109799-61-3Relevant academic research and scientific papers
Binuclear transition-metal complexes of cyclophanoid cyclopentadienone and cyclopentadienyl ligands
Jutzi, Peter,Siemeling, Ulrich,Müller, Achim,B?gge, Hartmut
, p. 1744 - 1750 (1989)
The double-layered cyclophanoid cyclopentadienone 2,3,10,11-tetraphenyltricyclo[12.2.1.1 9,12]octadeca-1,3,9,11-tetraene-17,18-dione (7) is obtained by aldol condensation of cyclotetradecane-1,8-dione (8) with 2 equiv of benzil (9). 7 (= L) reacts with Ni(COD)2, Fe2(CO)9, and Cp*Co(C2H4)2 to give the binuclear cyclopentadienone complexes (COD)Ni-L-Ni(COD) (11a), (CO)3Fe-L-Fe(CO)3 (11b), and Cp*Co-L-CoCp* (11c). 11a reacts with tetrafluoroboric acid and trifluoromethanesulfonic acid to yield the respective (hydroxycyclopentadienyl)nickel complexes [(COD)Ni-LH2-Ni(COD)]2+·2BF4- (14a) and [(COD)Ni-LH2-Ni(COD)]2+·2CF3SO 3- (14b); likewise, (tetracyclone)Ni(COD) (13a) reacts with tetrafluoroboric acid to give the mononuclear hydroxycyclopentadienyl complex [(Ph4CpOH)Ni]+BF4- (14e); 11a and 11c react with triethyloxonium tetrafluoroborate to afford the binuclear ethoxycyclopentadienyl complexes [(COD)Ni-LEt2-Ni(COD)]2+·2BF4 - (14c) and [Cp*Co-LEt2-CoCp*]2+·2BF 4- (14d). The electrochemical properties of the binuclear (cyclopentadienone)cobalt complex 11c and the binuclear (ethoxycyclopentadienyl)nickel complex 14c are examined; both complexes show interacting redox sites. X-ray structural investigations on 11a show an anti conformation of the two quasi-planar cyclopentadienone rings, the distance between them being approximately 410 pm; each nickel atom is bonded η4 to its cyclopentadienone moiety, the Ni-Ni distance being 805 pm; the whole molecule is centrosymmetric (crystal system monoclinic; space group C2/c; a = 2433.1 (10) pm, b = 1425.1 (6) pm, c = 1850.0 (7) pm, β = 97.83 (3)° Z = 4).
ORGANIC CHEMISTRY OF SUBVALENT TRANSITION METAL COMPLEXES XI. OXIDATIVE ADDITIONS OF NICKEL(0) COMPLEXES TO CARBON-CARBON BONDS IN ALKYNES: NICKELIRENES AND NICKELOLES AS CATALYTIC CARRIERS IN THE OLIGOMERIZATION OF ALKYNES
Eisch, John J.,Galle, James E.,Aradi, Allen A.,Boleslawski, Marek P.
, p. 399 - 416 (2007/10/02)
The formation of 2,3,4,5-tetraphenylnickelole-bis(triphenylphosphine) (IIIa) and 2,3,4,5-tetraphenylnickelole-bis(1,2-diphenylphosphino)ethane (IIIb), either from (E,E)-1,2,3,4-tetraphenyl-1,3-butadien-1,4-ylidenedilithium (I) and the corresponding nickel(II) chloride-phosphine complexes (II) or from the reduction of η4-tetraphenylcyclobutadienenickel(II) bromide dimer (XII) in the presence of phosphines, proceeds in good yields.Nickelole IIIa displays physical and chemical properties consistent with its structure and is a catalyst for the trimerization of diphenylacetylene.Nickelole IIIb is a highly associated structure but in its chemical response to alkynes, HOAc, O2, Br2, NaAlEt2H2 and heat displays the properties of a nickelole, rather than a cyclobutadienenickel(0) complex.Attempts to generate IIIb photochemically from η4-1,5-cyclooctadiene(η4-tetraphenylcyclopentadienone)nickel and diphos failed, but it was shown that structural types, such as η4-tetraphenylcyclopentadienone(diphos)nickel (a model for the structure suggested by Hoberg and Richter for IIIb), are unstable.Oligomerizations of diphenylacetylene by bis(1,5-cyclooctadiene)nickel were retarded by conducting the reaction in THF or in the presence of diphos.This retardation permitted the interception of products (cis-stilbene and (E,E)-1,2,3,4-tetraphenyl-1,3-butadiene)diagnostic for the intermediacy of nickelirenes and nickeloles.Deuterium labeling verified the presence of carbo-nickel bonds.These trapping experiments, together with findings on the thermal behavior of nickeloles, are combined into a comprehensive view of the cyclotrimerization, cyclotetramerization and linear polymerization of alkynes by nickel(0).
