Syntheses, crystal structures and DFT studies of [Me3EM(CO)5] (E = Sb, Bi; M = Cr, W), cis-[(Me3Sb)2Mo(CO)4], and [Bu3BiFe(CO)4]

Syntheses of [Me₃SbM(CO)₅] [M = Cr (1), W (2)], [Me₃BiM(CO)₅] [M = Cr (3), W (4)], cis-[(Me₃Sb)₂Mo(CO)₄] (5), [^tBu₃BiFe(CO)₄] (6), crystal structures of 1-6 and DFT studies of 1-4 are reported.     

Selenium-capped trimolybdenum and tritungsten carbonyl clusters [Se2M3(CO)10] (M = Mo, W)

A facile synthesis of the novel selenium-capped trimolybdenum and tritungsten ring carbonyl clusters [Se₂M₃(CO)₁₀]²⁻ (M = Mo, 1; W, 4) have been achieved. The selenium-capped trimolybdenum cluster compound [Et₄N]₂[Se₂Mo₃(CO)₁₀] ([Et₄N]₂[1]) can be obtained from the reaction of the trichromium cluster compound [Et₄N]₂[Se₂Cr₃(CO)₁₀] with 4 equiv. of Mo(CO)₆ in refluxing acetone. On the other hand, when [Et₄N]₂[Se₂Cr₃(CO)₁₀] reacted with 4 equiv. of W(CO)₆ in refluxing acetone, the planar cluster compound [Et₄N]₂[Se₂W₄(CO)₁₈] ([Et₄N]₂[3]) was isolated, which could further transform to the tritungsten cluster compound [Et₄N]₂[Se₂W₃(CO)₁₀] ([Et₄N]₂[4]) in good yield. Alternatively, clusters 1 and 4 could be formed from the reactions of the monosubstituted products [Et₄N]₂[Se₂Cr₂M(CO)₁₀] (M = Mo; W, [Et₄N]₂[2]) with 3 equiv. of M(CO)₆ in acetone, respectively. Complexes 1-4 are fully characterized by IR, ⁷⁷Se NMR spectroscopy, and single-crystal X-ray analysis. Clusters 1, 2, and 4 are isostructural and each display a trigonal bipyramidal structure with a homometallic M₃ ring (M = Mo, 1; W, 4) or a heterometallic Cr₂W ring that is further capped above and below by μ₃-Se atoms. Further, the intermediate planar complex 3 exhibits a Se₂W₂ square with each Se atom externally coordinated to one W(CO)₅ group. This paper describes a systematic route to a series of selenium-capped trimetallic carbonyl clusters and the formation and the structural features of the resultant clusters are discussed.     

Some complexes containing carbon chains end-capped by M(CO)2Tp′ [M = Mo, W; Tp′ = HB(pz)3, HB(dmpz)3] groups

Complexes M(CCCSiMe₃)(CO)₂Tp′ (Tp′ = Tp [HB(pz)₃], M = Mo 2, W 4; Tp′ = Tp^∗ [HB(dmpz)₃], M = Mo 3) are obtained from M(CCCSiMe₃)(O₂CCF₃)(CO)₂(tmeda) (1) and K[Tp′].Reactions of 2 or 4 with AuCl(PPh₃)/K₂CO₃ in MeOH afforded M{CCCAu(PPh₃)}(CO)₂Tp′ (M = Mo 5, W 6) containing C₃ chains linking the Group 6 metal and gold centres.In turn, the gold complexes react with Co₃(μ₃-CBr)(μ-dppm)(CO)₇ to give the C₄-bridged {Tp(OC)₂M}CCCC{Co₃(μ-dppm)(CO)₇} (M = Mo 7, W 8), while Mo(CBr)(CO)₂Tp^∗ and Co₃{μ₃-C(CC)₂Au(PPh₃)}(μ-dppm)(CO)₇ give {Tp^∗(OC)₂Mo}C(CC)₂C{Co₃(μ-dppm)(CO)₇} (9) via a phosphine-gold(I) halide elimination reaction. The C₃ complexes Tp′(OC)₂MCCCRu(dppe)Cp^∗ (Tp′ = Tp, M = Mo 10, W 11; Tp′ = Tp^∗, M = Mo 12) were obtained from 2-4 and RuCl(dppe)Cp^∗ via KF-induced metalla-desilylation reactions. Reactions between Mo(CBr)(CO)₂Tp^∗ and Ru{(CC)_nAu(PPh₃)}(dppe)Cp^∗ (n = 2, 3) afforded {Tp^∗(OC)₂Mo}C(CC)_n{Ru(dppe)Cp^∗} (n = 2 13, 3 14), containing C₅ and C₇ chains, respectively. Single-crystal X-ray structure determinations of 1, 2, 7, 8, 9 and 12 are reported.     

Syntheses, structures and DFT study of [W(CO)5(Ph2SbX)] X = Cl, Br, I

The complexes [W(CO)₅(Ph₂SbX)], X = Cl (1), Br (2) and I (3) were prepared by reaction of [W(CO)₅(tetrahydrofuran)] with Ph₂SbX. The structures of 1-3 were studied by X-ray diffraction. In the crystals there are weak contacts between the oxygen atoms of the CO ligands and antimony atoms of neighbouring molecules. DFT calculations were carried out for 1 using gradient corrected functional B3LYP. The bonding between Ph₂SbCl and the W(CO)₅ fragment in 1 was analysed using charge decomposition analysis.     

Backbone modified small bite-angle diphosphines: Synthesis and molecular structures of [M(CO)4{X2PC(RR)PX2}] (M = Mo, W; X = Ph, Cy; R = H, Me, Et, Pr, allyl, R = Me, allyl)

A range of new small bite-angle diphosphine complexes, [M(CO)₄{X₂PC(R¹R²)PX₂}] (M = Mo, W; X = Ph, Cy; R¹ = H, Me, Et, Pr, allyl, R² = Me, allyl), have been prepared via elaboration of the methylene backbones in [M(CO)₄(X₂PCH₂PX₂)] as a result of successive deprotonation and alkyl halide addition. When X = Ph it proved possible to replace both methylene protons but for X = Cy only one substitution proved possible. This is likely due to the electron-releasing nature of the cyclohexyl groups but may also be due to steric constraints. Attempts to prepare the bis(allyl) substituted complex [Mo(CO)₄{Ph₂PC(allyl)₂PPh₂}] were only moderately successful. The crystal structures of nine of these complexes are presented.     

Reactions of the cycloheptatrienyl complexes [MX(CO)2(η-C7H7)] (M=Mo, X=Br; M=W, X=I) with CNBu: X-ray crystal structure of [WI(CO)2(CNBu)2(η-C7H7)]

Reaction of [MX(CO)₂(η⁷-C₇H₇)] (M=Mo, X=Br; M=W, X=I) with two equivalents of CNBu^t in toluene affords the trihapto-bonded cycloheptatrienyl complexes [MX(CO)₂(CNBu^t)₂(η³-C₇H₇)] (1, M=Mo, X=Br; 2, M=W, X=I). The X-ray crystal structure of 2 reveals a pseudo-octahedral molecular geometry with an asymmetric ligand arrangement at tungsten in which one CNBu^t is located trans to the η³-C₇H₇ ring. Treatment of 2 with tetracyanoethene results in 1,4-cycloaddition at the η³-C₇H₇ ring to give [WI(CO)₂(CNBu^t)₂{η³-C₉H₇(CN)₄}], 3. The principal reaction type of the molybdenum complex 1 is loss of carbonyl and bromide ligands to afford substituted products [MoBr(CNBu^t)₂(η⁷-C₇H₇)] 4 or [Mo(CO)(CNBu^t)₂(η⁷-C₇H₇)]Br. Reaction of [MoBr(CO)₂(η⁷-C₇H₇)] with one equivalent of CNBu^t in toluene at 60°C affords [MoBr(CO)(CNBu^t)(η⁷-C₇H₇)], 5, which is a precursor to [Mo(CO)(CNBu^t)(NCMe)(η⁷-C₇H₇)][BF₄], 6, by reaction with Ag[BF₄] in acetonitrile. In contrast with the parent dicarbonyl systems [MoX(CO)₂(η⁷-C₇H₇)], complexes of the Mo(CO)(CNBu^t)(η⁷-C₇H₇) auxiliary, 5 and 6, do not afford observable η³-C₇H₇ products by ligand addition at the molybdenum centre.     

Electrochemistry of P(CH2Fc)3 and derivatives

The oxidative electrochemistry of P(CH₂Fc)₃ and three of its derivatives was examined. The electrochemistry of these compounds is sensitive to the functionality added to the phosphorus lone pair and the supporting electrolyte used.     

The synthesis of phosphine derivatives of [Fe4N(CO)12]: Crystal structures of [Fe4N(CO)9(NO)(PPh3)2], [HFe4N (CO)11)PPh3)] and [(PPh3)2N][Fe4N(CO)11(PMe2Ph)]

Phosphines react with butterfly tetranuelear nitrido-iron clusters, [Fe₄N(CO)₁₂]⁻ and [Fe₄N(CO)₁₁(NO)], to give mono- and di-substituted complexes. X-Ray analyses of the title compounds showed that the phosphine ligands are bound to the wing-tip atoms.     

Synthesis and structures of silicon-, germanium- and tin-containing tungsten imido alkyl complexes (ArN)2W(CH2EMe3)2 (E = Si, Ge, Sn)

The novel silicon-, germanium- and tin-containing imido alkyl complexes of tungsten of the type (ArN)₂W(CH₂EMe₃)₂ (; E = Si (1), Ge (2), Sn (3)) have been prepared by the reactions of (ArN)₂WCl₂(dme) (dme = 1,2-dimethoxyethane) with heteroelement-containing alkyllithium or Grignard reagents Me₃ECH₂Li (E = Si, Ge), Me₃ECH₂MgCl (E = Ge, Sn). The title compounds were isolated in high yields as crystalline solids and characterized by elemental analysis, IR, ¹H, ¹³C, ²⁹Si and ¹¹⁹Sn NMR spectroscopy and X-ray diffraction studies. The geometry of the W atoms in the compounds can be described as a distorted tetrahedron.     

Molybdenum and tungsten complexes of the neutral tripod ligands HC(pz)3 and MeC(CH2PPh2)3

Starting from [M(CO)₆], seven-coordinated complexes of tungsten and molybdenum containing the facially coordinating ligands HC(pz)₃ (1) and MeC(CH₂PPh₂)₃ (2) were obtained in a two-step reaction sequence. The complexes have a 4:3 piano stool geometry with almost perfect C_S symmetry in the crystal. In solution, they show the typical fluxional behavior for seven-coordinated complexes even at low temperature. Complete oxidative decarbonylation occurs when [HC(pz)₃Mo(CO)₃] (4) or [MeC(CH₂PPh₂)₃Mo(CO)₃] (6) are treated with an excess of I₂ or Br₂.     

Synthesis and crystal structure of the novel trimanganese tetrathiolate incomplete cubane: [Mo(η-C5H5)2(H)CO][Mn3(CO)9(μ-SC6H5)4]

An unexpected trimanganese(I) tetrathiolate-bridged complex, [Mn₃(CO)₉(μ-SC₆H₅)₄]⁻, with an incomplete cubane structure, was obtained by thermal reaction of [Mn₂(CO)₁₀] with [Mo(η⁵-C₅H₅)₂(SC₆H₅)₂]. The structure, established by single-crystal X-ray diffraction studies, shows the cation, [Mo(η⁵-C₅H₅)₂(H)CO]⁺, directed towards the vacant site of the cubane structure. Possible routes by which the anion and the cation could be formed are discussed.     

The reactions between [RuHCl(CO)(PPh3)3] and quinoline carboxylic acids

The reactions of [RuHCl(CO)(PPh₃)₃] with 8-hydroxy-2-methyl-quinoline-7-carboxylic acid and quinoline-2-carboxylic acid have been examined, and two novel ruthenium(II) complexes – [(PPh₃)₂RuH(CO)(C₁₀H₈NO₃)] and [(PPh₃)₂RuCl(CO)(C₉H₆O₂)] – have been obtained. The compounds have been studied by IR and UV–Vis spectroscopy, and X-ray crystallography. The molecular orbital diagrams of the complexes have been calculated with the density functional theory (DFT) method. The spin-allowed singlet–singlet electronic transitions of the compounds have been calculated with the time-dependent DFT method, and the UV–Vis spectra of the compounds have been discussed on this basis.     

The reaction of (μ-H)2Os3(CO)9(PPh3) with ethylene affords the ethylidene complex (μ-H)2Os3(CO)9(PPh3)(μ-CHCH3)

The product isolated from the reaction of (μ-H)₂Os₃(CO)₉(PPh₃) with ethylene is shown to be the ethylidene complex (μ-H)₂Os₃(CO)₉(PPh₃)(μ-CHCH₃) (1) rather than the ethylene complex (μ-H)(H)Os₃(CO)₉(PPh₃)(C₂H₄), as previously claimed. The characterization of 1 is based on a combination of ¹H and ¹³C NMR results. The ¹H NMR data (δ 6.84 (1 H_D), 2.53 (3 H_C), J(CD) = 7.4 Hz) establish the presence of the ethylidene moiety, whereas detailed analysis of the 1-D and 2-D ¹³C NMR spectra of ¹³CO-enriched 1 indicates the relative positions of the ethylidene, hydride, and phosphine ligands on the triosmium framework.     

Haptotropic migration of M(CO)3 (M = Cr, Mo, W) on substituted phenanthrene

The haptotropic migration of Cr(CO)₃, Mo(CO)₃ and W(CO)₃ moieties on a substituted phenanthrene has been studied theoretically using gradient-corrected density functional theory. The stationary points (minima and transition states) on the energy hypersurface characterizing the migrating process of the metal fragment over the aromatic system have been located. Furthermore, the energetic and structural differences between complexes of the three metals Cr, Mo and W and the effect of a high substitution of one arene ring on the reaction energy profile have been analyzed. The possibility to design a molecular switch based on the substituent pair R = O⁻/OH is investigated. It is concluded that the Mo and W complexes undergo a haptotropic migration more easily than the corresponding Cr system.     

Trifluoroacetylacetonate rhodium(III) methyl complexes, cis-[Rh(TFA)(PPh3)2(CH3)(L)][BPh4] and cis-[Rh(TFA)(PPh3)2(CH3)(I)] (L = CH3CN, NH3, pyridine), in comparison with their acetylacetonate analogs

The oxidative addition of CH₃I to planar rhodium(I) complex [Rh(TFA)(PPh₃)₂] in acetonitrile (TFA is trifluoroacetylacetonate) leads to the formation of cationic, cis-[Rh(TFA)(PPh₃)₂(CH₃)(CH₃CN)][BPh₄] (1), or neutral, cis-[Rh(TFA)(PPh₃)₂(CH₃)(I)] (4), rhodium(III) methyl complexes depending on the reaction conditions. 1 reacts readily with NH₃ and pyridine to form cationic complexes, cis-[Rh(TFA)(PPh₃)₂(CH₃)(NH₃)][BPh₄] (2) and cis-[Rh(TFA)(PPh₃)₂(CH₃)(Py)][BPh₄] (3), respectively. Acetylacetonate methyl complex of rhodium(III), cis-[Rh(Acac)(PPh₃)₂(CH₃)(I)] (5), was obtained by the action of NaI on cis-[Rh(Acac)(PPh₃)₂(CH₃)(CH₃CN)][BPh₄] in acetone at −15 °C. Complexes 1-5 were characterized by elemental analysis, ³¹P{¹H}, ¹H and ¹⁹F NMR. For complexes 2, 3, 4 conductivity data in acetone solutions are reported. The crystal structures of 2 and 3 were determined. NMR parameters of 1-5 and related complexes are discussed from the viewpoint of their isomerism.     

Synthesis and characterisation of HRuRh3(CO)12. Crystal structures of HRuRh3(CO)12, HRuRh3(CO)10(PPh3)2 and HRuCo3(CO)10(PPh3)2

A new ruthenium-rhodium mixed-metal cluster HRuRh₃(CO)₁₂ and its derivatives HRuRh₃(CO)₁₀(PPh₃)₂ and HRuCo₃(CO)₁₀(PPh₃)₂ have been synthesized and characterized. The following crystal and molecular structures are reported: HRuRh₃(CO)₁₂: monoclinic, space group P2₁/c, a 9.230(4), b 11.790(5), c 17.124(9) Å, β 91.29(4)°, Z = 4; HRuRh₃(CO)₁₀(PPh₃)₂·C₆H₁₄: triclinic, space group P$\text{1}$, a 11.777(2), b 14.079(2), c 17.010(2) Å, α 86.99(1), β 76.91(1), γ 72.49(1)°, Z = 2; HRuCo₃(CO)₁₀(PPh₃)₂·CH₂Cl₂: triclinic, space group P$\text{1}$, a 11.577(7), b 13.729(7), c 16.777(10) Å, α 81.39(4), β 77.84(5), γ 65.56°, Z = 2. The reaction between Rh(CO)₄^? and (Ru(CO)₃Cl₂)₂ tetrahydrofuran followed by acid treatment yields HRuRh₃(CO)₁₂ in high yield. Its structural analysis was complicated by a 80–20% packing disorder. More detailed structural data were obtained from the fully ordered structure of HRuRh₃(CO)₁₀(PPh₃)₂, which is closely related to HRuCo₃(CO)₁₀(PPh₃)₂ and HFeCo₃(CO)₁₀(PPh₃)₂. The phosphines are axially coordinated.     

Synthesis of [Ru(CO)2(PPh3)(SP)] and [Ru(CO)(PPh3)2(SP)] and their catalytic activities for the hydroamination of phenylacetylene

The reaction of [Ru(CO)₂(PPh₃)₃] (1) with o-styryldiphenylphophine (SP) (2) gave [Ru(CO)₂(PPh₃)(SP)] (3) in 83% yield. This styrylphosphine ruthenium complex 3 can also be synthesized by the reaction of [Ru(p-MeOC₆H₄NN)(CO)₂(PPh₃)₂]BF₄ (4) with NaBH₄ and 2 in 50% yield. When “Ru(CO)(PPh₃)₃” generated by the reaction of [RuH₂(CO)(PPh₃)₃] (8) with trimethylvinylsilane reacted with 2, [Ru(CO)(PPh₃)₂(SP)] (10) was produced in moderate yield as an air sensitive solid. The spectral and X-ray data of these complexes revealed that the coordination geometries around the ruthenium center of both complexes corresponded to a distorted trigonal bipyramid with the olefin occupying the equatorial position and the C-C bonding in the olefin moiety in 3 and 10 contained a significant contribution from a ruthenacyclopropane limiting structure. Complexes 3 and 10 showed catalytic activity for the hydroamination of phenylacetylene 11 with aniline 12. Ruthenium complex 3 in the co-presence of NH₄PF₆ or H₃PW₁₂O₄₀ proves to be a superior catalyst system for this hydroamination reaction. In the case of the reaction using H₃PW₁₂O₄₀ as an additive, ketimines (13) was obtained in 99% yield at a ruthenium-catalyst loading of 0.1 mol%. Some aniline derivatives such as 4-methoxy, 4-trifluoromethyl-, and 4-bromoanilines can also be used in this hydroamination reaction.