172294-42-7Relevant articles and documents
Synthesis and reactions of nickel(0) η2-cyclohexyne complexes and X-ray crystal structure of Ni(η2-C6H8)(C6H 11)2PCH2CH2P(C6H 11)2
Bennett, Martin A.,Johnson, Julian A.,Willis, Anthony C.
, p. 68 - 74 (2008/10/08)
Reduction of 1,2-dibromocyclohexene with 1% sodium amalgam in the presence of Ni(η2-C2H4)L2 gives cyclohexyne nickel(O) complexes Ni(η2-C6H8)L2 [L2 = 2PPh3 (1), dcpe (2), 2PEt3 (3); dcpe = 1,2-bis(dicyclohexylphosphino)ethane, Cy2PCH2CH2PCy2], which are structurally similar to, but less stable than, the corresponding platinum(O) compounds. The crystal structure of 2 has been determined. The molecule contains a nickel atom bound to η2-cyclohexyne [Ni-C(1) = 1.875(4) A?, Ni-C(2) = 1.867(4) A?] and to dcpe [Ni-P(1) = 2.139-(1) A?, Ni-P(2) = 2.138(1) A?]. The geometry is close to trigonal planar if the midpoint of the coordinated triple bond is regarded as occupying one coordination site, and the C=C distance [1.272(5) A?] is slightly less than that in Pt(η2-C6H8)(PPh3)2 [1.297(8) A?]. Complex 2 reacts with methyl iodide and with CO2 to give insertion products containing nickel(II), NiI(2-MeC6H8)(dcpe) (7) and Ni{C6H8C(O)O}(dcpe)(9), respectively. Dimethyl acetylenedicarboxylate inserts into the Ni-C σ-bond of 9 to give a seven-membered nickelacycle Ni{C(CO2-Me)=C(CO2Me)C6H 8C(O)C-(dcpe) (10).