Bridging Hydride Ligands Research Articles

New Mode of Coordination for the Dinitrogen Ligand: Formation, Bonding, and Reactivity of a Tantalum Complex with a Bridging N2 Unit That Is Both Side-On and End-On

The reaction of a mixture of 1 equiv of PhPH(2) and 2 equiv of PhNHSiMe(2)CH(2)Cl with 4 equiv of Bu(n)Li followed by the addition of THF generates the lithiated ligand precursor [NPN]Li(2).(THF)(2) (where [NPN] = PhP(CH(2)SiMe(2)NPh)(2)). The reaction of [NPN]Li(2).(THF)(2) with TaMe(3)Cl(2) produces [NPN]TaMe(3), which reacts under H(2) to yield the diamagnetic dinuclear Ta(IV) tetrahydride ([NPN]Ta)(2)(mu-H)(4). This hydride reacts with N(2) with the loss of H(2) to produce ([NPN]Ta(mu-H))(2)(mu-eta(1):eta(2)-N(2)), which was characterized both in solution and in the solid state, and contains strongly activated N(2) bound in the unprecedented side-on end-on dinuclear bonding mode. A density functional theory calculation on the model complex [(H(3)P)(H(2)N)(2)Ta(mu-H)](2)(mu-eta(1):eta(2)-N(2)) provides insight into the molecular orbital interactions involved in the side-on end-on bonding mode of dinitrogen. The reaction of ([NPN]Ta(mu-H))(2)(mu-eta(1):eta(2)-N(2)) with propene generates the end-on bound dinitrogen complex ([NPN]Ta(CH(2)CH(2)CH(3)))(2)(mu-eta(1):eta(1)-N(2)), and the reaction of [NPN]Li(2).(THF)(2) with NbCl(3)(DME) generates the end-on bound dinitrogen complex ([NPN]NbCl)(2)(mu-eta(1):eta(1)-N(2)). These two end-on bound dinitrogen complexes provide evidence that the bridging hydride ligands are responsible for the unusual bonding mode of dinitrogen in ([NPN]Ta(mu-H))(2)(mu-eta(1):eta(2)-N(2)). The dinitrogen moiety in the side-on end-on mode is amenable to functionalization; the reaction of ([NPN]Ta(mu-H))(2)(mu-eta(1):eta(2)-N(2)) with PhCH(2)Br results in C-N bond formation to yield [NPN]Ta(mu-eta(1):eta(2)-N(2)CH(2)Ph)(mu-H)(2)TaBr[NPN]. Nitrogen-15 NMR spectral data are provided for all the tantalum-dinitrogen complexes and derivatives described.

Insertion of bis-ferrocenylbutadiyne into an osmium hydride bond. The synthesis, structure and electrochemical response of Os 4(CO) 11(μ-η- Z-FcCC(H)C 2Fc)(μ-H) 3

The reaction of Os 4(CO) 12(μ-H) 4 with Me 3NO followed by 1,4-bis(ferrocenyl)butadiyne ( 1) has yielded the tetraosmium product Os 4(CO) 11(μ-η 2-FcCC(H)C 2Fc)(μ-H) 3 ( 5), Fc=C 5H 5FeC 5H 4 in 9% yield by decarbonylation and insertion of the 1,4-bis(ferrocenyl)butadiyne into one of the metal–hydrogen bonds in the cluster. Compound 5 was characterized by IR, 1H-NMR spectroscopy and single crystal X-ray diffraction analysis. The molecule contains a closed tetrahedral cluster of four osmium atoms with three bridging hydride ligands. One of the C–C triple bonds of 1 was inserted into one of the Os–H bonds to form a (bis-ferrocenyl)yneenyl ligand that bridges one edge of the cluster in a θ-π coordination mode. Compound 5 exhibits two one-electron oxidations for the ferrocenyl groups at E°=+0.443 and +0.486 V versus Ag/AgCl, Δ E°=0.043 V. This small difference indicates that there is little or no electronic communication between the two ferrocenyl groups.

New alkyne bridged mixed-metal clusters and studies of their activity for catalytic hydrosilylation of alkynes

The homologous series of compounds MPt 2(CO) 5(PPh 3) 2(PhC 2Ph), M=Fe ( 1), M=Ru ( 3) and M=Os ( 4) were obtained in the yields 55%, 24% and 30% from the reactions of Pt(PPh 3) 2(PhC 2Ph) with Fe(CO) 5, Ru 3(CO) 10, and Os(CO) 5, respectively. Each of the products was characterized by IR, elemental analysis and a single crystal X-ray diffraction analysis. A second mixed-metal cluster product, Ru 2Pt(CO) 7(PPh 3) 2(PhC 2Ph) ( 2) (45% yield) was also obtained from the reaction that yielded 3. In fact, it is obtained in a higher yield than that of 3. Compounds 1, 3, and 4 are isostructural and are comprised of a MPt 2 (M=Fe, Ru or Os) triangular metal cluster containing a triply bridging diphenylacetylene ligand. The structure of compound 2 is similar to that of 1, 3, and 4, but contains two ruthenium and one platinum atom in the triangular cluster. One coproduct Os(CO) 2(PPh 3) 2(PhC 2Ph) ( 5) (25% yield) was obtained from the reaction of Os(CO) 5 with Pt(PPh 3) 2(PhC 2Ph). Compound 5 contains only one metal atom with an approximately trigonal bipyramidal coordination having the two phosphine ligands in the axial positions and the alkyne in an equatorial site. The reaction of 2 with H 2 in refluxing hexane afforded the tetranuclear complex H 2Ru 2Pt 2(CO) 8(PPh 3) 2 ( 6) (11% yield) that contains an Ru 2Pt 2 tetrahedral shaped cluster with two bridging hydride ligands. The ability of the solutions of compounds 1–6 and Pt(PPh 3) 2(PhC 2Ph) to produce catalytic hydrosilylation of diphenylacetylene by triethylsilane to yield ( E)-[(1,2-diphenyl)ethenyl]triethylsilane at 30°C, and 1,4-bis(trimethylsilyl)butadiyne with triethylsilane to yield ( E)-2-triethylsilyl-1,4-bis(trimethylsilyl)-1-buten-3-yne at 60°C was investigated. Pt(PPh 3) 2(PhC 2Ph) was the best catalyst for these reactions. Compound 5 is completely inactive. A combination of evidence suggests that the catalytic activity exhibited by the mixed-metal cluster complexes is produced principally by fragmentation products which are almost certainly mononuclear platinum complexes.

Studies on the reactivity of Nb(η 5-C 5H 4SiMe 3) 2(X)(L), X=H,Cl; L=CNXylyl, CNCy, CO and Nb(η 5-C 5H 4SiMe 3) 2(H) 3 complexes toward the Lewis acids B(C 6F 5) 3 and BF 3

The reaction of the electron-rich, coordinatively saturated, niobocene–hydride or –halide complexes Nb(η 5-C 5H 4SiMe 3) 2(X)(L), X=H or Cl, L=2,6-dimethylphenylisocyanide (CNXylyl), cyclohexylisocyanide (CNCy) and carbonyl (CO), with the strong Lewis acid (B(C 6F 5) 3) gives the zwitterionic compounds [(η 5-C 5H 4SiMe 3) 2(CNXylyl)Nb(μ-X)(B(C 6F 5) 3)] ( 1), [(η 5-C 5H 4SiMe 3) 2(CNCy)Nb(μ-X)(B(C 6F 5) 3)] ( 2), [(η 5-C 5H 4SiMe 3) 2(CO)Nb(μ-X) (B(C 6F 5) 3)] ( 3), respectively, where the complexes possess a bridging hydride or halide group. Similarly, the starting niobocene-hydride species react with BF 3 to afford the corresponding zwitterionic complexes containing a bridging hydride ligand, namely [(η 5-C 5H 4SiMe 3) 2(CNXylyl)Nb(μ-H)(BF 3)] ( 4), [(η 5-C 5H 4SiMe 3) 2(CNCy)Nb(μ-H)(BF 3)] ( 5), [(η 5-C 5H 4SiMe 3) 2(CO)Nb(μ-H)(BF 3)] ( 6). The reaction of the hydride containing compounds 1– 3 with the appropriate ligand L (1:1 molar ratio for 1 and 2) in toluene at room temperature leads to the ionic compounds [(η 5-C 5H 4SiMe 3) 2Nb(CNXylyl) 2][(HB(C 6F 5) 3)] ( 7), [(η 5-C 5H 4SiMe 3) 2Nb(CNCy) 2][(HB(C 6F 5) 3)] ( 8), and [(η 5-C 5H 4SiMe 3) 2Nb(CO) 2][(HB(C 6F 5) 3)] ( 9), which contain two coordinated L ligands and a noncoordinated [(HB(C 6F 5) 3)] − counteranion. Analogous complexes were not observed in the same reaction for 4– 6. Finally, the compound [Nb(η 5-C 5H 4SiMe 3) 2(H) 3] reacts in acetone with (B(C 6F 5) 3) in a clean reaction to give the ionic compound [(η 5-C 5H 4SiMe 3) 2Nb][((CH 3) 2CHO)B(C 6F 5) 3)] ( 10), which contains the isopropoxide borate ion [((CH 3) 2CHO)B(C 6F 5) 3)] − as the counteranion.

Coordinations of vinyltetrahydrothiophene to a trirhenium cluster

The reaction of Re 3(CO) 10(NCMe) 2(μ-H) 3 with 2-vinyltetrahydrothiophene (VTHT) at 25°C for 22 h yielded two products: Re 3(CO) 10(μ-H) 3(μ-S(CH 2) 3CHCHCH 2) ( 1; 50% yield), and Re 3(CO) 9(μ-H) 3(μ-η 3-S(CH 2) 3CHCHCH 2) ( 2; 12% yield). Compound 1 exists in solution as a mixture of isomers in a dynamic equilibrium at room temperature. One of the isomers of 1 and 2 were characterized by single-crystal X-ray diffraction analyses. Compound 1 contains a triangular trirhenium cluster with ten linear terminal carbonyl ligands, three bridging hydride ligands and a bridging vinyltetrahydrothiophene ligand coordinated to two metal atoms by using both of the lone pairs of the electrons on the sulfur atom of the vinyltetrahydrothiophene molecule. Compound 2 contains a triangular cluster of three rhenium atoms and a triple-bridging vinyltetrahydrothiophene ligand that is coordinated to two of the rhenium atoms through the sulfur atom and a π-coordination of the vinyl group to the third metal atom. In both complexes there is a bridging hydride ligand across each of the three rhenium–rhenium bonds in the cluster. Facile interconversion of the two isomers of 1 was observed by 2D EXSYS 1H-NMR spectroscopy. Compound 2 can be obtained from 1 in 98% yield via thermal decarbonylation by refluxing a solution in methylene chloride for 18 h.

Synthesis and characterisation of tetraosmium carbonyl clusters bearing an azo type ligand: crystal and molecular structures of [Os 4(μ-H) 4(CO) 11(NC 5H 4NNPh)] and [Os 4(μ-H) 4(CO) 10(MeCN)(NC 5H 4NNPh)

Reaction of [Os 4(μ-H) 4(CO) 10(MeCN) 2] with one equivalent of 4-phenylazopyridine (4-PAP) in CH 2Cl 2 at ambient conditions afforded two new tetraosmium clusters [Os 4(μ-H) 4(CO) 11(NC 5H 4NNPh)] ( 1) and [Os 4(μ-H) 4(CO) 10(MeCN)(NC 5H 4NNPh)] ( 2) in moderate yields. Compound 1 exists as a pair of isomers in solution, which differ in the location of the bridging hydride ligands. The molecular structures of clusters 1 and 2 consist of a highly distorted tetrahedral metal skeleton, with the azo ligand terminally bonded to an osmium atom.

Tantalum-Gold and Tantalum-Copper Trihydride Complexes [Cp'(2)TaH(3)MPPh(3)][PF(6)] (Cp' = C(5)H(4)C(CH(3))(3)). Structure Determination from (1)H T(1) Relaxation Studies.

The reaction of Cp'(2)TaH(3) (Cp' = C(5)H(4)C(CH(3))(3)) with [MPPh(3)][PF(6)] yields the bimetallic complexes [Cp'(2)TaH(3)MPPh(3)][PF(6)] (M = Au (1),M = Cu (2)). The detailed NMR study of 1 and 2 showed the structure with two bridging hydride ligands. The mutual orientation of the Cp' rings has been determined by NOE experiments. The variable-temperature NMR data showed an intramolecular exchange between two outer hydride ligands. The exchange is faster in 1 (DeltaG()(210 K) = 9.3 kcal/mol) than in 2 (DeltaH() = 8.6 +/- 0.2 kcal/mol, DeltaS() = - 5.0 +/- 0.4 eu, DeltaG() (210 K) = 9.6 +/- 0.2 kcal/mol). In contrast, complex 2 undergoes the faster intermolecular PPh(3)/PPh(3) exchange. It has been demonstrated that T(1min), T(1), T(1sel) and T(1bis) measurements are a powerful instrument for quantitative localization of the hydride ligands in solutions of bimetallic complexes. The determined hydride-hydride and metal-hydride distances reproduce well the structural tendencies in the related niobium trihydride [{Nb(C(5)H(3)RR')(2)H(3)}(2)Au][PF(6)] (R = R' = Si(CH(3))(3)) established by the X-ray method. Tantalum-gold complex 1 showed weak exchange couplings.

Models for the Homogeneous Hydrodesulfurization of Benzothiophenes. Carbon−Sulfur Bond Cleavage, Hydrogenolysis, and Desulfurization Reactions Mediated by Coordination of the Carbocyclic Ring to Manganese and Ruthenium

Chemical reduction of a series of (η6-benzothiophene)Mn(CO)3+ complexes (10a−c) under CO affords neutral dimanganese metallathiacyclic complexes (12a−c), which have a Mn(CO)4 moiety inserted into the C(aryl)−S bond. Reduction of (η6-benzothiophene)Ru(C6Me6)2+ in the presence of CO and (η6-1-Me-naphthalene)Mn(CO)3+ affords an analogous cationic bimetallic (15), which is converted to a neutral cyclohexadienyl complex (16) by hydride addition to the carbocyclic benzothiophene ring. The sulfur atom in the metallathiacyclic ring in 12 and 16 is nucleophilic and reacts with electrophiles CF3SO3Me, HBF4, and W(CO)5(THF) to afford complexes such as 6, 14, and 17. Treatment of 12 with H2 results in hydrogenolysis of the Mn−C σ bond and formation of the bimetallic Mn2(CO)8(H)(SCHCHPh) (8), which contains a Mn−Mn bond and bridging hydride and thiolate ligands. Reaction of 6 and 17 with H2 results in desulfurization of the benzothiophene and formation of a mixture of Mn(CO)5SR and [Mn(CO)4SR]2 (R = H, Me). Crystal st...

Insertion of manganese into a C–S bond of dibenzothiophene: a model for homogeneous hydrodesulfurization

Coordination of Mn(CO)3+ to a carbocyclic ring of dibenzothiophene activates a C–S bond to reductive cleavage, affording a novel tetramanganese metallathiacycle 5 that reacts with H2 to form a dimanganese complex 9 containing bridging hydride and thiolate ligands; methylation of 5 followed by hydrogenation results in desulfurization of the dibenzothiophene and formation of [Mn(CO)5(SMe)].

Models for the Homogeneous Hydrodesulfurization of Thiophenes: Manganese-Mediated Carbon−Sulfur Bond Cleavage and Hydrogenation Reactions

Chemical reduction of a series of (η5-thiophene)Mn(CO)3+ complexes (3a−d) under an atmosphere of CO affords dimanganese metallathiacyclic complexes (4a−d), which have a Mn(CO)4 moiety regioselectively inserted into a C−S bond. Reaction of 4 with H2, the rate of which is strongly influenced by substituents on the thiophene ring, leads to hydrogenolysis of the Mn−C σ-bond and formation of (OC)3Mn(μ-H)(μ-SCRCHCHCHR‘)Mn(CO)3 (8; R, R‘ = H, Me), which contains bridging hydride and thiolate ligands and a Mn−Mn bond. The addition of PhMgBr to 3 occurs at the sulfur to give zwitterionic complexes (6a−c, 14), which undergo regioselective hydrogenolysis of a C−S bond and, in some cases, partial desulfurization with concomitant formation of (OC)4Mn(μ-H)(μ-SPh)Mn(CO)4 (5a). Crystal structures are reported for complexes 4b,d, 5a, 8d, 10, 12c, and 14b,c. It is suggested that the reactions reported herein may be relevant to the general problem of hydrodesulfurization (HDS) of thiophenic molecules.

Preparation of a series of dinuclear Ir(III) and Ir(II) complexes containing bridging thiolate ligands

Reactions of [Cp ∗IrCl(μ-Cl) 2IrCp ∗Cl] ( Cp ∗ = η- 5 C 5 Me 5) with RSH in CH 2Cl 2 at room temperature afforded two types of thiolate-bridged dinuclear Ir(III) complexes, [Cp ∗IrCl(μ-SR) 2IrCp ∗Cl] (2; RPr i, Cy, CH 2Ph; Cy = cyclohexyl) or [Cp ∗Ir(μ-SEt) 3IrCp ∗]Cl, depending upon the nature of the substituent R. Reduction of 2 (RPr i (2a), Cy) with excess NaHg in THF resulted in the formation of the dinuclear Ir(II) complexes [Cp ∗Ir(μ-SR) 2IrCp ∗] (3). X-ray diffraction studies were undertaken for 2a and 3b (RCyto) to determined their detailed structures 2a: C 26H 44Cl 2S 2Ir 2, space group C2/ c, a = 21.255(8), b = 8.606(6), c = 17.788(6) A ̊ , β = 118.39(2)°, Z = 4 , 3b: C 32H 52S 2Ir 2, space group P2/ n, a = 8.9122(6), b = 11.224(6), c = 16.496(6) A ̊ , β = 97.78(4)°, Z = 2 . Complexes 3 reacted with CF 3COOH to give the cationic Ir(III) complexes having a bridging hydride ligand [Cp ∗Ir(μ-H)(μ-SR) 2IrCp ∗][OCOCF 3].

Reactions of Pt3Ru6(CO)2(μ3‐H)(μ‐H)3 with Phos[phanes — The Synthesis and Structural Characterizations of [Pt(PMe3)3H][Pt3Ru6(CO)21(μ3‐H)(μ‐H)2] and [Pt3Ru6(CO)20(PPh3)(μ‐H)3(μ3H)

AbstractThe reactions of [Pt3Ru6(CO)21(μ‐H)3(μ3‐H)] (1) with PMe3 and PPh3 have produced the salts [Pt(PR3)3H]‐[Pt3Ru6(CO)21(μ3‐H)(μ‐H)2], 5a and 5d, R = Me and Ph in the yields 9% and 22%, respectively. By contrast the reaction of 1 with PPh3 in the presence of Me3NO has yielded the phosphane‐substituted derivative [Pt3Ru6(CO)20(PPh3)μ‐H)3(μ3‐H)] }(6) in 22% yield. Compounds 5a and 6 were characterized by single crystal X‐ray diffraction analysis. Compounds 5a and 5d are salts of the anion [Pt3Ru6(CO)21(μ3‐H)(μ‐H)2]−. The anion contains a layer segregated Ru3Pt3Ru3 structure similar to that of 1 with two bridging hydride ligands on one Ru3 triangle and one semi‐triply bridging hydride ligand on the other. The cation [Pt(PR3)3H]+ was evidently formed by the abstraction of platinum from other molecules of 1. Compound 6 is a PPh3 derivative of the parent 1 that also contains the layer segregated stacking of Ru3 and Pt3 triangles. The PPh3 ligand is coordinated to one of the ruthenium atoms in an axial position.

Crystal structure of μ2-hydridododecacarbonyltriosmiumdioxooctafluoro- μ2-fluoroditungsten

Protonation of [Os 3(CO) 12] occurs readily in anhydrous HF; the addition of WF 6 gives a route to the title compound, [HOs 3(CO) 12][W 2O 2F 9], which forms as triclinic crystals. The anion is a fluoride-bridged dimer, whilst the bridging hydride ligand in the carbonyl cluster cation has been located by difference Fourier techniques and the geometry of the carbonyl ligands.

Hydrido(1,4,8,11,15,18,22,25-octa-n-pentylphthalocyaninato)- rhodium Dimers: Single-Crystal X-ray Structure and the Isomerization of the Four Isomers

The hydrido(phthalocyaninato)rhodium dimer [(R8Pc)RhH]2 (1; R8Pc2- = dianion of 1,4,8,11,15,18,22,25-octa-n-pentylphthalocyanine) was synthesized from the reaction of [(R8Pc)(MeOH)2Rh]Cl with H2 at 110 °C in 1-pentanol. A single-crystal X-ray diffraction study shows that 1 is a dimer. The two Pc ligands are essentially planar and staggered by 35(2)°. The two Rh atoms are not significantly displaced from the planes of the ligands; they are separated by 3.347(3) A. This long Rh−Rh separation suggests that 1 has a bridging hydride ligand. The dimeric structure of 1 is maintained in benzene solution. The 1H NMR spectra show that 1 contains one Rh−H and one N−H moiety for every two R8Pc2- ligands. The νNH band at 3373 cm-1 (the νND band at 2478 cm-1) supports the presence of an N−H moiety in 1. Our belief that protonation occurs on a meso (or peripheral) nitrogen, rather than a pyrrolic nitrogen, is derived from X-ray structural data and 1H NMR results. (1) No uniquely long Rh−N bond is present, and all four p...

Structural investigation of homonuclear Pt2 and heteronuclear PdPt complexes containing a metal–metal bond bridged by hydrido and sulfido ligands

The complex [Pt2(μ-H)(μ-S)(dppe)2](PF6) undergoes a displacive order–disorder transformation at ca 230 K. The low-temperature structure is ordered with one cation–anion pair as the asymmetric unit in space group P21/n. At room temperature the b axis is halved and the space group is P2/n, imposing crystallographic twofold rotation symmetry on both ions; the anion shows major disorder and there is probably minor disorder in the cation, but its internal geometry remains essentially unchanged. The heteronuclear complex [PdPt(μ-H)(μ-S)(dppe)2](PF6) is isostructural with the Pt2 complex at room temperature. All three structures have been determined crystallographically and both complexes have been extensively characterized by NMR spectroscopy, unambiguously confirming the genuine heteronuclear nature of the mixed-metal complex and the presence of the bridging hydride ligand.

Synthesis and characterization of cationic dinuclear complexes of platinum with bridging hydrides; crystal structures of [Pt2(µ-H)2{But2P(CH2)3PBut2}2][BF4]2and [Pt2(µ-H)2{(C6H11)2P(CH2)3P(C6H11)2}2][BF4]2

A series of diplatinum dications [Pt2(µ-H)2(L–L)2][BF4]2[L–L =(C6H11)2P(CH2)nP(C6H11)2, But2P(CH2)nPBut2, n= 2 or 3] with two chelating diphosphine and two bridging hydride ligands has been prepared by the elimination of ethene from the agostic alkyl complexes [PtEt(L–L)]+ or alkene–hydride complexes [PtH(C2H4)(L–L)]+, or by the reaction of the dihydride complexes [PtH2(L–L)] with an excess of HBF4·OMe2. The complexes have been characterized by multinuclear (1H, 31P and 195Pt) NMR spectroscopy and for [Pt2(µ-H)2{But2P(CH2)3PBut2}2][BF4]2 and [Pt2(µ-H)2{(C6H11)2P(CH2)3P(C6H11)2}2][BF4]2 by single-crystal X-ray crystallography. The latter complex has a structure in which the platinum and phosphorus atoms are coplanar whereas in the former the co-ordination planes of the platinum atoms are twisted with respect to each other by 36.6°. The twisting in [Pt2(µ-H)2{But2P(CH2)3PBut2}2][BF4]2 is ascribed to the steric pressure of the large diphosphine which destabilises the planar geometry. Significantly this complex is fluxional on the NMR time-scale at 290 K whereas the others are static and there is a shift in colour from yellow to red for the strained complex. The dinuclear species are useful synthetic precursors of the [PtH(L–L)]+ fragment, particularly when L–L is large. Thus [Pt2(µ-H)2{But2P(CH2)3PBut2}2]2+, which has the most sterically demanding diphosphine, reacts with alkenes [e.g. ethene (reversibly) or norbornene] to form mononuclear alkyl complexes with a three-centre, two-electron (agostic) bond.

Synthesis and reactivity of the formally co-ordinatively unsaturated diruthenium hydride [Ru2(µ-H)(µ-CO)(CO)3{µ-(PriO)2PNEtP(OPri)2}2]+and its co-ordinatively saturated parent [Ru2H(CO)5{µ-(PriO)2PNEtP(OPri)2}2]+

Protonation of the co-ordinatively unsaturated species [Ru2(µsb-CO)2(CO)2(µ-etipdp)2][sb = semi-bridging, etipdp =(PriO)2PNEtP(OPri)2] by acids of non-co-ordinating conjugate bases, e.g. HBF4·OEt2, produced [Ru2(µ-H)(µ-CO)(CO)3(µ-etipdp)2]+ which, as established X-ray crystallographically for the PF6– salt, contains both a bridging carbonyl and a bridging hydride ligand. This cationic species is very susceptible to attack by both neutral and anionic nucleophiles affording a range of product types. For instance, its reactions with anions X– which are capable of functioning as monodentate bridging ligands and which preferentially adopt the closed bridging co-ordination mode, e.g. halide and hydrogensulfide ions, afforded products of the type [Ru2(µ-X)H(µsb-CO)(CO)2(µ-etipdp)2](X = Cl, Br, I, SH, etc.), resulting from the substitution of a carbonyl group by the nucleophile. On the other hand, anionic nucleophiles such as H– and CN– gave addition products of the type [Ru2HX(CO)4(µ-etipdp)2](X = H, CN, etc.) in which the hydride and the X– ligand occupy equatorial sites trans disposed with respect to each other, as established in a separate study for [Ru2H2(CO)4(µ-etipdp)2]. Carbon monoxide also afforded a simple addition product, viz.[Ru2H(CO)5(µ-etipdp)2]+, but the majority of the other neutral nucleophiles studied, particularly the unsaturated systems, yielded products resulting from formal insertion of the nucleophile into the Ru–H bond. Thus sulfur produced [Ru2(µ-SH)(CO)4(µ-etipdp)2]+, while unsaturated nucleophiles of general formula X′Y′, e.g. PhCN and RCCH (R = H, Ph, etc.), gave products of the type [Ru2{µ-X′Y′(H)}(CO)4(µ-etipdp)2]+, e.g.[Ru2{µ-NC(H)Ph}(CO)4(µ-etipdp)2]+ or of the type [Ru2{µ-η2-X′Y′(H)}(CO)4(µ-etipdp)2]+, e.g.[Ru2(µ-η1 : η2-CHCHR)(CO)4(µ-etipdp)2]+. Heterocumulenes X″Y″Z″ such as CS2 and PhNCS behaved similarly affording products of general formula [Ru2{µ-η2-X″Y″(H)Z″}(CO)4(µ-etipdp)2]+ containing five-membered RuX″Y″Z″Ru rings. The co-ordinatively saturated pentacarbonyl [Ru2H(CO)5(µ-etipdp)2]PF6 gave products similar to those afforded by [Ru2(µ-H)(µ-CO)(CO)3(µ-etipdp)2]PF6 on reaction with systems of the type X′Y′ and X″Y″Z″ except that, for terminal alkynes such as PhCCH, alkenylcarbonyl-bridged products, e.g.[Ru2{µ-η2-OC(CHCHPh)}(CO)4(µ-etipdp)2]PF6, are produced. The crystal structures of the following compounds were determined : [Ru2(µ-H)(µ-CO)(CO)3(µ-etipdp)2]PF6, [Ru2(µ-I)H(µsb-CO)(CO)2(µ-etipdp)2], [Ru2{µ-N(CHPh)}(CO)4(µ-etipdp)2]PF6, [Ru2(µ-η1 : η2-CHCH2)(CO)4(µ-etipdp)2]PF6, [Ru2{µ-η2-OC(CHCHPh)}(CO)4(µ-etipdp)2]PF6 and [Ru2{µ-η2-SC(H)NPh}(CO)4(µ-etipdp)2]PF6.

Reactions of tridentate phosphine ligand [HC(PPh 2) 3] with metal carbonyl clusters HRuCO 3(CO) 12 and H 3Ru 3Co(CO) 12 : synthesis and crystal structures of HRuCo 3(CO) 9 [HC(PPh 2) 3] and [formula omitted

Two tetranuclear phosphine-substituted mixed metal clusters of ruthenium and cobalt were made by reactions between tridentate phosphine ligand HC(PPh 2) 3 and the clusters HRuCo 3(CO) 12 and H 3Ru 3Co(CO) 12. The tridentate phosphine ligand is coordinated to a Co 3 face in HRuCo 3(CO) 9[HC(PPh 2) 3] and to an Ru 2Co face in H 3Ru 3Co(CO) 9[HC(PPh 2) 3]. Both compounds containan unusual bridging hydride ligand on the Ru(μ-H)Co edge.

Catalytic Cyclooligomerization of Thietane by Tetraosmium and Tetraruthenium Tetrahydride Carbonyl Cluster Complexes

The new compounds, Os{sub 4}(CO){sub 11}(SCH{sub 2}CH{sub 2}CH{sub 2} )({mu}-H){sub 4}, 3, Os{sub 4}(CO){sub 11}(12S3)({mu}-H){sub 4}, 4, Ru{sub 4} (CO){sub 11}(SCH{sub 2}CH{sub 2}CH{sub 2})({mu}-H){sub 4}, 5, and Ru{sub 4} (CO){sub 11}(12S3)({mu}-H){sub 4}, 6 (12S3 = 1,5, 9-trithiacyclododecane) have been obtained from the reactions of Os{sub 4}(CO){sub 11}(NCMe)({mu}-H){sub 4} and Ru{sub 4}(CO){sub 12} ({mu}-H){sub 4} with thietane and 12S3, respectively. The molecular structure of 4 was established by a single-crystal X-ray diffraction analysis. The molecule contains a tetrahedral cluster of four osmium atoms with four bridging hydride ligands and a 12S3 ligand coordinated to one of the metal atoms through one of its three sulfur atoms. Compounds 3 and 4 were found to be efficient catalysts for the cyclooligomerization of thietane to 12S3 and 24S6 (24S6 = 1,5,9,13,17,21-hexathiacyclotetracosane) with a 6/1 preference for 12S3 after a 24 h reaction period. A kinetic study of the catalysis by 4 showed that the formation of 12S3 is first order in the concentration of 4, which is consistent with the catalysis being produced by a tetranuclear cluster complex. Significant amounts of 12S3 and 24S6 were also obtained from thietane when 5 and 6 were used as catalyst precursors; however, the selectivity for 12S3 wasmore » significantly lower, and analysis after the reactions showed that most of the cluster complexes had decomposed. 17 refs., 2 figs., 5 tabs.« less

A zirconium polyhydride dimer, [Zr2H4(BH4)4(PMe3)4

The dimer tetra-μ-hydrido-bis[bis(tetrahydroborato)bis(trimethylphosphine)zirconium(IV)], [Zr(BH 4 ) 2 H 2 (C 3 H 9 P) 2 ] 2 consists of two Zr atoms linked by four bridging hydride ligands. Each Zr atom is ligated by two PMe 3 ligands and two bidentate BH 4 - groups. The single crystallographically independent Zr atom lies on a twofold axis and the molecule has exact 4 point symmetry