A. Miyashita

The metallacyclopentane–olefin interchange reaction

Tris(triphenylphosphine)tetramethylenenickel(II) and biscyclopentadienyltetramethylenetitanium, prepared from the reaction of a 1,4-dilithiobutane and the transition metal dihalides react with olefins to produce substituted metallacyclopentanes; the stereochemistry and substitution pattern of the metallocycles formed from propene, octa-1,7-diene, and norbornadiene has been determined.

Chemical synthesis with metal atoms: the reaction of chromium and nickel atoms with styrene

The preparation of C8H8Cr(CO)3 (or C8H8Cr(PF3)3) and polystyrenechromium tricarbonyl (or polystyrenechromium tris(trifluorophosphine) from chromium atoms, styrene and carbon monoxide (or trifluorophosphine) is described; nickel atoms and styrene produce tristyrenenickel, which reacts with α,α′-bipyridyl to yield bipyridylstyrenenickel.

Chemical synthesis with metal Atoms. Cyclodimerization of norbornadiene via nickela-cyclopentane intermediates.

Abstract The catalytic cyclodimerization of norbornadiene by reaction with nickel atoms has been re-investigated. Nickela-cyclopentane derivatives are formed in the presence of α,α′-dipyridyl, α,α′-dipyridyl- exo-trans-endo -3-nickela-pentacyclo[9.2.1.1 5,8 0 2,10 .0 4,9 ]-pentadeca-6,12-diene being the major component. By contrast, the catalytic dimerization leads predominantly to the exo-trans-exo isomer of pentacyclo[8.2.1.1 4,7 .0 2,9 .0 3,8 ] tetradeca-5,11-diene. A norbornadiene cyclotrimer of exo-trans-exo-trans-exo structure is subsequently formed.

Chemical synthesis with metal atoms: The reaction of 1,4- and 1,3-cyclohexadiene with chromium atoms and trifluorophosphine

Abstract The reaction of 1,3-cyclohexadiene, chromium atoms, and PF3 yields bis(tetrahapto-cyclohexadiene)bis(trifluorophosphine)chromium (I). The reaction of the 1,4-cyclohexadiene, chromium atoms and PF3 initially yields pentahapto-cyclohexadienylhydridotris(trifluorophosphine)chromium(II), which rearranges to I in the presence of silica gel.

Mechanism of the fluxional behaviour in (1–5-η-cycloheptadienyl)-(1–5-η-cycloheptatrienyl)iron

Evidence for a 1,2-shift mechanism of the 1–5-η-cycloheptatrienyl moiety with respect to the central iron atom of the title compound is presented together with absolute assignments of the 13C n.m.r. chemical shifts of the C7H7 ring. A low-temperature rocking motion of both rings can be frozen out at –70 °C.