Reactions of Tungsten Propargyl and Allenyl Complexes with Hydrido Triosmium Cluster: Molecular and Crystal Structure of Cp(CO)2[P(OMe)3]W(μ, η1, η2-CH2CH=CH)OS3(CO)10H and H2(CH2CH = CH)2Os6(CO)20

Reactions of H₂Os₃(CO)₁₀, 3, with the monophosphite-substituted and non-substituted tungsten propargyl and allenyl carbonyl complexes Cp(CO)₂LWCH₂C≡CH (1a, L = CO; 1b, L = P(OMe)₃) and Cp(CO)₂LWCH = C = CH₂ (2a, L = CO; 2b, L = P(OMe)₃) were investigated. In the reaction of 1b with 3, a tetranuclear complex 4b is obtained. The molecules of 4b crystallize as Cp(CO)₂[P(OMe)₃]W(μ, η¹, η²-CH₂CH=CH)(μ-H)Os₃(CO)_l0 in space group PI with a = 9.490 (4), b = 13.072 (7), c = 13.770 (9) Å, α = 91.89 (5), β = 106.71 (5), γ = 104.07(4)°, V = 1577(2) ų, Z = 2. In the reaction of 2a with 3, from the reaction mixture exposed to air followed by workup using silica-gel packed column chromatography, a complex consisting of two triosmium clusters bridged by a hexadiene ligand from the coupling of allenyl ligand was obtained. The molecules of the hexanuclear complex crystallize as [CH₂CH = CH)₂(μH)₂OS₆(CO)₂₀in space group P2₁/c with a = 14.448 (7), b = 13.689 (4), c = 19.224 (4) Å, β = 107.14(3)°, V = 3633 (2) Å Z = 4.     

Isomerization and conformational transformations of theN-allyl-N-methylcarbamoyl bridging ligand in the (μ-H)Os3{μ-OCN(Me)CH2CH=CH2}(CO)10 complex

The (μ-H)Os₃{μ-OCN(Me)CH₂CH=CH₂}(CO)₁₀ complex containing an allylic fragment in theN,N-dialkylsubstituted carbamoyl briding ligand was synthesized. The stereo-chemical behavior of this complex in solution was investigated. As follows from the NMR spectral data, the complex undergoes reversible conformational (about the amide C−N bond) and irreversible allylic isomerization. Both conformers were isolated in the solid state by chromatography at a reduced temperature. The allylic isomerization occurs stereospecifically to produce the (μ-H)Os₃{μ-OCN(Me)CH=CHMe}(CO)₁₀ complex with thetrans-oriented olefinic hydrogen atoms. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 158–162, January, 1998.     

Synthesis and characterization of the substituted products from the reaction of a bulky phosphite with [Os3(CO)12]

Reaction of (acetonitrile)-undeca(carbonyl)-tri-osmium and tris(2,4-di-tert-butylphenyl) phosphite yielded the phosphite clusters [Os₃(CO)₁₁L] (4) and [Os₃(CO)₁₀L₂] (5) [L = P(O-2,4- ^t Bu₂C₆H₃)₃]. These compounds were characterized spectroscopically and the molecular structure of 5 was determined by single crystal X-ray diffraction, the first reported structural analysis of a tri-osmium cluster containing aromatic phosphite ligands. Compound 5 crystallized in the triclinic space group P 1, and revealed an equatorial trans–trans position of the bulky phosphite ligands.     

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.     

Reaction of ethylene with the unsaturated cluster complex H2Os3 (CO)10

Treatment of H₂Os₃(CO)₁₀ with excess ethylene forms ethane and a hydridovinyl cluster complex HOs₃(CO)₁₀(CHCH₂), which rearranges in refluxing octane to the vinylidene complex H₂Os₃(CO)₉(CCH₂).     

Heterometallic cuboidal complexes as derivatives of the [MO3S4(H2O)9]4+ cluster

Heterometallic atoms can be incorporated into the Mo ₃ ^IV trinuclear ion [Mo₃S₄(H₂O)₉]⁴⁺ to give cuboidal complexes of the kind Mo₃MS₄, or related edge-linked species {Mo₃MS₄}₂, or corner-shared Mo₃S₄MS₄Mo₃ double cubes, depending on the heteroatom used. All of the products formed can be obtained as aqua ions. With four recent additions there are now 15 different heterometal atoms participating in this chemistry from Cr in Group 6 to Bi in Group 15. Preparative procedures, X-ray crystal structures, and distinctive properties including UV-Vis spectra, elution characteristics using Dowexcation exchange chromatography, ICP metal analyses, and the stoichiometries of reactions in which the heterometallic product is oxidized back to [Mo₃S₄(H₂O)₉]⁴⁺ (with release of the heterometal in an ionic form) are considered.Dedicated to Professor Jiaxi Lu on the occasion of his 80th birthday.     

Synthesis and diphosphine ligand fluxionality in Os3(CO)10(bmi): Kinetic evidence for nondissociative diphosphine isomerization and X-ray crystal structure of 1,1-Os3(CO)10(bmi)

The triosmium cluster 1,2-Os₃(CO)₁₀(MeCN)₂ reacts rapidly with the diphosphine ligand 2,3-bis(diphenylphosphino)-N-p-tolylmaleimide (bmi) at room temperature to give bmi-bridged cluster 1,2-Os₃(CO)₁₀(bmi) (2b) as the major product, along with the chelating isomer 1,1-Os₃(CO)₁₀(bmi) (2c) and the hydride-bridged cluster HOs₃(CO)₉[μ-(PPh₂)CC{PPh(C₆H₄)}C(O)N(tolyl-p)C(O)] (3) as minor by-products. All three cluster compounds have been isolated and fully characterized in solution by IR and NMR spectroscopies (¹H and ³¹P), and X-ray crystallography in the case of 2c. Cluster 2b is unstable and readily isomerizes to 2c in quantitative yield on mild heating. The kinetics for the conversion of 2b → 2c have been measured over the temperature range of 318-348 K in toluene solution, and based on the observed activation parameters a nondissociative isomerization process that proceeds via a transient μ₂-bridged phosphine moiety is presented. Near-UV photolysis of cluster 2c at room temperature affords HOs₃(CO)₉[μ-(PPh₂)CC{PPh(C₆H₄)}C(O)N(tolyl-p)C(O)] (3) with a quantum yield of 0.017. The reactivity of clusters 2b, 2c, and 3 is discussed with respect to related diphosphine-substituted Os₃(CO)₁₀(P-P) clusters prepared by our groups.     

Pincer ligand coordination at a triosmium cluster: X-ray structures of 1,2-Os3(CO)10[4,6-bis(diphenylphosphinomethyl)-m-xylene] and 1,2-Os3(CO)10[1-diphenylphosphino-1-{(2,4-dimethyl-5-diphenylphosphinomethyl)phenyl}-propan-2-ol]

The reaction between the triosmium cluster 1,2-Os₃(CO)₁₀(MeCN)₂ and the diphosphine pincer ligand 4,6-bis(diphenylphosphinomethyl)-m-xylene (dppx) has been examined and found to yield the pincer-bridged cluster 1,2-Os₃(CO)₁₀(dppx) (2) as the major product, in addition to the pincer-bridged cluster 1,2-Os₃(CO)₁₀[1-diphenylphosphino-1-{(2,4-dimethyl-5-diphenylphosphinomethyl)phenyl}-propan-2-ol] (3) in trace amounts (<2% yield). Both cluster products have been isolated and their molecular structures determined by crystallographic analyses. The structural highlights of compounds 2 and 3, which represent the first examples of pincer-ligated metal clusters, are discussed. The origin of the functionalized diphosphine ligand in 3 is traced to the ethanol solvent that was used in the recrystallization of the dppx ligand.     

Synthesis of mixed metal decaosmium carbido clusters: The X-ray structures of the monoanions [Os10C(CO)24Cu(NCMe)]− and [Os10C(CO)24AuPPh3]−

The high nuclearity mixed metal cluster monoanions [Os₁₀C(CO)₂₄Cu(NCMe)]^? (I) and [Os₁₀C(CO)₂₄AuPPh₃]^? (II) have been obtained by reaction of the carbido-dianion [Os₁₀C(CO)₂₄]^2? (III) with one equivalent of [Cu(NCMe)₄] [BF₄] and Ph₃PAuCl, respectively, in CH₂Cl₂. X-ray analysis of the [PPh₃Me]⁺ salts of I and II show that the Cu and Au ligands have added to capping tetrahedra of the dianion III in μ₃- and μ₂-bridging positions, respectively.     

Pd(PBu 3 t ) Adducts of Os3(CO)12. Synthesis and Structures of Pd2Os3(CO)12(PBu 3 t )2 and Pd3Os3(CO)12 (PBu 3 t )3

Two new compounds Pd₂Os₃(CO)₁₂ , 13 and Pd₃Os₃(CO)₁₂ , 14 have been obtained from the reaction of with Os₃(CO)₁₂ at room temperature. The products were formed by the addition of two and three groups to the Os–Os bonds of Os₃(CO)₁₂. Compounds 13 and 14 interconvert between themselves by intermolecular exchange of the groups in solution. Compounds 13 and 14 have been characterized by single crystal X-ray diffraction analyses.Dedicated to Professor Brian F. G. Johnson on the occasion of his retirement – 2005.     

Four isomers from the oxidative addition of Me3SnH to Os(CO)2(PPh3)3 and the crystal structure of Os(SnMeI2)I(CO)2(PPh3)2, in which the pairs of CO and PPh3 ligands are mutually trans

Reaction between Os(CO)₂(PPh₃)₃ and Me₃SnH produces Os(SnMe₃)H(CO)₂(PPh₃)₂ (1). Multinuclear NMR studies of solutions of 1 reveal the presence of four geometrical isomers, the major one being that with mutually cis triphenylphosphine ligands and mutually trans CO ligands. Os(SnMe₃)H(CO)₂(PPh₃)₂ undergoes a redistribution reaction, at the trimethylstannyl ligand, when treated with Me₂SnCl₂ giving Os(SnMe₂Cl)H(CO)₂(PPh₃)₂ (2). Solutions of 2 again show the presence of four isomers but now the major isomer is that with mutually trans triphenylphosphine ligands and mutually cis CO ligands. The redistribution reaction of 1 with SnI₄ produces Os(SnMeI₂)H(CO)₂(PPh₃)₂ (3) which exists in solution as only one isomer, that with mutually trans triphenylphosphine ligands and mutually trans CO ligands. Treatment of 3 with I₂ cleaves the Os-H bond with retention of geometry giving Os(SnMeI₂)I(CO)₂(PPh₃)₂ (4). The crystal structure of 4 has been determined. No isomerization of the trans dicarbonyl complex 4 occurs when 4 is heated, instead there is a formal loss of “MeSnI” and formation of OsI₂(CO)₂(PPh₃)₂ (5).     

The activation of tertiary amines by osmium cluster complexes: Further studies of the reaction of Os3(CO)10(NCMe)2 with triethylamine

The reactions of Os₃(CO)₁₂ and Os₃(CO)₁₀(NCMe)₂ with NEt₃ have been reinvestigated. Two new products, Os₃(CO)₁₀(μ-CH₂C(H)?NEt₂)(μ-H)) (2) and Os₃(CO)₁₀(syn-μ-η¹-CHCHNEt₂)(μ-H) (3) were obtained in low yields, 4% and 7%, in addition to the previously reported compound Os₃(CO)₁₀(anti-μ-η¹-CHCHNEt₂(μ-H) (1) (20% yield) when the reaction was conducted at 25°C using Os₃(CO)₁₀(NCMe)₂. Compounds 2 and 3 were characterized by IR, ¹H NMR and single-crystal X-ray diffraction analyses. Compound 2 contains a bridging methyl-metallated N-ethylimine ligand formed by the cleavage of one ethyl group from the NEt₃. Compound 3 is an isomer of 1 in which the bridging ligand has a syn conformation with respect to the cluster as compared with the anti conformation in 1. Compound 3 slowly isomerizes to 1. Compound 3 is de-carbonylated by exposure to UV radiation and is transformed to the new compound Os₃(CO)₉(μ₃-CC(H)?NEt₂)(μ-H)₂ (4) (58% yield) by an additional CH activation to form a triply bridging η¹-diethylaminovinylidene ligand. Compound 4 isomerizes to the compound Os₃(CO)₉(μ₃-HCCNEt₂)(μ-H)₂ (5) (70% yield) at 68°C. The latter contains a triply briding ynamine ligand which exhibits structural and reactivity features that are characteristic of a carbene ligand at the amine-substituted carbon atom. Crystal data: for 2, space group = P2₁/c, a = 9.236(2) Å, b = 12.469(2) Å, c = 18.107(3) Å, β = 104.67(1)°, Z = 4, 2518 reflections, R = 0.031; for 3, space group = P2₁/m, a = 7.644(1) Å, b = 12.706(2) Å, c = 11.912(2) Å, β = 108.02(1)°, Z = 2, 1295 reflections, R = 0.030; for 4, space group = P2₁/n, a = 10.233(2) Å, b = 14.834(4) Å, c = 14.538(2) Å, β = 99.88(2)°, Z = 4, 2403 reflections, R = 0.036.     

Oxide promoted isomerisation of an isonitrile complex,H2Os3(CO)10[CN(CH2)3Si(OEt)3]

The isomerisation of H₂Os₃(CO)₁₀[CN(CH₂)₃Si(OEt)₃] to HOs₃(CO)₁₀-[CN(H)(CH₂)₃Si(OEt)₃] is accelerated by interaction with some oxides; both complexes afford HOs₃(CO)₁₀[CN(H)(CH₂)₃Si(OEt)_3it-x(O)x] as oxide supported clusters.     

Theoretical study on the mechanism of the (3)CH(2) + NO(2) reaction

The complex doublet potential energy surface of the CH(2)NO(2) system is investigated at the B3LYP/6-31G(d,p) and QCISD(T)/6-311G(d,p) (single-point) levels to explore the possible reaction mechanism of the triplet CH(2) radical with NO(2). Forty minimum isomers and 92 transition states are located. For the most relevant reaction pathways, the high-level QCISD(T)/6-311 + G(2df,2p) calculations are performed at the B3LYP/6-31G(d,p) geometries to accurately determine the energetics. It is found that the top attack of the (3)CH(2) radical at the N-atom of NO(2) first forms the branched open-chain H(2)CNO(2) a with no barrier followed by ring closure to give the three-membered ring isomer cC(H(2))ON-O b that will almost barrierlessly dissociate to product P(1) H(2)CO + NO. The lesser followed competitive channel is the 1,3-H-shift of a to isomer HCN(O)OH c, which will take subsequent cis-trans conversion and dissociation to P(2) OH + HCNO. The direct O-extrusion of a to product P(3) (3)O + H(2)CNO is even much less feasible. Because the intermediates and transition states involved in the above three channels are all lower than the reactants in energy, the title reaction is expected to be rapid, as is consistent with the measured large rate constant at room temperature. Formation of the other very low-lying dissociation products such as NH(2) + CO(2), OH + HNCO and H(2)O + NCO seems unlikely due to kinetic hindrance. Moreover, the (3)CH(2) attack at the end-O of NO(2) is a barrier-consumed process, and thus may only be of significance at very high temperatures. The reaction of the singlet CH(2) with NO(2) is also briefly discussed. Our calculated results may assist in future laboratory identification of the products of the title reaction.     

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.     

Platinum-osmium cluster complexes from the addition of Pt(PBut3) groups to Os3(CO)12

Three new compounds, PtOs(3)(CO)(12)(PBu(t)(3)) (10), Pt(2)Os(3)(CO)(12)(PBu(t)(3))(2) (11), and Pt(3)Os(3)(CO)(12)(PBu(t)(3))(3) (12), have been obtained from the reaction of Pt(PBu(t)(3))(2) with Os(3)(CO)(12) (9). The products were formed by the sequential addition of 1-3 Pt(PBu(t)(3)) groups to the three Os-Os bonds of the metal cluster of Os(3)(CO)(12). In solution, compounds 10-12 interconvert among themselves by intermolecular exchange of the Pt(PBu(t)(3)) groups. When 11 is treated with PPh(3), the mono- and bis(PPh(3)) derivatives of 9, Os(3)(CO)(11)(PPh(3)) and Os(3)(CO)(10)(PPh(3))(2), were obtained by elimination of the Pt(PBu(t)(3)) groups together with one and two CO ligands, respectively. When heated, compound 11 was transformed into the new compound Pt(2)Os(3)(CO)(10)(PBu(t)(3))(PBu(t)(2)CMe(2)CH(2))(mu-H) (13) by the loss of two CO ligands and a metalation of one of the methyl groups of one of the PBu(t)(3) ligands. Compounds 10-13 have been characterized by single-crystal X-ray diffraction analyses.