Showing papers by "Malcolm L. H. Green published in 1976"

Some 1 and 3-allylic and metallocyclobutane derivatives of molybdenum and tungsten

Abstract: Nucleophilic attack by R–= H– or Me– on [W(η5-C5H5)2(η3-CH2CHCH2)]+PF6– occurs on the central carbon of the η3-allylic group giving the metallocyclobutane compounds [W(η5-C5H5)2(CH2CHRCH2)] which, for RH, undergo deuteriation giving [W(η5-C5H5)2H(CH2CHCH2D)]+PF6–; similar attack occurs on the analogous molybdenum compounds.

Preparation and reactions of cyclo-tetra-µ-lithio-tetrakis[bis(η-cyclo-pentadienyl)hydrido-molybdenum] and -tungsten] and some bis(η-cyclopentadienyl) derivatives of molybdenum and tungsten

Abstract: The dihydrides [M(η-C5H5)2H2](M = MO or W) react in toluene with n-butyl-lithium to give the tetramers [{M(η-C5H5)2HLi}4]. The tetramers react with PhCH2Br or PhCOX [X = Cl, OMe, or (M = W)H] giving [M(CH2Ph)2(η-C5H5)2] or [M(η-C5H5)2(COPh)H] respectively. With carbon dioxide the monocarbonyls [M(η-C5H5)2(CO)] are formed in high yield. The tetramer (M = W) reacts with acetyl chloride or benzophenone giving the compounds [W(η-C5H5)2(COMe)H] or [W(η-C5H5)2{C6H4(COPh-p)H] respectively. These compounds in carbon tetrachloride give the chloro-analogues [W(η-C5H5)2(COMe)Cl] and [W(η-C5H5)2{C6H4(COPh-p)}Cl]. The molybdenum tetramer with carbon monoxide gives both the monocarbonyl [Mo(η-C5H5)2(CO)] and the cyclopentenyl compound [Mo(η-C5H5)(η3-C5H7)2(Co)2] The products of reaction between the dihydrides [M(η-C5H5)2H2] and methyl- or phenyl-lithium appear to be identical to those formed from LiBun. With ZnR2(R = Et or Bun) the dihydrides give polymeric compounds [{M(η-C5H5)2Zn}n]. The compounds [M(η-C5H5)2–(COPh)Cl](M = Mo or W), [W(CH2SiMe3)2(η-C5H5)2], [M(η-C5H5)2(C6F5)2](M = Mo or W), and [Mo(η-C5H5)2(η3-C3H4Me)][PF6] are also described.

Photochemical reactions of metallocyclobutane derivatives of tungsten: evidence for the mechanism of olefin metathesis

Abstract: Irradiation of the metallocyclobutane derivatives [W(η5-C5H5)2(-CH2CHR2CHR1-)], where R1= R2= H, R1= H, R2= Me, or R1= Me, R2= H, gives rise to the olefins CH2CHR1 and CH2CHR2 in good yield.

Organometallic intercalation of metal dichalcogenides: intercalates of zirconium disulphide and low ionisation potential sandwich compounds

Abstract: The new organometallic intercalation compounds {[(η6-C6H6)2M]1/6ZrS2}(M = Cr or Mo), {[(η6-arene)2MO]xZrS2}, (arene = toluene or mesitylene, x < ⅙), {[(η5C5H5)(η7-C7H7)Cr]1/4ZrS2}, {[(η6-C6H6)(η5-C5H5)Cr]1/4ZrS2}, {[(η5-C5H5)2Cr]1/4ZrS2}, and {[(η8-C8H8)(η5-C5H5)Ti]1/4ZrS2} have been prepared and characterised.

Preparations and reactions of bis(η-cyclopentadienyl) compounds containing covalent aluminium–molybdenum or –tungsten bonds

Abstract: The dihydride [Mo(η-C5H5)2H2] reacts with AlMe3 to give compounds (II) and (III) containing Mo–Al bonds Compound (II) reacts with allyl chloride to give the compound [Mo(η-C3H5)(η-C5H5)2][PF6] Following treatment of compound (II) with carbon dioxide, the carbonyl compound [MoBr(η-C5H5)2(CO)][PF6] may be isolated The dihydride [W(η-C5H5)2H2] reacts with AlMe3 to give a related tungsten–aluminium compound The compounds and reactions are discussed

Preparations and reactions of bis(η-cyclopentadienyl) compounds of molybdenum or tungsten containing covalent bonds to magnesium

Abstract: The dihydride [Mo(η-C5H5)2H2] reacts with bromo(cyclohexyl)magnesium to give the cyclic dimer [H(η-H5C5)2-Mo{µ-( H11C6)MgBr2Mg(OEt2)}2Mo(η-C5H5)2H], (III). The Grignard reagents MgRX (RX = PriBr, BunBr, Mel, or PhBr) give generally similar products. Derivative (III) reacts with carbon dioxide, carbon monoxide, benzyl bromide, or butadiene to give the compounds [Mo(η-C5H5)2(CO)], [Mo(η5-C5H5)(η3-C5H7)(CO)2], [Mo(η-C5H5)2(CH2Ph)2], and [Mo(η3-C4H7)(η-C5H5)2][PF6] respectively. The isopropyl analogue of (III) reacts similarly. Also, with iodomethane, the compound [MoMe(η-C5H5)2I] is formed. The methyl and phenyl analogues of (III) react with benzyl bromide to give [MoMe(η-C5H5)2(CH2Ph)] and [Mo(η-C5H5)2Ph(CH2Ph)] respectively. The dihvdride [W(η-C5H5)2H2] reacts with the Grignard reagents MgRX (RX = Mel, Pri, or PhBr) to give tungsten–magnesium compounds which appear to be generally similar to the molybdenum adducts.

New synthetic route to mono-η5-cyclopentadienylmolylbdenum compounds: X-ray crystal structure of [(η-C5H5)Mo(Ph2PCH2CH2PPh2)(η-C6H8)][PF6]·SO2

Abstract: The compound [(η5-C5H5)Mo(η6-C6H6)Cl]is shown to be a versatile precursor for carbonyl-free monocyclopentadienylmolybdenum derivatives and the new compounds [(η5-C5H5)Mo(dppe)L2][PF6](L2= dppe, (MeCN)2, C4H6, η4-C8H8, Ph2C2, or Me2C2), [(η5-C5H5)Mo(η8-C8H8)][PF6], [η5-C5H5)Mo(η6-C8H8)L][PF6](L = PPh3 or CO), and [(η5-C5H5)Mo(dppe)(C6H8)][PF6] are described (dppe = Ph2PCH2CH2PPh2); the crystal structure of the last compound has been determined.

Arene–molybdenum chemistry: reactions of di-µ-chloro-bis[(η-allyl)-(η-arene)molybdenum] with cyclic olefins

Abstract: The violet solutions formed form (AlEtCl2)2 and the compounds [{Mo(η-C3H5)(η-arene)Cl}2](arene = C6H6, C6H5Me, or C6H3Me3-1,3,5) react with norbornadiene (nbd), cyclo-octa-1,3,5,7-tetraene(cot), or cyclohepta-1,3,5-triene (cht), and the corresponding cations [Mo(η-C3H5)(η-arene)(η-olefin)]+ have been is olated from the hydrolysed reaction mixtures. Prolonged reaction with cht yields the cycloheptatrienly sandwich compounds [Mo(η-C7H7)(η-arene)][PF6]. The comound [Mo(η-C3H5)(η-C6H6)(cht)][PF6] undergoes deprotonation on an alumina column to the neutral compound [Mo(η-C3H5)(η-C6H6)(η3-C7H7)]. The violet solution reacts with cyclopentene and hydrolysis of the product in the presence of lithium chloride or alkaline sodium dithionite gives [Mo(η-C5H5)(η-C6H6)Cl] or paramagnetic [Mo(η-C5H5)(η-C6H6)] respectively; with cyclohexene the 17-electron cation [Mo(η-C6H6)2]+ is formed in high yield.