Group V complexes of the tricarbonyl(η-cycloheptatrienylium)molybdenum cation and their reduction to monosubstituted derivatives of tricarbonyl(1-6-η-cycloheptatriene)molybdenum

Reaction of [(η-C₇H₇)Mo(CO)₃][PF₆] with certain Group V donor ligands afforded monosubstituted complexes [(η-C₇H₇)Mo(CO)₂L][PF₆] (L = P(OPh)₃, PPh₃, PPh₂Me, PPhMe₂, AsPh₃, SbPh₃). These were reduced by NaBH₄ to the corresponding cycloheptatriene complexes (1-6-η-C₇H₈)Mo(CO)₂L. In addition, the preparation of alkylcycloheptatriene complexes (1-6-η-C₇H₇R)Mo(CO)₂L (R = Me, L = P(OPh)₃, PPh₃, PPh₂Me; R = t-Bu, L = PPh₃) is described. Spectroscopic properties, including ¹³C NMR, are reported.     

Synthesis and Spectra of Cationic Bis(tertiary phosphine) derivatives of cycloheptatrienyliummolybdenum and cyclopentadienyliron complexes

Reaction of [(η-C₇H₇)Mo(CO)₃][PF₆] and [(η-C₅H₅)Fe(CO)₂CH₃CN][PF₆] with ditertiary phosphine ligands afforded products of three types; the monosubstituted complexes [(Ring)M(CO)₂Ph₂P(CH₂)_nPPh₂][PF₆] (Ring = η-C₇H₇, M = Mo, N = 1; Ring = η-C₅H₅, M = Fe, N = 1 and 2), the chelated complexes [(Ring)M(CO)Ph₂P(CH₂)_nPPh₂][PF₆] (Ring = η-C₇H₇, M = Mo, N = 1 and 2; Ring = η-C₅H₅, M = Fe, N = 1 and 2), and the dinuclear complex [{(η-C₇H₇)Mo(CO)₂}₂ -μ- Ph₂PCH₂CH₂PPh₂][(PF₆)₂]. Spectroscopic properties, including ³¹P NMR, are reported.     

η-Alkynyl and vinylidene transition metal complexes: 10. Reaction of the metal-acetylide [(η-C5H5)(CO)(NO)W---CC---C(CH3)3]Li with 1,2-diiodoethane as electrophile and with various nucleophiles

Treatment of the η¹-acetylide complex [(η⁵-C₅H₅)(CO)(NO)W---CC---C(CH₃)₃]Li (4) with 1,2-diiodoethane in THF at −78 °C, followed by the addition of Li---CC---R [R=C(CH₃)₃, C₆H₅, Si(CH₃)₃, 6a–6c] or n-C₄H₉Li and protonation with H₂O, afforded the corresponding oxametallacyclopentadienyl complexes (η⁵-C₅H₅)W(I)(NO)[η²-O=C(CC---R)CH=CC(CH₃)₃] (7a–7c), 8c and (η⁵-C₅H₅)W(I)(NO)[η²-O=C(n-C₄H₉)CH=CC(CH₃)₃] (9). The formation of these metallafuran derivatives is rationalized by the electrophilic attack of 1,2-diiodoethane onto the metal center of 4 to form first the neutral complex [(η⁵-C₅H₅)(I)(CO)(NO)W---CC---C(CH₃)₃] (5). Subsequent nucleophilic addition of Li---CC---R 6a–6c or n-C₄H₉Li and a reductive elimination step followed by protonation leads to the products 7a–7c and 9. One reaction intermediate could be trapped with CF₃SO₃CH₃ and characterized by a crystal structure analysis. The identity of another intermediate was established by infrared spectroscopic data. The oxametallacyclopentadienyl complex 10 forms in the presence of excess 1,2-diiodoethane through an alternative pathway and crystallizes as a clathrate containing iodine.     

Synthesis,Characterization and Crystal Structures of New Ruthenium Carbonyl Clusters Derived from (9-Anthracenyl)diphenylphosphine*

Thermal reaction of [Ru₂(CO)₆(μ-PFu₂)(μ-η¹,η²-Fu)] (Fu=2-furyl) with (9-anthracenyl)diphenylphosphine (AnPPh₂) produces a novel diruthenium complex [Ru₂(CO)₅(μ-PFu₂)(μ-η¹,η¹,η²-C₁₄H₈PPh₂)] (1) in good yield whereas the corresponding reaction between [(μ-H)₄Ru₄(CO)₁₂] and AnPPh₂ gives [HRu(CO)₃(PPh₂C₁₄H₈)][(μ-H)₄Ru₄(CO)₁₁(AnPPh₂)] (2). Both compounds 1 and 2 were fully characterized by spectroscopic methods and their X-ray crystal structures were determined. For 1, initial coordination of the PPh₂ functionality at the Ru atom is accompanied by cyclometalation of the anthracenyl ring to form a Ru–C σ bond together with concomitant formation of a π bond to the adjacent Ru center and loss of the furyl ligand. The formation of 2 involves the cleavage of two Ru–Ru bonds, and the making of a Ru–P bond, followed by orthometalation of the anthracenyl ring. The optical absorption and emission spectra of 1 were recorded and the results were correlated to the DFT calculations.Dedicated to Professor F. Albert Cotton on the occasion of his 75th birthday.     

Synthesis and molecular structure of cisoid and transoid isomers of [Re2(CO)6(1,1′-bis(indenylidene)] derived from the reaction of [Re2(CO)8(MeCN)2] and diazoindene

The compound [Re₂(CO)₈(MeCN)₂] reacts with diazoindene (C₉H₆N₂) while refluxing in THF to afford three dirhenium products in which C₉H₆N₂ is cleaved with loss of N₂ and with incorporation of the residual indenylidene group into the products. Two indenylidene groups are coupled in two diastereomers of [Re₂(CO)₆(μ,η⁵:η⁵-1,1′-C₁₈H₁₂)] where C₁₈H₁₂=bis(indenylidene). X-ray structures show that these isomers are related as RR/SS and RS isomers. These have the two Re(CO)₃ groups coordinated transoid and cisoid, respectively to a trans bis(indenylidene) bridge. The third product is the μ-indenylidene complex [Re₂(CO)₈(μ,η¹:η⁵-C₉H₆)], which was also structurally characterised by X-ray diffraction.     

Synthesis and reaction chemistry of 4-nitrile-substituted NCN-pincer palladium(II) and platinum(II) complexes (NCN = [NC-4-C6H2(CH2NMe2)2-2,6])

Nitrile-functionalized NCN-pincer complexes of type [MBr(NC-4-C₆H₂(CH₂NMe₂)₂-2,6)] (6a, M = Pd; 6b, M = Pt) (NCN = [C₆H₂(CH₂NMe₂)₂-2,6]⁻) are accessible by the reaction of Br-1-NC-4-C₆H₂(CH₂NMe₂)₂-2,6 (2b) with [Pd₂(dba)₃ · CHCl₃] (5a) (dba = dibenzylidene acetone) and [Pt(tol-4)₂(SEt₂)]₂ (5b) (tol = tolyl), respectively. Complex 6b could successfully be converted to the linear coordination polymer {[Pt(NC-4-C₆H₂(CH₂NMe₂)₂-2,6)](ClO₄)}_n (8) upon its reaction with the organometallic heterobimetallic π-tweezer compound {[Ti](μ-σ,π-CCSiMe₃)₂}AgOClO₃ (7) ([Ti] = (η⁵-C₅H₄SiMe₃)₂Ti).The structures of 6a (M = Pd) and 6b (M = Pt) in the solid state are reported. In both complexes the d⁸-configurated transition metal ions palladium(II) and platinum(II) possess a somewhat distorted square-planar coordination sphere. Coordination number 4 at the group-10 metal atoms M is reached by the coordination of two ortho-substituents Me₂NCH₂, the NCN ipso-carbon atom and the bromide ligand. The NC group is para-positioned with respect to M.     

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.     

2-Phosphinothioyl- and 2-phosphinoylethylcyclopentadienyl zirconium and titanium complexes. Crystal structure of [η5:η1-C5H4CH2CH2P(O)Ph2]TiCl3

The intracomplex conversion of (2-diphenylphosphanoethyl)cyclopentadienyl zirconium and titanium complexes into the corresponding 2-phosphinothioyl and 2-phosphinoyl derivatives, viz., (η⁵-C₅H₅)[η ⁵-C₅H₄CH₂CH₂P(S)Ph₂]ZrCl₂, [η⁵-C₅H₄CH₂CH₂P(S)Ph₂]ZrCl₃, [η⁵:η¹C₅H₄CH₂CH₂P(O)Ph₂]ZrCl₃·THF, and [η⁵:η ¹-C₅H₄CH₂CH₂P(O)Ph₂]TiCl₃ (7), was performed. The NMR spectroscopy data revealed the following order of the coordination ability of the functional groups with respect to the Zr center: Ph₂P=O > Ph₂P > Ph₂P=S. An analogous order was found for the monodentate ligands (Ph₃P=O > Ph₃P > Ph₃P=S) with respect to (η⁵-C₅H₅)ZrCl₃. The molecular structure of complex 7 was established by X-ray diffraction analysis. Coordination of the Ph₂P=O group to the titanium atom was found retained both in the crystalline state and solution.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 116–122, January, 2005.     

Complexes containing the unit Rh2 P PM (M = Cr or Mn, P P = bis(diphenylphosphino) alkane); the independence of the metal centres

Treatment of (η⁵-C₅H₅)₂Rh₂(CO)η¹-Ph₂P(CH₂)_n PPh₂(μ-η¹:η¹-CF₃C₂CF₃) (I) with (η⁵-CH₃C₅H₄)Mn(CO)₂(thf) or Cr(CO)₅(thf) gives the hetero-trinuclear products (η-C₅H₅)₂Rh₂(CO)(μ-CF₃C₂CF₃)μ:η¹:η¹-Ph₂P(CH₂)_nPPh₂(η-CH₃C₅H₃C₄)Mn(CO₂) (II, n = 1–4) and (η⁵-C₅H₅)₂Rh₂(CO)(μ-CF₃C₂CF₃)μ:η¹:η¹-Ph₂P(CH₂)nPPh₂Cr(CO)₅ (IV, n = 1–4) in good yields. In these products, the configuration of the CO and bisphosphine units on the Rh-Rh bond is trans. Related reactions between (η⁵:η⁵-C₅H₄CH₂C₅H₄)Rh₂(CO)η¹-Ph₂P(CH₂)nPPh₂(μ-η¹:η¹- (V) and the same solvated manganese and chromium complexes give (η⁵:η⁵-C₅H₄CH₂C₅H₄)Rh₂(CO)(μ-CF₃C₂CF₃)μ:η¹:η¹-Ph₂P(CH₂) (VI, n = 1, 2 or 4) and (η⁵:η⁵-C₅H₄CH₂C₅H₄)Rh₂(CO)(μ-CF₃C₂CF₃)μ:η¹:η¹-Ph₂P(CH₂) (VIII). The complexes (VI) and (VIII) have a mutually cis arrangement of CO and the bisphosphine on the Rh-Rh bond. Attempts to induce the complexes (IV), (V), (VI), and (VIII) to form clusters by loss of CO and Rh-M bond formation were not successful. Treatment with trimethylamine oxide or sunlight irradiation generally resulted in loss of the hetero-metal and formation of the dirhodium phosphine oxide complexes (III, n = 2 or 4) and (VII, n = 2, 3).     

Guaianolide Sesquiterpene Lactones from Centaurothamnus maximus

Centaurothamnus maximus (family Asteraceae), is a leafy shrub indigenous to the southwestern Arabian Peninsula. With a paucity of phytochemical data on this species, we set out to chemically characterize the plant. From the aerial parts, two newly identified guaianolides were isolated: 3β-hydroxy-4α(acetoxy)-4β(hydroxymethyl)-8α-(4-hydroxy methacrylate)-1αH,5αH, 6αH-gual-10(14),11(13)-dien-6,12-olide (1) and 15-descarboxy picrolide A (2). Seven previously reported compounds were also isolated: 3β, 4α, 8α-trihydroxy-4-(hydroxymethyl)-lαH, 5αH, 6βH, 7αH-guai-10(14),11(13)-dien-6,12-olide (3), chlorohyssopifolin B (4), cynaropikrin (5), hydroxyjanerin (6), chlorojanerin (7), isorhamnetin (8), and quercetagetin-3,6-dimethyl ether-4’-O-β-d-pyranoglucoside (9). Chemical structures were elucidated using spectroscopic techniques, including High Resolution Fast Atom Bombardment Mass Spectrometry (HR-FAB-MS), 1D NMR; ¹H, ¹³C NMR, Distortionless Enhancement by Polarization Transfer (DEPT), and 2D NMR (¹H-¹H COSY, HMQC, HMBC) analyses. In addition, a biosynthetic pathway for compounds 1–9 is proposed. The chemotaxonomic significance of the reported sesquiterpenoids and flavonoids considering reports from other Centaurea species is examined.     

Preparation of new dinuclear half-titanocene complexes with ortho- and meta-xylene linkages and investigation of styrene polymerization

Half-titanocene is well-known as an excellent catalyst for the preparation of SPS (syndiotactic polystyrene) when activated with methylaluminoxane (MAO). Dinuclear half-sandwich complexes of titanium bearing a xylene bridge, (TiCl₂L)₂{(μ-η⁵, η⁵-C₅H₄-ortho-(CH₂–C₆H₄–CH₂)C₅H₄}, (4 (L = Cl), 7 (L = O-2,6-iPr₂C₆H₃)) and (TiCl₂L)₂{(μ-η⁵, η⁵-C₅H₄-meta-(CH₂–C₆H₄–CH₂)C₅H₄} (5 (L = Cl), 8(L = O-2,6-iPr₂C₆H₃)), have been successfully synthesized and introduced for styrene polymerization. The catalysts were characterized by ¹H- and ¹³C NMR, and elemental analysis. These catalysts were found to be effective in forming SPS in combination with MAO. The activities of the catalysts with rigid ortho- and meta-xylene bridges were higher than those of catalysts with flexible pentamethylene bridges. The catalytic activity of four dinuclear half-titanocenes increased in the order of 4 < 5 < 7 < 8. This result displays that the meta-xylene bridged catalyst is more active than the ortho-xylene bridged and that the aryloxo group at the titanium center is more effective at promoting catalyst activity compared to the chloride group at the titanium center. Temperature and ratio of [Al]:[Ti] had significant effects on catalytic activity. Polymerizations were conducted at three different temperatures (25, 40, and 70 °C) with variation in the [Al]:[Ti] ratio from 2000 to 4000. It was observed that activity of the catalysts increased with increasing temperature, as well as higher [Al]:[Ti]. Different xylene linkage patterns (ortho and meta) were recognized to be a principal factor leading to the characteristics of the dinuclear catalyst due to its different spatial arrangement, causing dissimilar intramolecular interactions between the two active sites.     

Cyclopentadienyl-ruthenium and -osmium chemistry : XXXIX. Syntheses of novel alkynyl-ruthenium complexes. X-Ray structures of two forms of {Ru(PPh3)2(η-C5H5)}2(μ-C4) and of Ru{CCC(O)Me}(PPh3)2(η-C5H5)

Reactions between [Ru(thf)(PPh₃)₂(η-C₅H₅)]⁺ and lithium acetylides have given further examples of substituted ethynylruthenium complexes that are useful precursors of allenylidene and cumulenylidene derivatives. From Li₂C₄, mono- and bi-nuclear ruthenium complexes were obtained: single-crystal X-ray studies have characterised two rotamers of {Ru(PPh₃)₂(η-C₅H₅)}₂(μ-C₄), which differ in the relative cis and trans orientations of the RuL_n groups. Protonation of Ru(CCCCH)(PPh₃)₂(η-C₅H₅) afforded the butatrienylidene cation [Ru(C=C=C=CH₂)(PPh₃)₂(η-C₅H₅)]⁺, which reacted readily with atmospheric moisture to give the acetylethynyl complex Ru{CCC(O)Me}(PPh₃)₂(η-C₅H₅), also fully characterised by an X-ray structural study.     

New dimeric, trimeric and supramolecular organotin(IV) dithiocarboxylates: Synthesis, structural characterization and biocidal activities

Some new tri-, chlorodi- and diorganotin(IV) dithiocarboxylates (1–10) of 4-benzylpiperidine-1-carbodithioate ligand (L), with general formulae R₃SnL {R = n-C₄H₉ (1), C₆H₁₁ (2), CH₃ (3) and C₆H₅ (4)}, R₂SnClL {R = n-C₄H₉ (5), C₂H₅ (7), CH₃ (9)} and R₂SnL₂ {R = n-C₄H₉ (6), C₂H₅ (8), CH₃ (10)}, have been synthesized by the reaction of organotin(IV) chlorides with the ligand-salt in the appropriate molar ratio. Elemental analysis, Raman, IR, multinuclear NMR (¹H, ¹³C and ¹¹⁹Sn) and X-ray crystallographic studies have been undertaken to elucidate the structures of the complexes, both in solution and in solid state. Single-crystal X-ray diffraction study indicate trimeric, dimeric, supramolecular cyclic and supramolecular zig–zag chain structures for complexes 2, 4, 6 and 9, respectively. Square-pyramidal geometry is attributed to complex 9 on the basis of the τ value (0.4). A subsequent antimicrobial study indicates that the compounds are biologically active.     

Übergangsmetall-fulven-komplexe : XXVIII. Reaktionen von (fulven)Cr(CO)3-komplexen und α-ferrocenyl-carbeniumionen mit nukleophilen

Tricarbonyl(fulvene)chromium complexes react with anionic nucleophiles to give functionally substituted cyclopentadienyl derivatives. The nucleophilic attack occurs at the exocyclic carbon atom of the fulvene ligand. Addition of PPh₂⁻ to (η⁶-6,6-dimethylfulvene)Cr(CO)₃ (1) yields the novel anion [(η⁵-C₅H₄C(CH₃)₂PPh₂)Cr-(CO)₃]⁻, which can be isolated as a K⁺, (C₂H₅)₄N⁺, (C₆H₅)₄P⁺, or Tl⁺ derivative (2–5). The potassium salt of the uncoordinated C₅H₄C(CH₃)₂PPh₂⁻ anion (7) is obtained by treatment of 6,6-dimethylfulvene with KPPh₂·2C₄H₈O₂. Similarly, NaC₅H₅ reacts with 1 to give Na[(η⁵-C₅H₄C(CH₃)₂C₅H₅)Cr(CO)₃] (8). The reactions of (6-dimethylaminofulvene)Cr(CO)₃ (15) with nucleophiles are accompanied by elimination of dimethylamine. Addition of Ph₃P=CH₂ to 15 gives an unstable product, but after reaction of 6-dimethylaminofulvene with Ph₃P=CH₂, the free ligand C₅H₄=CHCH=PPh₃ (17) can be isolated in moderate yields. Deeply colored anions of the type [(η⁵:η⁵-C₅H₄C(R)=C₅H₄)Cr₂(CO)₆]⁻ (R = H, N(CH₃)₂) are synthesized by reaction of 15 or (6-dimethylamino-6-methylthiofulvene)Cr(CO)₃ with NaC₅H₅ and subsequent complexation of the mononuclear intermediate with (CH₃CN)₃Cr(CO)₃. In addition, the synthesis of the new fulvene complexes [C₅H₄=CH(CH=CH)₂N(CH₃)Ph]M(CO)₃ (23, 24; M = Cr, Mo) is described. The investigation is extended to α-ferrocenylcarbenium ions, which are isoelectronic with (fulvene)Cr(CO)₃ complexes. [(η⁵-C₅H₅)Fe(C₅H₄CPh₂)]⁺ BF₄⁻ (25) adds tertiary phosphines at the exocyclic carbon atom to give phosphonium salts of the type [(η⁵-C₅H₅)Fe(C₅H₄CPh₂PR₃)]⁺BF₄⁻. A CO-substititution product of a tricarbonyl (fulvene)chromium complex is obtained for the first time by irradiation of (η⁶-6,6-diphenylfulvene)Cr(CO)₃ in the presence of PPh₃. In addition, an improved synthesis of the (CH₃CN)₃M(CO)₃ complexes (M = Cr, Mo, W) is reported.     

Bis(diphenylphosphino)methane trimethylphosphine alkyl and η-cyclopentadienyl compounds of rhodium(I); P{H} two dimensional δ/J resolved and Overhauser effect nuclear magnetic resonance spectroscopy

Neutral mononuclear tertiary phosphine rhodium(I) complexes of the formula RhX(PMe₃)(dppm), X = Cl, CH₂SiMe₃, CH₂CMe₃, CH₂CMe₂Ph, η⁵-C₅H₅, DPPM = bis(diphenylphosphino)methane, RhCl(PPh₃)(dppm), RhX(dppm)₂, X = Cl, Me and Rh(η⁵-C₅H₅(dppm) have been synthesised. In Rh(η⁵-C₅H₅)(PMe₃)(dppm), the dppm ligand is unidentate according to ³¹P{¹H} NMR and X-ray data.The ³¹P{¹H} NMR spectral parameters of RhX(PR₃)(dppm) have been determined by a combination of two dimensional δ/J resolved spectroscopy and heteronuclear nuclear Overhauser effect difference spectroscopy (NOEDS) in conjunction with iterative analysis of the one dimensional spectra.     

Polymerisations of -caprolactone and β-butyrolactone with Zn-, Al- and Mg-based organometallic complexes

The reaction of EtAlCl₂ with 1,2-{LiN(PMes₂)}₂C₆H₄ (Mes = 2,4,6-Me₃C₆H₂) and of butyloctylmagnesium with 1,2-{NH(PPh₂)}₂C₆H₄ gave [AlEt(1,2-{N(PMes₂)}₂C₆H₄-κ²N,N′)(THF)] (1) and [Mg(1,2-{N(PPh₂)}₂C₆H₄-κ²N,N′)(THF)₂] (2), respectively. Complexes 1 and 2 were fully characterised by NMR (¹H, ¹³C, ³¹P) and IR spectroscopy and mass spectrometry. Complexes 1 and 2 were employed as catalysts in the polymerisation of -caprolactone, which produced polymers with a narrow molecular weight distribution. For comparison the polymerisations of -caprolactone and β-butyrolactone were carried out with the Zn complex [ZnPr{1-N(PMes₂)-2-N(PHMes₂)C₆H₄-κ²N,N′}] (3) as catalyst, which produced polymers with narrow molecular weight distributions and high molecular weights.     

The synthesis of functional derivatives of the [1-CB9H10] anion by Brellochs reaction

Reactions of decaborane with various aldehydes in alkaline media were studied. The reactions with HCOH and 2-MeOC₆H₄CHO give the corresponding arachno-carboranes [6-R-arachno-CB₉H₁₃]⁻ (R = H, C₆H₄-2-OMe), whereas the reactions with C₆H₅CHO, 4-BrC₆H₄CHO, 4-MeCONHC₆H₄CHO, and 2-SC₄H₃CHO result in the nido-carboranes [6-R-nido-CB₉H₁₁]⁻ (R = C₆H₅, C₆H₄-4-Br, C₆H₄-4-NHCOMe, 2-SC₄H₃). Both the arachno- and nido-carboranes can be easily oxidized with elemental iodine in an alkaline aqueous solution giving the corresponding closo-derivatives [2-R-closo-2-CB₉H₉]⁻. These closo-2-isomers, under heating in solution, undergo rearrangement to more thermodynamically favorable closo-1-isomers [1-R-closo-1-CB₉H₉]⁻. The structure of (Bu₄N)[1-(4-BrC₆H₄)-1-CB₉H₉] was determined using single crystal X-ray diffraction.     

A directly ring-to-ring linked ferrocene–pseudotitanocene complex

Addition of excess ferrocenylacetylene (FcCCH) to [η⁵-(C₅H₅)Ti][μ:η²:η²-C₂(SiMe₃)₂]₂[η⁵-(C₅H₅)Mg] (1) affords the novel ferrocene–pseudotitanocene complex [η⁵-1,2,5,6-tetrakis(trimethylsilyl)-4-ferrocenylcyclohexa-1,4-dienyl](η⁵-cyclopentadienyl)titanium(II), [η⁵-(Me₃Si)₄FcC₆H₂]Ti(η⁵-C₅H₅) (2), as the sole isolated titanium-containing product. Its structure was established by EI MS, NMR and UV–vis spectroscopy. The formation of 2 follows the general reaction route of terminal acetylenes with 1.     

Reactions of [Cp*Ru(H<Subscript>2</Subscript>O)(NBD)]<Superscript>+</Superscript> with diynes

Abstract  Formal [2 + 2 + 2] addition reaction of [Cp*Ru(H₂O)(NBD)][BF₄] (NBD = norbornadiene) with 4,4′-Diethynylbiphenyl generates [C₉H₉-η⁶-C₆H₄(RuCp*)–C₆H₄(RuCp*)-η⁶-C₉H₉][BF₄]₂. The reaction of [Cp*Ru(H₂O)(NBD)][BF₄] with 1,4-diphenylbutadiyne generates the unusual [2 + 2 + 2] additional organic compound Ph–C≡C–C₉H₈–Ph in addition to the organometallic compound [Cp*Ru(η⁶-C₆H₅–C≡C–C≡C–Ph)][BF₄]. [C₉H₉-η⁶-C₆H₄(RuCp*)–C₆H₄(RuCp*)-η⁶-C₉H₉][BPh₄]₂ is generated after the reaction of compound [C₉H₉-η⁶-C₆H₄(RuCp*)–C₆H₄(RuCp*)-η⁶-C₉H₉][BF₄]₂ with Na[BPh₄]. The structure of this compound was confirmed by X-ray diffraction. A possible approach to form Ph–C≡C–C₉H₈–Ph and [Cp*Ru(η⁶-C₆H₅–C≡C–C≡C–Ph)][BF₄] is suggested. Graphical Abstract  Formal [2 + 2 + 2] addition reaction of [Cp*Ru(H₂O)(NBD)]BF₄ (NBD = norbornadiene) with 4,4′-Diethynylbiphenyl generates [C₉H₉-η⁶-C₆H₄(RuCp*)–C₆H₄(RuCp*)-η⁶-C₉H₉][BF₄]₂. The reaction of [Cp*Ru(H₂O)(NBD)][BF₄] with 1,4-diphenylbutadiyne simply generates unusual [2 + 2 + 2] additional organic compound Ph–C≡C–C₉H₈–Ph in addition to the organometallic compound [Cp*Ru(η⁶-C₆H₅–C≡C–C≡C–Ph)][BF₄]. [C₉H₉-η⁶-C₆H₄(RuCp*)–C₆H₄(RuCp*)-η⁶-C₉H₉][BPh₄]₂ is generated after the reaction of compound [C₉H₉-η⁶-C₆H₄(RuCp*)–C₆H₄(RuCp*)-η⁶-C₉H₉][BF₄]₂ with Na[BPh₄]. The structure of this compound was confirmed by X-ray diffraction. And the possible approach to form Ph–C≡C–C₉H₈–Ph and [Cp*Ru(η⁶-C₆H₅–C≡C–C≡C–Ph)][BF₄] was suggested. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Synthesis of the first metallacarborane triple-decker complexes with a central cyclopentadienyl ligand

The previously unknown metallacarboranes (η-C₅R₅)Ru(η-9-Me₂S-7,8-C₂B₉H₁₀) (R=H or Me) and (η-C₅H₅)Ni(η-9-Me₂S-7,8-C₂B₉H₁₀) were prepared and used in the synthesis of the first metallacarborane triple-decker complexes with a central cyclopentadienyl ligand, viz., [(η-C₅R₅)Ru(μ-η:η-C₅Me₅)Ru(η-9-Me₂S-7,8-C₂B₉H₁₀)]PF₆ (R=H or Me), [(η-9-Me₂S-7,8-C₂B₉H₁₀)Ni(μ-η:η-C₅H₅)Ni(η-9-Me₂S-7,8-C₂B₉H₁₀)]PF₆, and [(η-C₅H₅)Ni(μ-η:η-C₅H₅)Ni(η-9-Me₂S-7,8-C₂B₉H₁₀)]BF₄. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1368–1373, July, 1999.