J.H. Holloway

Metal (II) hexafluoroarsenates: Preparation and vibrational spectroscopy of MF2·2AsF5 (M = Mg, Ca, Sr, Ba, Mn, Co, Ni, Cd, Hg, Pb) adducts [1]

Abstract Adducts of the type MF2·2AsF5 (M = Mg, Ca, Sr, Ba, Mn, Co, Ni, Cd, Hg, Pb) have been prepared by reaction of the metal difluorides with AsF5 in anhydrous HF at room temperature. Vibrational spectroscopic studies and X-ray powder diffraction patterns of the solids indicate that adducts of three distinct structural types occur. The differences in structure have been rationalized in terms of the fluoride ion donor abilities of the metal difluorides.

Metal (II) hexafluoroarsenates: preparations and some properties of 2MF2·3AsF5 (M = Fe, Cu, Zn), MF2·AsF5 (M = Cr, Fe, Cu, Zn, Ag, Sn) and 2MF2·AsF5 (M = Ag, Sn)

Abstract Reactions of iron, copper and zinc difluorides with AsF5 in anhydrous HF at room temperature have been shown to result in the formation of adducts of the type 2MF2·3AsF5. The intermediate thermal decomposition products of these compounds have the composition MF2·AsF5. The products of the reactions of chromium, silver and tin difluorides with AsF5 in anhydrous HF can be formulated as adducts of the type MF2·AsF5. The thermal decompositions of the silver and tin compounds have been shown to proceed via intermediates of the type, 2MF2·AsF5. The compositions of the adducts have been established by gravimetry, chemical analysis and X-ray powder diffraction methods and indications of the chemical nature of some of the species have been obtained from vibrational spectroscopic and magnetic susceptibility measurements.

Intermediates and action effects in the activation of carbon-fluorine bonds by eta(5)-pentamethylcyclopentadienylrhodium halide complexes; crystal structure of [{eta(5)-C5Me3[CH2C6F4P(C6F5)CH2](2)-1,3}RhBr](+)center dot Br-

The reaction between [(η 5 -C 5 Me 5 )RhBr(μ-Br)] 2 and the diphosphine, (C 6 F 5 ) 2 PCH 2 CH 2 P(C 6 F 5 ) 2 (dfppe), in benzene proceeded via the intermediate cation [(η 5 -C 5 Me 5 )RhBr(dfppe)] + , which underwent CF and CH bond activation and CC bond formation to give sequentially [{η 5 -C 5 Me 4 CH 2 C 6 F 4 P(C 6 F 5 )CH 2 CH 2 P(C 6 F 5 ) 2 }RhBr] + and then [{η 5 -C 5 Me 3 [CH 2 C 6 F 4 P(C 6 F 5 )CH 2 ] 2 -1,3}RhBr] + , as evidenced by mass spectrometry and NMR spectroscopy. The bromide salt of the final product ( 4c ) has been structurally characterized by X-ray diffraction. Compound 4c crystallizes in the triclinic space group P with a =10.616(1), b =13.904(2), c =14.911(1) A, α =66.86(1), β =86.38(1), γ =84.72(1)° and Z =2. Refinement gave final R 1 and wR 2 [ I =2 σ ( I )] values of 0.0581 and 0.1641, respectively, for 6837 unique reflections. In contrast to the BF 4 − salt, the Cl − and BPh 4 − salts of cation [(η 5 -C 5 Me 5 )RhCl(dfppe)] + undergo reaction upon thermolysis in benzene to give the cation [{η 5 -C 5 Me 3 [CH 2 C 6 F 4 P(C 6 F 5 )CH 2 ] 2 -1,3}RhCl] + .

Synthesis and structure of the coordinatively unsaturated σ-aryl rhodium(III) complex Rh(C6H5)Cl2(PPh3)2

Abstract The reaction between RhHCl2(PPh3)3 and Hg(C6H5)2 yields the five-coordinate, 16-electron rhodium(III) complex Rh(C6H5)Cl2(PPh3)2. The molecular structure was determined by single-crystal X-ray diffraction (triclinic, P 1 , a = 9.532(28), b = 9.523(24), c = 21.800(19) A, α = 112.9(1), β = 85.9(1), γ = 94.0(1)°, Z = 2). Rh(C6H5)Cl2(PPh3)2 exhibits square pyramidal geometry with close approach of two of the ortho hydrogen atoms of the triphenylphosphine ligands to the rhodium atom.

Metal k-edge exafs (extended x-ray absorption fine structure) studies of CrO2F2 and MnO3F at 1OK

Abstract I.R. spectroscopy shows that the title compounds are monomeric in the solid state. Metal K-Edge EXAFS data have been obtained from the solids at 10K, and refined to give d(Cr-O) = 1.55A, d(Cr-F) = 1.71A, d(Mn-O) = 1.59A, and d(Mn-F) = 1.72A.

Isolation of oxides and hydroxides derived from fluoro[60]fullerenes

Oxygen-containing fluoro[60]fullerenes have been isolated from HPLC purification of C60F36 (obtained by fluorination of [60]fullerene with MnF3) and partly characterised by mass, IR, and 19F NMR spectroscopy. They include C60F35OH (1402 amu), arising from nucleophilic substitution of F in C60F36 by OH, and C60F34O (1382 amu) due to subsequent elimination of HF. Both C60F33O·OH (1380 amu) and C60F32O2 (1360 amu), obtained by repetition of these steps, are also formed. The EI mass spectra show the presence of C59F34 (1354 amu), C59F32O (1332 amu) and C58F32 (1304 amu), due to CO loss from the oxide precursors. The corresponding hydroxides and epoxides, derived from the presence of traces of C60F34/38/40, are also observed. The slow conversion of C60F36 to C60F34O in CDCl3, arising from reaction with traces of water in the solvent, was monitored by 19F NMR spectroscopy. On a Cosmosil Buckyprep column, compounds containing more fluorines elute faster than those with correspondingly less, oxides elute slower than the precursor fluorides, and hydroxides elute faster than the corresponding fluorides. The oxides are more soluble in hexane than C60F36, which aids preliminary purification. Some fluorofullerene epoxides show strong IR bands in the carbonyl region but this probably does not reflect alternative ketonic structures (derivable in principle by six-centre eliminations from fluorohydroxyfullerenes) since they would be cage-opened.

Isolation, characterization, and chemical reactions of fullerenes

Extension of the chromatographic work that led to the first isolation of pure Go and 00 has resulted h the isolation and characterisation of c76 and three isomers of c78. Comparison with other work indicates the composition ratio of c78 to be dependent upon the method of chon production. Halogenation of Go gives derivatives that have been charactwised either by NMR, or by single aystal X-ray diffraction. The halogeno derivatives readily undergo nucleophilic substitution, which provides a route to the formation of many fullerene compounds, but precludes use of the fluoro derivatives as lubricants. In the presence of Friedel-Crafts catalysts, the bromo derivatives substitute into aromatics to give aryl derivatives of Go, especially those containing either 6, 8, 12, or 16 aryl groups per C6o molecule. Possible structures for these are compared with those for addition products which have only low eclipsing steric interactions.

Preparation of high-oxidation-state platinum group metal fluorides in flow systems. Synthesis of the metal hexafluorides, MF6 (M Ru, Rh, Os, Ir, Pt), ruthenium pentafluoride tetramer, (RuF5)4, and the novel trimer, (RuF5)3

Abstract The fluorination of platinum metals under anhydrous conditions in a flow system yields the volatile metal hexafluorides (M  Ru, Rh, Os, Ir, Pt) in high yield. The flow fluorination of ruthenium also affords green {RuF5}4 and bright red {RuF5}3. In the case of palladium, no volatile products were observed, the only product of the reaction being PdII[PdIVF6].

The transition-metal fluorides and oxide fluorides as selective fluorinating agents for hydrohalogenoalkanes

Abstract The reactions of the transition-metal fluorides, ReF 7 , ReF 6 , OsF 6 , IrF 6 , UF 6 , RuF 5 , VF 5 and CrF 5 , and the transition-metal oxide fluorides, VOF 3 , MoOF 4 , WOF 4 , ReOF 4 , ReOF 5 , OsO 3 F 2 , OsO 2 F 3 , OsOF 5 and OsOF 4 , with a variety of hydrohalogenoalkanes have been studied. Some of the transition-metal compounds exhibit remarkable specificity in their reactions. For example, in the reaction of CH 2 Cl 2 with ReF 6 , 85% of available fluorine is used to yield CH 2 ClF whereas, with UF 6 , all of the available fluorine is utilised to give CHCl 2 F; like ReF 6 , ReOF 4 produces efficient halogen exchange, some 98% of the available fluorine yielding CH 2 ClF. The selectivity and reactivity will be discussed in terms of the oxidation state and coordination geometry of the transition metal fluorinating agents.

Enthalpies of polymerisation of SbF5, NbF5 and TaF5

Abstract The enthalpies of polymerisation of SbF 5(g) , NbF 5(g) and TaF 5(g) have been estimated from molecular weight data to be −18.5, −25.9 and −25.7 kJ mol −1 respectively assuming mixtures of monomer and tetramer. Estimates of the entropy changes have also been made.