David W. A. Sharp

Redox reactions involving molybdenum, tungsten and uranium hexafluorides in acetonitrile

Abstract The redox properties of molybdenum, tungsten and uranium hexafluorides in acetonitrile at 298 K have been compared with other redox couples using cyclic voltammetry, and by carrying out appropriate redox reactions under carefully controlled conditions. The order of oxidizing ability established is UF 6 > MoF 6 > NO +1 > solvated Cu 2+ ⩾ WF 6 . The position of the solvated Tl 3+ cation probably lies between MoF 6 and Cu 2+ Reactions which occur in the Cu metal/solvated Cu n+ (n = 1 or 2)/WF 6 system are accounted for by redox and fluoride-ion-transfer equilibria.

Reactions de quelques cyclopentadienyl methanethiolato fer et ruthenium avec des acetylenes fluores. Mise en evidence d'une double insertion d'un carbonyle et d'un acetylene

[(η5-C5H5)(CO)2Fe(SCH3)] reacts with trifluoropropyne to give a number of products [(η5-C5H5)(CO)2Fe[CC(CF3)]], [(η5-C5H5)(CO)FeC(O)C(CF3)CHS(CH3)], [(η5-C5H5)(CO)FeC(CF3)CHS(CH3)Fe(CO)(η5-C5H5)S(CH3)], [(η5-C5H5)(CO)Fe[(CF3C2H)2SCH3]],[(η5-C5H5)(CO)2Fe[C(CF3)CHSCH3]], [(η5-C5H5)(CO)Fe[(CF3C2H)2S(CH3)]] and [(η5-C5H5)(CO)FeC(CF3)CHS(CH3)] and with hexafluorobut-2-yne to give [η5-C5H5)(CO)FeC(O)C(CF3)C(CF3)S(CH3)]], [(η5-C5H5)(CO)FeC(CF3)C(CF3)S(CH3)], [(η5-C5H5)Fe[η4-CF3C2CF3CF3C2HS(CH3)]] and [(η5-C5H5)(CO)Fe(CF3C2H)(CF3C2CF3)S(CH3)]. With the analogous ruthenium thiolate complex a compound [(η5-C5H5)(CO)RuC(O)C(CF3)C(CF3)S(CH3)] is obtained. Many of the products are heterocyclic compounds containing iron and sulphur. The acetylenic and carbonyl groups readily insert into FeSCH3 bonds and the resultant groups can undergo further insertion by acetylenes.

Reactivite d'alcynes fluores vis-a-vis de methylthiolates [(η5-C5H5)M(SMe)(CO)3] et d'hydrures [(η5-C5H5)MH(CO)3] de molybdene et de tungstene

Abstract The electron deficient acetylene, hexafluorobut-2-yne, reacts with molybdenum and tungsten methanethiolate derivatives (prepared in situ) to give vinyl and three-, five-, or six-membered heterocyclic derivatives: [Cp(OC)- MoC(O)C(CF 3 )C(CF 3 )C(O)S Me], [Cp(OC)2 MC(CF 3 )C(CF 3 )C(CF 3 )C(O)S Me], [CpW(CO)3C(CF3C(CF3)SMe], [CpW{η3- C(CF 3 )C(CF 3 )C(SMe)OC (O)}-(CO)2]. These reactions contrast with those of trifluoropropyne where no organometallic species are obtained. On heating or irradiation with CF3CCCF3 [CpMH(CO)3] gives known bridged species and in the presence of dimethyl disulphide the vinyl derivative [CpM(CO)3C(CF3)C(CF3)H]and an isomer of undetermined structure.

Molybdenum alkyl- and aryl-thiolates

Abstract The reaction between [(η 5 -C 5 H 5 )MoH(CO) 3 ] and disulphides gives dimeric or trimeric complexes depending upon the conditions. The syntheses of the novel trinuclear molybdenum carbonyl complex [{Mo(η 5 -C 5 H 5 )(SR)(μ-CO)(CO)} 3 ] (R = Me), and dinuclear compounds [Mo 2 (η 5 -C 5 H 5 )(μ-SR) 3 (CO) 4 ] (R = Me) and [Mo 2 (η 5 -C 5 H 5 ) 2 (SR) 2 (CO) 2 (μ-SR)(μ-Br)] (R = Me or Ph) are reported.

Niobium, Tantalum and molybdenum pentafluoride complexes with organic ligands

Abstract The following new transition metal pentafluoride complexes with organic ligands have been prepared: MF5L (M = Nb or Ta, L =; Me2SO, EtCN, or CH2ClCN) (nc), TaF5(2-Me-py) (nc), MoF5L (L = MeCN or CH2ClCN) (nc) and TaF5(4-Me-py)2 (nc). Their vibrational spectra and those of MF5NCMe (M = Nb or Ta) and MF5L2 (M = Nb or Ta, L = Me2SO or py) are discussed in terms of the previously proposed structures, monomeric MF5L and [MF4L4+] [MF6−].

Redox reactions involving rhenium and uranium hexafluorides, a convenient synthesis of β-uranium pentafluoride

Abstract Rhenium and uranium hexafluorides oxidise elemental iodine in iodine pentafluoride at ambient temperature to give the I 2 + cation. With UF 6 an additional reaction occurs to give β-uranium pentafluoride as one product, β-UF 5 is soluble in acetonitrile without disproportionation and is also formed from the reduction of UF 6 by MeCN. Copper, cadmium, and thallium metals are oxidised by ReF 6 in MeCN giving Cu I , Cd II , and Tl I hexafluororhenates(V) but the reactions are complicated by reaction between ReF 6 and the solvent.

Metal perfluoroalkane- and perfluoroarene-thiolates. Part V. The reactions of tricarbonyl(π-cyclopentadienyl)-molybdenum and -tungsten thiolates and acetylenes

The thiolates [(η5-C5H5)M(CO)3SRF](M = Mo or W; RF = CF3 or C6F5) react with acetylenes, RCCR (R = CF3, Me, or Ph) to give the formally electron-deficient π-acetylene complexes [(η5-C5H5)M(CO)(RC2R)SRF]. The bonding and isomerism in these complexes at low temperatures is discussed. On oxidation [(η-C5H5)MoO(CF3C2CF3)SC6F5] can be isolated. Trifluoropropyne reacts with the thiolates to give the acetylene complex [(η5-C5H5)Mo(CO)(CF3C2H)SC6F5] and cyclopentadienone complexes [(η5-C5H5)Mo(CO){(CF3C2H)2CO}SCF3] and [{(η5-C5H5)[(CF3C2H)2CO]SCF3}2].

Reactions of fluorinated alkynes with the tungsten Hydride [(η5-C5H5)(CO)3WH] II. Phosphine and phosphite substitution reactions and the x-ray structures of the η3-acryloyl complexes [(η5-C5H5)(CO)LWC(O)C(CF3)C(CF3)H], L = CO, P(OMe)3

Abstract Insertion of hexafluorobut-2-yne into the WH bond of the complex [(η5-C5H5)(CO)3WH] yields the η1-vinyl complex [η5-C5-C5H5)(CO)3WC(CF3)C(CF3)H] (I). Migration and insertion of CO into the metal-vinyl bond gives the η3-acryloyl complex [(η5-C5H5)(CO)2 WC(O)C(CF 3 ) C(CF3)H] (II) for which the crystal structure has been determined. Phosphites and phosphines (L = P(OMe)3, PPh3, PMe3, PMe2Ph, PPh2H) displace CO from II to give IIIa in which the η3-acryloyl structure is conserved and CO is adjacent to the acryloyl carbonyl group, as shown by an X-ray analysis of IIIa1, the product with P(OMe)3. Heating IIIa generates the η1-vinyl complexes [(η5-C5H5 )(CO)2 LWC(CF3)C(CF3)H] (IV) whereas prolonged photolysis of IIIa yields isomeric η3-acryloyl compounds (IIIb) in which the phosphorus donor ligands are now adjacent to the acryloyl carbonyl groups.

The preparation, NMR spectra, and structure of unsymmetrical ditertiary phosphine complexes of platinum(II)

The 1J(PtP) coupling constants in the complexes cis-PtCl2 (R2PCH2 - CH2 PPh2), where R = CF3, C6 F5, and the bond lengths in the complex with R = CF3 indicate that the metalligand bonding is strongly influenced by the substituents on phosphorus.

Metal complexes of novel sulphur- and phosphorus-containing heterocycles. Preparation and structure of tricarbonyl-η4-(1-pentafluorophenyl-2,3,4,5,-tetrakistrifluoromethylthiophen)manganese and π-Cyclopentadienyl(1-hydroxy-2,3,4,5,-tetrakistrifluoromethylphosphole 1-oxide)cobalt

Heterocyclic derivatives Mn(CO)3(C4F6)2SR and C5H5Co(C4F6)2PF3 are formed by reaction between hexafluorobut-2-yne and [Mn(CO)4SR]2, (R = CF3, C6F5), and (π-C5H5)Co(PF3)2; these derivatives contain non-planar heterocyclic rings with non-bonding metal heteroatom separations.