19224-77-2Relevant academic research and scientific papers
Insertion reactions of benzyne-nickel(0) complexes with acetylenes
Bennett, Martin A.,Wenger, Eric
, p. 1267 - 1277 (2008/10/09)
Complexes of nickel(0) containing η2-4,5-difluorobenzyne, Ni((1,2-η)-4,5-F2C6H2)(PEt 3)2 (10) and Ni((1,2-η)-4,5-F2C6H2)(dcpe) (11; dcpe = 1,2-bis(dicyclohexylphosphino)ethane, Cy2PCH2-CH2PCy2) have been synthesized by alkali-metal reduction of the appropriate (2-halogenoaryl)nickel(II) halides. Spectroscopic measurements (13C NMR, FAB-MS) indicate that 10, 11, and the parent benzyne complex Ni((1,2-η)-C6H4)(PEt3)2 (2) are monomeric, analogous to the structurally characterized species Ni((1,2-η)-C6H4)(Cy2PCH2CH 2PCy2). Complexes 2 and 10 undergo rapid intermolecular exchange with PEt3 at room temperature and react with disubstituted acetylenes by double insertion into the metal-benzyne bond to form 1,2,3,4-tetrasubstituted naphthalenes. With electrophilic acetylenes (MeO2CC2CO2Me, MeC2-CO2Me, HC2CO2Me, and CF3C2CF3) an aromatic cyclotrimer is also formed; exceptionally, hexafluorobut-2-yne also gives with 10 a phenanthrene derived from two benzyne units and the acetylene. The unsymmetrical acetylenes tert-butylacetylene and methyl 2-butynoate give rise to good regioselectivity in the resulting naphthalenes, the favored isomers being very dependent on the steric and electronic influence of the substituents. The dcpe complexes react similarly but more slowly with acetylenes, and with MeO2CC2CO2Me the monoinsertion complexes Ni{C(CO2Me)=C(CO2Me)C6H2R 2-o}(dcpe) (R = H, F) can be observed.
Influence of the amino substituents of potentially bis ortho chelating aryl ligands (2,6-{R1R2NCH2}2C6H 3)- on the synthesis and properties of their organonickel(II) complexes
Van Beek, Johannus A. M.,Van Koten, Gerard,Ramp, Maarten J.,Coenjaarts, Norbert C.,Grove, David M.,Goubitz, Kees,Zoutberg, Martin C.,Stam, Casper H.,Smeets, Wilberth J. J.,Spek, Anthony L.
, p. 3059 - 3068 (2008/10/08)
Two series of square-planar organometallic Ni(II) complexes that contain various monoanionic, potentially terdentate ligands (2,6-{R1R2NCH2}2C6H 3)- (=R1R2NCN′) have been synthesized. In the first series [NiX(R1R2NCN′)], i.e., [NiBr(Me2NCN′)], [NiX(Et2NCN′)] (X = Br, I), [NiBr(i-Pr2NCN′)], [NiX((i-Pr)MeNCN′)] (X = Br, I), and [NiBr((t-Bu)MeNCN′)], this ligand is terdentate bonded to the Ni(II) center via C(ipso) and the two N donor atoms. In the second series [NiX(R1R2NCN′)(PR3)2], i.e., [NiBr((t-Bu)MeNCN′)(PR3)2] (R = Me, Et) and [NiX((Ph)MeNCN′)(PR3)2] (X = Br, R = Me, Et, Bu; X = Cl, I, R = Et), the Nt(II) center is bonded to a halide anion, to two phosphorus ligands, and to only C(ipso) of the R1R2NCN′ ligand. From two Ni(II) complexes [NiBr(Et2NCN′)] and [NiBr((t-Pr)MeNCN′)] were synthesized the corresponding ionic complexes [Ni(R1R2NCN′)(OH2)]Otf (Otf = CF3SO3), by reaction with 1 equiv of AgOtf, and the organonickel(III) species [NiBr2(R1R2NCN′)], by reaction with 0.5 equiv of Br2. The molecular structures of three complexes have been determined by X-ray crystallographic methods. [NiBr(C6H3{CH2N(i-Pr)Me}2-2,6)] (4b): C16H27N2NiBr, monoclinic, space group P21/n, with unit cell dimensions a = 11.632 (6) ?, b = 14.259 (7) ?, c = 10.636 (2) ?, β = 99.12 (4)°, and Z = 4. [NiBr(C6H3{CH2N(t-Bu)Me}2-2,6)] (5): C18H31N2NiBr, monoclinic, space group P21/n, with unit cell dimensions a = 14.148 (6) ?, b = 13.044 (2) ?, c = 11.149 (3) ?, β = 112.04 (2)°, and Z = 4. [NiBr(C6H3{CH2N(Ph)Me} 2-2,6)(PEt3)2]·0.5Et2O (8b): C34H53N2P2NiBr·0.5C 4H10O, monoclinic, space group P21/c, with unit cell dimensions a = 20.044 (2) ?, b = 9.8127 (7) ?, c = 20.857 (1) ?, β = 110.519 (5)°, and Z = 4. The crystal structures were solved either by direct methods (4b, 5) or Patterson methods (8b). Anisotropic least-squares refinement converged at R = 0.059 (1371 observed reflections) for 4b, 0.069 (1318 observed reflections) for 5 and 0.055 (3164 observed reflections) for 8b. The ligand strength of the various amino groups toward the Ni(II) center decreases in the order Me2N > Et2N > (i-Pr)MeN > (t-Bu)MeN > (Ph)MeN. Resonance Raman spectroscopic data indicate that in solution the complexes [NiI(Et2NCN′)] and [NiI((i-Pr)MeNCN′)] interact with added I2.
Reactions of Dialkylnickel(II) Complexes NiR2L2 with Alkyl (or Aryl) Halides, R'COY (Y=Cl, Br, OPh, OCOPh), and CS2
Yamamoto, Takakazu,Kohara, Teiji,Osakada, Kohtaro,Yamamoto, Akio
, p. 2147 - 2153 (2007/10/02)
Reactions of Ni(CH3)2(bpy) (1), Ni(C2H5)2(bpy) (2) (bpy=2,2'-bipyridine), trans-Ni(CH3)2(triethylphosphine)2 (3), Ni(CH3)2(1,2-bis(diphenylphosphino)ethane) (4), and Ni(CH3)2(1,3-bis(diphenylphosphino)propane) (5) with alkyl or aryl halides, R'COY (Y=Cl, Br, OC6H5, OCOC6H5), and CS2 have been investigated.The reactions of NiR2L2 with alkyl or aryl halides are classified into three types of reactions by their reaction products: Type A: NiR2L2 + R'X ->NiX(R')L2 + R-R, Type B: NiR2L2 + R'X -> alkane (RH) + olefin (R'(-H)), and Type C: NiR2L2 + R'X -> NiR(X)L2 + R-R'.Complexes 1 and 2 undergo mainly Type A reaction.Complex 3 gives Type A reaction product on treatment with C6H5Br, but it gives Type B reaction product on treatment with C2H5Br.On the other hand, 4 undergoes Type C reaction on interaction with C6H5Cl.The reactions with R'COY (Y=Cl, Br, OPh, OCOPh) are classiffed into two types of reactions by their reaction products: Type D: NiR2L2 + R'COY -> NiY(R)L2 + RCOR' and Type E: NiR2L2 + R'COY -> NiY(R')L2 + RCOR.Complexes 1-3 undergo mainly Type D reaction, whereas complexes 4 and 5 mainly Type E reaction.The diffrence in the reaction route is discussed on the basis of presence or absence of vacant coordination site for attack by R'COY.The reaction of 4 with CS2 affords Ni(CS2)(1,2-bis(diphenylphoshino)ethane) with evolution of a reductive elimination product, ethane, whereas the reaction of 3 with CS2 gives a 1:1 adduct of 3 and CS2.
