Selective cis-Isomerization of 1-Pentene Catalyzed by Ni(I)-Triphenylphosphine Complexes

Abstract

Selective cis-isomerization of 1-pentene was carried out by NiX(PPh3)3 (X=halogen and pseudohalogen). First-order plots were obtained except for the iodo-complex. The addition of tin(II) chloride increased both activities and ratios of cis-2-pentene to the trans-isomer. Protic solvents accelerated the isomerization. Isotopic exchange between C2D4 and C2H4 or 1-pentene reveals that a metal hydride addition-elimination mechanism is operative.

Reactivity of [Ge9{Si(SiMe3)3}3]− Towards Transition‐Metal M2+ Cations: Coordination and Redox Chemistry

“…The arrangement is symmetric, which might be due to the d 5 configuration of the transition-metala tom. [18] The Fe + and Co + compounds [Fe(dppe) 2 ][Ge 9 Hyp 3 ]( 3)a nd [Co(dppe) 2 ][Ge 9 Hyp 3 ]( 4)a re isostructural and show an unusual arrangement of the [M(dppe) 2 ] + cations (M = Fe, Co) and [Ge 9 Hyp 3 ] À anionsi nt he solid state (see the Supporting Informationf or furtheri nformation). [14] The presence of unpaired electrons within 2 was provenb y EPR measurements, which give only one signal without hyperfine splitting with a g value of 1.995 ( Figure S7, Supporting Information),which is in line with other Mn 2 + complexes.…”

“…[1] In addition to naked Zintl anionslike E 9 4À ,the metalloid germanium cluster [Ge 9 Hyp 3 ] À 1 (Hyp = Si(SiMe 3 ) 3 ) [2] is becoming am ajor focus of actual research, not only due to its good solubility in different solvents, but also due to its high yield synthesis from the Zintl anion Ge 9 4À as introduced by Sevov et al [3] Compound 1 exhibits an incompletely shielded clusterc ore, giving accesst oavariety of furtheri nvestigations.T hereby build-up reactions were possible to give clusters of the composition [Hyp 3 Ge 9 -M-Ge 9 Hyp 3 ] x (x = À1: M = Cu, Ag, Au; x = 0: M= Zn, Cd, Hg) [4] and recently ac ompound exhibiting al inear chain build-up of two coppera toms and two Ge 9 Hyp 3 units: [Ge 9 Hyp 3 -Cu-Ge 9 Hyp 3 -Cu-PPh 3 ]w as synthesized,s howing the potentialof1 for the synthesis of novel materials. [6,7] The addition of af ourth ligand to 1 gives neutralc ompounds of the composition R-(Ge 9 Hyp 3 )( R= SnPh 3 ,E t) [8,9] and recently we could show that 1 can be coupled, by means of oxidation, to give the largest metalloid Group 14 cluster Ge 18 Hyp 6, in which the germani-um atoms are arranged in au nique way, giving insighti nto the formation processo ft he new solid-state structure of ger-maniumG e(cF136) [10] on an atomics cale. [6,7] The addition of af ourth ligand to 1 gives neutralc ompounds of the composition R-(Ge 9 Hyp 3 )( R= SnPh 3 ,E t) [8,9] and recently we could show that 1 can be coupled, by means of oxidation, to give the largest metalloid Group 14 cluster Ge 18 Hyp 6, in which the germani-um atoms are arranged in au nique way, giving insighti nto the formation processo ft he new solid-state structure of ger-maniumG e(cF136) [10] on an atomics cale.…”

Light-promoted catalytic hydrogenation of olefins with nickel complexes: the formation of nickel hydrides from the reaction of Ni(I) complexes with hydrogen

“…[3] by analogy with the commonly accepted (4, 5 ) intramolecular addition of the Ni-H bond across a coordinated olefinic bond and hydrogenolysis to regenerate Ni-H complex 10. Elimination of a Ni-H moiety in Ni-alkyl complexes, such as 11, is apparently facile at ambient temperature or even lower (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20): such processes are the source of Ni-H catalysed isomerization of olefins (9)(10)(11)(12). The hydrogenolysis of 11 requires a vacant coordination site to accommodate oxidative addition of hvdrogen followed by reductive elimination to give products and the regeneration of 10.…”

Nickel Catalyzed Oligomerization of Alkenes and Related Reactions

“…The active species in this case is suggested to have the composition [NiSnCl 2 X(PPh 3 )3] and the selectivity to be associated with the bulk of the SnCl 2 X group. 190 Vinylcyclo-alkenes and -alkanes are isomerized to the corresponding ethylidene derivatives (equations 15 and 16),U6,64,i04,i62 wm *le the most convenient synthesis of 1,3-and 1,4-cyclooctadiene involves the isomerization of 1,5-cyclooctadiene in the presence of the ternary catalyst Ni(acac) 2 -Al 2 Cl 3 Et3-PMe3; the reaction occurs in a stepwise manner and the 1,4-isomer can be isolated in ca. 40% yield if it is terminated before completion.…”