Halbsandwichkomplexe des Iridiums mit Tetramethylcyclopentadienyl als Ringligand

Halfsandwich‐Type Complexes of Iridium with Tetramethylcyclopentadienyl as Ligand The iridium(I) complexes [(η⁵‐C₅HMe₄)Ir(C₂H₄)₂] ( 2 ) and [(η⁵‐C₅HMe₄)Ir(CO)₂] ( 4 ), which have been prepared from [IrCl(C₂H₄)₂]₂ or [IrCl(CO)₃]_n and LiC₅HMe₄, react with tosylchloride as well as with X₂ (X = Cl, Br, I) by oxidative addition to yield the corresponding iridium(III) compounds. Treating the complexes [(η⁵‐C₅HMe₄)IrX₂]_n ( 7 — 9 ) with CO or PR₃ leads to a cleavage of the halide bridges and to the formation of the mononuclear products [(η⁵‐C₅HMe₄)IrX₂(CO)] ( 10 , 11 ) and [(η⁵‐C₅HMe₄)IrX₂(PR₃)] ( 12 — 20 ), respectively. The molecular structure of [(η⁵‐C₅HMe₄)IrBr₂(PiPr₃)] ( 18 ) was determined crystallographically. The reactions of 8 (X = Br) and 9 (X = I) with Ph₂P(CH₂)_nPPh₂ (n = 1 or 2) afford the bridged compounds [{(η⁵‐C₅HMe₄)IrX₂}₂{μ‐Ph₂P(CH₂)_nPPh₂}] ( 21—23 ). The dihalide complexes [(η⁵‐C₅HMe₄)IrI₂(PPh₃)] ( 16 ) and [(η⁵‐C₅HMe₄)IrX₂(PiPr₃)] ( 17—19 ) react with hydride sources to give the dihydrido‐ and monohydrido derivatives [(η⁵‐C₅HMe₄)IrH₂(PPh₃)] ( 24 ) and [(η⁵‐C₅HMe₄)IrH(X)(PiPr₃)] ( 25—27 ). The related dimethyl and monomethyl compounds [(η⁵‐C₅HMe₄)Ir(CH₃)₂(PiPr₃)] ( 28 ) and [(η⁵‐C₅HMe₄)IrCH₃(I)(PiPr₃)] ( 29 ) have been obtained from the dihalide precursors 18 or 19 and CH₃MgI in the molar ratio of 1:2 or 1:1, respectively.     

Synthesis of homo- and heterodinuclear metal complexes with dimethylsilylene bridged unsymmetrical bis(cyclopentadienyl) ligand

The reaction of the dilithium salt Li₂[Me₂Si(C₅H₄)(C₅Me₄)] (2) of Me₂Si(C₅H₅)(C₅HMe₄) (1) with [MCl(C₈H₁₂)]₂ (M=Rh, Ir) and [RhCl(CO)₂]₂ afforded homodinuclear metal complexes [{Me₂Si(η⁵-C₅H₄)(η⁵-C₅Me₄)}{M(C₈H₁₂)}₂] (M=Rh: 3; M=Ir: 4) and [{Me₂Si(η⁵-C₅H₄)(η⁵-C₅Me₄)}Rh₂(CO)₂(μ-CO)] (5), respectively. The reaction of 2 with RhCl(CO)(PPh₃)₂ afforded a mononuclear metal complex [{Me₂Si(C₅HMe₄)(η⁵-C₅H₄)}Rh(CO)PPh₃] (6) leaving the C₅HMe₄ moiety intact. Taking advantage of the difference in reactivity of the two cyclopentadienyl moieties of 2, heterodinuclear complexes were prepared in one pot. Thus, the reaction of 2 with RhCl(CO)(PPh₃)₂, followed by the treatment with [MCl(C₈H₁₂)]₂ (M=Rh, Ir) afforded a homodinuclear metal complex [Rh(CO)PPh₃{(η⁵-C₅H₄)SiMe₂(η⁵-C₅Me₄)}Rh(C₈H₁₂)] (7) consisting of two rhodium centers with different ligands and a heterodinuclear metal complex [Rh(CO)(PPh₃){(η⁵-C₅H₄)SiMe₂(η⁵-C₅Me₄)}Ir(C₈H₁₂)] (8). The successive treatment of 2 with [IrCl(C₈H₁₂)]₂ and [RhCl(C₈H₁₂)]₂ provided heterodinuclear metal complex [Ir(C₈H₁₂){(η⁵-C₅H₄)SiMe₂(η⁵-C₅Me₄)}Rh(C₈H₁₂)] (9). The reaction of 2 with CoCl(PPh₃)₃ and then with PhCCPh gave a mononuclear cobaltacyclopentadiene complex [{Me₂Si(C₅Me₄H)(η⁵-C₅H₄)}Co(CPhCPhCPhCPh)(PPh₃)] (10). However, successive treatment of 2 with CoCl(PPh₃)₃, PhCCPh and [MCl(C₈H₁₂)]₂ in this order afforded heterodinuclear metal complexes [M(C₈H₁₂){(η⁵-C₅H₄)SiMe₂(η⁵-C₅Me₄)}Co(η⁴-C₄Ph₄)] (M=Rh: 11; M=Ir: 12) in which the cobalt center was connected to the C₅Me₄ moiety. Although the heating of 10 afforded a tetraphenylcyclobutadiene complex [{Me₂Si(C₅Me₄H)(η⁵-C₅H₄)}Co(η⁴-C₄Ph₄)] (13), in which the cobalt center was connected to the C₅H₄ moiety, simple heating of the reaction mixture of 2, CoCl(PPh₃)₃ and PhCCPh resulted in the formation of a tetraphenylcyclobutadiene complex [{Me₂Si(C₅H₅)(η⁵-C₅Me₄)}Co(η⁴-C₄Ph₄)] (14), in which the cobalt center was connected to the C₅Me₄ moiety. The mechanism of the cobalt transfer was suggested based on the electrophilicity of the formal trivalent cobaltacyclopentadiene moiety. In the presence of 1,5-cyclooctadiene, the reaction of 2 with CoCl(PPh₃)₃ provided a mononuclear cobalt cyclooctadiene complex [{Me₂Si(C₅Me₄H)(η⁵-C₅H₄)}Co(C₈H₁₂)] (15). The reaction of 15 with n-BuLi followed by the treatment with [MCl(C₈H₁₂)]₂ (M=Rh, Ir) afforded the heterodinuclear metal complexes of [Co(C₈H₁₂){(η⁵-C₅H₄)SiMe₂(η⁵-C₅Me₄)}M(C₈H₁₂)] (M=Rh: 16; M=Ir: 17). Treatment of 6 with Fe₂(CO)₉ at room temperature afforded a heterodinuclear metal complex [{Me₂Si(C₅HMe₄)(η⁵-C₅H₄)}{Rh(PPh₃)(μ-CO)₂Fe(CO)₃}] (18) in which the C₅HMe₄ moiety was kept intact. Treatment of dinuclear metal complex 5 with Fe₂(CO)₉ afforded a heterotrinuclear metal complex [{(η⁵-C₅H₄)SiMe₂(η⁵-C₅Me₄)}{Rh(CO)Rh(μ-CO)₂Fe(CO)₃}] (19) having a triangular metal framework. The crystal and molecular structures of 3, 11, 12, 18 and 19 have been determined by single-crystal X-ray diffraction analysis.     

Isolation of New Disilanylene-bridged Bis（cyclopentadienyl）tetracarbonyldiiron Complexes and Molecular Structure of [η^5, η^5-C5H4SiMe（SiMePh2）C5H4]Fe2（CO）2（μ-CO）2

1,2-Diphenyl-1,2-dimethyldisilanylene-bridged bis-cyclopentadienyl complex[η~5,η~5-C_5H_4PhMeSiSiMePh-C_5H_4]Fe_2(CO)_2(μ-CO)_2(1)was synthesized by a modified procedure,from which the trans-isomer 1b that was pre-viously difficult to obtain has been isolated for the first time.More interestingly,two new regio-isomers[η~5,η~5C_5H_4SiMe(SiMePh_2)C_5H_4]Fe_2(CO)_2(μ-CO)_2(2)and [η~5,η~5-C_5H_4Me_2SiSiPh_2C_5H_4]Fe_2(CO)_2(μ-CO)_2(3)were occa-sionally obtained during above process,the novel structures of which opened up new options for further study ofthis type of Si—Si bond-containing transition metal complexes.The molecular structure of 2 has been determinedby the X-ray diffraction method.     

2, 4‐Dimethylpenta‐1, 3‐dien‐ und 2, 4‐Dimethylpentadienyl‐Komplexe des Rhodiums und Iridiums

2, 4‐Dimethylpenta‐1, 3‐diene and 2, 4‐Dimethylpentadienyl Complexes of Rhodium and Iridium The complexes [(η⁴‐C₇H₁₂)RhCl]₂ ( 1 ) (C₇H₁₂ = 2, 4‐dimethylpenta‐1, 3‐diene) and [(η⁴‐C₇H₁₂)₂IrCl] ( 2 ) were obtained by interaction of C₇H₁₂ with [(η²‐C₂H₄)₂RhCl]₂ and [(η²‐cyclooctene)₂IrCl]₂, respectively. The reaction of 1 or 2 with CpTl (Cp = η⁵‐C₅H₅) yields the compounds [CpM(η⁴‐C₇H₁₂)] ( 3a : M = Rh; 3b : M = Ir). The hydride abstraction at the pentadiene ligand of 3a , b with Ph₃CBF₄ proceeds differently depending on the solvent. In acetone or THF the “half‐open” metallocenium complexes [CpM(η⁵‐C₇H₁₁)]BF₄ ( 4a : M = Rh; 4b : M = Ir) are obtained exclusively. In dichloromethane mixtures are produced which additionally contain the species [(η⁵‐C₇H₁₁)M(η⁵‐C₅H₄CPh₃)]BF₄ ( 5a : M = Rh; 5b : M = Ir) formed by electrophilic substitution at the Cp ring, as well as the η³‐2, 4‐dimethylpentenyl compound [(η³‐C₇H₁₃)Rh{η⁵‐C₅H₃(CPh₃)₂}]BF₄ ( 6 ). By interaction of 2, 4‐dimethylpentadienyl potassium with 1 or 2 the complexes [(η⁴‐C₇H₁₂)M(η⁵‐C₇H₁₁)] ( 7a : M = Rh; 7b : M = Ir) are generated which show dynamic behaviour in solution; however, attempts to synthesize the “open” metallocenium cations [(η⁵‐C₇H₁₁)₂M]⁺ by hydride abstraction from 7a , b failed. The new compounds were characterized by elemental analysis and spectroscopically, 4b and 5a also by X‐ray structure analysis.     

The Versatile Coordination Modes of Monophosphine‐o‐Carborane in the Formation of Iridium and Rhodium Complexes: Synthesis,Reactivity, and Characterization

Monophosphine‐o‐carborane has four competitive coordination modes when it coordinates to metal centers. To explore the structural transitions driven by these competitive coordination modes, a series of monophosphine‐o‐carborane Ir,Rh complexes were synthesized and characterized. [Cp*M(Cl)₂{1‐(PPh₂)‐1,2‐C₂B₁₀H₁₁}] (M=Ir ( 1 a ), Rh ( 1 b ); Cp*=η⁵‐C₅Me₅), [Cp*Ir(H){7‐(PPh₂)‐7,8‐C₂B₉H₁₁}] ( 2 a ), and [1‐(PPh₂)‐3‐(η⁵‐Cp*)‐3,1,2‐MC₂B₉H₁₀] (M=Ir ( 3 a ), Rh ( 3 b )) can be all prepared directly by the reaction of 1‐(PPh₂)‐1,2‐C₂B₁₀H₁₁ with dimeric complexes [(Cp*MCl₂)₂] (M=Ir, Rh) under different conditions. Compound 3 b was treated with AgOTf (OTf=CF₃SO₃^?) to afford the tetranuclear metallacarborane [Ag₂(thf)₂(OTf)₂{1‐(PPh₂)‐3‐(η⁵‐Cp*)‐3,1,2‐RhC₂B₉H₁₀}₂] ( 4 b ). The arylphosphine group in 3 a and 3 b was functionalized by elemental sulfur (1 equiv) in the presence of Et₃N to afford [1‐{(S)PPh₂}‐3‐(η⁵‐Cp*)‐3,1,2‐MC₂B₉H₁₀] (M=Ir ( 5 a ), Rh ( 5 b )). Additionally, the 1‐(PPh₂)‐1,2‐C₂B₁₀H₁₁ ligand was functionalized by elemental sulfur (2 equiv) and then treated with [(Cp*IrCl₂)₂], thus resulting in two 16‐electron complexes [Cp*Ir(7‐{(S)PPh₂}‐8‐S‐7,8‐C₂B₉H₉)] ( 6 a ) and [Cp*Ir(7‐{(S)PPh₂}‐8‐S‐9‐OCH₃‐7,8‐C₂B₉H₉)] ( 7 a ). Compound 6 a further reacted with nBuPPh₂, thereby leading to 18‐electron complex [Cp*Ir(nBuPPh₂)(7‐{(S)PPh₂}‐8‐S‐7,8‐C₂B₉H₁₀)] ( 8 a ). The influences of other factors on structural transitions or the formation of targeted compounds, including reaction temperature and solvent, were also explored.     

Stereoselectivity in Diphos Addition to Molybdenum Complex with Pyridine‐2‐thionate (pyS) and η3‐Methallyl Coordinated Ligands

The conformational isomers endo‐ and exo‐[Mo{η³‐C₃H₄(CH₃)}(η²‐pyS)(CO)(η²‐diphos)] (diphos: dppm = {bis(diphenylphosphino)methane}, 2 ; dppe = {1,2‐bis(diphenylphosphino)ethane}, 3 ) are prepared by reacting the double‐bridged pyridine‐2‐thionate (pyS) complex [Mo{η³‐C₃H₄(CH₃)}(CO)₂]₂(η¹:η²:μ‐pyS)₂, 1 with diphos in refluxing acetonitrile. Stereoselectivity of the methallyl, C₃H₄(CH₃), ligand improves the formation of the exo‐conformation of 2 and 3 . Orientations and spectroscopy of these complexes are discussed.     

Dicarbonyldi‐μ‐chloro‐cis,cis‐η4‐1,5‐cyclo­octa­dienedirhodium(I)

The title compound, dicarbonyl‐1κ²C‐di‐μ‐chloro‐1:2κ⁴Cl‐[cis,cis‐2(η⁴)‐1,5‐cyclo­octa­diene]­di­rhodium(I), [Rh₂Cl₂(C₈H₁₂)(CO)₂], consists of a di­chloro‐bridged dimer of rhodium, with a non‐bonded Rh?Rh distance of 3.284 (2) Å. One Rh atom is coordinated to two carbonyl ligands, while the other Rh atom is coordinated to the cyclo­octa­diene moiety.     

Decacarbonylbis(methylcyclopentadienyl)‐tetrahedro‐diiridiumdimolybdenum and decacarbonylbis(tetramethylcyclopentadienyl)‐tetrahedro‐diiridiumdimolybdenum dichloromethane hemisolvate

The two title compounds, [Mo₂Ir₂(C₆H₇)₂(CO)₁₀] and [Mo₂Ir₂(C₉H₁₃)₂(CO)₁₀]·0.5CH₂Cl₂, respectively, or collectively [Mo₂Ir₂(μ‐CO)₃(CO)₇(η⁵‐C₅H_5?nMe_n)₂] (n = 1 or 4), have a pseudo‐tetrahedral Mo₂Ir₂ core geometry, an η⁵‐­C₅H_5?nMe_n group ligating each Mo atom, bridging carbonyls spanning the edges of an MoIr₂ face and seven terminally bound carbonyl groups.     

Ligand Bridged Heterodinuclear Transition Metal Complexes – Syntheses,Structures and Electrochemical Investigations

The syntheses of the homo‐ and hererobimetallic compounds [L_n¹M(η⁵‐C₅H₄)CMe₂(η⁵‐C₉H₆)²ML_n] ( 2a‐5d ), [(C₉H₇)CMe₂(η⁵‐C₅H₄)Fe(η⁵‐C₅H₄)CMe₂(η⁵‐C₉H₆)²ML_n] ( 6a‐c ), and [(η⁵‐C₅H₄)CMe₂(η⁵‐C₉H₆)²ML_n]₂Fe ( 7a‐b ) are reported with ¹ML_n = Rh(cod) 2 , Ir(cod) 3 , Mn(CO)₃ 4 and FeCp 5 , ²ML_n = Rh(cod) a , Ir(cod) b , Mn(CO)₃ c and FeCp d , respectively. Crystal structures of 3a, 3b and 5c are described showing two different ligand conformations in form of two rotamers. The energetic difference between these both rotamers is insignificant small in the gas phase according to DFT calculations. The rotation barrier for the species has been determined to 23 kJ/mol. According to the absence of intermolecular interactions in the solid state, the preference for one of the conformers is deduced from packing effects. All complexes are investigated by cyclic voltammetry. The shift of the redox potentials with respect to the mononuclear reference systems is a suitable tool to determine intermetallic electronic interaction. For some compounds, the normal behaviour with an increasing separation of the redox potentials is observed. A second group of complexes shows the opposite behaviour with a decreasing in the potential differences. A mechanism of intramolecular catalytic oxidation is supposed for that species.     

Reactions of Cyclohexyl Isocyanide with η5‐Substituted Cyclo‐pentadienyl MoMo Triply Bonded Complexes. Crystal Structure of [Mo(CO)2(η5‐C5H4CO2CH3)]2(μ‐η2‐CNC6H11)

Reactions of one or two equiv. of cyclohexyl isocyanide in THF at room temperature with Mo?Mo triply bonded complexes [Mo(CO)₂(η⁵‐C₅H₄R)]₂ (R=COCH₃, CO₂CH₃) gave the isocyanide coordinated Mo? Mo singly bonded complexes with functionally substituted cyclopentadienyl ligands, [Mo(CO)₂(η⁵‐C₅H₄R)]₂(μ‐η²‐CNC₆H₁₁) ( 1a , R=COCH₃; 1b , R=CO₂CH₃) and [Mo(CO)₂(η⁵‐C₅H₄R)(CNC₆H₁₁)]₂ ( 2a , R=COCH₃; 2b , R=CO₂CH₃), respectively. Complexes 1a , 1b and 2a , 2b could be more conveniently prepared by thermal decarbonylation of Mo? Mo singly bonded complexes [Mo(CO)₃(η⁵‐C₅H₄R)]₂ (R=COCH₃, CO₂CH₃) in toluene at reflux, followed by treatment of the resulting Mo?Mo triply bonded complexes [Mo(CO)₂(η⁵‐C₅H₄R)]₂ (R=COCH₃, CO₂CH₃) in situ with cyclohexyl isocyanide. While 1a , 1b and 2a , 2b were characterized by elemental analysis and spectroscopy, 1b was further characterized by X‐ray crystallography.     

Transition‐Metal‐Mediated Cleavage of Fluoro‐Silanes under Mild Conditions

Si?F bond cleavage of fluoro‐silanes was achieved by transition‐metal complexes under mild and neutral conditions. The Iridium‐hydride complex [Ir(H)(CO)(PPh₃)₃] was found to readily break the Si?F bond of the diphosphine‐ difluorosilane {(o‐Ph₂P)C₆H₄}₂Si(F)₂ to afford a silyl complex [{[o‐(iPh₂P)C₆H₄]₂(F)Si}Ir(CO)(PPh₃)] and HF. Density functional theory calculations disclose a reaction mechanism in which a hypervalent silicon species with a dative Ir→Si interaction plays a crucial role. The Ir→Si interaction changes the character of the H on the Ir from hydridic to protic, and makes the F on Si more anionic, leading to the formation of H^δ+???F^δ? interaction. Then the Si?F and Ir?H bonds are readily broken to afford the silyl complex and HF through σ‐bond metathesis. Furthermore, the analogous rhodium complex [Rh(H)(CO)(PPh₃)₃] was found to promote the cleavage of the Si?F bond of the triphosphine‐monofluorosilane {(o‐Ph₂P)C₆H₄}₃Si(F) even at ambient temperature.     

Azido­[1,1′‐bis­(di­phenyl­phosphino)­ferrocene](penta­methyl­cyclo­penta­dienyl)­rhodium(III) hexa­fluoro­phosphate

In the title compound, azido‐2κN‐bis­[μ‐(1η⁵:2κP)‐di­phenyl­phosphino­cyclo­penta­dienyl][2(η⁵)‐penta­methyl­cyclo­penta­di­enyl]­iron(III)­rhodium(III) hexa­fluoro­phosphate, [{Rh(C₁₀H₁₅)(N₃)}{Fe(μ‐C₁₇H₁₄P)₂}]PF₆ or [FeRh(C₁₀H₁₅)(μ‐C₁₇H₁₄P)₂(N₃)]PF₆, the coordination sphere of Rh^III can be described as pseudo‐tetrahedral, composed of two P atoms from a 1,1′‐bis­(di­phenyl­phosphino)­ferrocene (dppf) ligand, an azido N atom and the centroid of the ring of a C₅Me₅ (Cp*) ligand. The two cyclo­penta­dienyl rings in the dppf moiety adopt an eclipsed conformation. The Rh⋯Fe distance is 4.340 (2) Å.     

High‐Resolution Photoelectron Imaging of IrB3−: Observation of a π‐Aromatic B3+ Ring Coordinated to a Transition Metal

In a high‐resolution photoelectron imaging and theoretical study of the IrB₃^? cluster, two isomers were observed experimentally with electron affinities (EAs) of 1.3147(8) and 1.937(4) eV. Quantum calculations revealed two nearly degenerate isomers competing for the global minimum, both with a B₃ ring coordinated with the Ir atom. The isomer with the higher EA consists of a B₃ ring with a bridge‐bonded Ir atom (C_s , ²A′), and the second isomer features a tetrahedral structure (C_3v , ²A₁). The neutral tetrahedral structure was predicted to be considerably more stable than all other isomers. Chemical bonding analysis showed that the neutral C_3v isomer involves significant covalent Ir?B bonding and weak ionic bonding with charge transfer from B₃ to Ir, and can be viewed as an Ir–(η³‐B₃⁺) complex. This study provides the first example of a boron‐to‐metal charge‐transfer complex and evidence of a π‐aromatic B₃⁺ ring coordinated to a transition metal.     

Synthetic and structural Studies on Organomolybdenum-Bismuth Halide Complexes

The reactions between either BiBr₂Ph and Na/K[Mo(CO)₃(η? C₅H₅)], [BiPh{Mo(CO)₃(η? C₅H₅)}₂] and BiBr₂Ph, or BiBr₃ and BiPh₃ and [Bi{Mo(CO)₃(η? C₅H₅)}₃] afford the complex [BiBrPh{Mo(CO)₃(η? C₅H₅)}] 1 which has been characterised by X-ray crystallography. Complex 1 comprises a bismuth centre bonded to a bromine atom, a phenyl group and a Mo(CO)₃(η? C₅H₅) fragment together with a longer secondary intermolecular interaction between a bromine from an adjacent molecule which results in a one-dimensional polymeric structure. Addition of a source of bromide anion to 1 affords the anionic complex [BiBr₂Ph{Mo(CO)₃(η? C₅H₅)}]^? 3 ^? although prolonged reaction results in the complex [BiBr₂{Mo(CO)₃(η? C₅H₅)}₂]^? 5 ^? which was characterised by X-ray crystallography as its [Ph₄P]⁺ salt. Complex 5 ^? comprises a mononuclear bismuth centre bonded to two bromine atoms and two Mo(CO)₃(η? C₅H₅) fragments in a geometry which lies between equatorially vacant trigonal bipyramidal and tetrahedral. The complex [PPN]₂[Bi₂Cl₆{Mo(CO)₃(η? C₅H₅)}₂] 8 has also been synthesised and characterised by X-ray crystallography. A dimeric dianion is observed which can be viewed as two edge-shared square-based pyramids with chlorine atoms in the basal planes and Mo(CO)₃(η? C₅H₅) fragments in the apical positions on opposite sides of the Bi₂Cl₆ plane.     

[μ‐1κ2O,O′:2(η5)‐Cyclopentadienylcarboxylato][2(η5)‐diphenylphosphinocyclopentadienyl]bis[1,1(η5)‐tetramethylcyclopentadienyl]iron(II)titanium(III)

Reacting stoichiometric amounts of 1‐(diphenylphosphino)ferrocene­carboxylic acid and [Ti(η⁵‐C₅HMe₄)₂(η²‐Me₃SiC[triple‐bond]CSiMe₃)] produced the title carboxyl­atotitanocene complex, [{μ‐1κ²O,O′:2(η⁵)‐C₅H₄CO₂}{2(η⁵)‐C₅H₄P(C₆H₅)₂}{1(η⁵)‐C₅H(CH₃)₄}₂Fe^IITi^III] or [FeTi(C₉H₁₃)₂(C₆H₄O₂)(C₁₇H₁₄P)]. The angle subtended by the Ti/O/O′ plane, where O and O′ are the donor atoms of the κ²‐carboxy­late group, and the plane of the carboxyl‐substituted ferrocene cyclo­penta­dienyl is 24.93 (6)°.     

Synthesis and Characterization of Heterobimetallic Tantalum–Rhodium and Tantalum–Iridium Complexes Connected by a Tantalacyclopentadiene Fragment

We report the synthesis of heterobimetallic Ta–Rh and Ta–Ir complexes bridged by a 2,5‐di‐tert‐butyltantalacyclopentadiene fragment. A mononuclear 2,5‐di‐tert‐butyltantalacyclopentadiene complex 2 was prepared by the reaction of (η²‐Me₃SiC≡CSiMe₃)TaCl₃(dme) ( 1 ) with excess amounts of 3,3‐dimethylbut‐1‐yne in the presence of AlCl₃. The tantalacyclopentadiene moiety of complex 2 served as a η⁴‐diene unit for coordinating the Rh and Ir centers; treatment of 2 with [M(μ‐Cl)(cod)]₂ (M = Rh and Ir; cod = cycloocta‐1,5‐diene) in toluene gave TaRh(μ‐C₄H₂^tBu₂)Cl₄(cod) ( 3 ) and [TaIr(μ‐C₄H₂^tBu₂)Cl₄]₂ ( 5 ), respectively. The X‐Ray diffraction study of 3 revealed a dative bond from an electron‐rich Rh toward an electron‐deficient Ta. Upon dissolving 3 in THF, [(thf)TaRh(μ‐C₄H₂^tBu₂)Cl₃]₂(μ‐Cl)₂ ( 4 ) was isolated together with free cycloocta‐1,5‐diene. When complex 5 was treated with 1,2‐bis‐(diphenylphosphino)ethane (dppe), a monomeric Ta–Ir complex, TaIr(μ‐C₄H₂^tBu₂)Cl₄(dppe) ( 6 ), was isolated. Ta–Rh and Ta–Ir heterobimetallic complexes 3 and 6 were reduced by a two‐electron process upon reaction with 2,3,5,6‐tetramethyl‐1,4‐bis(trimethylsilyl)‐1,4‐dihydropyrazine ( 7a : Si‐Me₄‐DHP) or 2,5‐dimethyl‐1,4‐bis(trimethylsilyl)‐1,4‐dihydropyrazine ( 7b : Si‐Me₂‐DHP) to afford the corresponding complexes TaM(μ‐C₄H₂^tBu₂)Cl₂(L) ( 8 : M = Rh, L = cod; 9 : M = Ir, L = dppe), where the metallacycle moiety was assigned to have a tantalacyclopentadiene fragment with a large contribution of a tantalacyclopentatriene canonical form.     

Der Dihydridoiridium(III)‐Komplex [IrH2Cl(PiPr3)2] als Molekülbaustein für unsymmetrische Rhodium–Iridiumund Iridium–Iridium‐Zweikernverbindungen

The Dihydridoiridium(III) Complex [IrH₂Cl(P i Pr₃)₂] as a Molecular Building Block for Unsymmetrical Binuclear Rhodium–Iridium and Iridium–Iridium Compounds The title compound [IrH₂Cl(PiPr₃)₂] ( 3 ) reacts with the chloro‐bridged dimers [RhCl(PiPr₃)₂]₂ ( 1 ) and [IrCl(C₈H₁₄)(PiPr₃)]₂ ( 5 ) by cleavage of the Cl‐bridges to give the unsymmetrical binuclear complexes 4 and 6 with Rh(μ‐Cl)₂Ir and Ir(μ‐Cl)₂Ir as the central building block. The reactions of 3 with the bis(cyclooctene) and (1,5‐cyclooctadiene) compounds [MCl(C₈H₁₄)₂]₂ ( 7 , 8 ) and [MCl(η⁴‐C₈H₁₂)]₂ ( 9 , 10 ) (M = Rh, Ir) occur analogously and afford the rhodium(I)‐iridium(III) and iridium(I)‐iridium(III) complexes 11 – 14 in 70–80% yield. Treatment of [(η⁴‐C₈H₁₂)M(μ‐Cl)₂IrH₂(PiPr₃)₂] ( 13 , 14 ) with phenylacetylene leads to the formation of the substitution products [(η⁴‐C₈H₁₂)M(μ‐Cl)₂IrH(C≡CPh)(PiPr₃)₂] ( 15 , 16 ) without changing the central molecular core. Similarly, the compound [(η⁴‐C₈H₁₂)Rh(μ‐Br)₂IrH(C≡CPh)(PiPr₃)₂] ( 18 ) has been prepared; it was characterized by X‐ray crystallography.     

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.     

Activation of Open‐Cage Fullerenes with Ruthenium Carbonyl Clusters

Reactions of the open‐cage fullerene C₆₃NO₂(Py)(Ph)₂ ( 1 ) with [Ru₃(CO)₁₂] produce [Ru₃(CO)₈(μ,η⁵‐C₆₃NO₂(Py)(Ph)₂)] ( 2 ), [Ru₂H(CO)₃(μ,η⁷‐C₆₃N(Py)(Ph)(C₆H₄))] ( 3 ), and [Ru(CO)(Py)₂₍η³‐C₆₃NO₂(Py)(Ph)₂)] ( 4 ), in which the orifice sizes are modified from 12 to 8, 11, and 15‐membered ring, through ruthenium‐mediated C?O and C?C bond activation and formation.     

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.