91513-98-3Relevant academic research and scientific papers
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).
Synthesis and single-crystal X-ray study of the mononuclear η2-benzyne (dehydrobenzene) nickel(0) complex Ni(η2-C6H4)((C6H 11)2PCH2CH2P(C6H 11)2). Insertion reactions with simple molecules and X-ray crystal structure of the ...
Bennett, Martin A.,Hambley, Trevor W.,Roberts, Nicholas K.,Robertson, Glen B.
, p. 1992 - 2000 (2008/10/08)
Full title: Synthesis and single-crystal X-ray study of the mononuclear η2-benzyne (dehydrobenzene) nickel(0) complex Ni(η2-C6H4)((C6H 11)2PCH2CH2P(C6H 11)2). Insertion reactions with simple molecules and X-ray crystal structure of the nickelaindan complex Ni(CH2CH2C6H4-o)((C 6H11)2PCH2CH2P(C 6H11)2). Sodium amalgam reduction of NiCl(C6H4Br-2)(Cy2PCH2CH 2PCy2)·0.5THF (6) (Cy = cyclohexyl, C6H11) gives a mononuclear nickel(0) complex, Ni(η2-C6H4)(Cy2PCH 2CH2PCy2) (3), which has been characterized by microanalysis, by mass, infrared, and NMR (1H, 13C, 31P) spectroscopy, and by single-crystal X-ray structural analysis. Crystals of 3 are orthorhombic, space group Pbca, with a = 16.068 (1) A?, b = 17.189 (1) A?, c = 22.358 (1) A?, and Z = 8. The structure was solved by heavy-atom methods and refined by least-squares methods to R = 0.035 and Rw = 0.055 for 4203 independent reflections. The molecule consists of a central nickel atom coordinated by a symmetric η2-benzyne ligand [Ni-C(1) = 1.870 (4) A?, Ni-C(2) = 1.868 (4) A?], the coordination geometry being close to trigonal planar. The coordinated C-C bond length of 1.332 (6) A? is significantly larger than those observed in alkyne complexes of zerovalent nickel and platinum. The remaining C-C bonds of the six-membered ring are almost equal in length (average 1.385 A?), consistent with a delocalized aromatic structure for the benzyne ligand. Complex 3 reacts with iodine and methyl iodide at room temperature to give, respectively, the 2-iodophenyl and o-tolyl complexes NiI(C6H4Y-2)(Cy2PCH2CH 2PCy2) (Y = I (7), Me (8)). Carbon dioxide, ethylene, and dimethyl acetylenedicarboxylate insert into the nickel-benzyne bond of 3 to give the nickelacycles Ni(C6H4COO)(Cy2PCH2CH 2PCy2) (10), Ni(CH2CH2C6H4-o)(Cy 2PCH2CH2PCy2) (11), and Ni(C(CO2Me)=C(CO2Me)C6H4-o)(Cy 2PCH2CH2PCy2) (12), respectively, whereas diphenylacetylene displaces benzyne to give Ni(PhC≡CPh)(Cy2PCH2CH2PCy2) (13). Crystals of 11 are monoclinic, space group P21/n, with a = 15.792 (6) A?, b = 17.471 (6) A?, c = 12.104 (4) A?, β = 104.09 (2)°, and Z = 4. The structure was solved and refined as for 3 to R = 0.070 and Rw = 0.071 for 2379 independent reflections. The nickel atom is coordinated in an approximately planar arrangement by the bidentate di(tertiary phosphine) and by two carbon atoms of a five-membered, half-chair-shaped chelate ring, the Ni-C(aryl) and Ni-C(alkyl) bond lengths being 1.951 (12) and 1.988 (12) A?, respectively.
NICKEL(0)-INDUZIERTE C-C-VERKNUEPFUNG ZWISCHEN KOHLENDIOXID UND ALKINEN SOWIE ALKENEN
Hoberg, H.,Schaefer, D.,Burkhart, G.,Krueger, C.,Romao, M. J.
, p. 203 - 224 (2007/10/02)
CO2 and alkynes or alkenes undergo a 1/1 coupling in the presence of (Lig)Ni0 complexes to give five-membered cyclic nickela complexes of types V and XVII.The influence of temperature and of the ligands upon the regioselectivity of the C-C coupling in the case of monosubstituted olefins is reported, and the significance of these ring systems in preparative chemistry is emphasized.Oxanickelacyclopentenones (V) react with alkynes to form oxanickelacycloheptadienones (XIII).The structure of one of the compounds of this class has been determined by X-ray crystallography.Special features of these novel compounds, which can be readily prepared from CO2, are discussed together with the probable reaction mechanisms.
