Organometallic ruthenium, rhodium and iridium complexes containing a P-bound thiophene-2-(N-diphenylphosphino)methylamine ligand: Synthesis, molecular structure and catalytic activity

Reaction of Ph₂PNHCH₂-C₄H₃S with [Ru(η⁶-p-cymene)(μ-Cl)Cl]₂, [Ru(η⁶-benzene)(μ-Cl)Cl]₂, [Rh(μ-Cl)(cod)]₂ and [Ir(η⁵-C₅Me₅)(μ-Cl)Cl]₂ yields complexes [Ru(Ph₂PNHCH₂-C₄H₃S)(η⁶-p-cymene)Cl₂], 1, [Ru(Ph₂PNHCH₂-C₄H₃S)(η⁶-benzene)Cl₂], 2, [Rh(Ph₂PNHCH₂-C₄H₃S)(cod)Cl], 3 and [Ir(Ph₂PNHCH₂-C₄H₃S)(η⁵-C₅Me₅)Cl₂], 4, respectively. All complexes were isolated from the reaction solution and fully characterized by analytical and spectroscopic methods. The structure of [Ru(Ph₂PNHCH₂-C₄H₃S)(η⁶-benzene)Cl₂], 2 was also determined by single crystal X-ray diffraction. 1-4 are suitable precursors forming highly active catalyst in the transfer hydrogenation of a variety of simple ketones. Notably, the catalysts obtained by using the ruthenium complexes [Ru(Ph₂PNHCH₂-C₄H₃S)(η⁶-p-cymene)Cl₂], 1 and [Ru(Ph₂PNHCH₂-C₄H₃S)(η⁶-benzene)Cl₂], 2 are much more active in the transfer hydrogenation converting the carbonyls to the corresponding alcohols in 98-99% yields (TOF ≤ 200 h⁻¹) in comparison to analogous rhodium and iridium complexes.     

π-Olefin-iridium-komplexe : II. Synthese und dynamisches verhalten von bis(η4-Cyclodien)-hydrido-iridium(I)-komplexen

By reaction of [Ir(COD)Cl]₂ (COD = 1,5-cyclooctadiene) with i-C₃H₇MgBr in the presence of cyclic dienes, complexes of the type [IrH(COD)L] (L = 1,3-cyclohexadiene, 2-methyl-],3-cyclohexadiene, 5-ethyl-1,3-cyclohexadiene, 1,3-cycloheptadiene) are obtained. The system IrCl₃/i-C₃H₇MgBr/1,3-C₆H₈ yields [IrH(1,3-C₆H₈)₂]. According to NMR spectroscopic investigations the pure hydrido forms exist in solution only at low temperatures while at room temperature dynamic H-addition—elimination equilibria of the type [IrH(η⁴-diene)(COD)] ? [Ir(η³-enyl)(COD)] and [IrH(η⁴-1,3-C₆H₈)₂] ? [Ir(η³-C₆H₉)-(η⁴-1,3-C₆H₈)], respectively, are observed; the hydrogen at the iridium atom is thereby transferred to the endo positions of the diene ligands.     

π-Olefin—iridium -komplexe : III. Über (η4-cyclodien)(η5-cyclodienyl)iridium-verbindungen,einen neuartigen hydridoiridium-komplex und das (η4-cyclooctadien)(η6-cyclooctatrien)iridium-kation

The complexes [Ir(COD)(η⁵-C₇H₉)] and [Ir(COD)(η⁵-C₈H₁₁)] are obtained by the isoprophyl Grignard synthesis of [Ir(COD)Cl]₂ (COD = η⁴-1,5-cyclooctadiene) in the presence of cycloheptatriene, and cyclooctatriene, respectively. The later reaction yields [IrH(COD)(δ⁴-1,3,6-C₈H₁₀)] as a by-product which, in contrast to other [IrH(η⁴-cyclodiene)₂] complexes, does not show H-addition-elimination equilibria. Reduction of [Ir(1,3-C₇H₁₀)₂Cl] with C₂H₅OH/Na₂CO₃ yields [Ir(η⁴-1,3-C₇H₁₀)](η⁵-C₇H₉)] which was characterized by X-ray analysis. [Ir(COD)Cl]₂ reacts with Na₂C₈H₈, and after hydrolysis unstable [Ir(COD)(η⁵-C₈H₉)] is formed which by protonation with HPF₆ is converted into the [Ir(COD)(η⁶-1,3,5-C₈H₁₀)]⁺ cation. All these compounds are fluxional in solution.     

A modular design of metal catalysts for the transfer hydrogenation of aromatic ketones

The ability of transition metal catalysts to add or remove hydrogen from organic substrates by transfer hydrogenation is a valuable synthetic tool. Towards a series of novel metal complexes with a P―NH ligand, [Ph₂PNHCH₂―C₄H₃O] derived from furfurylamine were synthesized. Reaction of [Ph₂PNHCH₂―C₄H₃O] 1 with [Ru(η⁶‐p‐cymene)(μ‐Cl)Cl]₂, [Ru(η⁶‐benzene)(μ‐Cl)Cl]₂, [Rh(μ‐Cl)(cod)]₂ and [Ir(η⁵‐C₅Me₅)(μ‐Cl)Cl]₂ gave a range of new monodentate complexes [Ru(Ph₂PNHCH₂―C₄H₃O)(η⁶‐p‐cymene)Cl₂] 2 , [Ru(Ph₂PNHCH₂―C₄H₃O)(η⁶‐benzene)Cl₂] 3 , [Rh(Ph₂PNHCH₂‐C₄H₃O)(cod)Cl] 4 , and [Ir(Ph₂PNHCH₂‐C₄H₃0)(η⁵‐C₅Me₅)Cl₂] 5 , respectively. All new complexes were fully characterized by analytical and spectroscopic methods. ³¹P‐{¹H} NMR, distortionless enhancement by polarization transfer (DEPT) or ¹H‐¹³C heteronuclear correlation (HETCOR) experiments were used to confirm the spectral assignments. Following activation by KOH, compounds 1 , 2 , 3 , 4 catalyzed the transfer hydrogenation of acetophenone derivatives to 1‐phenylethanol derivatives in the presence of iso‐PrOH as the hydrogen source. Notably [Ru(Ph₂PNHCH₂‐C₄H₃O)(η⁶‐benzene)Cl₂] 3 acts as an excellent catalyst, giving the corresponding alcohols in 98–99% yield in 20 min at 82°C (time of flight ≤ 297 h^?1) for the transfer hydrogenation reaction in comparison to analogous rhodium or iridium complexes. Copyright © 2012 John Wiley & Sons, Ltd.     

Amido PNP complexes of iridium: Synthesis and catalytic olefin and alkyne hydrogenation

In situ lithiation of HN(o-C₆H₄PPh₂)₂ (H[ 1a ]) or HN(o-C₆H₄PiPr₂)₂ (H[ 1b ]) with nBuLi in THF at −35°C followed by addition of [Ir(μ-Cl)(COD)]₂ (COD = 1,5-cyclooctadiene) in toluene at −35°C generates 5-coordinate [ 1a ]Ir(η⁴-COD) ( 2a ) or 4-coordinate [ 1b ]Ir(η²-COD) ( 2b ), respectively. Oxidative addition of N-H in H[ 1b ] to [Ir(μ-Cl)(COD)]₂ affords square pyramidal [ 1b ]Ir(H)(Cl) ( 3b ). Metathetical reaction of 3b with LiBHEt₃ in the presence of 1 atm of H₂ in toluene produces [ 1b ]Ir(H)₂ ( 4b ). Both 2a and 4b are active for catalytic hydrogenation of olefins and alkynes under extremely mild conditions.     

Platinum,iridium and rhodium complexes with substituted bis-(diphenylphosphino)methane ligands Ph2PCH(R)PPh2 (R = Me,Ph or SiMe3)

Substituted phosphines of the type Ph₂PCH(R)PPh₂ and their Pt^II complexes [PtX₂{Ph₂PCH(R)PPh₂}] (R = Me, Ph or SiMe₃; X = halide) were prepared. Treatment of [PtCl₂(NCBu^t)₂] with Ph₂PCH(SiMe₃)-PPh₂ gave [PtCl₂(Ph₂PCH₂PPh₂)], while treatment with Ph₂PCH(Ph)PPh₂ gave [Pt{Ph₂PCH(Ph)PPh₂}₂]Cl₂. Reaction of p-MeC₆H₄C≡CLi or PhC≡CLi with [PtX₂{Ph₂PCH(Me)PPh₂}] gave [Pt(C≡CC₆H₄Me-p)₂-{Ph₂PCH(Me)PPh₂}] (X = I) and [Pt{Ph₂PC(Me)PPh₂}₂](X = Cl),while reaction of p-MeC₆H₄C≡CLi with [Pt{Ph₂PCH(Ph)PPh₂}₂]Cl₂ gave [Pt{Ph₂PC(Ph)PPh₂}₂]. The platinum complexes [PtMe₂(dpmMe)] or [Pt(CH₂)₄(dpmMe)] fail to undergo ring-opening on treatment with one equivalent of dpmMe [dpmMe = Ph₂PCH(Me)PPh₂]. Treatment of [Ir(CO)Cl(PPh₃)₂] with two equivalents of dpmMe gave [Ir(CO)(dpmMe)₂]Cl. The PF₆ salt was also prepared. Treatment of [Ir(CO)(dpmMe)₂]Cl with [Cu(C≡CPh)₂], [AgCl(PPh₃)] or [AuCl(PPh₃)] failed to give heterobimetallic complexes. Attempts to prepare the dinuclear rhodium complex [Rh₂(CO)₃(μ-Cl)(dpmMe)₂]BPh₄ using a procedure similar to that employed for an analogous dpm (dpm = Ph₂PCH₂PPh₂) complex were unsuccessful. Instead, the mononuclear complex [Rh(CO)(dpmMe)₂]BPh₄ was obtained. The corresponding chloride and PF₆ salts were also prepared. Attempts to prepare [Rh(CO)(dpmMe)₂]Cl in CHCl₃ gave [RhHCl(dpmMe)₂]Cl. Recrystallization of [Rh(CO)(dpmMe)₂]BPh₄ from CHCl₃/EtOH gave [RhO₂(dpmMe)₂]BPh₄. Treatment of [Rh(CO)₂Cl₂]₂ with one equivalent of dpmMe per Rh atom gave two compounds, [Rh(CO)(dpmMe)₂]Cl and a dinuclear complex that undergoes exchange at room temperature between two formulae: [Rh₂(CO)₂(μ-Cl)(μ-CO)(dpmMe)₂]Cl and [Rh₂(CO)₂-(μ-Cl)(dpmMe)₂]Cl. This revised version was published online in June 2006 with corrections to the Cover Date.     

Applications of transition metal complexes containing aminophosphine ligand to transfer hydrogenation of ketones

Hydrogen transfer reduction processes are attracting increasing interest from synthetic chemists in view of their operational simplicity. Reaction of [Ph₂PNHCH₂‐C₄H₃S] with [Ru(η⁶‐benzene)(µ‐Cl)Cl]₂, [Rh(µ‐Cl)(cod)]₂ and [Ir(η⁵‐C₅Me₅)(µ‐Cl)Cl]₂ gave a range of new monodendate complexes [Ru(Ph₂PNHCH₂‐C₄H₃S)(η⁶‐benzene)Cl₂], 1, [Rh(Ph₂PNHCH₂‐C₄H₃S)(cod)Cl], 2, and [Ir(Ph₂PNHCH₂‐C₄H₃S)(η⁵‐C₅Me₅)Cl₂], 3, respectively. All new complexes were fully characterized by analytical and spectroscopic methods. ¹H? ³¹P NMR, ¹H? ¹³C HETCOR or ¹H? ¹H COSY correlation experiments were used to confirm the spectral assignments. 1–3 are suitable catalyst precursors for the transfer hydrogenation of acetophenone derivatives. Notably [Ru(Ph₂PNHCH₂‐C₄H₃S)(η⁶‐benzene)Cl₂], 1, acts as an excellent catalyst, giving the corresponding alcohols in 98–99% yields in 30 min at 82 °C (TOF ≤200 h^?1) for the transfer hydrogenation reaction in comparison to analogous rhodium or iridium complexes. This transfer hydrogenation is characterized by low reversibility under these conditions. Copyright © 2011 John Wiley & Sons, Ltd.     

Synthesis of hetero-binuclear derivatives of the tetrathiolato complexes [Mo(η-C5H5CH2SR)2)], R = Prn and Ph,with platinum,palladium, and rhodium

The compound Mo(η-C₅H₄(CH₂)₂SPrⁿ)₂(SPrⁿ)₂ acts as a bidentate ligand giving the heteronuclear bi-metallic compounds [Mo(η-C₅H₄CH₂CH₂SPrⁿ)₂-(SPrⁿ)₂(PtCl₂)],[Mo(η-C₅H₄CH₂CH₂SPrⁿ)₂(SPrⁿ)₂(PdCl₂)₂], [Mo(η-C₅C₄CH₂CH₂SPrⁿ)₂(SPrⁿ)₂(RhCl₃)₂], [Mo(η-C₅H₄CH₂CH2SPrⁿ)₂(μ-SPrⁿ)₂Rh(dppe)]BF₄, [Mo(η-C₅H₄CH₂CH₂SPrⁿ)₂(μ-SPrⁿ)₂(COD)Rh]Cl, [Mo(η-C₅H₄CH₂CH₂SPrⁿ)₂-(μ-SPrⁿ)₂Pt(PPh₃)₂](PF₆)₂, and the compound [Mo(η-C₅H₄(CH₂)₂-μ-SPh)₂Cl₂Rh(COD)]Cl bonds via the ring-sulphur substituents giving [Mo(η-C₅H₄(CH₂)₂-μ-SPh)₂-Cl₂Rh(COD)]Cl.     

Reactions of 1,4-diaza-3-methylbutadien-2-ylpalladium(II) derivatives with chloro-bridged rhodium(I) complexes

The reactions of the organometallic 1,4-diazabutadienes, RN=C(R′)C(Me)=NR″ [R = R″ = p-C₆H₄OMe, R′ = trans-PdCl(PPh₃)₂ (DAB); R = p-C₆H₄OMe, R″ = Me, R′ = trans-PdCl(PPh₃)₂ (DAB^I; R = R″ = p-C₆H₄OMe, R′ = Pd(dmtc)-(PPh₃), dmtc = dimethyldithiocarbamate (DAB^II); R = R″ = p-C₆H₄OMe, R′ = PdCl(diphos), diphos = 1,2-bis(diphenylphosphino)ethane (DAB^III)] with [RhCl(COD)]₂ (COD = 1,5-cyclooctadiene, Pd/Rh ratio = $\text{1}\text{2}$) depend on the nature of the ancillary ligands at the Pd atom in group R′. In the reactions with DAB and DAB^I transfer of one PPh₃ ligand from Pd to Rh occurs yielding [RhCl(COD)(PPh₃)] and the new binuclear complexes [Rh(COD) {RN=C(R?)-C(Me)=NR″}], in which the diazabutadiene moiety acts as a chelating bidentate ligand. Exchange of ligands between the two different metallic centers also occurs in the reaction with DAB^II. In this case, the migration of the bidentate dmtc anion yields [Rh(COD)Pdmtc] and [Rh(COD) {RN=C(R?)C(Me)=NR″}]. In contrast, the reaction with DAB^III leads to the ionic product [Rh(COD)- (DAB^III)][RhCl₂(COD)], with no transfer of ligands. The cationic complex [Rh(COD)(DAB^III)]⁺ can be isolated as the perchlorate salt from the same reaction (Pd/Rh ratio = 1/1) in the presence of an excess of NaClO₄. In all the binuclear complexes the coordinated 1,5-cyclooctadiene can be readily displaced by carbon monoxide to give the corresponding dicarbonyl derivatives. The reaction of [RhCl(CO)₂]₂ with DAB and/or DAB^I yields trinuclear complexes of the type [RhCl(CO)₂]₂(DAB), in which the diazabutadiene group acts as a bridging bidentate ligand. Some reactions of the organic diazabutadiene RN=C(Me)C(Me)=NR (R = p-C₆H₄OMe) are also reported for comparison.     

Enantioselective transfer hydrogenation of pro-chiral ketones catalyzed by novel ruthenium and iridium complexes of well-designed phosphinite ligand

Abstract

The interaction of [Ru(η⁶-arene)(μ-Cl)Cl]₂ and Ir(η⁵-C₅Me₅)(μ-Cl)Cl]₂ with a new Ionic Liquid-based phosphinite ligand, [(Ph₂PO)-C₆H₉N₂Ph]Cl, (2) gave [Ru((Ph₂PO)-C₆H₉N₂Ph)(η⁶-p-cymene)Cl₂]Cl (3), [Ru((Ph₂PO)-C₆H₉N₂Ph)(benzene)Cl₂]Cl (4) and [Ir((Ph₂PO)-C₆H₉N₂Ph)(C₅Me₅)Cl₂]Cl (5), complexes. All the compounds were characterized by a combination of multinuclear NMR and IR spectroscopy as well as elemental analysis. Furthermore, the Ru(II) and Ir(III) catalysts were applied to asymmetric transfer hydrogenation of acetophenone derivatives using 2-propanol as a hydrogen source. The results showed that the corresponding alcohols could be obtained with good activity (up to 55% ee and 99% conversion) under mild conditions. Notably, [Ir((Ph₂PO)-C₆H₉N₂Ph)(C₅Me₅)Cl₂]Cl (5) is more active than the other analogous complexes in the transfer hydrogenation (up to 81% ee).     

Oxidative addition of different electrophiles with rhodium(I) carbonyl complexes of unsymmetrical phosphine–phosphine monoselenide ligands

Dimeric chlorobridge complex [Rh(CO)₂Cl]₂ reacts with two equivalents of a series of unsymmetrical phosphine–phosphine monoselenide ligands, Ph₂P(CH₂)_nP(Se)Ph₂ {n = 1( a ), 2( b ), 3( c ), 4( d )}to form chelate complex [Rh(CO)Cl(P∩Se)] ( 1a ) {P∩Se = η²‐(P,Se) coordinated} and non‐chelate complexes [Rh(CO)₂Cl(P～Se)] ( 1b–d ) {P～Se = η¹‐(P) coordinated}. The complexes 1 undergo oxidative addition reactions with different electrophiles such as CH₃I, C₂H₅I, C₆H₅CH₂Cl and I₂ to produce Rh(III) complexes of the type [Rh(COR)ClX(P∩Se)] {where R = ? C₂H₅ ( 2a ), X = I; R = ? CH₂C₆H₅ ( 3a ), X = Cl}, [Rh(CO)ClI₂(P∩Se)] ( 4a ), [Rh(CO)(COCH₃)ClI(P～Se)] ( 5b–d ), [Rh(CO)(COH₅)ClI‐(P～Se)] ( 6b–d ), [Rh(CO)(COCH₂C₆H₅)Cl₂(P～Se)] ( 7b–d ) and [Rh(CO)ClI₂(P～Se)] ( 8b–d ). The kinetic study of the oxidative addition (OA) reactions of the complexes 1 with CH₃I and C₂H₅I reveals a single stage kinetics. The rate of OA of the complexes varies with the length of the ligand backbone and follows the order 1a > 1b > 1c > 1d . The CH₃I reacts with the different complexes at a rate 10–100 times faster than the C₂H₅I. The catalytic activity of complexes 1b–d for carbonylation of methanol is evaluated and a higher turnover number (TON) is obtained compared with that of the well‐known commercial species [Rh(CO)₂I₂]^?. Copyright © 2006 John Wiley & Sons, Ltd.     

Carbonyl rhodium(I) complexes with α-diimines ligands

The reactions of [Rh(CO)₂Cl]₂ with α-diimines, RN=CR′-CR′=NR (R = c-Hex, C₆H₅, p-C₆H₄OH, p-C₆H₄CH₃, p-C₆H₄OCH₃, R′ = H; R = c-Hex, C₆H₅, p-C₆H₄OH, p-C₆H₄OCH₃; R′ = Me) in 2:1 Rh/R-dim ratio gave rise to ionic compounds [(CO)₂Rh.R-dim(R′,R′)][Rh(CO)₂Cl₂] which have been characterized by elemental analyses, electrical conductivity, ¹H-NMR and electronic and IR spectroscopy. Some of these complexes must involve some kind of metal-metal interaction. The complex [Rh(CO)₂Cl.c-Hex-dim(H,H)] has been obtained by reaction of [Rh(CO)₂Cl]₂ with the c-Hex-dim(H,H) ligand in 1:1 Rh/R-dim ratio. The reactions between [(CO)₂Rh.R-dim(H,H)][Rh(CO)₂Cl₂](R = c-Hex or p-C₆H₄OCH₃) with the dppe ligand have been studied. The known complex RhCl(CO)(PPh₃)₂ has been isolated from the reaction of [(CO)₂Rh.R-dim(H,H)]-[Rh(CO)₂Cl₂] (R = c-Hex or p-C₆H₄OCH₃) with PPh₃ ligand.     

Darstellung und chemie von Me2TlN(SiMe3)2 und Tl[N(SiMe3)2]3

The complexes [Rh(η³-C₃H₄R)(η⁵-C₅R′₅)L]⁺BF₄^- (R  1-Me, R′  H, Me; R  2-Me, R′  H) (L  C₅H₅N, Ph₃P, Ph₃As) have been prepared from Rh(η³-C₃H₄R)(η⁵-C₅R′₅)Cl and AGBF₄ in acetone, followed by reaction with the stoicheiometric quantity of L. The ¹H and ¹³C NMR spectra of the salts are reported and discussed.     

Anionic and neutral rhodium(I) complexes containing trichlorostannato ligands

The complexes Et₄N[Rh(SnCl₃)₂(diolefin)(PR₃)] (diolefin = COD or NBD) have been isolated and their reactions studied. Reaction with arylic tertiary phosphines led to SnCl₃⁻ displacement and isolation of neutral pentacoordinated Rh(SnCl₃)(diolefin)(PR₃)₂ complexes. Reaction with carbon monoxide involved diolefin displacement when the diolefin was COD, thus giving Et₄N[Rh(SnCl₃)₂(CO)₂(PR₃)] compounds, but SnCl₃⁻ displacement when it was NBD, thus yielding Rh(SnCl₃)(CO)(NBD)(PR₃) complexes. The complexes [Rh(diolefin)Cl]₂ were found to react with triarylphosphines in the presence of SnCl₂ and with CO bubbling through the solution to give Rh(SnCl₃)(CO)(NBD)(PR₃) when the diolefin was NBD but Rh(Cl)(CO)(PR₃)₂ when the diolefin was COD.     

Cyclopentadienyl- and pentamethylcyclopentadienyl-rhodium(III) complexes containing isocyanide ligands

The complexes [(η⁵-C₅H₅)RhCl₂]₂ and [(η⁵-C₅Me₅)RhCl₂]₂ react with stoichiometric amounts of isocyanide ligands L to give (η⁵-C₅H₅)RhLCl₂ and (η⁵-C₅Me₅)RhLCl₂ (L = CNC₆H₁₁, CNC₆H₄CH₃-p); an excess of ligand L reacts further with (η⁵-C₅Me₅)RhLCl₂ to give the cationic complex [(η⁵-C₅Me₅)RhL₂Cl]⁺ which was isolated as tetraphenylborate salt. The cationic complexes [(η⁵-C₅Me₅)RhL(PPh₃)Cl]⁺ and [(η⁵-C₅Me₅)Rh(Ph₂PC₂H₄PPh₂)Cl]⁺ were obtained in the reaction of (η⁵-C₅Me₅)RhLCl₂ with PPh₃ and Ph₂PC₂H₄PPh₂ respectively. Unidentified solids which do not contain the cyclopentadienyl moiety were obtained in the analogous reactions of (η⁵-C₅H₅)RhLCl₂ with an excess of isocyanide or of tertiary phosphine.The complexes (η⁵-C₅H₅)Rh(CNC₆H₁₁)Cl₂ and (η⁵-C₅Me₅)Rh(CNC₆H₁₁)Cl₂ react with SCN^? or SeCN^? giving the corresponding dithiocyanate or diselenocyanate derivatives in which the pseudohalogen groups are S- or Se-bonded to the metal atom. The analogous reactions with C₆Cl₅MgCl gave the chiral complexes (η⁵-C₅H₅)Rh(CNC₆H₁₁)(C₆Cl₅)Cl and (η⁵-C₅Me₅)Rh(CNC₆H₁₁)(C₆Cl₅)Cl.The potentially chelating anion Ph₂PSS^? reacts with (η⁵-C₅H₅)Rh(CNC₆H_n11)Cl₂ and (η⁵-C₅Me₅)Rh(CNC₆H₁₁)Cl₂ to give (η⁵-C₅H₅)Rh(CNC₆H¹¹)(SSPPh₃)Cl and (η⁵-C₅Me₅)Rh(CNC₆H¹¹)(SSPPh₂)Cl in which the dithio ligand acts as monodentate; these compounds react with MeI or EtI to give the dihalide derivatives and the esters Ph₂PSSMe and PSSEt. The complex [(η⁵-C₅Me₅)Rh(CNC₆H₁₁)(SSPPh₂)]Cl was obtained by refluxing a benzene solution of the corresponding neutral complex; the cyclopentadienyl derivative failed to give the analogous chelate complex.The complexes (η⁵-C₅H₅)RhLCl₂, (η⁵-C₅Me₅)RhLCl₂ and [(η⁵-C₅Me₅)RhL₂Cl]⁺ (L = CNC₆H₁₁) were found to be unreactive towards amines.     

Heteroleptic rhodium complexes containing both the dipyrrin/cyclooctadiene ligands and application of [(η-C8H12)Rh(4-pyrdpm)] in the construction of homo-/hetero-bimetallic complexes

Heteroleptic rhodium(I) complexes with the general formulations [(η⁴-C₈H₁₂)Rh(L)] [η⁴-C₈H₁₂ = 1,5-cyclooctadiene; L = 5-(4-cyanophenyl)dipyrromethene, cydpm; 5-(4-nitrophenyl)dipyrromethene, ndpm; and 5-(4-benzyloxyphenyl)dipyrromethene, bdpm; 5-(4-pyridyl)dipyrromethene, 4-pyrdpm; 5-(3-pyridyl)dipyrromethene, 3-pyrdpm] have been synthesized. The complex [(η⁴-C₈H₁₂)Rh(4-pyrdpm)] have been used as a synthon in the construction of homo-bimetallic complex [(η⁴-C₈H₁₂)Rh(μ-4-pyrdpm)Rh(η⁵-C₅Me₅)Cl₂] and hetero-bimetallic complexes [(η⁴-C₈H₁₂)Rh(μ-4-pyrdpm)Ir(η⁵-C₅Me₅)Cl₂], [(η⁴-C₈H₁₂)Rh(μ-4-pyrdpm)Ru(η⁶-C₁₀H₁₄)Cl₂] and [(η⁴-C₈H₁₂)Rh(μ-4-pyrdpm)Ru(η⁶-C₆H₆)Cl₂]. Resulting complexes have been characterized by elemental analyses and spectral studies. Molecular structures of the representative mononuclear complexes [(η⁴-C₈H₁₂)Rh(ndpm)] and [(η⁴-C₈H₁₂)Rh(4-pyrdpm)] have been authenticated crystallographically.     

Chiral arene ruthenium complexes: Part 3. [Ruthenium(η6-arene)(η4-1,5-cyclooctadiene)] complexes with N or O donor functions in the arene side chain

Arene ruthenium(0) complexes with carbonyl side chain functionalities like [Ru(η⁶-C₆H₅COR)(η⁴-COD)] or [Ru(η⁶-o-C₆H₄{R¹}COR)(η⁴-COD)] (COD=1,5-cyclooctadiene; R=H, CH₃; R¹=H, CH₃, OCH₃) are easily accessible by replacing the naphthalene ligand of [Ru(η⁶-naphthalene)(η⁴-COD)] (1) through an arene exchange reaction. These carbonyl species are susceptible to standard organic reactions of the carbonyl function, thus allowing the introduction of dangling side chains bearing highly polar functions like hydroxyl or amino groups. Aldol reaction of [Ru(o-C₆H₄{CH₃}COCH₃)(COD)] (3) with (−)-menthylchloroformate in the presence of LDA (LDA=lithium diisopropylamide) leads to a diastereomeric mixture of [Ru(menthyl-{3-oxo-3-η⁶-o-tolyl}propionate)(COD)] (10). However, treatment of 3 with LDA and o-tolylaldehyde or benzaldehyde affords the unexpected products [Ru(1-η⁶-o-tolyl-3-o-tolylpropan-1-one)(COD)] (11) and [Ru(1-η⁶-o-tolyl-1-phenylpropan-1-one)(COD)] (12). A diastereoselective addition (88% de) of deprotonated menthylacetate to [Ru(o-tolylaldehyde)(COD)] (4) results in the formation of [Ru(menthyl 3-η⁶-o-tolyl-3-hydroxypropionate)(COD)] (13). Racemic planar-chiral aldehyde complexes 2 and 4 react with amines giving the imination products in good yield. In case of reaction between 2 and (R)-N-amino-2-(methoxymethyl)-pyrrolidine (RAMP), diastereomeric [Ru(N-[[η⁶-(2-methylphenyl]methylene]-(R)-2-(methoxymethyl)-1-pyrrolidinamine)(COD)] (17) is formed. The diastereomers (R,R)-17 and (S,R)-17 have been separated by fractional crystallisation. Asymmetric arene ruthenium complexes with a defined planar-chiral configuration are thus accessible. Reduction of [Ru(3-η⁶-phenyl-(R)-methylbutyrate)(COD)] (7) with LiAlH₄ yields the chiral γ-alcohol [Ru(3-η⁶-phenyl-(R)-1-butanol)(COD)] (18). A Wittig olefination converts the aldehyde complex 4 into a mixture of E- and Z-isomeric [Ru(1-η⁶-o-tolyl-2-phenylethylene)(COD)] 21a and 21b, which were separated again by fractional crystallisation.     

Monodentate phosphites with carbohydrate substituents and their application in rhodium catalysed asymmetric hydrosilylation reactions

Several monodentate phosphites derived from d-glucofuranose were prepared and examined as ligands in the rhodium catalysed enantioselective hydrosilylation of acetophenone. A substantial variation in the e.e. values, from racemic to 58% e.e., was seen depending on the nature of the phosphite ligand used and the ligand to metal ratio. The reactivity of the selected phosphite P(DAG)₃ towards [Rh(μ-Cl)(COD)]₂ and [Rh(μ-Cl)(C₂H₄)₂]₂ (DAG=(1:2;5:6)-di(O-isopropylidene)-d-glucofuranosyl) allowed the synthesis of monosubstitued Rh(Cl)(COD)P(dag)₃ and [Rh(μ-Cl)(C₂H₄)P(dag)₃]₂ complexes, and the disubstituted Rh(Cl)(P(dag)₃)₂ and Rh(Cl)(C₂H₄)(P(dag)₃)₂ complexes. This study indicated that the disubstituted compounds offer better enantioselectivities than the monosubstituted ones.     

Metal dimers as catalysts: IX. The catalysed reaction between [η5-C5H5)Fe(CO)2I] and group 15 donor ligands

The reaction between [η⁵-C₅H₅)Fe(CO)₂I] (I) and 1 equivalent of L (group 15 donor ligand) in the presence of catalysts (e.g. Pd/CaCO₃, PdO, [η⁵-C₅H₅)Fe(CO)₂]₂ (II)) yields [η⁵-C₅H₅)Fe(CO)(L)I] (phosphines, diphosphines, phosphite), [η⁵-C₅H₅)Fe(CO)₂L]I (phosphines) and [η⁵-C₅H₅)Fe(CO)(LL)]I (diphosphines). [η⁵-C₅H₅)Fe(CO)₂L]I can be converted into [η⁵-C₅H₅)Fe(CO)(L)I] in the presence of II. The reaction between [η⁵-C₅H₅)Fe(CO)(PMePh₂)I] or [η⁵-C₅H₅)Fe(CO)₂(PMePh₂)]I and PMePh₂ is also catalysed by II and yields in both instances [η⁵-C₅H₅)Fe(CO)(PMePh₂)₂]I. In the series of catalysed reactions the displacement sequence was found to be PMePh₂ > I⁻ > CO.     

Dirhodium(II) dicarboxylato complexes containing carbonyl and C-bonded methoxycarbonyl ligands

Oxidation of rhodium(I) carbonyl chloride, [Rh(CO)₂Cl]₂, with copper(II) acetate or isobutyrate in methanol solutions yields binuclear double carboxylato bridged rhodium(II) complexes with RhRh bonds, [Rh(μ-OOCRκO)(COOMeκC)(CO)(MeOH)]₂, where R=CH₃ or i-C₃H₇. According to X-ray data, surrounding of each rhodium atom in these complexes is close to octahedral and consists of another rhodium atom, two oxygens of carboxylato ligands, terminal carbonyl group, C-bonded methoxycarbonyl ligand, and axial CH₃OH. Methoxycarbonyl ligand is shown to originate from CO group of the parent [Rh(CO)₂Cl]₂ and OCH₃ group of solvent. N- and P-donor ligands L (p-CH₃C₆H₄NH₂, P(OPh)₃, PPh₃, PCy₃) readily replace the axial MeOH yielding [Rh(μ-OOCRκO)(COOMeκC)(CO)(L)]₂. The X-ray data for the complex with R=i-C₃H₇, L=PPh₃ showed the same molecular outline as with L=MeOH. Electronic effects of axial ligands L on the spectral parameters of terminal carbonyl group are essentially the same as in the known series of rhodium(I) complexes (an increase of δ¹³C and a decrease of ν(CO) with strengthening of σ-donor and weakening of π-acceptor ability of L).