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.     

Synthese,Struktur und Photochemie von Olefiniridium(I)‐Komplexen mit Acetylacetonatoliganden

Synthesis, Structure, and Photochemical Behavior of Olefine Iridium(I) Complexes with Acetylacetonato Ligands The bis(ethene) complex [Ir(κ²‐acac)(C₂H₄)₂] ( 1 ) reacts with tertiary phosphanes to give the monosubstitution products [Ir(κ²‐acac)(C₂H₄)(PR₃)] ( 2 – 5 ). While 2 (R = iPr) is inert toward PiPr₃, the reaction of 2 with diphenylacetylene affords the π‐alkyne complex [Ir(κ²‐acac)(C₂Ph₂)(PiPr₃)] ( 6 ). Treatment of [IrCl(C₂H₄)₄] with C‐functionalized acetylacetonates yields the compounds [Ir(κ²‐acacR^1,2)(C₂H₄)₂] ( 8 , 9 ), which react with PiPr₃ to give [Ir(κ²‐acacR^1,2)(C₂H₄)(PiPr₃)] ( 10 , 11 ) by displacement of one ethene ligand. UV irradiation of 5 (PR₃ = iPr₂PCH₂CO₂Me) and 11 (R² = (CH₂)₃CO₂Me) leads, after addition of PiPr₃, to the formation of the hydrido(vinyl)iridium(III) complexes 7 and 12 . The reaction of 2 with the ethene derivatives CH₂=CHR (R = CN, OC(O)Me, C(O)Me) affords the compounds [Ir(κ²‐acac)(CH₂=CHR)(PiPr₃)] ( 13 – 15 ), which on photolysis in the presence of PiPr₃ also undergo an intramolecular C–H activation. In contrast, the analogous complexes [Ir(κ²‐acac)(olefin)(PiPr₃)] (olefin = (E)‐C₂H₂(CO₂Me)₂ 16 , (Z)‐C₂H₂(CO₂Me)₂ 17 ) are photochemically inert.     

Über einige ein‐ und zweikernige Hydroxoiridium(I)‐Komplexe

Some mono‐ and dinuclear Hydroxoiridium(I) Complexes The chloro‐bridged iridium(I) compound [Ir₂(μ‐Cl)₂(C₈H₁₄)₄] ( 1 ) reacts in the biphasic system benzene/water with KOH in the presence of [NEt₃(CH₂Ph)]Cl (TEBA) to give the corresponding dinuclear complex [Ir₂(μ‐OH)₂(C₈H₁₄)₄] ( 2 ). Stepwise substitution of the cyclooctene ligands by PiPr₃ and ethene affords via the intermediate [Ir₂(μ‐OH)₂(C₈H₁₄)₂(PiPr₃)₂] (isolated as a mixture of isomers 3 a , b ) the product [Ir₂(μ‐OH)₂(C₂H₄)₂(PiPr₃)₂] ( 4 ) in excellent yield. Reaction of 4 with PiPr₃in the molar ratio of 1:2 leads to the formation of the mononuclear compound trans‐[Ir(OH)(C₂H₄)(PiPr₃)₂] ( 5 ), the ethene ligand of which cannot be replaced by CPh₂ upon treatment with Ph₂CN₂.     

Synthese und dynamisches Verhalten von [Rh2(μ-H)3H2(PiPr3)4]+. Beiträge zur Reaktivität des Tetrahydridodirhodium-Komplexes [Rh2H4(PiPr3)4]

Synthesis and Dynamic Behaviour of [Rh₂(μ-H)₃H₂(PiPr₃)₄]⁺. Contributions to the Reactivity of the Tetrahydridodirhodium Complex [Rh₂H₄(PiPr₃)₄] An improved synthesis of [Rh₂H₄(PiPr₃)₄] ( 2 ) from [Rh(η³-C₃H₅)(PiPr₃)₂] ( 1 ) or [Rh(η³-CH₂C₆H₅)(PiPr₃)₂] ( 3 ) and H₂ is described. Compound 2 reacts with CO or CH₃OH to give trans-[RhH(CO)(PiPr₃)₂] ( 4 ) and with ethene/acetone to yield a mixture of 4 and trans-[RhCH₃(CO)(PiPr₃)₂] ( 5 ). The carbonyl(methyl) complex 5 has also been prepared from trans-[RhCl(CO)(PiPr₃)₂] ( 6 ) and CH₃MgI. Whereas the reaction of 2 with two parts of CF₃CO₂H leads to [RhH₂(η²-O₂CCF₃) · (PiPr₃)₂] ( 8 ), treatment of 2 with one equivalent of CF₃CO₂H in presence of NH₄PF₆ gives the dinuclear compound [Rh₂H₅(PiPr₃)₄]PF₆ ( 9a ). The reactions of 2 with HBF₄ and [NO]BF₄ afford the complexes [Rh₂H₅(PiPr₃)₄]BF₄ ( 9b ) and trans-[RhF(NO)(PiPr₃)₂]BF₄ ( 11 ), respectively. In solution, the cation [Rh₂(μ-H)₃H₂(PiPr₃)₄]⁺ of the compounds 9a and 9b undergoes an intramolecular rearrangement in which the bridging hydrido and the phosphane ligands are involved.     

Boryl‐Functionalized σ‐Alkynyl and Vinylidene Rhodium Complexes: Synthesis and Electronic Properties

The synthesis, reactivity, and properties of boryl‐functionalized σ‐alkynyl and vinylidene rhodium complexes such as trans‐[RhCl(?C?CHBMes₂)(PiPr₃)₂] and trans‐[Rh(C?CBMes₂)(IMe)(PiPr₃)₂] are reported. An equilibrium was found to exist between rhodium vinylidene complexes and the corresponding hydrido σ‐alkynyl complexes in solution. The complex trans‐[Rh(C?CBMes₂)(IMe)(PiPr₃)₂] (IMe=1,3‐dimethylimidazol‐2‐ylidene) was found to exhibit solvatochromism and can be quasireversibly oxidized and reduced electrochemically. Density functional calculations were performed to determine the reaction mechanism and to help rationalize the photophysical properties of trans‐[Rh(C?CBMes₂)(IMe)(PiPr₃)₂].     

Aromatic Osmacyclopropenefuran Bicycles and Their Relevance for the Metal‐Mediated Hydration of Functionalized Allenes

The aromatic osmacyclopropenefuran bicycles [OsTp{κ³‐C¹,C²,O‐(C¹H₂C²CHC(OEt)O)}(PⁱPr₃)]BF₄ (Tp=hydridotris(1‐pyrazolyl)borate) and [OsH{κ³‐C¹,C²,O‐(C¹H₂C²CHC(OEt)O)}(CO)(PⁱPr₃)₂]BF₄, with the metal fragment in a common vertex between the fused three‐ and five‐membered rings, have been prepared via the π‐allene intermediates [OsTp(η²‐CH₂=CCHCO₂Et)(OCMe₂)(PⁱPr₃)]BF₄ and [OsH(η²‐CH₂=CCHCO₂Et)(CO)(OH₂)(PⁱPr₃)₂]BF₄, and their aromaticity analyzed by DFT calculations. The bicycle containing the [OsH(CO)(PⁱPr₃)₂]⁺ metal fragment is a key intermediate in the [OsH(CO)(OH₂)₂(PⁱPr₃)₂]BF₄‐catalyzed regioselective anti‐Markovnikov hydration of ethyl buta‐2,3‐dienoate to ethyl 4‐hydroxycrotonate.     

Chirale Halbsandwich‐Pentamethylcyclopentadienyl‐Rhodium(III)‐ und Iridium(III)‐Komplexe mit Schiff‐Basen aus Salicylaldehyd und α‐Aminosäureestern [1]

Chiral Half‐sandwich Pentamethylcyclopentadienyl Rhodium(III) and Iridium(III) Complexes with Schiff Bases from Salicylaldehyde and α‐Amino Acid Esters [1] A series of diastereoisomeric half‐sandwich complexes with Schiff bases from salicylaldehyde and L‐α‐amino acid esters including chiral metal atoms, [(η⁵‐C₅H₅)(Cl)M(N,O‐Schiff base)], has been obtained from chloro bridged complexes [(η⁵‐C₅Me₅)(Cl)M(μ‐Cl)]₂ (M = Rh, Ir). Abstraction of chloride from these complexes with Ag[BF₄] or Ag[SO₃CF₃] affords the highly sensitive compounds [(η⁵‐C₅Me₅)M(N,O‐Schiff base]⁺X^? (M = Rh, Ir; X = BF₄, CF₃SO₃) to which PPh₃ can be added under formation of [(η⁵‐C₅Me₅)M(PPh₃)(N,O‐Schiff base)]⁺X^?. The diastereoisomeric ratio of the complexes ( 1 ‐ 7 and 11 ‐ 12 ) has been determined from NMR spectra.     

Ruthenium Complexes of an Abnormally Bound,Anionic N‐Heterocyclic Carbene

The abnormally bound, anionic NHC–borane complex [Ru(IDipp‐BF₃)(p‐cymene)Cl]₂ ( 4 ; IDipp‐BF₃=1,3‐(2,6‐iPr₂C₆H₃)₂‐2‐BF₃(C₃HN₂)‐4‐yl) was synthesized by transmetalation from Li[(IDipp‐BF₃)₂Ag]. Addition of donors gave species of the form [Ru(IDipp‐BF₃)(p‐cymene)(L)Cl], whereas halide abstraction with Ag(Et₂O)[B(C₆F₅)₄] gave C?H activation of the methine position of the IDipp?BF₃ ligand.     

Tripropylarsane Complexes of Palladium(II) and Platinum(II) — Syntheses,Spectroscopy, and Structures

Several palladium(II) and platinum(II) complexes of tripropylarsanes (AsR₃; R = Pr, iPr) with the formulae, [MCl₂(AsR₃)₂], [M₂Cl₂(μ‐Cl)₂(AsR₃)₂], [Pd₂Me₂(μ‐Cl)₂(AsR₃)₂], [Pd₂X₂(μ‐Pz)₂(AsR₃)₂] (X = Cl or Me, Pz = pyrazolate), [Pd₂Cl₂(μ‐Y)₂(AsR₃)₂] (Y = OAc or SPh), [MCl(S₂CNEt₂)(AsR₃)] and [PdCp(Cl)(AsiPr₃)] (M = Pd or Pt) have been prepared. All the complexes have been characterised by elemental analyses, IR and ¹H NMR spectroscopy. The stereochemistry of the complexes has been deduced from the spectroscopic data. The structures of [Pd₂Me₂(μ‐X)₂(AsiPr₃)₂] (X = Cl or Pz) have been established by single crystal X‐ray diffraction analyses. Both of the complexes have sym‐trans configuration. Strong trans influence of the methyl group is reflected on the Pd—X bond distances.     

Nickel Tetracarbonyl as Starting Material for the Synthesis of NHC-stabilized Nickel(II) Allyl Complexes

A novel, useful in situ synthesis for NHC nickel allyl halide complexes [Ni(NHC)(η³-allyl)(X)] starting from [Ni(CO)₄], NHC and allyl halides is presented. The reaction of [Ni(CO)₄] with (i) one equivalent of the corresponding NHC and (ii) with an excess of the corresponding allyl chloride at room temperature leads with elimination of carbon monoxide to complexes of the type [Ni(NHC)(η³-allyl)(X)]. This approach was used to synthesize the complexes [Ni(tBu₂Im)(η³-H₂C -C (Me)-C H₂)(Cl)] ( 2 ), [Ni(iPr₂Im^Me)(η³-H₂C -C (Me)-C H₂)(Cl)] ( 3 ), [Ni(iPr₂Im)(η³-H₂C -C (Me)-C H₂)(Cl)] ( 4 ), [Ni(iPr₂Im)(η³-H₂C -C (H)-C (Me)₂)(Br)] ( 5 ), [Ni(Me₂Im^Me)(η³-H₂C -C (Me)-C H₂)(Cl)] ( 6 ), and [Ni(EtiPrIm^Me)(η³-H₂C -C (Me)-C H₂)(Cl)] ( 7 ). The complexes 1 to 7 were characterized using NMR and IR spectroscopy and elemental analysis, and the molecular structures are provided for 2 and 7 . The allyl nickel complexes 1 – 7 are stereochemically non-rigid in solution due to (i) NHC rotation about the nickel-carbon bond, (ii) allyl rotation about the Ni–η³-allyl axis and (iii) π–σ–π allyl isomerization processes. The allyl halide complexes can be methylated as was demonstrated by the methylation of a number of the complexes [Ni(NHC)(η³-allyl)(X)] with methylmagnesium chloride or methyllithium, which led to isolation of the complexes [Ni(Me₂Im)(η³-H₂C -C (Me)-C H₂)(Me)] ( 8 ), [Ni(tBu₂Im)(η³-H₂C -C (Me)-C H₂)(Me)] ( 9 ), [Ni(iPr₂Im^Me)(η³-H₂C -C (Me)-C H₂)(Me)] ( 10 ), [Ni(iPr₂Im)(η³-H₂C -C (Me)-C H₂)(Me)] ( 11 ), [Ni(iPr₂Im)(η³-H₂C -C (H)-C (Me)₂)(Me)] ( 12 ), and [Ni(EtiPrIm^Me)(η³-H₂C -C (Me)-C H₂)(Me)] ( 13 ). These complexes were fully characterized including X-ray molecular structures for 10 and 11 .     

Bis[μ3‐1,8‐bis(triisopropylsilylamido)naphthalene]bis(tetrahydrofuran)di‐μ3‐oxido‐dimanganese(III)disodium

The solid‐state structure of the title compound, [Na₂Mn₂(C₃₂H₅₆N₂OSi₂)₂O₂] or [1,8‐C₁₀H₆(NSiⁱPr₃)₂Mn(μ₃‐O)Na(THF)]₂, which lies across a crystallographic twofold axis, exhibits a central [Mn₂O₂Na₂]⁴⁺ core, with two oxide groups, each triply bridging between the two Mn^III ions and an Na⁺ ion. Additional coordination is provided to each Mn^III centre by a 1,8‐C₁₀H₆(NSiⁱPr₃)₂ [1,8‐bis(triisopropylsilylamido)naphthalene] ligand and to the Na⁺ centres by a tetrahydrofuran molecule. The presence of an additional Na...H—C agostic interaction potentially contributes to the distortion around the bridging oxide group.     

Vinyliden-Übergangsmetallkomplexe XXVI. Synthese und struktur kationischer Carbonyl-, Alken-, Vinyliden-, Alkinyl- und Alkin-Rhodiumkomplexe mit der Baueinheit trans-[Rh(PPr3)2]

The complex trans-[Rh(CO)(NH₃)(PiPr₃)₂]PF₆ (2) was prepared from [(η³-C₃H₅)Rh(PⁱPr₃)₂] (1), NH₄PF₆ and CO or from 1 and NH₄PF₆ in presence of an excess of methanol. With an excess of CO, the dicarbonyl and tricarbonyl compounds trans-[Rh(CO)₂(PⁱPr₃)₂]PF₆ (3) and [Rh(CO)₃(PⁱPr₃)₂]PF₆ (4) were obtained. Displacement of one CO ligand in 3 by pyridine and acetone led to the formation of trans-[Rh(CO)(py)PⁱPr₃)₂]PF₆ (5a) and trans-[Rh(CO) (O=CMe₂(PⁱPr₃)₂]PF₆ (6), respectively. Treatment of 1 with [pyH]BF₄ and pyridine gave trans-[Rh(py)₂(PⁱPr₃)₂]BF₄ (7); in presence of H₂ the dihydrido complex [RhH₂(py)₂(PⁱPr₃)₂]BF₄ (8) was formed. The reaction of 1 with NH₄PF₆ and ethylene produced trans [Rh(C₂H₄(NH₃(PⁱPr₃)₂]PF₆(9) whereas with methylvinylketone and acetophenone the octahedral hydridorhodium(III) complexes [RhH(η²-CH=CHC(=O)CH₃ (NH₃(PⁱPr₃)₂]PF₆(11) and [RhH(η2-C₆H₄C(=O)CH₃(NH₃(Pⁱpr₃)₂]PF₆ (13) were obtained. The synthesis of the cationic vinylidenerhodium(I) compounds trans-[Rh(=C=CHR)(py)(PⁱPr₃)₂]BF₄ (14–16) and trans-[Rh(=C=CHR)(NH₃)(PⁱPr₃) ₂]PF6 (17–19) was achieved either on treatment of 1 with [pyH]BF₄ or NH₄PF₆ in presence of 1-alkynes or by ethylene displacement from 9 by HCCR. With tert-butylacetylene as substrate, the alkinyl(hydrido)rhodium(III) complex [RhH(CC^tBu)(NH₃)(O=CMe₂)(PⁱPr₃) ₂]PF₆ (20) was isolated which in CH₂Cl₂ solution smoothly reacted to give 19 (R =^tBu). The cationic but-2-yne compound trans-[Rh(MeCCMe)(NH₃)(Pⁱ Pr₃)₂]PF₆ (21) was prepared from 1, NH₄PF₆ and C₂Me₂. The molecular structures of 3 and 14 were determined by X-ray crystallography; in both cases the square-planar coordination around the metal and the trans disposition of the phosphine ligands was confirmed.

Abstract

Der Komplex trans-[Rh(CO)(NH₃)(PⁱPr₃)₂]PF₆ (2) wurde aus [(η³-C₃H₅)Rh(PⁱPr₃)₂] (1), NH₄PF₆ und CO oder aus 1, NH₄PF₆ und Methanol hergestellt. In Gegenwart von überschüssigem CO wurden die Dicarbonyl- und Tricarbonyl-Verbindungen trans-[Rh(CO)₂(PⁱPr₃)₂]PF₆ (3) und [Rh(CO)₃(PⁱPr₃)₂]PF₆ (4) erhalten. Die Verdrängung eines CO-Liganden in 3 durch Pyridin oder Aceton führte zur Bildung von trans-[Rh(CO)(py)(PⁱPr₃)₂]PF₆ (5a) bzw. trans-[Rh(CO)(O=CMe₂)(PⁱPr₃)₂]PF₆ (6). Bei Einwirkung von [pyH]BF₄ und Pyridin auf 1 entstand trans-[Rh(py)₂(PⁱPr₃)₂]BF₄ (7); in Gegenwart von H₂ bildete sich der Dihydrido-Komplex [RhH₂(py)₂(PⁱPr₃) ₂]BF₄ (8). Die Reaktion von 1 mit NH₄PF₆ und Ethen lieferte trans-[Rh(C₂H₄)(NH₃)(PⁱPr₃)₂] PF₆ (9) während mit Methylvinylketon und Acetophenon die oktaedrischen Hydridorhodium(III)-Komplexe [RhH(η²-CH=CHC(=O)CH₃ (NH₃)-(PⁱPr₃)₂]PF₆ (11) und [RhH(η-²-C₆H₄C(=O)CH₃(NH₃)(PⁱPr₃)₂)₂]PF₆ (13) erhalten wurden. Die Synthese der kationischen Vinyli-denrhodium(I)-Verbindungen trans-[Rh(=C=CHR(py)(PⁱPr₃)₂]BF₄ (14–16) und trans-[Rh(=C=CHR)(NH₃)(PⁱPr₃)₂]PF₆ (17–19) gelang durch Einwirkung von [pyH]BF₄ bzw. NH₄PF₆ auf 1 in Gegenwart von 1-Alkinen oder durch Ethen-Verdrängung aus 9 mit HCCR. Mit tert-Butylacetylen als Reaktionspartner wurde der Alkinyl(hydrido)rhodium(III)-Komplex [RhH(CC^tBu)(NH₃(O=CMe₂)(PⁱPr₃)₂]PF₆ (20) isoliert, der in CH₂Cl₂-Lösung sofort zu 19 (R =^tBu) reagiert. Die kationische 2-Butin-Verbindung trans -[Rh(MeCCMe)(NH₃)PⁱPr₃)₂]PF₆ (21) wurde aus 1, NH₄PF₆ und C₂Me₂ hergestellt. Die Strukturen von 3 und 14 wurden kristallographisch bestimmt; in beiden Fa len ließ sich die quadratisch-planare Koordination des Metalls und die trans-Anordnung der Phosphanliganden bestätigen.     

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.     

Ein‐ und zweikernige Rhodiumkomplexe mit Arsino(phosphino)methanen in unterschiedlichen Koordinationsformen

Mono‐ and Dinuclear Rhodium Complexes with Arsino(phosphino)methanes in Different Coordination Modes The cyclooctadiene complex [Rh(η⁴‐C₈H₁₂)(κ²‐tBu₂AsCH₂PiPr₂)](PF₆) ( 1a ) reacts with CO and CNtBu to give the substitution products [Rh(L)₂(κ²‐tBu₂AsCH₂PiPr₂)](PF₆) ( 2 , 3 ). From 1a and Na(acac) in the presence of CO the neutral compound [Rh(κ²‐acac)(CO)(κ‐P‐tBu₂AsCH₂PiPr₂)] ( 4 ) is formed. The reactions of 1a , the corresponding B(Ar_F)₄‐salt 1b and [Rh(η⁴‐C₈H₁₂)(κ²‐iPr₂AsCH₂PiPr₂)](PF₆) ( 5 ) with acetonitrile under a H₂ atmosphere affords the complexes [Rh(CH₃CN)₂(κ²‐R₂AsCH₂PiPr₂)]X ( 6a , 6b , 7 ), of which 6a (R = tBu; X = PF₆) gives upon treatment with Na(acac‐f₆) the bis(chelate) compound [Rh(κ²‐acac‐f₆)(κ²‐tBu₂AsCH₂PiPr₂)] ( 8 ). From 8 and CH₃I a mixture of two stereoisomers of composition [Rh(CH₃)I(κ²‐acac‐f₆)(κ²‐tBu₂AsCH₂PiPr₂)] ( 9/10 ) is generated by oxidative addition, and the molecular structure of the racemate 9 has been determined. The reactions of 1a and 5 with CO in the presence of NaCl leads to the formation of the “A‐frame” complexes [Rh₂(CO)₂(μ‐Cl)(μ‐R₂AsCH₂PiPr₂)₂](PF₆) ( 11 , 12 ), which have been characterized crystallographically. From 11 and 12 the dinuclear substitution products [Rh₂(CO)₂(μ‐X)(μ‐R₂AsCH₂PiPr₂)₂](PF₆) ( 13 ‐ 16 ) are obtained by replacing the bridging chloride for bromide, hydride or hydroxide, respectively. While 12 (R = iPr) reacts with NaI to give the related “A‐frame” complex 18 , treatment of 11 (R = tBu) with NaI yields the mononuclear chelate compound [RhI(CO)(κ²‐tBu₂AsCH₂PiPr₂)] ( 20 ). The reaction of 20 with CH₃I affords the acetyl complex [RhI₂{C(O)CH₃}(κ²‐tBu₂AsCH₂PiPr₂)] ( 21 ) with five‐coordinate rhodium atom.     

Oxorhenium(V) Complexes with 1,3,4‐Triphenyl‐1,2,4‐triazol‐5‐ylidene

Reactions of the oxorhenium(V) complexes [ReOX₃(PPh₃)₂] (X = Cl, Br) with the N‐heterocyclic carbene (NHC) 1,3,4‐triphenyl‐1,2,4‐triazol‐5‐ylidene (L^Ph) under mild conditions and in the presence of MeOH or water give [ReOX₂(Y)(PPh₃)(L^Ph)] complexes (X = Cl, Br; Y = OMe, OH). Attempted reactions of the carbene precursor 5‐methoxy‐1,3,4‐triphenyl‐4,5‐dihydro‐1H‐1,2,4‐triazole ( 1 ) with [ReOCl₃(PPh₃)₂] or [NBu₄][ReOCl₄] in boiling xylene resulted in protonation of the intermediately formed carbene and decomposition products such as [HL^Ph][ReOCl₄(OPPh₃)], [HL^Ph][ReOCl₄(OH₂)] or [HL^Ph][ReO₄] were isolated. The neutral [ReOX₂(Y)(PPh₃)(HL^Ph)] complexes are purple, airstable solids. The bulky NHC ligands coordinate monodentate and in cis‐position to PPh₃. The relatively long Re–C bond lengths of approximate 2.1Å indicate metal‐carbon single bonds.     

The Nature of the UC Double Bond: Pushing the Stability of High‐Oxidation‐State Uranium Carbenes to the Limit

Treatment of [K(BIPM^MesH)] (BIPM^Mes={C(PPh₂NMes)₂}^2?; Mes=C₆H₂‐2,4,6‐Me₃) with [UCl₄(thf)₃] (1 equiv) afforded [U(BIPM^MesH)(Cl)₃(thf)] ( 1 ), which generated [U(BIPM^Mes)(Cl)₂(thf)₂] ( 2 ), following treatment with benzyl potassium. Attempts to oxidise 2 resulted in intractable mixtures, ligand scrambling to give [U(BIPM^Mes)₂] or the formation of [U(BIPM^MesH)(O)₂(Cl)(thf)] ( 3 ). The complex [U(BIPM^Dipp)(μ‐Cl)₄(Li)₂(OEt₂)(tmeda)] ( 4 ) (BIPM^Dipp={C(PPh₂NDipp)₂}^2?; Dipp=C₆H₃‐2,6‐iPr₂; tmeda=N,N,N′,N′‐tetramethylethylenediamine) was prepared from [Li₂(BIPM^Dipp)(tmeda)] and [UCl₄(thf)₃] and, following reflux in toluene, could be isolated as [U(BIPM^Dipp)(Cl)₂(thf)₂] ( 5 ). Treatment of 4 with iodine (0.5 equiv) afforded [U(BIPM^Dipp)(Cl)₂(μ‐Cl)₂(Li)(thf)₂] ( 6 ). Complex 6 resists oxidation, and treating 4 or 5 with N‐oxides gives [{U(BIPM^DippH)(O)₂‐ (μ‐Cl)₂Li(tmeda)] ( 7 ) and [{U(BIPM^DippH)(O)₂(μ‐Cl)}₂] ( 8 ). Treatment of 4 with tBuOLi (3 equiv) and I₂ (1 equiv) gives [U(BIPM^Dipp)(OtBu)₃(I)] ( 9 ), which represents an exceptionally rare example of a crystallographically authenticated uranium(VI)–carbon σ bond. Although 9 appears sterically saturated, it decomposes over time to give [U(BIPM^Dipp)(OtBu)₃]. Complex 4 reacts with PhCOtBu and Ph₂CO to form [U(BIPM^Dipp)(μ‐Cl)₄(Li)₂(tmeda)(OCPhtBu)] ( 10 ) and [U(BIPM^Dipp)(Cl)(μ‐Cl)₂(Li)(tmeda)(OCPh₂)] ( 11 ). In contrast, complex 5 does not react with PhCOtBu and Ph₂CO, which we attribute to steric blocking. However, complexes 5 and 6 react with PhCHO to afford (DippNPPh₂)₂C?C(H)Ph ( 12 ). Complex 9 does not react with PhCOtBu, Ph₂CO or PhCHO; this is attributed to steric blocking. Theoretical calculations have enabled a qualitative bracketing of the extent of covalency in early‐metal carbenes as a function of metal, oxidation state and the number of phosphanyl substituents, revealing modest covalent contributions to U?C double bonds.     

Synthese und reaktivität des diphenylacetyleniridium-komplexes C5H5Ir(C2Ph2)PPr3i und bildung einer isomeren iridainden-verbindung

trans-[IrCl(C₂R₂)(PPr₃ⁱ)₂] complexes are prepared from [(C₈H₁₄)₂IrCl]₂, PPr₃ⁱ and C₂R₂ (R = H, Me, Ph) via the intermediate [IrCl(PPr₃ⁱ)₂]. With phenylacetylene, a mixture of two isomers, trans-[IrCl(PhC₂H)(PPr₃ⁱ)₂] and IrHCl(C₂Ph)(PPr₃ⁱ)₂ is formed which reacts with pyridine to give IrHCl(C₂Ph)(py)(PP₃ⁱ)₂. Reaction of trans-[IrCl(C₂Ph₂)(PPr₃ⁱ)₂] with NaC₅H₅ yields the compound C₅H₅Ir(C₂Ph₂)PPr₃ⁱ (VI) which is transformed via the vinyl complex C₅H₅Ir(CPhCHPh)(OCOCF₃)PPr₃ⁱ (VII) into the iridaindene derivative IX. Using VII as the starting material, C₅H₅Ir(OCOCF₃)₂PPr₃ⁱ, C₅H₅Ir(CPhCHPh)(I)PPr₃ⁱ and C₅H₅Ir(CPhCHPh)(CH₃)PPr₃ⁱ are also obtained. Treatment of VI with Br₂ and I₂ respectively yields the complexes C₅H₅IrX₂PPr₃ⁱ) (XII, X = Br; XIII, X = I), of which XIII reacts with CH₃MgI to give C₅H₅Ir(CH₃)₂PPr₃ⁱ.     

Di­chloro­bis(3,5‐di­methyl­pyrazole‐N2)methyl­phenyl­tin(IV)

The title compound, [SnCl₂(CH₃)(C₆H₅)(C₅H₈N₂)₂], was obtained by reaction of di­chloro­methyl­phenyl­tin(IV) and 3,5‐di­methyl­pyrazole (dmpz) in chloro­form, and was recrystallized from acetone. The structure consists of octahedral all‐trans [SnMePhCl₂(dmpz)₂] mol­ecules, with the Sn atom coordinated to two C [Sn—C 2.127 (5) and 2.135 (4) Å], two Cl [Sn—Cl 2.5753 (8) Å] and two N atoms [Sn—N 2.357 (3) Å]. The dmpz ligands, bound to the metal through their unprotonated N atoms, form weak intra‐ and intermolecular hydrogen bonds with the Cl ligands via their NH groups, giving rise to a polymeric chain along the c axis.     

Synthesis of 2‐(N‐arylimino)pyrrolide nickel complexes and polymerization of methyl methacrylate

The synthesis, characterization and methyl methacrylate polymerization behaviors of 2‐(N‐arylimino)pyrrolide nickel complexes are described. The nickel complex [NN]₂Ni ( 1 , [NN] = [2‐C(H)NAr‐5‐tBu‐C₄H₂N]^?, Ar = 2,6‐iPr₂C₆H₃) was prepared in good yield by the reaction of [NN]Li with trans‐[Ni(Cl)(Ph)(PPh₃)₂] in THF. Reaction of [NN]Li with NiBr₂(DME) yielded the nickel bromide [NN]Ni(Br)[NNH] ( 2 ). Complexes 1 and 2 were characterized by ¹H NMR and IR spectroscopy and elemental analysis, and by X‐ray single crystal analysis. Both complexes, upon activation with methylaluminoxane, are highly active for the polymerization of methyl methacrylate to give high molecular weight polymethylmethacrylate with narrow molecular distributions. Copyright © 2009 John Wiley & Sons, Ltd.     

Isomorphous rare‐earth bis[bis(2,6‐diisopropylphenyl)phosphate] complexes and their self‐assembly into two‐dimensional frameworks by intramolecular hydrogen bonds

The crystal structures of rare‐earth diaryl‐ or dialkylphosphate derivatives are poorly explored. Crystals of bis[bis(2,6‐diisopropylphenyl)phosphato‐κO ]chloridotetrakis(methanol‐κO )neodymium methanol disolvate, [Nd(C₂₄H₃₄O₄P)Cl(CH₄O)₄]·2CH₃OH, (1), and of the lutetium, [Lu(C₂₄H₃₄O₄P)Cl(CH₄O)₄]·2CH₃OH, (2), and yttrium, [Y(C₂₄H₃₄O₄P)Cl(CH₄O)₄]·2CH₃OH, (3), analogues have been obtained by reactions between lithium bis(2,6‐diisopropylphenyl)phosphate and LnCl₃(H₂O)₆ (in a 2:1 ratio) in methanol. Compounds (1)–(3) crystallize in the C 2/c space group. Their crystal structures are isomorphous. The molecule possesses C ₂ symmetry with a twofold crystallographic axis passing through the Ln and Cl atoms. The bis(2,6‐diisopropylphenyl)phosphate ligands all display a κ¹O‐monodentate coordination mode. The coordination polyhedron for the metal atom [coordination number (CN) = 7] is a distorted pentagonal bipyramid. Each [Ln{O₂P(O‐2,6‐ⁱPr₂C₆H₃)₂}₂Cl(CH₃OH)₄] molecular unit exhibits two intramolecular O—H…O hydrogen bonds, forming six‐membered rings, and two intramolecular O—H…Cl interactions, forming four‐membered rings. Intermolecular O—H…O hydrogen bonds connect each unit via four noncoordinating methanol molecules with four other units, forming a two‐dimensional hydrogen‐bond network. Crystals of bis[bis(2,6‐diisopropylphenyl)phosphato‐κO ]tetrakis(methanol‐κO )(nitrato‐κ²O ,O ′)neodymium methanol disolvate, [Nd(C₂₄H₃₄O₄P)(NO₃)(CH₄O)₄]·2CH₃OH, (4), have been obtained in an analogous manner from NdCl₃(H₂O)₆. Compound (4) also crystalizes in the C 2/c space group. Its crystal structure is similar to those of (1)–(3). The κ²O ,O ′‐bidentate nitrate anion is disordered over a twofold axis, being located nearly on it. Half of the molecule is crystallographically unique (CN_Nd = 8). Unlike (1)–(3), complex (4) exhibits disorder of all three methanol molecules, one isopropyl group of the phosphate ligand and the NO₃⁻ ligand. The structure of (4) displays intra‐ and intermolecular O—H…O hydrogen bonds similar to those in (1)–(3). Compounds (1)–(4) represent the first reported mononuclear bis[bis(diaryl/dialkyl)phosphate] rare‐earth complexes.