anions Re₂(μ-PCy₂)(CO)₈^? (Re? Re) in the presence of a steric expansive amidine cation DBUH⁺ with bromine and iodine in tetrahydrofuran solution gave the two isomers Re₂(PCy₂)(CO)₈X (Re? Re) and Re₂(μ-PCy₂)(μ-X)(CO)₈ (X = Br, I), of which the isomer with a terminal X ligand as major product was formed under maintenance of the Re? Re bond. The monotropic isomerization process of Re₂(μ-PCy₂)(CO)₈I runs thermically relative slowly, but more rapid in photochemical and electrochemical processes. The analogeous reaction of the heterometallic anion ReMo(η⁵-C₅H₅)(μ-PPh₂)(CO)₆^? with iodine delivers opposite to the former reaction mainly the bridged isomer ReMo(η⁵-C₅H₅)(μ-PPh₂μ-I)(CO)₆ besides ReMo(η⁵-C₅H₅)(μ-PPh₂)(CO)₆I. The obtained complexes were characterized by means of v(CO) and ³¹P NMR spectroscopic measurements. Single-crystal analyses led to the subsequent metal—metal bond lengths: Re? Re of 308.0(1) pm in Re₂(μ-PCy₂)(CO)₈Br and Re? Mo of 313.6(1) pm in ReMo(η⁵-C₅H₅)(μ-PPh₂)(CO)₆I.     

Exploratory organometal-sulfur chemistry; syntheses and unusual properties of rhenium CH2SR,CHSRR′, and CHSR]+ complexes

The methylidene complex [(η-C₅H₅)Re(NO)(PPh₃)(CH₂)]⁺PF₆^?(I) yields kinetically labile sulfonium salts when treated with CH₃SCH₃, CH₃SCH₂C₆H₅, and (η-C₅H₅)Re(NO)(PPh₃)(CH₂SCH₃) (V);the binuclear adduct formed in the latter case, [(η-C₅H₅)Re(NO)(PPh₃)CH₂]₂S⁺CH₃ (VI), is substantially more stable than the others and undergoes hydride transfer disproportionation to [(η-C₅H₅)Re(NO)(PPh₃)(CHSCH₃)]⁺PF₆^?(VII) and (η-C₅H₅)Re(NO)(PPh₃)(CH₃) (VIII) when heated.     

Partial incorporation of a cyclopentadienyl ligand into a molybdaborane to form a molybdacarbaborane

Reaction of the molybdaborane arachno-2-[Mo(η-C₅H₅)(η⁵:η¹-C₅H₄)B₄H₇] (I) with NEt₃ in toluene at 120 °C for 7 days gives a 90% yield of the molybdacarbaborane nido-1-[Mo(η-C₅H₅)(η³:η²-C₃H₃)C₂B₃H₅] (II). Two of the carbon atoms in the substituted cyclopentadienyl ring in I are incorporated into the metallacarbaborane cluster II. The carbaborane {C₂B₃H₅} fragment in II is attached to an allylic {C₃H₃} group and can be thought of as a new non-planar {C₅B₃H₈} ligand providing seven electrons to the molybdenum atom. Reaction of I with KH in thf at 20 °C gives the anion via deprotonation of a B-H-B bridging proton.     

New η-allyl η-cyclopentadienylcobalt cations

[Co(R-η-C₃H₄)(η-C₅H₅)I] is a good precursor for the preparation of some new cationic complexes as the iodide can easily be replaced; thus addition of PEt₃ to the iodo-complex (R  H) gives [Co(η-C₃H₅)(η-C₅H₅)(PEt₃)]⁺. The reactions of [Co(R-η-C₃H₄)(η-C₅H₅))I] (R  H or 2-Me) with AgBF₄ give solutions containing the coordinatively unsaturated species [Co(R-η-C₃H₄)(η-C₅H₅)⁺. The presence of traces of water leads to the formation of [Co(R-ηC₃H₄)-(η-C₅H₅)(H₂O)]⁺. The addition of monodentate ligands L  PEt₃ PPh₃, AsPh₃, SbPh₃, CNCH₃ and bidentate ligands LL  Ph₂PCH₂CH₂PPh₂(dppe) and o-C₆H₄(AsMe₂)₂(diars), gives, respectively mononuclear [Co(2-Me-ηC₃H₄)-(η-C₅H₅)L]⁺ and binuclear ligand-bridged [(2-Me-ηC₃H₄)(η-C₅H₅)CoLLCo(2-Me-ηC₃H₄)(η-C₅H₅))]²⁺ complexes. Crystals of [Co(2-Me-ηC₃H₄)(η-C₅H₅)-(H₂O)]⁺[BF₄]^- are monoclinic, space group P2₁/c, with a 7.858(3), b 10.262(4), c 15.078(4) Å, β 98.36(1)°. The molecular structure contains the cobalt atom bonded to planar 2-Me-allyl and cyclopentadienyl substituents, which are almost parallel with the H₂O molecule in a staggered conformation with respect to the 2-Me group.     

Synthesis,Reactivity and Crystal Structures of the Palladium(II) Complexes with the Pyrimidine Containing Ligand: Crystal Structures of [Pd(PPh3)(η1‐C4H3N2)(η2‐S2CNC4H8)] and [Pd(PPh3)(η1‐C4H3N2)(η2‐Tp)]

Treatment of Pd(PPh₃)₄ with 5‐bromo‐pyrimidine [C₄H₃N₂Br] in dichloromethane at ambient temperature cause the oxidative addition reaction to produce the palladium complex [Pd(PPh₃)₂(η¹‐C₄H₃N₂)(Br)], 1 , by substituting two triphenylphosphine ligands. In acetonitrile solution of 1 in refluxing temperature for 1 day, it do not undergo displacement of the triphenylphosphine ligand to form the dipalladium complex [Pd(PPh₃)Br]₂{μ,η²‐(η¹‐C₄H₃N₂)}₂, or bromide ligand to form chelating pyrimidine complex [Pd(PPh₃)₂(η²‐C₄H₃N₂)]Br. Complex 1 reacted with bidentate ligand, NH₄S₂CNC₄H₈, and tridentate ligand, KTp {Tp = tris(pyrazoyl‐1‐yl)borate}, to obtain the η²‐dithiocarbamate η¹‐pyrimidine complex [Pd(PPh₃)(η¹‐C₄H₃N₂)(η²‐S₂CNC₄H₈)], 4 and η²‐Tp η¹‐pyrimidine complex [Pd(PPh₃)(η¹‐C₄H₃N₂)(η²‐Tp)], 5 , respectively. Complexes 4 and 5 are characterized by X‐ray diffraction analyses.     

Mono-η-arenebis(trimethylphosphine(rhenium chemistry: alkyl,hydrido, halogeno and olefin derivatives

Co-condensation of rhenium atoms with a benzene-trimethylphosphine mixture gives the dimer [Re(ν-C₆H₆)(PMe₃)₂]₂ which is a precursor to the new compounds Re(η-C₆H₆)(PMe₃)₂R (R = H, Cl, I, Me, Et, CHCH₂ or Ph), [Re(η-C₆H₆)(PMe₃)₂X₂]BF₄ (X₂ = H₂ or HI), [Re(η-C₆H₆)(PMe₃)₂H₂][BF₄]₂, and [Re(η-C₆H₆)(PMe₃)₂L]BF₄ (L = η-C₂H₄ or CO). Co-condensation of manganese atoms with benzene-trimethylphosphine gives Mn(η-C₆H₆)(PMe₃)₂H.     

Dimanganese Bridging Borylene Complexes and their Reactions with Unsaturated Palladium(0) Complexes – Syntheses,Structures and Calculated Properties

The dimanganese bridging borylene complex [μ‐BMes {(η⁵‐C₅H₄Me)Mn(CO)₂}₂] was synthesized from Mes(Cl)BB(Cl)Mes and K[(η⁵‐C₅H₄Me)Mn(CO)₂H] at low temperature, providing a small sample after manual separation of crystals, allowing a perfunctory spectroscopic analysis, but affording conclusive X‐ray crystallographic structural data. The trimetallic bridging borylene complex [(μ³‐BCl){{(η⁵‐C₅H₄Me)Mn(CO)₂} {Pd(PCy₃)}₂}] was prepared by the addition of [Pd(PCy₃)₂] to a solution of [μ‐BCl{(η⁵‐C₅H₄Me)Mn(CO)₂}₂], affording pure crystals that were fully characterised including X‐ray crystallographic analysis. The structure is reconciled with detailed theoretical analysis for related model complexes, [(μ³‐BX){{(η⁵‐C₅H₅)Mn(CO)₂}{Pd(PMe₃)}₂}] (X = Me, Cl).     

Insight into the structures of [M(C5H4I)(CO)3] and [M2(C12H8)(CO)6] (M = Mn and Re) containing strong I...O and π(CO)–π(CO) interactions

The compounds tricarbonyl(η⁵‐1‐iodocyclopentadienyl)manganese(I), [Mn(C₅H₄I)(CO)₃], (I), and tricarbonyl(η⁵‐1‐iodocyclopentadienyl)rhenium(I), [Re(C₅H₄I)(CO)₃], (III), are isostructural and isomorphous. The compounds [μ‐1,2(η⁵)‐acetylenedicyclopentadienyl]bis[tricarbonylmanganese(I)] or bis(cymantrenyl)acetylene, [Mn₂(C₁₂H₈)(CO)₆], (II), and [μ‐1,2(η⁵)‐acetylenedicyclopentadienyl]bis[tricarbonylrhenium(I)], [Re₂(C₁₂H₈)(CO)₆], (IV), are isostructural and isomorphous, and their molecules display inversion symmetry about the mid‐point of the ligand C[triple‐bond]C bond, with the (CO)₃M(C₅H₄) (M = Mn and Re) moieties adopting a transoid conformation. The molecules in all four compounds form zigzag chains due to the formation of strong attractive I...O [in (I) and (III)] or π(CO)–π(CO) [in (I) and (IV)] interactions along the crystallographic b axis. The zigzag chains are bound to each other by weak intermolecular C—H...O hydrogen bonds for (I) and (III), while for (II) and (IV) the chains are bound to each other by a combination of weak C—H...O hydrogen bonds and π(Csp²)–π(Csp²) stacking interactions between pairs of molecules. The π(CO)–π(CO) contacts in (II) and (IV) between carbonyl groups of neighboring molecules, forming pairwise interactions in a sheared antiparallel dimer motif, are encountered in only 35% of all carbonyl interactions for transition metal–carbonyl compounds.     

Isocyanide insertion reactivity of dinuclear niobium and tantalum imido complexes: X-ray crystal structure of [{Nb(η-C5H4SiMe3)(CH2Ph)2}2(μ-1,4-NC6H4N)]

The reactivity of dinuclear niobium and tantalum imido complexes with the isocyanide compound 2,6-Me₂C₆H₃NC has been studied. The trialkyl complexes [{NbR₃(CH₃CN)}₂(μ-1,3-NC₆H₄N)], [{NbR₃(CH₃CN)}₂(μ-1,4-NC₆H₄N)] and [{TaR₃(CH₃CN)}₂(μ-1,4-NC₆H₄N)] (R=CH₂SiMe₃) gave [{Nb(η²-RCNAr)₂R}₂(μ-1,3-NC₆H₄N)] (1), [{Nb(η²-RCNAr)₂R}₂(μ-1,4-NC₆H₄N)] (2) and [{Ta(η²-RCNAr)₂R}₂(μ-1,4-NC₆H₄N)] (3) (R=CH₂SiMe₃; Ar=2,6-Me₂C₆H₃), from the isocyanide insertion in two of the metal alkyl carbon bonds. The reaction of the isocyanide reagent with the di-alkyl mono-cyclopentadienyl derivatives [{Nb(η⁵-C₅H₄SiMe₃)R₂}₂(μ-1,3-NC₆H₄N)] (R=Me, CH₂Ph, CH₂SiMe₃), [{Nb(η⁵-C₅H₄SiMe₃)R₂}₂(μ-1,4-NC₆H₄N)] (R=Me, CH₂Ph (4), CH₂SiMe₃) and [{Ta(η⁵-C₅Me₅)(CH₂SiMe₃)₂}₂(μ-1,4-NC₆H₄N)] yielded [{Nb(η⁵-C₅H₄SiMe₃)(η²-RCNAr)R}₂(μ-1,3-NC₆H₄N)] (R=Me (5), CH₂Ph (6), CH₂SiMe₃ (7)), [{Nb(η⁵-C₅H₄SiMe₃)(η²-RCNAr)R}₂(μ-1,4-NC₆H₄N)] (R=Me (8), CH₂Ph (9), CH₂SiMe₃ (10)) and [{Ta(η⁵-C₅Me₅)(η²-Me₃SiCH₂CNAr)CH₂SiMe₃}₂(μ-1,4-NC₆H₄N)] (11) (Ar=2,6-Me₂C₆H₃), respectively, from a single insertion process. The reaction with the mono-alkyl complex [{Nb(η⁵-C₅H₄SiMe₃)(Me)Cl}₂(μ-1,4-NC₆H₄N)] gave [{Nb(η⁵-C₅H₄SiMe₃)(η²-MeCNAr)Cl}₂(μ-1,4-NC₆H₄N)] (12), produced from the isocyanide insertion in the metal-alkyl carbon bond. The alkyl-amido complex [{Nb(η⁵-C₅H₄SiMe₃)(Me)NMe₂}₂(μ-1,4-NC₆H₄N)] gave, from the preferential isocyanide insertion in the metal-amide nitrogen bond, [{Nb(η⁵-C₅H₄SiMe₃)(η²-Me₂NCNAr)Me}₂(μ-1,4-NC₆H₄N)] (13). The molecular structure of one of the alkyl precursors, [{Nb(η⁵-C₅H₄SiMe₃)(CH₂Ph)₂}₂(μ-1,4-NC₆H₄N)] (4), has been determined.     

Syntheses,Structures, Reactivities,and Basicities of Quinolinyl and Isoquinolinyl Complexes of an Electron Rich Chiral Rhenium Fragment and Their Electrophilic Addition Products

Reactions of Li⁺ [(η⁵-C₅H₅)Re(NO)(PPh₃)]⁻ with 2- and 4-chloroquinoline or 1-chloroisoquinoline give the corresponding σ quinolinyl and isoquinolinyl complexes 3 , 6 , and 8 . With 3 and 8 there is further protonation to yield HCl adducts, but additions of KH give the free bases. Treatment of 3 with HBF₄⋅OEt₂ or H(OEt₂)₂⁺ BAr_f⁻ gives the quinolinium salts [(η⁵-C₅H₅)Re(NO)(PPh₃)(C(NH)C(CH)₄C (CH)(CH))]⁺ X⁻ ( 3-H ⁺ X⁻; X⁻=BF₄⁻/BAr_f⁻, 94–98 %). Addition of CF₃SO₃CH₃ to 3 , 6 , or 8 affords the corresponding N-methyl quinolinium salts. In the case of [(η⁵-C₅H₅)Re(NO)(PPh₃)(C(NCH₃)C(CH)₄C (CH)(CH))]⁺ CF₃SO₃⁻ ( 3-CH₃ ⁺ CF₃SO₃⁻), addition of CH₃Li gives the dihydroquinolinium complex (S_ReR_C,R_ReS_C)-[(η⁵-C₅H₅)Re(NO)(PPh₃)(C(NCH₃)C(CH)₄C (CHCH₃)(CH₂))]⁺ CF₃SO₃⁻ ((S_ReR_C,R_ReS_C)- 5 ⁺ CF₃SO₃⁻, 76 %) in diastereomerically pure form. Crystal structures of 3-H ⁺ BAr_f⁻, 3-CH₃ ⁺ CF₃SO₃⁻, (S_ReR_C, R_ReS_C)- 5 ⁺ Cl⁻, and 6-CH₃ ⁺ CF₃SO₃⁻ show that the quinolinium ligands adopt Re⋅⋅⋅ C conformations that maximize overlap of their acceptor orbitals with the rhenium fragment HOMO, minimize steric interactions with the bulky PPh₃ ligand, and promote various π interactions. NMR experiments establish the Brønsted basicity order 3 > 8 > 6 , with K_a(BH⁺) values >10 orders of magnitude greater than the parent heterocycles, although they remain less active nucleophilic catalysts in the reactions tested. DFT calculations provide additional insights regarding Re⋅⋅⋅ C bonding and conformations, basicities, and the stereochemistry of CH₃Li addition.     

Protonation and methylation of η4-2,3,5,6-tetramethyl-1,4-benzoquinone(η5-pentamethylcyclopentadienyl)cobalt

The preparation of the η⁴-4-2,3,5,6-tetramethyl-1,4-benzoquinonecomplex [CO(C₅Me₅)(C₁₀H₁₂O₂)] (I) is reported. Complex I undergoesreversible protonation to yield the 2-6-η-4-hydroxy-1-oxo-2,3,5,6-tetramethylcyclohexadienyl complex [Co(C₅Me₅)(C₁₀H₁₃O₂)BF₄ (II) and diprotonation to yield the η⁶-6-1,4-dihydroxy-2,3,5,6-tetramethylbenzene complex [Co(C₅Me₅)(C₁₀H₁₄O₂)] (BF₄)₂ (III). Methylation of complex I with MeI/AgPF₆ gives the 26-η-4-methoxy-1-oxo-2,3,5,6-tetramethylcyclohexadienyl complex [Co(C₅Me₅)(C₁₁H₁₅O₂])PF₆ (IV). In trifluoroacetic acid solution complex IV is protonated to form the η⁶-1-hydroxy-4-methoxy-2,3,5,6-tetramethylbenzene cation [Co(C₅Me₅)-(C₁₁H₁₆O₂)]²⁺     

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.     

Synthese,Struktur und Reaktivität von η3‐1,2‐Diphosphaallylkomplexen sowie von [{(η5‐C5H5)(CO)2W–Co(CO)3}{μ‐AsCH(SiMe3)2}(μ‐CO)]

Syntheses, Structure and Reactivity of η³‐1,2‐Diphosphaallyl Complexes and [{(η⁵‐C₅H₅)(CO)₂W–Co(CO)₃}{μ‐AsCH(SiMe₃)₂}(μ‐CO)] Reaction of ClP=C(SiMe₂iPr)₂ ( 3 ) with Na[Mo(CO)₃(η⁵‐C₅H₅)] afforded the phosphavinylidene complex [(η⁵‐C₅H₅)(CO)₂Mo=P=C(SiMe₂iPr)₂] ( 4 ) which in situ was converted into the η¹‐1,2‐diphosphaallyl complex [η⁵‐(C₅H₅)(CO)₂Mo{η³‐tBuPPC(SiMe₂iPr)₂] ( 6 ) by treatment with the phosphaalkene tBuP=C(NMe₂)₂. The chloroarsanyl complexes [(η⁵‐C₅H₅)(CO)₃M–As(Cl)CH(SiMe₃)₂] [where M = Mo ( 9 ); M = W ( 10 )] resulted from the reaction of Na[M(CO)₃(η⁵‐C₅H₅)] (M = Mo, W) with Cl₂AsCH(SiMe₃)₂. The tungsten derivative 10 and Na[Co(CO)₄] underwent reaction to give the dinuclear μ‐arsinidene complex [(η⁵‐C₅H₅)(CO)₂W–Co(CO)₃{μ‐AsCH(SiMe₃)₂}(μ‐CO)] ( 11 ). Treatment of [(η⁵‐C₅H₅)(CO)₂Mo{η³‐tBuPPC(SiMe₃)₂}] ( 1 ) with an equimolar amount of ethereal HBF₄ gave rise to a 85/15 mixture of the saline complexes [(η⁵‐C₅H₅)(CO)₂Mo{η²‐tBu(H)P–P(F)CH(SiMe₃)₂}]BF₄ ( 18 ) and [Cp(CO)₂Mo{F₂PCH(SiMe₃)₂}(tBuPH₂)]BF₄ ( 19 ) by HF‐addition to the PC bond of the η³‐diphosphaallyl ligand and subsequent protonation ( 18 ) and/or scission of the PP bond by the acid ( 19 ). Consistently 19 was the sole product when 1 was allowed to react with an excess of ethereal HBF₄. The products 6 , 9 , 10 , 11 , 18 and 19 were characterized by means of spectroscopy (IR, ¹H‐, ¹³C{¹H}‐, ³¹P{¹H}‐NMR, MS). Moreover, the molecular structures of 6 , 11 and 18 were determined by X‐ray diffraction analysis.     

Reaction of some tertiary phosphines and phosphites with [Co(η5-C5H5)(S2C2{CN}2)]

Reaction of the 16 electron monomer [Co(η⁵-C₅H₅)(S₂C₂{CN}₂)] with various tertiary phosphines and phosphites (L) gives readily the 18 electron monomers [Co(η⁵-C₅H₅)(S₂C₂{CN}₂)L] which for L = P(OR)₃ have J($\text{P}$C₅$\text{H}$₅) ca. 6 Hz but J($\text{P}$C₅$\text{H}$₅) = 0 for L = PR₃.     

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.