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⁺     

[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)°.     

Tandem β‐Boration/Arylation of α,β‐Unsaturated Carbonyl Compounds by Using a Single Palladium Complex To Catalyse Both Steps

Diphenyl(3‐methyl‐2‐indolyl)phosphine (C₉H₈NPPh₂, 1 ) gives stable dimeric palladium(II) complexes that contain the phosphine in P,N‐bridging coordination mode. On treating 1 with [Pd(O₂CCH₃)₂], the new complexes [Pd(μ‐C₉H₇NPPh₂)(NCCH₃)]₂ ( 2 ) or [Pd(μ‐C₉H₇NPPh₂)(μ‐O₂CCH₃)]₂ ( 3 ) were isolated, depending on the solvent used, acetonitrile or toluene, respectively. Further reaction of 3 with the ammonium salt of 1 led to the substitution of one carboxylate ligand to afford [Pd(μ‐C₉H₇NPPh₂)₃(μ‐O₂CCH₃)] ( 4 ), in which the bimetallic unit is bonded by three C₉H₇NPPh₂^? moieties and one carboxylate group. Using this methodology, [Pd₂(μ‐C₆H₄PPh₂)₂(μ‐C₉H₇NPPh₂)(μ‐O₂CCX₃)] (X=H ( 7 ); X=F ( 8 )) were synthesised from the ortho‐metalated compounds [Pd(C₆H₄PPh₂)(μ‐O₂CCX₃)]₂ (X=H ( 5 ); X=F ( 6 )). Complexes 3 , 4 , 7 , and 8 have been found to be active in the catalytic β‐boration of α,β‐unsaturated esters and ketones under mild reaction conditions. Hindrance of the carbonyl moiety has an influence on the reaction rate, but quantitative conversion was achieved in many cases. More remarkably, when aryl bromides were added to the reaction media, complex 7 induced a highly successful consecutive β‐boration/cross‐coupling reaction with dimethyl acrylamide as the substrate (99 % conversion, 89 % isolated yield).     

Synthesis of Cationic 2,4-Dimethylpenta-2,4-dienylruthenium Complexes. Crystal Structure of Carbonyl(η4-cyclohexa-1,3-diene)-(η5-2,4-dimethylpenta-2,4-dienyl)ruthenium Tetrafluoroborate

The complex [Ru(η⁵-C₇H₁₁)₂H]BF₄ (C₇H₁₁ = 2,4-dimethylpenta-2,4-dienyl) is highly reactive towards two- and six-electron ligands. e.g. giving with CO complex [RuCO(η⁴-C₇H₁₂)(η⁵-C₇H₁₁)]BF₄. The 2,4-dimethylpenta-1,3-diene ligand (C₇H₁₂) of the latter complex is readily displaced giving, e.g. with excess cyclohexa-1,3-diene (C₆H₈) complex [RuCO(η⁴-C₆H₈)(η⁵-C₇H₁₁)]BF₄. These reactions provide a convenient entry into monopentadienylruthenium chemistry.     

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.     

The reactions of [Co(η-C5H5)(CO)(L)] (L = R3P or RNC) with carbon disuphide and organoisothiocyanates

The reactions of [Co(η-C₅H₅)(CO)(PR₃)] or [Co(η-C₅GH₅)(CO)₂]/R₃P mixtures (R = alkyl or aryl) with CS₂ in refluxing CS₂ or CS₂/toluene gives rise to [Co(η-C₅H₅)(PR₃)(CS)], [Co(η-C₅H₅)(PR₃)(CS₂)], [Co(η-C₅H₅)(PR₃)(CS₃)], and [Co₃(η-C₅H₅)₃ (CS)(S)] in reasonable yields. The corresponding reactions using PhNCS give [Co(η-C₅H₅)(PPh₃)(PhNCS)] and a polymeric species which appears to be [Co₄(η-C₅H₅)₄ (PhNCS)]. Similar products are obtained with [Co(η-C₅H₅)(CO)(CNR)] or [Co(η0C₅H₅)(CO)₂]/RNC mixtures.     

New series of platinum group metal complexes bearing η- and η-cyclichydrocarbons and Schiff base derived from 2-acetylthiazole: Syntheses and structural studies

The mononuclear complexes [(η⁶-arene)Ru(ata)Cl]PF₆ {ata = 2-acetylthiazole azine; arene = C₆H₆ [(1)PF₆]; p-ⁱPrC₆H₄Me [(2)PF₆]; C₆Me₆ [(3)PF₆]}, [(η⁵-C₅Me₅)M(ata)]PF₆ {M = Rh [(4)PF₆]; Ir [(5)PF₆]} and [(η⁵-Cp)Ru(PPh₃)₂Cl] {η⁵-Cp = η⁵-C₅H₅ [(6)PF₆]; η⁵-C₅Me₅ (Cp^*) [(7)PF₆]; η⁵-C₉H₇ (indenyl); [(8)PF₆]} have been synthesised from the reaction of 2-acetylthiazole azine (ata) and the corresponding dimers [(η⁶-arene)Ru(μ-Cl)Cl]₂, [(η⁵-C₅Me₅)M(μ-Cl)Cl]₂, and [(η⁵-Cp)Ru(PPh₃)₂Cl], respectively. In addition to these complexes a hydrolysed product (9)PF₆, was isolated from complex (4)PF₆ in the process of crystallization. All these complexes are isolated as hexafluorophosphate salts and characterized by IR, NMR, mass spectrometry and UV–Vis spectroscopy. The molecular structures of [2]PF₆ and [9]PF₆ have been established by single-crystal X-ray structure analyses.     

[Co(g5‐Me5C5)(g3‐tBu2PPCH–CH3)] aus [Co(g5‐Me5C5)(g2‐C2H4)2] und tBu2P–P=P(Me)tBu2

Coordination Chemistry of P‐rich Phosphanes and Silylphosphanes. XVII [1] [Co(g⁵‐Me₅C₅)(g³‐^tBu₂PPCH–CH₃)] from [Co(g⁵‐Me₅C₅)(g²‐C₂H₄)₂] and ^tBu₂P–P=P(Me)^tBu₂ [Co(η⁵‐Me₅C₅)(η³‐^tBu₂PPCH–CH₃)] 1 is formed in the reaction of [Co(η⁵‐Me₅C₅)(η²‐C₂H₄)₂] 2 with ^tBu₂P–P 4 (generated from ^tBu₂P–P=P(Me)^tBu₂ 3 ) by elimination of one C₂H₄ ligand and coupling of the phosphinophosphinidene with the second one. The structure of 1 is proven by ³¹P, ¹³C, ¹H NMR spectra and the X‐ray structure analysis. Within the ligand ^tBu₂P¹P²C¹H–CH₃ in 1 , the angle P1–P2–C1 amounts to 90°. The Co, P1, P2, C1 atoms in 1 look like a „butterfly”︁. The reaction of 2 with a mixture of ^tBu₂P–P=P(Me)^tBu₂ 3 and ^tBu–C?P 5 yields [Co(η⁵‐Me₅C₅){η⁴‐(^tBuCP)₂}] 6 and 1 . While 6 is spontaneously formed, 1 appears only after complete consumption of 5 .     

Mononuclear Complexes of Platinum Group Metals Containing η6‐ and η5‐Cyclic Π‐Perimeter Hydrocarbon and Pyridylpyrazolyl Derivatives: Syntheses and Structural Studies

Piano‐stool‐shaped platinum group metal compounds, stable in the solid state and in solution, which are based on 2‐(5‐phenyl‐1H‐pyrazol‐3‐yl)pyridine ( L ) with the formulas [(η⁶‐arene)Ru( L )Cl]PF₆ {arene = C₆H₆ ( 1 ), p‐cymene ( 2 ), and C₆Me₆, ( 3 )}, [(η⁶‐C₅Me₅)M( L )Cl]PF₆ {M = Rh ( 4 ), Ir ( 5 )}, and [(η⁵‐C₅H₅)Ru(PPh₃)( L )]PF₆ ( 6 ), [(η⁵‐C₅H₅)Os(PPh₃)( L )]PF₆ ( 7 ), [(η⁵‐C₅Me₅)Ru(PPh₃)( L )]PF₆ ( 8 ), and [(η⁵‐C₉H₇)Ru(PPh₃)( L )]PF₆ ( 9 ) were prepared by a general method and characterized by NMR and IR spectroscopy and mass spectrometry. The molecular structures of compounds 4 and 5 were established by single‐crystal X‐ray diffraction. In each compound the metal is connected to N1 and N11 in a k² manner.     

The synthesis, structure and reactivity of aldehyde substituted η-allylic complexes of molybdenum

Reaction of cis-[Mo(NCMe)₂(CO)₂(η⁵-L)][BF₄] (L=C₅H₅ or C₅Me₅) with 1-acetoxybuta-1,3-diene gives the cationic complexes [Mo{η⁴-syn-s-cis-CH₂CHCHCH(OAc)}(CO)₂(η⁵-L)][BF₄], which, on reaction with aqueous NaHCO₃/CH₂Cl₂, afford good yields of the anti-aldehyde substituted complexes [Mo{η³-exo-anti-CH₂CHCH(CHO)}(CO)₂(η⁵-L)] 2 (L=C₅Me₅), 4 (L=C₅H₅)]. The corresponding η⁵-indenyl substituted complex 5 was prepared by protonation (HBF₄·OEt₂) of [Mo(η³-C₃H₅)(CO)₂(η⁵-C₉H₇)] followed by addition of CH₂=CHCH=CH(OAc) and hydrolysis (aq. NaHCO₃/CH₂Cl₂). An X-ray crystallographic study of complex 2 confirmed the structure and showed that there is a contribution from a zwitterionic form involving donation of electron density from the molybdenum to the aldehyde carbonyl group. Treatment of 2 and 4, in methanol solution, with NaBH₄ afforded the alcohols [Mo{η³-exo-anti-CH₂CHCHCH₂(OH)}(CO)₂(η⁵-L)] [6 (L=C₅H₅), 8 (L=C₅Me₅)]; however, prolonged (30 h) reaction with NaBH₄/MeOH surprisingly gave good yields of the methoxy-substituted complexes [Mo{η³-exo-anti-CH₂CHCHCH₂(OMe)}(CO)₂(η⁵-L)] [7 (L=C₅H₅), 9 (L=C₅Me₅)], the structure of 7 being confirmed by single crystal X-ray crystallography. This methoxylation reaction can be explained by coordination of the hydroxyl group present in 6 and 8 onto B₂H₆ to form the potential leaving group HOBH₃⁻, which on ionisation affords [Mo(η⁴-exo-buta-1-3-diene)(CO)₂(η⁵-L)]⁺ which is captured by reaction with OMe⁻. Complex 8 is also formed in good yield on reaction of 2 with HBF₄·OEt₂ followed by treatment of the resulting cation [Mo{η⁴-exo-s-cis-syn-CH₂CHCHCH(OH)}(CO)₂(η⁵-C₅Me₅)][BF₄] with Na[BH₃CN]. Reaction of 4 with the Grignard reagents MeMgI, EtMgBr or PhMgCl afforded moderate yields of the alcohols [Mo{η³-exo-anti-CH₂CHCHCH(OH)R}(CO)₂(η⁵-C₅H₅)] [11 (R=Me), 12 (R=Et), 13 (R=Ph)]. Similarly, treatment of 2 with MeLi gave the corresponding alcohol 14. An attempt to carry out the Oppenauer oxidation [Al(OPr′)₃/Me₂CO] of 11 resulted in an elimination reaction and the formation of the η³-s-pentadienyl complex [Mo{η³-exo-anti-CH₂CHCH(CHCH₂)}(CO)₂(η⁵-C₅H₅)], which was structurally identified by X-ray crystallography. Interestingly, oxidation of 6 with [Bu₄ⁿN][RuO₄]/morpholine-N-oxide affords the aldehyde complex, 4 in good yield. Finally, reaction of 11 with [NO][BF₄] followed by addition of Na₂CO₃ affords the fur-3-ene complex [Mo{η²-

(H)Me}(CO)(NO)(η⁵-C₅H₅)].     

[(8a,9,9a‐η)‐9‐(η5‐Cyclopentadienyl)‐9‐nickelafluorenyl](η5‐pentamethylcyclopentadienyl)nickel(II)

The title compound, [Ni₂(C₅H₅)(C₁₀H₁₅)(C₁₂H₈)] or [Ni(C₁₀H₁₅){Ni(C₅H₅)(C₁₂H₈)}], is a rare example (and the first obtained from nickelafluorenyllithium) of an analogue of nickelocene in which the central Ni atom is coordinated to one pentamethylcyclopentadienyl ring and one nickelafluorenyl ring. Both rings lie almost parallel to one another: the dihedral angle between the planes which include these rings is 4.4 (1)°. Slip parameter analysis indicates that the bonding mode of the central Ni atom to the nickelacyclic ring is between η³ and η⁵. Two‐dimensional layers of molecules are formed by C—H...π interactions.     

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.     

Aqua­nitro(α,β,γ,δ‐tetra­phenyl­porphy­rinato)­cobalt(III) N,N‐di­methyl­form­amide disolvate

In the title compound, [Co(tpp)(NO₂)(H₂O)]·2dmf or [Co(C₄₄H₂₈N₄)(NO₂)(H₂O)]·2C₃H₇NO, a distorted octahedral Co^III complex shows an orientational disorder such that the positions of the nitro and aqua ligands are exchanged. As a result, the averaged structure has an inversion centre at the Co atom. The di­methyl­form­amide mol­ecule also has a positional disorder.     

The effect of counter‐ions on the supra­molecular arrangement of (benzonitrile)[1,2‐bis(diphenylphosphino)ethane](η5‐cyclo­penta­dienyl)­iron(II) cations

The title compound, [1,2‐bis(diphenylphosphino)ethane](η⁵‐cyclo­penta­dienyl)(4‐nitro­benzonitrile)iron(II) iodide, [Fe(η⁵‐C₅H₅)(C₇H₄N₂O₂)(C₂₆H₄P₂)]I, crystallizes in the non‐centrosymmetric space group Cc, which is a promising result for obtaining quadratic non‐linear optical properties. However, the packing shows that the iodide counter‐ion promotes the cancellation of almost all the dipoles, resulting in a supra­molecular motif of cationic chains aligned in opposite directions making an angle of 35.2°. The use of PF₆⁻ as counter‐ion induces the crystallization of the complex in a centrosymmetric space group. These results show that the introduction of different counter‐ions, of different size and geometry, allows specific and directional inter­molecular inter­actions that can determine the formation of a particular type of crystal packing.     

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.     

Ring Contraction by NHC‐Induced Pnictogen Abstraction

The reaction of [Cp′′′Co(η⁴‐P₄)] ( 1 ) (Cp′′′=1,2,4‐tBu₃C₅H₂) with ^MeNHC (^MeNHC=1,3,4,5‐tetramethylimidazol‐2‐ylidene) leads through NHC‐induced phosphorus cation abstraction to the ring contraction product [(^MeNHC)₂P][Cp′′′Co(η³‐P₃)] ( 2 ), which represents the first example of an anionic CoP₃ complex. Such NHC‐induced ring contraction reactions are also applicable for triple‐decker sandwich complexes. The complexes [(Cp*Mo)₂(μ,η^6:6‐E₆)] ( 3 a , 3 b ) (Cp*=C₅Me₅; E=P, As) can be transformed to the complexes [(^MeNHC)₂E][(Cp*M)₂(μ,η^3:3‐E₃)(μ,η^2:2‐E₂)] ( 4 a , 4 b ), with 4 b representing the first structurally characterized example of an NHC‐substituted As^I cation. Further, the reaction of the vanadium complex [(Cp*V)₂(μ,η^6:6‐P₆)] ( 5 ) with ^MeNHC results in the formation of the unprecedented complexes [(^MeNHC)₂P][(Cp*V)₂(μ,η^6:6‐P₆)] ( 6 ), [(^MeNHC)₂P][(Cp*V)₂(μ,η^5:5‐P₅)] ( 7 ) and [(Cp*V)₂(μ,η^3:3‐P₃)(μ,η^1:1‐P{^MeNHC})] ( 8 ).     

Polymerisations of -caprolactone and β-butyrolactone with Zn-, Al- and Mg-based organometallic complexes

The reaction of EtAlCl₂ with 1,2-{LiN(PMes₂)}₂C₆H₄ (Mes = 2,4,6-Me₃C₆H₂) and of butyloctylmagnesium with 1,2-{NH(PPh₂)}₂C₆H₄ gave [AlEt(1,2-{N(PMes₂)}₂C₆H₄-κ²N,N′)(THF)] (1) and [Mg(1,2-{N(PPh₂)}₂C₆H₄-κ²N,N′)(THF)₂] (2), respectively. Complexes 1 and 2 were fully characterised by NMR (¹H, ¹³C, ³¹P) and IR spectroscopy and mass spectrometry. Complexes 1 and 2 were employed as catalysts in the polymerisation of -caprolactone, which produced polymers with a narrow molecular weight distribution. For comparison the polymerisations of -caprolactone and β-butyrolactone were carried out with the Zn complex [ZnPr{1-N(PMes₂)-2-N(PHMes₂)C₆H₄-κ²N,N′}] (3) as catalyst, which produced polymers with narrow molecular weight distributions and high molecular weights.     

η-Alkynyl and vinylidene transition metal complexes: 10. Reaction of the metal-acetylide [(η-C5H5)(CO)(NO)W---CC---C(CH3)3]Li with 1,2-diiodoethane as electrophile and with various nucleophiles

Treatment of the η¹-acetylide complex [(η⁵-C₅H₅)(CO)(NO)W---CC---C(CH₃)₃]Li (4) with 1,2-diiodoethane in THF at −78 °C, followed by the addition of Li---CC---R [R=C(CH₃)₃, C₆H₅, Si(CH₃)₃, 6a–6c] or n-C₄H₉Li and protonation with H₂O, afforded the corresponding oxametallacyclopentadienyl complexes (η⁵-C₅H₅)W(I)(NO)[η²-O=C(CC---R)CH=CC(CH₃)₃] (7a–7c), 8c and (η⁵-C₅H₅)W(I)(NO)[η²-O=C(n-C₄H₉)CH=CC(CH₃)₃] (9). The formation of these metallafuran derivatives is rationalized by the electrophilic attack of 1,2-diiodoethane onto the metal center of 4 to form first the neutral complex [(η⁵-C₅H₅)(I)(CO)(NO)W---CC---C(CH₃)₃] (5). Subsequent nucleophilic addition of Li---CC---R 6a–6c or n-C₄H₉Li and a reductive elimination step followed by protonation leads to the products 7a–7c and 9. One reaction intermediate could be trapped with CF₃SO₃CH₃ and characterized by a crystal structure analysis. The identity of another intermediate was established by infrared spectroscopic data. The oxametallacyclopentadienyl complex 10 forms in the presence of excess 1,2-diiodoethane through an alternative pathway and crystallizes as a clathrate containing iodine.     

Synthesis,Structure, and Redox Properties of [{(η5-C5H5)Co(S2C6H4)}2Mo(CO)2], a Novel Metalladithiolene Cluster

Metal–metal bond formation by a cobaltadithiolene complex was observed for the first time in the reaction of [Co(η⁵-C₅H₅)(S₂C₆H₄)] with [Mo(CO)₃(py)₃] and BF₃ to give the Co-Mo-Co cluster 1 . Cyclic voltammetry reveals that 1 undergoes two one-electron reduction steps at the Co centers, which is indicative of transmission of the Co−Co electronic interaction through the Mo center.     

1,2-Diphosphaferrocene als Liganden in Übergangsmetallkomplexen. Röntgenstrukturanalyse von [(η5-1,3-tBu2C5H3){η5-1,2-[Co2(CO)6]-3,4-(Me3SiO)2-5-(Me3Si)P2C3}]

1,2-Diphosphaferrocenes as Ligands in Transition Metal Complexes. X-Ray Structure Analysis of [(η⁵-1,3-tBu₂C₅H₃){η⁵-1,2-[Co₂(CO)₆]-3,4-(Me₃SiO)₂-5-(Me₃Si)P₂C₃}] Reaction of metallo-1,2-diphosphapropene (η⁵-tBuC₅H₄)(CO)₂Fe? P(SiMe₃)? P?C(SiMe₃)₂ with (Z-cyclooctene)Cr(CO)₅ afforded the pentacarbonylchromium adduct of a 1,2-diphosphaferrocene [(η⁵-tBuC₅C₅H₄){η⁵-1-[Cr(CO)₅]-3,4-(Me₃SiO)₂-5-(Me₃Si)P₂C₃}Fe] ( 1 c ). Diphosphaferrocene [(η⁵-tBuC₅H₄){η⁵-3,4-(Me₃SiO)₂-5-(Me₃Si)P₂C₃}Fe] ( 2 c ) was formed when (η⁵-tBuC₅H₄)(CO)₂FeBr was treated with (Me₃Si)₂P? P?C(SiMe₃)₂ in toluene at 60°C. Photolysis of molybdenum- and tungsten hexacarbonyl in the presence of [(η⁵-1,3-tBu₂C₅H₃){η⁵-3,4-(Me₃SiO)₂-5-(Me₃Si)P₂C₃}Fe] ( 2 b ) gave the pentacarbonylmetal adducts 8 (M = Mo) and 9 (M = W), respectively. A corresponding manganese derivative resulted from the photochemical reaction of 2 b and (MeC₅H₄)Mn(CO)₃. Treatment of 2 b with Co₂(CO)₈ yielded trinuclear [(η⁵-1,3-tBu₂C₅H₃){η⁵-1,2-[Co₂(CO)₆]-3,4-(Me₃SiO)₂-5-(Me₃Si)P₂C₃}Fe] ( 11 ). Constitution and configuration of compounds 1 c, 2 c, 8 – 11 were determined by elemental analyses and spectra (IR, ¹H-, ¹³C-, ³¹P-NMR, MS). In addition the molecular structure of 11 was established by single crystal X-ray analysis.