Showing papers by "Malcolm L. H. Green published in 1994"
TL;DR: In this article, a general method that allows carbon nanotubes to be opened at the end and filled with a variety of metal oxides using wet chemical techniques is described, which might find applications in catalysis, separation and storage technology and in the development of materials with new magnetic and electrical properties.
Abstract: SINCE carbon nanotubes1 were first synthesized in macroscopic quantities2, it has become possible to explore their physical and chemical characteristics. There has been much speculation3 about the properties of materials encapsulated within the tubes, but experimental studies of this issue require a reliable means of open-ing and filling the tubes. Various approaches have been developed for opening up4–6 the tube ends and encapsulating material4,6,7, but these work only for a limited range of materials or in low yield. Here we describe a general method that allows carbon nanotubes to be opened at the end and filled with a variety of metal oxides using wet chemical techniques. We anticipate that this method will lead to extensive study of the chemistry and physics of filled nanotubes, which might find applications in catalysis, separation and storage technology and in the development of materials with new magnetic and electrical properties.
1,245 citations
TL;DR: In awake, stable outpatients acclimatised to nasal ventilation there were no clinically significant differences between volume cycledflow generator and bi‐level positive airway pressure techniques, but continuous positive air way pressure was less effective.
Abstract: The aims of noninvasive ventilation include the correction of hypoventilation and unloading of inspiratory muscles. Volume cycled flow generators, bi-level positive airway pressure and continuous positive airway pressure techniques have all been used with face and nasal masks. We have compared these modes of ventilatory support, administered by a nasal mask in stable, awake outpatients with chronic obstructive pulmonary disease or neuromusculo-skeletal disease in respect of their effects on ventilation, inspiratory muscle effort and oxygen saturation. There were no clinically significant differences between the volume cycled flow generator and bi-level positive airway pressure methods; compared to spontaneous ventilation, oxygen saturation increased and inspiratory muscle effort decreased. Tidal volume increased and respiratory rate reduced, the largest changes occurring with bi-level positive airway pressure. Only the volume cycled flow generator increased minute ventilation significantly. Ventilation and inspiratory muscle effort were unaffected by continuous positive airway pressure but oxygen saturation was lower than during spontaneous ventilation. In awake, stable outpatients acclimatised to nasal ventilation there were no clinically significant differences between volume cycled flow generator and bi-level positive airway pressure techniques, but continuous positive airway pressure was less effective.
59 citations
TL;DR: In this paper, a non-group VIII metal catalyst, rhenium supported on γ-alumina has been tested as a catalyst for the partial oxidation and dry reforming of methane at different temperatures.
54 citations
TL;DR: The base-free compounds [{Zr(η-C5R5] [N(SiMe3]2]Cl]], Zr(µ-Me)B(C6F5)3X] as mentioned in this paper ] were prepared using the transfer of a C5F5 group from [B(c6f5)4], where the crystal structure has been determined.
Abstract: The new base-free compounds [{Zr(η-C5R5)[η-CPh{N(SiMe3)}2]Cl}][B(C6F5)3X]2(R = H, X = Me, CH2Ph or R = Me, X = C6F5*) and [{(η-C5H5)[η-CPh{N(SiMe3)}2](C6F5)}Zr(µ-Me)B(C6F5)3}],* are prepared; the formation of the latter requires the transfer of a C6F5 group from [B(C6F5)4]:* indicates the crystal structure has been determined.
45 citations
TL;DR: In this article, a new family of salts [Ru(η 5 -C 5 H 5 ((+)-(DIOP)( p -NCC 6 H 4 NO 2 )][X] (X = p -CH 3 C 6H 4 SO 3 −, Cl −, NO 3 −, BF 4 −, PF 6 −, CLO 4 − and CF 3 SO 3 - ), has been synthesized.
42 citations
TL;DR: The ansa-bridged metallocenes [M{CR2(η-C5H4)(η -C9H6)}Cl2], [M = Ti, Zr or Hf; CR2= CMe2, CPh2 or C(CH2)5] have been prepared.
Abstract: The ansa-bridged metallocenes [M{CR2(η-C5H4)(η-C9H6)}Cl2], [M = Ti, Zr or Hf; CR2= CMe2, CPh2 or C(CH2)5] have been prepared. The crystal structure of [Zr{CMe2(η-C5H4)(η-C9H6)}Cl2] has been determined. Some of these new ansa-metallocenes in the presence of methylaluminoxane (AlMeO)n give homogeneous catalysts, which for the polymerization of propene yield isotactic rich polypropene and of styrene yield syndiotactic polystyrene.
42 citations
TL;DR: Incorporation of elemental phosphorus into hexagonal-packed C60 gives the new phase {(P4)2C60}; characterisation by powder diffraction and multinuclear solid-state NMR studies show the P4 tetrahedra occupy trigonal prismatic sites and confirm the retention of the molecular nature of the guest.
Abstract: Incorporation of elemental phosphorus into hexagonal-packed C60 gives the new phase {(P4)2C60}; characterisation by powder diffraction and multinuclear solid-state NMR studies show the P4 tetrahedra occupy trigonal prismatic sites and confirm the retention of the molecular nature of the P4 guest.
32 citations
TL;DR: In this paper, an efficient catalyst for the hydroformylation of alkenes to aldehydes at 90°C has been synthesized by reacting the hydroforming catalyst, RhH(CO) (C60) (PPh3)3, with an equimolar amount of C60 in toluene.
20 citations
TL;DR: The new bimetallic complexes have been prepared from the precursors [{Me2C(η5-C5H4)(η2-C9H6)}MCl2] and [Mn(CO)3].
Abstract: The new bimetallic complexes[(η5-C5H5)MCl2{(η5-C5H4)CMe2(η5-C9H6)}M*Cl2(η5-C5H5)](M = Zr, M*= Zr, Hf; M = Hf, M*= Zr, Hf), [(η5-C5H5)ZrCl2]{[(η5-C5H4)CM2(η5-C9H6)}ZrCl2(η5-C5Me5)], [(η5-C5H5)ZrCl2{(η5-C5H4)Cme2(η5-C9H6)}Rh(CO)2] and [(η5-C5H5)ZrCl2]{[(η5-C5H4)CMe2(η5-C9H6)}Mn(CO)3] have been prepared from the precursors [{Me2C(η5-C5H4)(η2-C9H6)}M(η5-C5H5)Cl](M = Zr 1, Hf 2); the X-ray crystal structure of 1 is reported.
19 citations
TL;DR: The new ansa-bridged compounds [{Me2C(η5-C5H4)(η2-C9H6)} and [{(CH2)5C (η 5-C 5H4), η 2-C 9H6] showed unusual modes of coordination of the indenyl or fluorenyl groups.
Abstract: The new ansa-bridged compounds [{Me2C(η5-C5H4)(η2-C9H6)}M(η5-C5H5)Cl], [{(CH2)5C(η5-C5H4)(η2-C9H6)}M(η5-C5H5)Cl](M = Zr, Hf) and [{[Me2C(η5-C5H4)(η3-C13H8)}Zr(η5-C5H5)Cl] show unusual modes of coordination of the indenyl or fluorenyl groups.
18 citations
TL;DR: Two new Diels-Alder adducts of C60 have been obtained from 1,3-diphenylisobenzofurn and 1,4-dihydroxy-2,3bis(bromomethyl)anthraquinone as discussed by the authors.
Abstract: Two new Diels–Alder adducts of C60 have been prepared from 1,3-diphenylisobenzofurn and the ortho-quinodimethane generated from 1,4-dihydroxy-2,3-bis(bromomethyl)anthraquinone: the dihydroxy anthraquinone–C60 adduct readily undergoes deprotonation to give the corresponding dianion.
TL;DR: In this article, the sodium salt of the monoanion [C60] was prepared and the 13C and 23Na solid state NMR, EPR and UV spectra were reported; variable-temperature magnetic susceptibility measurements show a sharp reduction in the magnetic moment below 200 K.
Abstract: The sodium salt of the monoanion [C60]–, namely {Na+[C60]–(thf)5} is prepared and the 13C and 23Na solid state NMR, EPR and UV spectra are reported; variable-temperature magnetic susceptibility measurements show a sharp reduction in the magnetic moment below 200 K.
TL;DR: In this paper, a capped-closo geometry with one FeMo-B face being capped by a boron atom and the other having a triply bridging hydrogen atom was obtained.
Abstract: The reaction of nido-[2-{Fe(η-C5H5)}B5H10] with [Mo(PMe2Ph)4H4] gave capped-closo-[1-{Fe(η-C5H5)}-2-{Mo(PMe2Ph)3H}B5H7] which has been characterised by X-ray crystallography as well as by 11B and 1H NMR spectroseopy. The structure determination [monoclinic, space group P21/c, a= 15.586(5), b= 11.523(4), c= 19.186(4)A, β= 106.23(2)°] reveals a capped-closo geometry with one Fe–Mo–B face being capped by a boron atom and the other having a triply bridging hydrogen atom. The isostructural tungsten compound capped-closo-[1-{Fe(η-C5H5)}-2-{W(PMe3)3H}B5H7] was similarly prepared from [W(PMe3)3H6] and nido-[2-{Fe(η-C5H5)}B5H10]. Reaction between [Re(PMe3)5H] and nido-[2-{Fe(η-C5H5)}B5H10] gave a mixture of nido-[2-{Re(PMe3)3}B5H10] and the salt [Re(PMe3)5H2]+[nido-2-{Fe(η-C5H5)}B5H9]–, a product of an acid–base reaction.
TL;DR: In this paper, the crystal structures of the new diamagnetic molybdenum (IV) compounds of general formula [Mo(η-C5H4R)Cl(L)(NR′)] have been determined, where L = ethene, propene, styrene, but-2-yne or carbon monoxide.
Abstract: The new paramagnetic compounds [M(η-C5H4R)X2(NR′)](M = Mo, X = Cl, R′= But, R = H, Me or Pri., M = Mo, X = Cl, R = H, R′= Pri, Prn or Ph; M = Mo, X = Cl, R = Me, R′= Ph; M = Mo, X = Br, R = Me, R′= But; M = W, X = Cl, R′= But, R = H or Me) have been prepared and the crystal structure of [Mo(η-C5H5)Cl2(NBut)] has been determined. The new diamagnetic molybdenum(IV) compounds of general formula [Mo(η-C5H4R)Cl(L)(NR′)] where L = ethene, propene, styrene, but-2-yne or carbon monoxide have been synthesised. The mercury-bridged compounds [{Mo(η-C5H4R)(C2H4)(NBut)}2(µ-Hg)](R = H or Me) have also been obtained, together with the compound [Mo(NBut)Cl2(PMe3)3]. The crystal structures of [Mo(η-C5H4Me)Cl(C2H4)(NBut)], [(Mo(η-C5H5)-(C2H4)(NBut)}2(µ-Hg)] and [Mo(NButCl2(PMe3)3] have been determined.
TL;DR: The first or rare examples of combinations of ligands with the imido group, for example, imido η3-allyl derivatives, have been determined in this paper.
Abstract: The following compounds have been prepared and characterized: [Mo(η-C5H4R)Cl3(NBut)](R = H, Me or Pri), [{MoCl3(µ-Cl)(NBut)}2], cis- and trans-[{Mo(η-C5H4Me)(NBut)(µ-NBut)}2], [{Mo(η-C5H4Me)O(µ-NBut)}2], [Mo(η-C5H4Me)(η-C2H4)Me(NBut)], [Mo(η-C5H5)(η-C2H4)Ph(NBut)], [Mo-(η-C6H4Me)(η-C2H4)(H or D)(NBut)], [Mo(η-C5H4Me)(PMe3)Cl(NBut)], [Mo(η-C5H4Me)(PMe3)-Me(NBut)], [Mo(η-C5H4Me)(PMe3)2(NBut)]+A–(A = Cl or BF4), [Mo(η-C5H4Me)(PMe2Ph)Cl-(NBut)], isomers of [Mo(η-C5H4R)(η-C3H5)(NBut)](R = Me or Pri), and [Mo(η-C5H4Me)(η-C2H4)-(σ-C3H5)(NBut)]. The crystal structure of [{MoCl3(µ-Cl)(NBut)}2] has been determined. These compounds include the first or rare examples of combinations of ligands with the imido group, for example, imido η3-allyl derivatives.
TL;DR: The properties as ligands of the primary phosphines PH2(CHCH2)1 and PH2CHCHCH 2 have been studied in this article, and the crystal structures of compounds 10 and 17 have been determined.
Abstract: The properties as ligands of the primary phosphines PH2(CHCH2)1 and PH2(CH2CHCH2)2 have been studied. The new compounds [W(η-C5R5)Cl4(PH2R′)](R5= H4Pri, R′= CHCH27 or CH2CHCH28; R5= Me4Et, R′= CHCH29 or CH2CHCH210), [W2(η-C5H4Pri)2X4(µ-H)(µ-PHR)](X = Cl, R = CHCH212 or CH2CHCH213; X = Br, R = CHCH215), [W2(η-C5Me5)2Cl4(µ-H)(µ-PHC2H3)]17 and [W2(η-C5Me5)2Cl2(µ-Cl)(µ-PHC2H3)]18 have been prepared. The crystal structures of compounds 10 and 17 have been determined.
TL;DR: The new compounds [W(η-C 5 H 4 CO 2 Me)Br 4 ], [W 2 (η -C 5H 4 CO2 Me) 2 (μ-Br 4 )], [W
TL;DR: In this article, superconducting alkali metal fullerides can be synthesized in less than 60 s reaction time using a microwave-induced argon plasma; the rapid synthesis of K3C60 is described.
Abstract: Superconducting alkali metal fullerides can be synthesized in less than 60 s reaction time using a microwave-induced argon plasma; the rapid synthesis of K3C60 is described.
TL;DR: In this paper, the formation of aromatics during the reaction between methane and oxygen between 970 and 1220K, at elevated pressure has been studied, and high selectivities and yields of the aromatics, i.e. benzene and toluene, are obtained over certain oxide catalysts, although, aromatics are also formed when no catalyst is present.
Abstract: The formation of aromatics during the reaction between methane and oxygen between 970 and 1220K, at elevated pressure has been studied. High selectivities and yields of the aromatics, i. e. benzene and toluene, are obtained over certain oxide catalysts, although, aromatics are also formed when no catalyst is present. A manganese oxide catalyst doped with sodium chloride gave the highest yield of aromatics, however, supported nickel or platinum catalysts, which have been reported to be active catalysts for aromatics formation, were found to give lower yields of aromatics than for the gas-phase reaction. The mechanism for the production of aromatics has been investigated.
TL;DR: In this paper, a parallel-bridging alkyne group was proposed to have a parallelbridging group with hex-3-neuron. But-2-neon was used to give a mixture of [Mo2(µ-η : η-C10H8)(η -C5H5)2(MeCCMe)2] and [Mo 2(´-δ : δ-C 10H8(δ)-C 5H5(EtCCEt)2 (MeCCE
Abstract: The reaction of [Mo2(µ-η : η-C10H8)(η-C5H5)2H2]1 with dihydrogen gives [Mo2(µ-η : η-C10H8)(η-C5H5)2H4] whose crystal structure has been determined. Treatment of 1 with ethylene at 10 atm gives [Mo2(µ-η : η-C10H8)(η-C5H5)2(C2H4)2], whilst ethylene at 1 atm gives [Mo2(µ-η : η-C10H8)2H2] whose crystal structure has been determined. Treatment of 1 with but-2-yne gives a mixture of [Mo2(µ-η : η-C10H8)(η-C5H5)2(MeCCMe)2] and [Mo2(µ-η : η-C10H8)(η-C5H5)2(µ-MeCCMe)]; the latter is proposed to have a parallel-bridging alkyne group. Reaction of 1 with hex-3-yne gives [Mo2(µ-η : η-C10H8)(η-C5H5)2(EtCCEt)2].
TL;DR: In this paper, a mixture of cobalt halide and cobalt metavanadate was used as catalysts for the activation of methane at 750°C in redox mode.
Abstract: Molten mixtures of sodium metavanadate and cobalt halide have been tested as catalysts for the activation of methane at 750°C in redox mode. It is found that these melts can convert methane selectively to C2+ products in the absence of molecular oxygen. The initial activity and selectivity of the melt can then be restored after dioxygen treatment. It is also found that the addition of cobalt chloride gives a higher CH4 conversion, C2+ selectivity and C2H4/C2H6 ratio than pure sodium metavanadate. Surprisingly, addition of cobalt bromide shows a similar enhancement. IR and ESR spectra of quenched catalyst samples showed that the cobalt and vanadium ions are reduced by methane and can be reoxidised by dioxygen
TL;DR: Incorporation of elemental phosphorus into hexagonal-packed C60 gives the new phase {(P4)2C60}; characterisation by powder diffraction and multinuclear solid-state NMR studies show the P4 tetrahedra occupy trigonal prismatic sites and confirm the retention of the molecular nature of the guest as discussed by the authors.
Abstract: Incorporation of elemental phosphorus into hexagonal-packed C60 gives the new phase {(P4)2C60}; characterisation by powder diffraction and multinuclear solid-state NMR studies show the P4 tetrahedra occupy trigonal prismatic sites and confirm the retention of the molecular nature of the P4 guest.
TL;DR: In this article, the derivatives of the fullerence C60, namely [Fe(CO)4(η2-C60)], [Mo(C5H4R)2 (η 2 -C60)] (R = H, Bun), and [Ta(C2 -C5)]( η 2 −C60), are described.
Abstract: Monoadduct derivatives of the fullerence C60, namely [Fe(CO)4(η2-C60)], [Mo(η-C5H4R)2(η2-C60)](R = H, Bun), [Ta(η2-C5)](η2-C60)] and Rh (ph(Ph3P)2(CO)(η2-C60)H], are described.
TL;DR: In this paper, a carbon soot formed by arc evaporation and activated by heating under carbon dioxide is found to have a surprisingly high internal micropore volume (> 0.25 ml g-1) and an apparent BET surface area of ca. 700 m2 g−1, a large proportion of the pores are ca.5 A.
Abstract: A carbon soot formed by arc evaporation and activated by heating under carbon dioxide is found to have a surprisingly high internal micropore volume (> 0.25 ml g–1) and an apparent BET surface area of ca. 700 m2 g–1, a large proportion of the pores are ca.⩽5 A; transmission electron microscopy shows a highly disordered microstructure, which electron irradiation readily transforms into quasi spherical concentric nanoparticles of diameter of ca. 60 A, the carbon material, which is highly absorbent to methane, shows molecular sieving properties and is more inert to oxidation than other forms of high surface area carbon.