Stepwise synthesis of [Os3(CO)8(R2C2)(R′2C2)] from [Os3(CO)10(R2C2)] under mild conditions,x-ray crystal structure of [Os3(CO)8(Ph2C2)2]; a bis(alkyne) without an osmacyclopentaidiene ring

Treatment of a solution of [Os₃(CO)₁₀(R₂C₂)] (R = Me (1, R = Ph (2)) in CH₂Cl₂ with Me₃No/MeCN in the presence of R′₂C₂ affords the new organometallic cluster [Os₃(CO)₈(R₂C₂)(R′₂C₂)] (R = R′ = Me (3), R = R′ = Ph (4) and R = Ph, R′ = Me (5)). A single crystal X-ray analysis of compound 4 has established a triangular metal framework with both the alkyne units coordinated in a μ₃-η²-6-mode. In toluene, at 80°C, compound 4 undergoes rearrangement to the known compound, [Os₃H(CO)₈(Ph)C₂(C₆H₄))] (6) in which CC bond formation has occurred to produce an osmacyclopentadiene ring.     

New triosmium metal clusters derived from the reactions between [Os3(CO)10(NCMe)2] and amides

Triosmium clusters of the type [Os₃(CO)₁₀(μ-H)(NHCOR)] (1; R = H, Me, Ph, Et or Pr) are formed in high yields form the reaction of [Os₃(CO)₁₀(NCMe)₂] (2) with amides. The nature of the products formed from thermolysis of 1 depend on the group, R.     

Intramolecular Cyclization of Butadiyne Functionalized Ligands coordinated to Triosmium‐Carbonyl Cluster

Reactions between diynes and [Os₃(CO)₁₁(CH₃CN)] in the presence of water give rise to the formation of intriguing hydride triosmium clusters [Os₃(μ‐H)(CO)₉{μ₃,η¹:η³:η¹‐RC₂COHC≡CR}] ( 1a – 1c ) under mild conditions in high yields. When these allylic alcohol compounds 1a – 1c are dissolved in dry polar and donor solvents, an intramolecular cyclization process takes place to give [Os₃(μ‐H)(CO)₉{μ₃,η¹:η³:η¹‐RC₂CH=COCR}] ( 2a – 2c ) in quantitative yield. The utilization of [Os₃(CO)₁₁(CH₃CN)] as starting material together with the addition of water can replace the inconvenient use of [Os₃(μ‐H)₂(CO)₁₀]. This method of synthesis provides a facile pathway for diyne cyclizations and has a clear advantage over those described to date in the literature. Additionally, the analogous cyclized mixed‐metal complex [Os₃(μ‐H)(CO)₉{μ₃,η¹:η³:η¹‐FcC₂CH=COCFc}] ( 2d ) (Fc = ferrocenyl), was synthesized in order to carry out a comparative electrochemical study with the related compounds [Os₃(CO)₁₁(μ₃‐FcC₄Fc)] ( I ) and [Os₃(CO)₁₀(μ₃‐FcC₄Fc)] ( II ), which were previously reported by R. D. Adams.     

Oxidative addition of 2-formyl-furan and related pyrrole and thiophene compounds at triosmium clusters

The bridging acyl complexes [Os₃H(μ-COC₄H₃X)(CO)₁₀] (X = NH, O, or S) have been prepared by oxidative addition of the 2-formyl derivatives of pyrrole, furan, or thiophene (C₄H₃XCHO) at [Os₃(CO)₁₀(MeCN)₂] with cleavage of the aldehydic CH bonds. On heating double decarbonylation of the acyl complexes occurs, to afford high yields of the compounds [Os₃H₂(CO)₉(μ₃-C₄H₂X)], reported previously for X = NH or O. For X = NH, two isomers with this formulation were characterised by ¹H NMR and IR data; the one containing the μ₃-2,3-C₄H₃N ligand isomerises to one containing μ₃-1,2-C₄H₃N. The direct reaction of pyrrole with [Os₃(CO)₁₂] has been re-examined at lower temperatures than before, and observed to give new products, including [Os₃H(CO)₁₀(C₄H₄N)], which contains a bridging non-aromatic tautomeric form of pyrrole. The ability of Os₃ clusters to stabilize non-aromatic tautomers of aromatic ligands is discussed.     

The Pyrolysis of Isonitrile Substituted Derivatives of Triosmium Dodecacarbonyl

The pyrolysis of the isonitrile substituted complexes Os₃(CO)_12?x(CNR)x (R = Bu^t, x = 1,2) in refluxing octane has been studied. From these pyrolysis reactions and from the reaction of Os₃(CO)₁₂ with Bu^tNC in refluxing octane the series of hexanuclear complexes Os₆(CO)_18?x(CNBu^t)_x (x = 1?5) has been isolated. The pyrolysis of Os₃(CO)₁₁(CNBuⁿ) also leads to the formation of higher nuclearity clusters and evidence is presented that one product of the reaction is Os₆(CO)₁₇(CNBuⁿ)₂. Possible structures for these isonitrile substituted hexanuclear complexes are discussed in the light of the known structures of Os₆(CO)₁₆(CNBu^t)₂ and Os₆(CO)₁₈(CNC₆H₄Me)₂.     

Enantiomerically Pure Cyclic trans-1,2-Diols,Diamines, and Amino Alcohols by Intramolecular Pinacol Coupling of Planar Chiral Mono-Cr(CO)3 Complexes of Biaryls

Without any formation of stereoisomers , the intramolecular pinacol cyclization of 1 —planar chiral mono-Cr(CO)₃ complexes of 1,1′-biphenyls with carbonyl functionalities at the 2- and 2′-positions—with samarium diiodide gives cyclic trans-1,2-diols 2 . Upon exposure to sunlight, the chromium-complexed diols 2 produce optically pure chromium-free trans-diols 3 . Similarly, the corresponding enantiomerically pure trans-1,2-diamines and amino alcohols are obtained from the planar chiral chromium complexes of biphenyls with diimino or keto-imino functionalities. R¹=H, OMe; R²=H, Me; R³=H, Me.     

Addition reactions of a polynuclear osmium hydrido compound leading to associative carbonyl substitution and catalytic alkene isomerisation

The ability of H₂Os₃(CO)₁₀ to undergo addition reactions under mild conditions allows associative CO substitution via isolable intermediates of the type H₂Os₃(CO)₁₀ (L = CO, PMe₂Ph, PPh₃ or PhCN) whose spectra and structures are discussed. It is probable that simple addition of alkenes to H₂Os₃(CO)₁₀ is in part responsible for its facile catalysis of alkene isomerisation. The kinetics of catalytic conversion of terminal to internal alkenes and of allylic alcohols to aldehydes or ketones are reported and discussed. The reactions of H₂Os₃(CO)₁₀ with allylic halides to give the complexes HOs₃X(CO)₁₀ and Os₃X₂(CO)₁₀ where X = Cl, Br or I are described. Compound H₂Os₃(CO)₁₀ complies with the 18ρ-rule but nevertheless has a chemistry much like that of coordinatively unsaturated molecules.     

POSSIBLE HYDRIDE AND METHIDE TRANSFER REACTIONS: REACTIONS OF Fe(CO)4R−(R = H,CH3) AND W(CO)5R− (R = H,CH3, Cl,Br, I) WITH METAL CARBONYL CATIONS

Abstract

Reactions of metal carbonyl cations (M(CO)₆ ⁺, M = Mn, Re) with hydride-, methide- or halide-containing metal carbonyl anions (Fe(CO)₄R^?, R = H, Me; W(CO)₅R^?, R = H, Me, Cl, Br, I) produce products that indicate several mechanisms are operative. Reactions of the halo-tungsten complexes produce neutral, solvated tungsten complexes, W(CO)₅(CH₃CN) and W(CO)₄(CH₃CN)₂ and M(CO)₅X in a reaction that appears to be initiated by decomposition of W(CO)₅X^?. In contrast, the tungsten hydride and methide complexes react, predominantly, by transfer of the hydride or methide to a carbonyl of the cation at a much faster rate. The iron hydride and methide complexes react by iron-based nucleophilicity involving a two-electron process.     

Soft Scorpionate Hydridotris(2-mercapto-1-methylimidazolyl) borate) Tungsten-Oxido and -Sulfido Complexes as Acetylene Hydratase Models

A series of W^IV alkyne complexes with the sulfur-rich ligand hydridotris(2-mercapto-1-methylimidazolyl) borate) (Tm^Me) are presented as bio-inspired models to elucidate the mechanism of the tungstoenzyme acetylene hydratase (AH). The mono- and/or bis-alkyne precursors were reacted with NaTm^Me and the resulting complexes [W(CO)(C₂R₂)(Tm^Me)Br] (R=H 1 , Me 2 ) oxidized to the target [WE(C₂R₂)(Tm^Me)Br] (E=O, R=H 4 , Me 5 ; E=S, R=H 6 , Me 7 ) using pyridine-N-oxide and methylthiirane. Halide abstraction with TlOTf in MeCN gave the cationic complexes [WE(C₂R₂)(MeCN)(Tm^Me)](OTf) (E=CO, R=H 10 , Me 11 ; E=O, R=H 12 , Me 13 ; E=S, R=H 14 , Me 15 ). Without MeCN, dinuclear complexes [W₂O(μ-O)(C₂Me₂)₂(Tm^Me)₂](OTf)₂ ( 8 ) and [W₂(μ-S)₂(C₂Me₂)(Tm^Me)₂](OTf)₂ ( 9 ) could be isolated showing distinct differences between the oxido and sulfido system with the latter exhibiting only one molecule of C₂Me₂. This provides evidence that a fine balance of the softness at W is important for acetylene coordination. Upon dissolving complex 8 in acetonitrile complex 13 is reconstituted in contrast to 9 . All complexes exhibit the desired stability toward water and the observed effective coordination of the scorpionate ligand avoids decomposition to disulfide, an often-occurring reaction in sulfur ligand chemistry. Hence, the data presented here point toward a mechanism with a direct coordination of acetylene in the active site and provide the basis for further model chemistry for acetylene hydratase.     

A novel reaction of Os6(CO)18 with Me3NO; isolation and NMR study of the new hexaosmium cluster anion [HOs6(CO)17]−

In the absence of a ligand and in non-coordinating solvents, Os₆(CO)₁₈ racts with 2 equivalents of R₃No (R = Me, Et) to give the new hexaosmium cluster [HOs₆(CO)₁₇]⁻. Variable temperature ¹H and ¹³C NMR and ²D NMR. techniques have been used to investigate the structure of this anion and its dynamic behviour in solution. The mechanism of the novel reaction is discussed.     

Os3(CO)9{μ3-η1-η1-η2-η2-C(SiMe3)C(Me)C(H)C(Fc)}, the second example of a cluster with the “face” coordination of the metallacyclopentadiene fragment and its conversion to the Os3(μ-H)(CO)8{μ3-η1-η1-η4-η1-C(SiMe3)C(Me)C(H)C(C5H3FeC5H5)} complex with theortho-metallated ferrocene moiety

Os₃(μ-CO)(CO)₉(μ₃-Me₃SiC₂Me) alkyne complexes react with ferrocenylacetylene in hot benzene to form Os₃(CO)₉{μ₃-η¹-η¹-η²-η²-C(SiMe₃)C(Me)C(H)C(Fe)} and a small amount of the isomeric Os₃(CO)₉(μ-η¹-η¹-η⁴-C(SiMe₃)C(Me)C(Fc)C(H)} complex. The structure of the major isomer was confirmed by X-ray structural analysis of the single crystal. Thermolysis of this complex in refluxing benzene affords the Os₃(μ-H)(CO)₈{μ₃-η¹-η¹-η⁴-η¹-C(SiMe₃)C(Me)C(H)(C₅H₃FeC₅H₅)} complex with theortho-metallated ferrocene moiety. The spectral characteristics of clusters with the μ₃-η¹-η¹-η²-η² and μ-η¹-η¹-η⁴ coordinations of the metallacyclopentadiene fragment have been established, which made it possible to choose between the alternative modes of bonding of diene with the trimetallic core.     

Synthetic studies of the reaction between aldehydes and the triosmium cluster [Os3(CO)10(NCMe)2]

The reaction of [Os₃(CO)₁₀(NCMe)₂] (1) with aldehydes in refluxing cyclohexane affords the metal clusters [Os₃(CO)₁₀(μ-H)(COR)] (2, R = Me, Ph, CH₂Ph or C₆H₁₃) in ca. 50% yield. The compound 2 (R = CH₂Ph) undergoes hydrogenation under pressure to give the corresponding alcohol, while decarbonylation occurs in the presence of Me₃NO to give the Me₃N-substituted derivative [Os₃(CO)₉(NMe₃)(μ-H)(COCH₂Ph)] in 90% yield.     

The reaction of H2Os3(CO)10 with trifluoroacetonitrile and the x-ray crystal structure of HOs3(CO)9(μ3-η2-HNCCF3)

The reaction of H₂Os₃(CO)₁₀ with CF₃CN in hexane at 80°C leads to two isomeric products. The isomer constituting the major product contains a 1,1,1-tri-fluoroethylidenimido ligand which bridges one edge of the Os₃ triangle via the nitrogen, atom and may be formulated as (μ-H)Os₃(CO)₁₀(μ-NC(H)CF₃) (I). The minor product, formulated as (μ-H)Os₃(CO)₁₀(μ-η²-HNCCF₃) (II), contains a 1,1,1-trifluoroacetimidoyl ligand which is also edge-bridging, being N-bonded to one Os atom and C-bonded to the other. Thermolysis of I and II in solution results in loss of a CO group in each case to give (μ-H)Os₃(CO)_9^? (μ₃-η²-NC(H)CF₃) (III) and (μ-H)Os₃(CO)₉(μ₃-η²-HNCCF₃) (IV), respectively, which, it is proposed, are structurally related to I and II, but with the CN group coordinated also to the third Os atom in place of a CO group. In the case of IV this proposal has been confirmed by an X-ray crystallographic analysis. The compound crystallises in space group C2/c with a = 14.258(7), b = 13.486(10), c = 18.193(8) Å, β = 92.68(4)°, and Z = 8. The structure was solved by a combination of direct methods and Fourier difference techniques, and refined by full-matrix least squares to R = 0.054 for 2489 unique observed diffractometer data. Reaction of I with Et₃P gives a 1 : 2 adduct which is formulated as (μ-H)Os₃(CO)₁₀[μ-N?C(H)(CF₃)PEt₃] (V) on the basis of NMR evidence.     

Metallorganische Lewis-Basen : XXXIX. Monomere Carbonylcobalt-Dimethylarsenide

The monomers R₃P(CO)₃Co-AsMe₂ (R = Me,MeO) decompose at ?10°C, the monomers (R₃P)₂(CO)₂Co-AsMe₂ (R = Me, MeO) are stable at room temperature. They are prepared from the very unstable (CO)₄Co-AsMe₂ by phosphine substitution at low temperatures or from KCo(CO)₃PR₃ and Me₂AsCl. They are organometallic Lewis bases forming dinuclear and trinuclear arsenic bridged complexes with metal carbonyls.     

Zur reaktion von metall-koordiniertem kohlenmonoxid mit yliden: XI. Einige neuartige η1-vinyl-komplexe des eisens durch deprotonierung kationischer carbenkomplexe mit trimethyl(methylen)phosphoran

Novel η¹-vinyl complexes of the type Cp(CO)(L)FeC(OMe)C(R)R′ (R = R′ = H, Me; R = H, R′ = Me; L = Me₃P, Ph₃P) are obtainied via methylation of the acyl complexes Cp(CO)(L)FeC(O)R (R = Me, Et, i-Pr) with MeOSO₂F and subsequent deprotonation of the resulting carbene complexes [Cp(CO)(L)FeC(OMe)R]SO₃F with the phosphorus ylide Me₃PCH₂. The same procedure can be applied for the synthesis of the pentamethylcyclopentadienyl derivative C₅Me₅(CO)(Me₃P)FeC(OMe)CH₂, while treatment of the hydroxy or siloxy carbene complexes [Cp(CO)(L)FeC(OR)Me]X (R = H, Me₃Si; X = SO₃CF₃) with Me₃CH₂ results in the transfer of the oxygen bound electrophile to the ylidic carbon. Some remarkable spectroscopic properties of the new complexes are reported.     

Carbonylate anion [(μ-H)Os<Subscript>3</Subscript>(CO)<Subscript>10</Subscript>L]<Superscript>−</Superscript> as a precursor in the synthesis of heterometallic Os<Subscript>3</Subscript>M clusters

A new method for the synthesis of heterometallic clusters Os₃M is developed. The reactions of hydridocarbonyl cluster (μ-H)₂Os₃(CO)₁₀ (I) with binuclear carbonyls Co₂(CO)₈ and Fe₂(CO)₉ in the presence of 1,4-diazabicyclo[2.2.2]octane (Dabco) afford anionic complexes [Os₃Co(CO)₁₃]⁻ (II) and [HOs₃Fe(CO)₁₃] (III) with the counterion N₂C₆H₁₃⁺. Similar reactions with halide complexes [MCp*Cl₂]₂ (M = Rh and Ir) yield neutral complexes [Os₃M(CO)₁₀(μ-H)(μ-Cl)] (M = Rh(IV) and Ir(V)). The reactions occur rapidly at room temperature with high yields. The newly obtained clusters are characterized by the data of IR and ¹H NMR spectroscopy, elemental analysis, and X-ray diffraction analysis.     

Alkyne-vinylidene coupling in the reactions of the alkyne complex Os3(μ-CO)(CO)9(μ3-Me3C2Me) with Me3SiC≡CR (R=Me, Bun). The structure and stereodynamic behavior of clusters Os3(CO)9{μ3-C(SiMe3)=C(Me)C=C(SiMe3)=C(Me)C=C(SiMe3)R} containing an osmacyclobutene moietycontaining an osmacyclobutene moiety

Reactions of the alkyne cluster Os₃(μ-CO)(CO)₉(μ₃-Me₃C₂Me) with alkynes Me₃SiC≡CR (R=Me, Buⁿ) in refluxing hexane result in the formation of clusters Os₃(CO)₉{μ₃-C(SiMe₃)=C(Me)C=C(SiMe₃)=C(Me)C=C(SiMe₃)R} (2a: R=Me;3a: R=Buⁿ). The dienediyl ligand in these complexes is formed by alkyne-vinylidene coupling, with vinylidene generated in the course of reaction from the alkyne molecule by the acetylene-vinylidene rearrangement involving a 1,2-shift of the Me₃Si group. The structure of cluster3a was determined by X-ray structural analysis. The dienediyl ligand is coordinated to three metal atoms of the cluster framework by two π-ethylene bonds with two osmium atoms and two σ-bonds with the third osmium atom with the formation of the osmacyclobutene moiety. The¹H and¹³C NMR study of¹³CO-enriched samples of clusters2a and3a revealed the stereochemical nonrigidity of these molecules due to the exchange of the hydrocarbon and carbonyl ligands.     

Reaction of alkyne cluster Os3(μ-CO)(CO)9(μ3-η1:η1:η2-Me3SiC2Me) with HC≡CCOOMe. Molecular and crystal structures of Os3(CO)9{μ3-η1:η1:η2:η2-C(SiMe3)C(Me)C(COOMe)CH× and Os3(CO)8{μ3-η1:η1:η4:η1-C(SiMe3)C(Me)C(H)C(COOMe)CH× complexes

Reaction of the cluster Os₃(μ-CO)(CO)₉(μ₃-η¹:η¹:η²-Me₃SiC₂Me) with HC≡CCOOMe in benzene at 70 °C results in Os₃(CO)₉{μ₃-η¹:η¹:η²:η²-C(SiMe₃)C(Me)C(COOMe)CH× (5), Os₃(CO)₉{μ₃-η¹:η¹:η²:η²-C(SiMe₃)C(Me)C(H)C(COOMe)CH× (6), Os₃(CO)₉{μ-η¹:η¹:η⁴-C(SiMe₃)C(Me)C(H)C(COOMe)CH× (7), and Os₃(CO)_δ{μ₃-η¹:η¹:η⁴:η¹-C(SiMe₃)C(Me)C(H)C(COOMe)× complexes (8), containing an osmacyclopentadiene moiety. Complexes5–8 were characterized by¹H NMR and IR spectroscopy. The structure of clusters5 and8 was confirmed by X-ray analysis. Complex7 is formed from cluster5 as a result of a new intramolecular rearrangement and complex8 is obtained by decarbonylation of compound6. Complex8 adds PPh₃ to give Os₃(CO)_δ(PPh₃){μ-η¹:η¹:η⁴-C(SiMe₃)C(Me)C(H)C(COOMe)×.     

Chalcogen–acetylide interaction and unusual reactivity of coordinated acetylide with water: synthesis and characterisation of [(η5-C5R5)Fe3(CO)6(μ3-E)(μ3-ECCH2RI)] (R=H,Me; RI=Ph,Fc; E=S,Se) and [(η5-C5R5)MoFe2(CO)6(μ3-S)(μ-SCCH2Ph)] (R=H,Me)

Photolysis of a benzene solution containing [Fe₃(CO)₉(μ₃-E)₂] (E=S, Se), [(η⁵-C₅R₅)Fe(CO)₂(CCR^I)] (R=H, Me; R^I=Ph, Fc), H₂O and Et₃N results in formation of new metal clusters [(η⁵-C₅R₅)Fe₃(CO)₆(μ₃-E)(μ₃-ECCH₂R^I)] (R=H, R^I=Ph, E=S 1 or Se 2; R=Me, R^I=Ph, E=S 3 or Se 4; R=H, R^I=Fc, E=S 5; R=Me, R^I=Fc, E=S 6 or Se 7). Reaction of [Fe₃(CO)₉(μ₃-S)₂]with [(η⁵-C₅R₅)Mo(CO)₃(CCPh)] (R=H, Me), under same conditions, produces mixed-metal clusters [(η⁵-C₅R₅)MoFe₂(CO)₆(μ₃-S)(μ-SCCH₂Ph)] (R=H 8; R=Me 9). Compounds 1–9 have been characterised by IR and ¹H and ¹³C-NMR spectroscopy. Structures of 1, 5 and 9 have been established crystallographically. A common feature in all these products is the formation of new C-chalcogen bond to give rise to a (ECCH₂R^I) ligand.     

Hydrido‐sulfido‐bridged triangular Os3 cluster compounds with different phosphine ligand substitution patterns

In the course of our studies of trinuclear osmium cluster complexes with bridging sulfido and hydrido ligands, the new compounds Os₃(μ‐H)(μ‐SR)(CO)₉(PHCy₂) (Cy = cyclo­hexyl) with R = phenyl, (I) (nona­carbonyl‐1κ³C,2κ³C,3κ³C‐di­cyclo­hexyl­phosphine‐3κP‐μ‐hydrido‐1:2κ²H‐μ‐phenyl­thio‐1:2κ²S‐triangulo‐triosmium), [Os₃H(C₆H₅S)(C₁₂H₂₃P)(CO)₉], and R = naphthyl, (II) [nona­carbonyl‐1κ³C,2κ²C,3κ⁴C‐di­cyclo­hexyl­phosphine‐2κP‐μ‐hydrido‐1:2κ²H‐μ‐(2‐naphthyl­thio)‐1:2κ²S‐triangulo‐triosmium], [Os₃H(C₁₀H₇S)(C₁₂H₂₃P)(CO)₉], were prepared. We report on these two phosphine‐substituted complexes, which exhibit perceptible changes of the Os—Os bond parameters due to the ligand‐substitution pattern.