Hydrido(hydrosilylene)tungsten Complexes: Dynamic Behavior and Reactivity Toward Acetone

Reaction of a labile tungsten nitrile complex, [(Cp*)W(CO)₂(NCMe)Me] (Cp*=η⁵‐C₅Me₅), with H₃SiC(SiMe₃)₃ gave the hydrido(hydrosilylene) complex [(Cp*)(CO)₂(H)W?Si(H){C(SiMe₃)₃}] ( 1a ). The hydrido(silylene) complex [(η⁵‐C₅Me₄Et)(CO)₂(H)W?SiMes₂] ( 2 ) (Mes=2,4,6‐Me‐C₆H₂) was synthesized by a similar reaction with H₂SiMes₂. There is a strong interligand interaction between the hydrido and silylene ligands of these complexes; this was confirmed by a neutron diffraction study of [D₂] 1b , that is, the deuterido and η⁵‐C₅Me₄Et derivative of 1a . The exchange between the W? H and the Si? D groups was observed in the deuterido complex [D] 1a . This H/D exchange proceeded slowly at room temperature, but very rapidly under UV irradiation. Variable‐temperature NMR spectroscopy measurements show the dynamic behavior of carbonyl ligands in 1a . Complex 1a reacted with acetone at room temperature to give mainly a hydrosilylation product, [(Cp*)(CO)₂(H)W?Si(OiPr){C(SiMe₃)₃}] ( 3a ), along with a siloxy complex, [(Cp*)(CO)₂WO(Si(H)iPr{C(SiMe₃)₃})] ( 4a ). At low temperature, a different reaction, namely, α‐H abstraction, proceeded to give an equilibrium mixture of 1a and a dihydrido(silyl) complex, [(Cp*)(CO)₂(H)₂W(Si(H){OC(?CH₂)Me}{C(SiMe₃)₃})] ( 5 ).     

Bildung und struktur der Cyclophosphane P4(CMe3)2[P(CMe3)2]2 und P4(SiMe3)2[P(CMe3)2]2

Formation and Structure of the Cyclophosphanes P₄(CMe₃)₂[P(CMe₃)₂]₂ and P₄(SiMe₃)₂[P(CMe₃)₂]₂ n-Triphosphanes showing a SiMe₃ and a Cl substituent at the atoms P¹ and P², like (Me₃C)₂P? P(SiMe₃)? P(CMe₃)Cl 3 or (Me₃C)₂P? P(Cl)? P(SiMe₃)₂ 4 are stable only at temperatures below ?30°C. Above this temperature these compounds lose Me₃SiCl, thus forming cyclotetraphosphanes, P₄(CMe₃)₂[P(CMe₃)₂]₂ 1 out of 3 , P₄(SiMe₃)₂[P(SiMe₃)₂]₂ 2a (cis) and 2b (trans) out of 4 . The formation of 1 proceeds via (Me₃C)₂P? P?PCMe₃ 5 as intermediate compound, which after addition to cyclopentadiene to give the Diels-Alder-adduct 6 (exo and endo isomers) was isolated. 6 generates 5 , which then forms the dimer compound 1 . Likewise (Me₃C)₂P? P?P-SiMe₃ 8 (as proven by the adduct 7 ) is formed out of 4 , leading to 2a (cis) and 2b (trans). Compound 1 is also formed out of the iso-tetraphosphane P[P(CMe₃)₂]₂[P(CMe₃)Cl] 9 , which loses P(CMe₃)₂Cl when warmed to a temperature of 20°C. 1 crystallizes monoclinically in the space group P2₁/a (no. 14); a = 1762.0(15) pm; b = 1687.2(18) pm; c = 1170.5(9) pm; β = 109.18(5)° and Z = 4 formula units in the elementary cell. The molecule possesses E conformation. The central four-membered ring is puckered (approx. symmetry 4 2m; dihedral angle 47.4°), thus bringing the substituents into a quasi equatorial position and the nonbonding electron pairs into a quasi axial position. The bond lengths in the four-membered ring of 1 (d (P? P) = 222.9 pm) are only slightly longer than the exocyclic bonds (221.8 pm). The endocyclic bond angles \documentclass{article}\pagestyle{empty}\begin{document}$ \bar \beta $\end{document}(P/P/P) are 85.0°, the torsion angles are ±33° and d (P? C) = 189.7 pm.     

Zweikernige silylenverbrückte Cyclopentadienylrhodiumbis(ethen)-Komplexe,photochemische Reaktion mit Benzolderivaten und selektiver Einschluß von Methylcyclopentan in das Kristallgitter von [Me2Si{3-But-C5H3Rh(C2H4)2}2]

Dinuclear Silylene Bridged Cyclopentadienylrhodiumbis(ethene) Complexes, Photochemical Reaction with Benzene Derivatives, and Selective Inclusion of Methylcyclopentane into the Crystal Lattice of [Me₂Si{3-Bu^t-C₅H₃Rh(C₂H₄)₂}₂] By reaction of [{(C₂H₄)₂RhCl}₂] with Na₂[Me₂Si(C₅H₄)₂] or with Li₂[Me₂Si(3-Bu^t-C₅H₃)₂] in THF the dinuclear silylene bridged complexes [Me₂Si{C₅H₄Rh(C₂H₄)₂}₂] 1 and [Me₂Si{3-Bu^t-C₅H₃Rh(C₂H₄)₂}₂] 2 , respectively, were synthesized. Due to the asymmetric substitution of the five-membered rings and their hindered rotation around the Si? C axes, 2 is formed as three isomers. The X-ray structure analysis of 2 obtained from hexane reveals the selective inclusion of methylcyclopentane, the content of which in the solvent is about 17%, into the crystal lattice. UV irradiation of 1 in hexane in the presence of benzene causes elimination of the ethene ligands yielding the μ-η³:η³ benzene complex [Me₂Si(C₅H₄Rh₂)₂C₆H₆] which cannot be separated from unreacted 1 . However, separation is possible in case of the hexamethylbenzene compound 4 analogous with 3 .     

CH Bond Activation during and after the Reactions of a Metallacyclic Amide with Silanes: Formation of a μ‐Alkylidene Hydride Complex,Its H–D Exchange,and β‐H Abstraction by a Hydride Ligand

Metallacyclic complex [(Me₂N)₃Ta(η²‐CH₂SiMe₂NSiMe₃)] ( 3 ) undergoes C?H activation in its reaction with H₃SiPh to afford a Ta/μ‐alkylidene/hydride complex, [(Me₂N)₂{(Me₃Si)₂N}Ta(μ‐H)₂(μ‐C‐η²‐CHSiMe₂NSiMe₃)Ta(NMe₂)₂] ( 4 ). Deuterium‐labeling studies with [D₃]SiPh show H–D exchange between the Ta?D ?Ta unit and all methyl groups in [(Me₂N)₂{(Me₃Si)₂N}Ta(μ‐D)₂(μ‐C‐η²‐CHSiMe₂NSiMe₃)Ta(NMe₂)₂] ([D₂]‐ 4 ) to give the partially deuterated complex [D_n]‐ 4 . In addition, 4 undergoes β‐H abstraction between a hydride and an NMe₂ ligand and forms a new complex [(Me₂N){(Me₃Si)₂N}Ta(μ‐H)(μ‐N‐η²‐C,N‐CH₂NMe)(μ‐C‐η²‐C,N‐CHSiMe₂NSiMe₃)Ta(NMe₂)₂] ( 5 ) with a cyclometalated, η²‐imine ligand. These results indicate that there are two simultaneous processes in [D_n]‐ 4 : 1) H–D exchange through σ‐bond metathesis, and 2) H?D elimination through β‐H abstraction (to give [D_n]‐ 5 ). Both 4 and 5 have been characterized by single‐crystal X‐ray diffraction studies.     

Ein Beitrag zur Reaktivität von (η5-C5Me5)(CO)2FeP(SiMe3)2 gegenüber P-Chlormethylenphosphanen

On the Reactivity of (η⁵-C₅Me₅)(CO)₂FeP(SiMe₃)₂ Toward P-Chloromethylene phosphanes The reaction of (η⁵-C₅Me₅)(CO)₂FeP(SiMe₃)₂ ( 2 ) with three equivalents of Cl? P?C(SiMe₃)₂ ( 3a ) afforded the 3-methanediyl-1,3,5,6-tetraphosphabicyclo[3.1.0]hex-2-ene (η⁵-C₅Me₅)(CO)₂Fe? ( 6a ). In contrast, 2 reacts with two equivalents of Cl? P?C(Ph)SiMe₃ ( 3b ) to give the thermolabile (η⁵-C₅Me₅) · (CO)₂Fe? P[P?C(Ph)SiMe₃]₂ ( 4b ) which decomposed during the reaction with further 3b. 4 b was also obtained from (η⁵-C₅Me₅)(CO)₂Fe? P(SiMe₃)? P?C(SiMe₃)₂ ( 1a ) and two equivalents of 3b .     

Zur Reaktivität von Titanocenkomplexen [Ti(Cp′)2(η2‐Me3SiC≡CSiMe3)] (Cp′ = Cp,Cp*) gegenüber Benzoldicarbonsäuren

On the Reactivity of Titanocene Complexes [Ti(Cp′)₂(η²‐Me₃SiC≡CSiMe₃)] (Cp′ = Cp, Cp*) towards Benzenedicarboxylic Acids Titanocene complexes [Ti(Cp′)₂(BTMSA)] ( 1a , Cp′ = Cp = η⁵‐C₅H₅; 1b , Cp′ = Cp* = η⁵‐C₅Me₅; BTMSA = Me₃SiC≡CSiMe₃) were found to react with iodine and methyl iodide yielding [Ti(Cp′)₂(μ‐I)₂] ( 2a / b ; a refers to Cp′ = Cp and b to Cp′ = Cp*), [Ti(Cp′)₂I₂] ( 3a / b ) and [Ti(Cp′)₂(Me)I] ( 4a / b ), respectively. In contrast to 2a , complex 2b proved to be highly moisture sensitive yielding with cleavage of HCp* [{Ti(Cp*)I}₂(μ‐O)] ( 7 ). The corresponding reactions of 1a / b with p‐cresol and thiophenol resulted in the formation of [Ti(Cp′)₂{O(p‐Tol)}₂] ( 5a / b ) and [Ti(Cp′)₂(SPh)₂] ( 6a / b ), respectively. Reactions of 1a and 1b with 1,n‐benzenedicarboxylic acids (n = 2–4) resulted in the formation of dinuclear titanium(III) complexes of the type [{Ti(Cp′)₂}₂{μ‐1,n‐(O₂C)₂C₆H₄}] (n = 2, 8a / b ; n = 3, 9a / b ; n = 4, 10a / b ). All complexes were fully characterized analytically and spectroscopically. Furthermore, complexes 7 , 8b , 9a ·THF, 10a / b were also be characterized by single‐crystal X‐ray diffraction analyses.     

Mono- und Di-t-butylcyclopentadienyl-Carbonyl-Komplexe des Eisens und Molybdäns. Die Kristallstruktur von [Cp″Mo(Co)2]2 (Cp″ = n5-C5H3t-Bu2-1,3)

Mono- and Di-t-Butylcyclopentadienyl Carbonyl Complexes of Iron and Molybdenum — Crystal Structure of [Cp″Mo(CO)₂]₂ (Cp″ = n⁵-C₅H₃-t-Bu₂-1,3) Cothermolysis of M(CO)_m (M = Fe, m = 5; M = Mo, m = 6) with t-Bu-substituted cyclopentadienyls constitutes a simple synthesis of complexes of the type [Cp*M(CO)_n]₂ (CP* = n⁵-C₅H₃ (t-Bu), R, R = H, t-Bu; M = Fe, Mo; n = 2, 3). Each synthesis has an optimal temperature. The yield of Fe complexes decreases at temperatures above 130°C because of decomposition of the product. Optimal yields of [Cp*Mo(CO)₃]₂ are obtained at 130–140°C, whereas at 160°C complexes of the type [Cp*Mo(CO)₂]₂ with formal Mo? Mo triple bonds are obtained. The structure of the complexes is discussed on the basis of ¹H-, ¹³C-NMR, IR, and mass spectrometry. The structure of [Cp″Mo(CO)₂]₂ (Cp″ = n⁵-C₅H₃t-Bu₂-1,3) was determined by X-ray crystallography at ?95°C. It crystallises in the space group Pbca, with cell constants a = 1808.6(6), b = 1308.5(4), c = 2507.9(9) pm, Z = 8, R = 0.031 for 3794 reflections. The Mo? Mo bond length of 253.3 pm is very long for a formal triple bond. The Cp″? Mo? Mo? Cp″ axis is non-linear.     

Reaktionen von LiNPPh3 mit den Cyclooctatetraenid-Komplexen [Ln(C8H8)Cl(THF)2]2 von Cer und Samarium. Die Kristallstrukturen von [LiNPPh3]6, [Ln(C8H8)Li3Cl2(NPPh3)2(THF)3] (Ln = Ce,Sm) und [Li(THF)4][Sm(C8H8)2]

Reactions of LiNPPh₃ with the Cyclooctatetraenide Complexes [Ln(C₈H₈)Cl(THF)₂]₂ of Cerium and Samarium. Crystal Structures of [LiNPPh₃]₆, [Ln(C₈H₈)Li₃Cl₂(NPPh₃)₂(THF)₃] (Ln = Ce, Sm) and [Li(THF)₄][Sm(C₈H₈)₂] LiNPPh₃ reacts with the cyclooctatetraenide complexes [Ln(C₈H₈)Cl(THF)₂]₂ of cerium and samarium in tetrahydrofuran solution forming the phosphorane iminato complexes [Ln(C₈H₈)Li₃Cl₂(NPPh₃)₂(THF)₃]. According to crystal structure analyses these complexes show heterocubane structures under participation of the lanthanoid metal atom, of the three Li atoms as well as of the two Cl und the two N atoms of the NPPh₃^– groups. The crystal structure of LiNPPh₃ shows hexameric molecules with a Li₆N₆ polyhedron which is peripherally shielded by the phenyl groups. The structure of [Li(THF)₄][Sm(C₈H₈)₂], which has been isolated as a by-product, contains the samarium atom in a sandwichlike coordination by the two η⁸-C₈H₈^2– rings as it is also known from the corresponding anions with cerium and neodymium.     

Triorganoantimony(V) carboxylates: Synthesis, characterization and crystal structure of [Me3Sb(O2C-C5H4N)2] · H2O

Reactions of [R₃Sb(OPrⁱ)₂] with N-heterocylic carboxylic acids gave compounds of the type [R₃Sb(O₂C-Ar)₂] (1) (R = Me, Et, Prⁱ, Ph; Ar = 2-C₅H₄N, 2-C₉H₆N). The mono-bromo compound [Me₃Sb(Br)(O₂C-C₅H₄N)] (2) exists in equilibrium with [Me₃Sb(O₂C-C₅H₄N)₂] and [Me₃SbBr₂]. All new compounds have been characterized by IR and NMR (¹H and ¹³C{¹H}) spectral data. X-ray structural analysis of one example, [Me₃Sb(O₂C-C₅H₄N)₂], isolated as its monohydrate, revealed an essentially trigonal bipyramidal geometry for the antimony atom defined by three equilaterally disposed methyl groups and two oxygen atoms from monodentate carboxylate groups, in apical positions. The crystal structure is consolidated into a three-dimensional network by cooperative O-H?O, O-H?N and C-H?O interactions.     

Oxidative cleavage of the FeFe bond in [C5Me5Fe(CO)2]2 using ferrocinium ion: A facile route to the synthetically useful complexes [C5Me5Fe(CO)2(solvent)]+

Complexes of the type {Fp′(solvent)}⁺ PF₆^?, 3a–3d, (Fp′ = (η -C₅Me₅)Fe(CO)₂, solvent = THF, CH₃COCH₃, CH₃CN, or pyridine) are conveniently prepared by the reaction between Fp′₂ and Cp₂Fe⁺ PF₆ (Cp = η⁵-C₅H₅) in the solvent under ambient conditions. The complexes {Fp′L}⁺ PF₆^?, 3e–3g, (L = CO, PPh₃, P(OPh)₃) are readily prepared from {Fp′THF}⁺. Fp′H is formed by treatment of 3a with NaBH₄. Fp′SC(S)NMe₂ can be prepared from 3a or 3e and NaSC(S)NMe₂.     

Photochemische Reaktionen von Cyclopentadienylbis(ethen)rhodium mit Phenanthren,Acenaphthylen und Triphenylen,sowie ungewöhnlicher H-Austausch zwischen η2-koordinierten Phenanthren- bzw. Acenaphthylen- und η5-Cyclopentadienyl-Liganden

Photochemical Reactions of Cyclopentadienylbis(ethene)rhodium with Phenanthrene, Acenaphthylene, and Triphenylene, and Unusual H Exchange between η²-Coordinated Phenanthrene or Acenaphthylene and η⁵-Cyclopentadienyl Ligands During UV irradiation of [CpRh(C₂H₄)₂] (Cp = η⁵-C₅H₅) in hexane/ether in the presence of phenanthrene one ethene ligand is displaced by coordination of the 9,10 double bond of phenanthrene, and (η⁵-cyclopentadienyl) (η²-ethene)(η²-9,10-phenanthrene)rhodium ( 1 ) is formed. The analogous reaction in hexane in the presence of acenaphthylene occurs with formation of the complexes (η²-1,2-acenaphthylene)(η⁵-cyclopentadienyl)(²-ethene)rhodium 2 and bis(η²-1,2-acenaphthylene)(η⁵-cyclopentadienyl)rhodium 3 in which one and two ethene molecules of [CpRh(C₂H₄)₂], respectively, are substituted by η²-1,2-acenaphthylene. The irradiation of [CpRh(C₂H₄)₂] with triphenylene in hexane yields the compounds [CpRh(η⁴-1,2,3,4-triphenylene)] ( 4 ), [(CpRh)₂(μ-η³: η³-triphenylene)] ( 5 ), and [(CpRh)₃(μ₃-η²: η²: η²-triphenylene)] ( 6 ). Despite the partially very low yields the new complexes could be unequivocally characterized spectroscopically and in the case of 1 and 3 by X-ray structural analysis. The compounds 1 and 2 in solution reveal a novel dynamic behaviour; via an intramolecular C? H activation, exchange occurs between the protons of the η²-coordinated arene and the Cp ligand. The complex 4 in solution is fluxional, too.     

Übergangsmetall-substituierte Acylphosphane und Phosphaalkene. 22 [1] Insertionen von Hexafluoraceton in die PX-Bindung von Metallophosphanen des Typs (η5-C5Me5)(CO)2M?PX2 (M = Fe,Ru; X = Me3Si,Cl). Strukturbestimmung von (η5-C5Me5)(CO)2Fe?P(SiMe3)C(CF3)2(OSiMe3)

Transition Metal-substituted Acylphosphanes and Phosphaalkenes. 22. Insertions of Hexafluoroacetone into the PX-Bond of Metallophosphanes (η⁵-C₅Me₅)(CO)₂M? PX₂ (M = Fe, Ru; X = Me₃Si, Cl). Structure Determination of (η⁵-C₅Me₅)(CO)₂Fe? P(SiMe₃)C(CF₃)₂(OSiMe₃) Reaction of the metallophosphanes (η⁵-C₅Me₅)(CO)₂M? P(SiMe₃)₂ ( 1a : M = Fe; 1b : M = Ru) with hexafluoroacetone (HFA) afforded the complexes (η⁵-C₅Me₅)(CO)₂M? P(SiMe₃)C(CF₃)₂(OSiMe₃) ( 2a, b ). The attempted synthesis of a metallophosphaalkene from 2a by thermal elimination of hexamethyldisiloxane failed. The acid catalyzed hydrolysis of 2a afforded compound (η⁵-C₅Me₅) · (CO)₂Fe? P(H)C(CF₃)₂(OSiMe₃) ( 3 ). Hexafluoracetone and (η⁵-C₅Me₅)(CO)₂Fe? PCl₂ ( 4 ) under-went reaction to give the metallochlorophosphan (η⁵-C₅Me₅) · (CO)₂Fe? P(Cl)? O? C(CF₃)₂Cl ( 5 ). Constitutions and configurations of the compounds ( 2–5 ) were established by elemental analyses and spectroscopic data (IR, ¹H-, ¹³C, ¹⁹F-, ²⁹Si-, ³¹P-NMR, MS). The molecular structure of 2a was determined by x-ray diffraction analysis.     

Unerwartete Reduktion von [Cp*TaCl4(PH2R)] (R = But,Cy, Ad,Ph, 2,4,6‐Me3C6H2; Cp* = C5Me5) durch Reaktion mit DBU – Molekülstruktur von [(DBU)H][Cp*TaCl4] (DBU = 1,8‐Diazabicyclo[5.4.0]undec‐7‐en)

Unexpected Reduction of [Cp*TaCl₄(PH₂R)] (R = Bu^t, Cy, Ad, Ph, 2,4,6‐Me₃C₆H₂; Cp* = C₅Me₅) by Reaction with DBU – Molecular Structure of [(DBU)H][Cp*TaCl₄] (DBU = 1,8‐diazabicyclo[5.4.0]undec‐7‐ene) [Cp*TaCl₄(PH₂R)] (R = Bu^t, Cy, Ad, Ph, 2,4,6‐Me₃C₆H₂ (Mes); Cp* = C₅Me₅) react with DBU in an internal redox reaction with formation of [(DBU)H][Cp*TaCl₄] ( 1 ) (DBU = 1,8‐diazabicyclo[5.4.0]undec‐7‐ene) and the corresponding diphosphane (P₂H₂R₂) or decomposition products thereof. 1 was characterised spectroscopically and by crystal structure determination. In the solid state, hydrogen bonding between the (DBU)H cation and one chloro ligand of the anion is observed.     

Synthesis and characterization of complexes η5,η5-(CO)3Mn(C5H4-C5H4)(CO)2Fe-η1,η5-C5H4Mn(CO)3 and μ-(C≡C)[C5H4(CO)2Fe-η1,η5-C5H4Mn(CO)3]2

The complex η⁵,η⁵-(CO)₃Mn(C₅H₄-C₅H₄)(CO)₂Fe-η¹,η⁵-C₅H₄Mn(CO)₃ was synthesized by the reaction of η⁵-Cp(CO)₂Fe-η¹,η⁵-C₅H₄Mn(CO)₃ with BuⁿLi (THF, ?78 °C) and then with anhydrous CuCl₂. The complex μ-(C≡C)[C₅H₄(CO)₂Fe-η¹,η⁵-C₅H₄Mn(CO)₃]₂ was prepared by the reaction of η⁵-IC₅H₄(CO)₂Fe-η¹,η⁵-C₅H₄Mn(CO)₃ with Me₃SnC≡CSnMe₃ (2:1) in the presence of Pd(MeCN)₂Cl₂.     

Synthesis, NMR and quantum chemical studies of the [Cp3Rh3Se2]2+ clusters (Cp = η5-C5Me5, η5-C5Me4Et, η5-C5H3 t Bu2)

Reactions of [CpRhCl₂]₂ (Cp = η⁵-C₅Me₅ (Cp*), η⁵-C₅Me₄Et (Cp′), η⁵-C₅H₃ ^t Bu₂(Cp″)) with in situ generated H₂Se give triangular [Cp₃Rh₃Se₂]²⁺ clusters. These clusters were isolated as PF₆ salts and characterized with ESI-MS, ⁷⁷Se, ¹H NMR and DFT calculations. [Cp₃Rh₃Se₂] undergoes two reversible two-electron reduction steps. Quantum-chemical calculations reveal non-trivial bonding situation in the cluster core and changes in the hapticity of the Cp* ligand upon reduction. Crystal structure of [Cp ₃ ^* Rh₃Se₂][Re₂(μ-Cl)₃(CO)₆]Cl · 3.3H₂O has been determined.     

Facile access to the pnictocenium ions [Cp*ECl]+ (E = P, As) and [(Cp*)2P]+: chloride ion affinity of Al(OR(F))3

The pnictocenium salts [Cp*PCl]⁺[μCl]^? ( 1 a ), [Cp*PCl]⁺[ClAl(OR^F)₃]^? ( 1 b ), [Cp*AsCl]⁺[ClAl(OR^F)₃]^? ( 2 ), and [(Cp*)₂P]⁺[μCl]^? ( 3 ), in which Cp*=Me₅C₅, μCl=(^FRO)₃Al? Cl? Al(OR^F)₃, and OR^F=OC(CF₃)₃, were prepared by halide abstraction from the respective halopnictines with the Lewis superacid PhF→Al(OR^F)₃. 1 The X‐ray crystal structures of 1 a , 2 , and 3 established that in the half as well as in the sandwich cations the Cp* rings are attached in an η²‐fashion. By using one or two equivalents of the Lewis acid, the two new weakly coordinating anions [μCl]^? and [ClAl(OR^F)₃]^? resulted. They also stabilize the highly reactive cations in PhF or 1,2‐F₂C₆H₄ solution at room temperature. The chloride ion affinities (CIAs) of a range of classical strong Lewis acids were also investigated. The calculations are based on a set of isodesmic BP86/SV(P) reactions and a non‐isodesmic reference reaction assessed at the G3MP2 level.     

Pentamethylcyclopentadienyl-übergangsmetall-komplexe: X. Halbsandwichkomplexe des Fe und Ni als reaktive zwischenprodukte

Reaction of NiX₂·DME (X = Cl, Br; DME = 1,2-Dimethoxyethane) with Cp′Li (Cp′ = η⁵-C₅Me₅) in THF at ?10°C yields as intermediates dimeric halogeno complexes [Cp′NiX]₂ (I) as shown by mass spectroscopy. 1 reacts with neutral and anionic donor ligands viz. PPh₃ to Cp′Ni(PPh₃)X, 1,5-COD to [Cp′NiCOD]⁺, CpNa to CpCp′Ni and with COTLi₂ to (Cp′Ni)₂COT (COT = cyclooctatetraene). Analogously the reaction product from FeBr₂·DME and Cp′Li at ?80°C in THF is converted by CpNa to CpCp′Fe and by CO to Cp′Fe(CO)₂Br.     

Reaktionen der Cycloheptatrienylkomplexe [η7-C7H7W(CO)3]BF4 und η7-C7H7Mo(CO)2 Br mit Neutralliganden und die elektrochemische Reduktion des Wolframkomplexes

Reactions of the Cycloheptatrienyl Complexes [η⁷-C₇H₇W(CO)₃]BF₄ and η⁷-C₇H₇Mo(CO)₂Br with Neutral Ligands and the Electrochemical Reduction of the Wolfram Complex Compounds of the type [η⁷-C₇H₇M(CO)₂L][BF₄] (L = P(C₆H₅)₃, As(C₆H₅)₃, Sb(C₆H₅)₃ for M = W and L = N₂H₄ for M = Mo) were synthesized and characterisized. The iodide η⁷-C₇H₇W(CO)₂I reacts with the diphosphine ((C₆H₅)₂PCH₂)₂ to give the trihapto complex η³-C₇H₇ W(CO)₂I((C₆H₅)₂PCH₂)₂. In the case of η⁷-C₇H₇Mo(CO)₂ Br reaction with hydrazine leads to the substitution product [η⁷-C₇H₇ Mo(CO)₂N₂H₄]^⊕, which can be stabilized by large anions. The binuclear complex [C₇H₇W(CO)₃]₂ has been synthesized electrochemically.     

Synthesis and reactivity of [2]disilaniobocenophanes

The paramagnetic ansa-niobocene [(Me₂Si)₂(η⁵-C₅H₄)₂NbCl₂] (1) was obtained from the reaction of Li₂[(Me₂Si)₂(C₅H₄)₂] with [NbCl₄(thf)₂]. Further treatment with Li[AlH₄] yielded [(Me₂Si)₂(η⁵-C₅H₄)₂NbH₃] (3), which is prone to decomposition within a few days at room temperature both in solution and in the solid-state, thus affording primarily an insoluble black material. However, after heating or irradiation of a solution of 3 small quantities of the dimeric niobium hydride species, [(Me₂Si)₂{μ-(η¹:η⁵-C₅H₃)}(η⁵-C₅H₄)NbH]₂ (4), were isolated and characterized by X-ray diffraction.     

Organoruthenaborane Chemistry. X. The SM2-catalysed formation of [ l-(η6-C6Me6)-isocloso-RuB9H9], and some B-phenylamino derivatives. NMR and X-ray diffraction studies

The action of SMe₂ on the ten-vertex nido-ruthenaborane [6-(η⁶-C₆Me₆)RuB₉H_l3] ( 1 ) provides a high-yield route to the unsubstituted isocloso-ruthenaborane [1-(η⁶-C₆Me₆)RuB₉H₉] (2). The benzene analogue [1-(η⁶-C₆Me₆)RuB₉H₉] is prepared similarly. By contrast, reaction of (1) with PhNH₂ gives a variety of B-phenylamino isocloso derivatives, including orange crystals of [1-(η⁶-C₆Me₆)-2-(PhNH)-isocloso-1-RuB 9 H₈] ( 3 ), red-orange [1-(η⁶-C₆Me₆)-2,3-(PhNH)₂-isocloso-1-RuB₉H₇] ( 4 ) and dark-red [1-(η⁶-C₆Me₆)-5,6,7-(PhNH)₃-isocloso-1-RuB₉H₆] ( 5 ). Detailed ¹H and ¹¹B nmr properties of these various compounds are described. The structure of ( 3 ) has been established by a single-crystal X-ray diffraction study of the solvate [1-(η⁶-C₆Me₆)-2-(PhNH)-isocloso-1-RuB₉H₈] · 1/2 CH₂Cl₂; the crystals were monoclinic, space group C2/c, with a = 1895.1(3), b = 1556.6(3), c = 1716.4(3) pm, β = 104.37(1)° and z = 8.