Buckminsterfullerene, c60, was prepared in gram quantities by contact-arc vaporization of a graphite rod in a 100-Torr atinospherc of helium. followed by extraction of the resultant graphitic soot with toluene. The dominance of C , in this extract was verified by mass, FTIR. and NMR spectroscopy. The molecule was successfully hydrogenated to C6,H,, via a Birch reduction and dehydrogenated back to bare c 6 0 by treatment with DDQ reagent. Cyclic voltammetry of C60 in methylene chloride rcvcaled highly reversible formation of at least two stable anionic forms of c 6 0 in solution. A broad new class of thcsc fulleride and fulleronium ions is anticipated, both with the internal cavity empty and with any one of a large number of elcmcnts inside, thus providing a means of fine-tuning the chemical, optical, and redox properties.

No abstract

No abstract

No abstract

Template condensation of 2,2‘-diaminobiphenyl, 1,4-bis(2-formylphenyl)-1,4-dithiabutane, and copper(II) tetrafluoroborate yields the new macrocyclic compound [CuI(bite)](BF4) (bite = biphenyldiimino dithioether). [CuI(bite)]BF4 crystallizes in the orthorhombic space group P212121 with a = 14.379(3) Å, b = 21.370(3) Å, c = 8.046(2) Å, V = 2534.7(7) Å3, Z = 4, R 1 = 0.045, and R 2 = 0.048. The X-ray structure of [CuI(bite)](BF4) reveals distorted tetrahedral N2S2 coordination about copper, with one unusually short Cu−S(thioether) bond of 2.194(2) Å. Oxidation of [CuI(bite)](BF4) with nitrosyl tetrafluoroborate gives [CuII(bite)](BF4)2. [CuII(bite)](BF4)2 crystallizes in the tetragonal space group I41/a with a = 11.640(2) Å, c = 39.527(3) Å, V = 5355.6(7) Å3, Z = 8, R 1 = 0.061, and R 2 = 0.063. X-ray crystallography of [CuII(bite)](BF4)2 reveals an approximately square planar CuN2S2 structure with two distant axial BF4 - anions (Cu−F 2.546(4) Å) completing a “pseudo-octahedral” coordination sphere. Comparative EXAFS studies of solid samples and acetonitrile solutions of [CuI(bite)](BF4) and [CuII(bite)](BF4)2 demonstrate that the primary coordination environments of both species are the same in solution as in the solid. Copper(I/II) electron self-exchange kinetics measured by 1H NMR line broadening of [CuI(bite)]+ in the presence of [CuII(bite)]2+ reveal an overall first-order process with a rate constant of 21.7(1.9) s-1 at 295 K in acetone-d 6. This result represents the first example of fully-gated electron transfer by small-molecule copper(I). The gating process likely involves inversion at sulfur and the tetrahedral → square planar structural change coincident with electron transfer. Variable-temperature 1H NMR coalescence temperatures for methylene ligand protons of [CuI(bite)](BF4) (287 K) demonstrate possible correlation of fast electron transfer with high ligand mobility for this and related small-molecule copper(I/II) couples. Comparison with other small-molecule copper systems also reveals that fast electron transfer is not always observed with coordination-number-invariance and conserved geometry during redox turnover, contrary to popular interpretations of the entatic state hypothesis for blue-copper protein active sites.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

One component of on-going investigations of -diketonates and related bidentate anions as ligands for chemical vapor deposition of certain metals 1 requires the preparation of various -dithione compounds. 2 Previous reports for transformation of ketone to thione functionality by treatment with P 4 S 10 indicated one potential route to the desired compositions. 3 Unexpected products were observed from the reactions between selected -diketone compounds and P 4 S 10 (Scheme 1) and are reported at this time.The solid state structures of compounds 1 and 2 (Figures 1 and 2, respectively), as determined by single-crystal X-ray diffraction, reveal phosphorus pentasulfide structural units often found in inorganic compounds but rarely found in organic compounds. In these new molecules, the P 2 S 5 group consists of two phosphorus atoms attached at C1, one sulfur atom (S5) bridging P1 to P2, one sulfur atom (S4) bridging P1 to C3, and one sulfur atom (S3) bridging P2 to C3. Terminal sulfur atoms (S1 and S2) are attached to each phosphorus atom, completing the P 2 S 5 fragment, which bears a strong resemblance to onehalf of the original P 4 S 10 skeleton. 4 The carbon backbone is unchanged from that of the starting -diketone. The P 2 S 5 fragments observed for 1 and 2 are isostructural, each retaining both the relic hydrocarbon component of the organic reactant and the pseudo-adamantoid framework of the inorganic reactant.A previous example of a structurally characterized organic compound containing the P 2 S 5 moiety was reported by Fluck et al. 5 (3) and is illustrated in Figure 3. The bicyclic compound 3 substantially differs from 1 and 2 in its regiochemistry. A crystal structure of another compound containing phosphorus in a similar environment has been reported by Roesky et al., 4 ( Figure 3). 6 Compound 5, reported by Grossmann et al., 7 was made by reacting 1,2-diphosphinylbenzene with elemental sulfur.The chair angles between the planes P2-S5-P1, P1-P2-S3-S4, and S3-S4-C3 are 69.4 and 74.3°in 1 and 70.0 and 76.1°in 2, compared to 73.8°in S 6 , 8 56.5°in P 4 S 10 , 9 and 72.7 and 65.4°in 5. 8 The dihedral angle between C1-C3-S5 and P1-P2-S3-S4 in 1 is 90.0°and in 2 is 89.2°. In 2 the C1-C3-S5 plane is 68.3°relative to the C3-bound phenyl ring and 1.7°relative to the C1 bound ring. The latter phenyl ring thus appears to be kept in registry with C1-C3-S5 by the influence of S1 and S2. The observed interatomic distances H15---S2 The IUPAC designation for compound 1 is 1,8-bis(tert-butyl)-2,4,6-trithia-3,5-di(thiaphosphoryl)tricyclo[2,2,1,1 3,5 ]octane.Retuert, P. J.; Fluck, E.; Riffel, H.; Hess, H. Z. Anorg Allg Chem. 1985, 521, 153-160. (6) Roesky, H. W.; Noltemeyer, M.; Sheldrick, G. M. Z. Naturforsch. 1986, 41B, 803-807. (7) Grossmann, G.; Beckmann, H.; Rademacher, O.; Kruger, K.; Ohms, G. in Table 1 average and standard deviations were calculated from these values; dihedral angles reported here were calculated from atomic coordinates in ref 10.Figure 1. ORTEP representation of the solid state single-crystal X-ray dif...

No abstract