• Title, Summary, Keyword: pincer complex

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Synthesis of a Platinum-Pincer Complex and Application to Catalytic Silylcyanation (백금 핀서 화합물의 합성 및 Silylcyanation 촉매반응에 대한 응용)

  • Kim, Yun Tae;Yoon, Myeong Sik
    • Applied Chemistry for Engineering
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    • v.27 no.4
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    • pp.366-370
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    • 2016
  • A platinum(II) pincer complex composed of two six-membered fused metallacycles was directly synthesized using 1,3-bis(2-pyridyloxy)benzene and $K_2PtCl_4$. The structure of the complex was elucidated via NMR and X-ray crystallography analysis. The stable complex was formed due to the six-membered fused cycle structure around the Pt(II) center which reduced the bond angle strain. The complex was applied to the silylcyanation reaction of aldehydes and imines and showed an efficient catalytic activity with 99% yield.

Molecular Structure of PCP Pincer Complexes: Poisoning Catalyst on the Dehydrogenation of Alkanes (알칸의 탈수소화반응에서의 촉매독 화합물의 분자구조)

  • Lee Ji Hyun;Chun Sang Jin;Kwon Ki Hyeok;Lee Do Weon
    • Korean Journal of Crystallography
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    • v.16 no.1
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    • pp.43-53
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    • 2005
  • The dihydrido P-C-P pincer complex, $IrH_2{C_6H_3-2,6-(CH_2PBu_2^t)_2}$ (1), was successfully prepared from the reaction of the hydrochloride complex, $IrClH (C_6H_3-2,6-(CH_2PBu_2^t)_2}$, and super acid $(LiBEt_3H)$ under 1 atm of hydrogen in pentane solution at room temperature and followed by Heating at $130^{\circ}C$ in vacuo. Jensen recently found that the dihydrido P-C-P pincer complex 1 is a highly active homogeneous catalyst for the transfer dehydrogenation of alkanes with unusual longterm stability at temperatures as high as $200^{\circ}C$. The treatment of dihydrido complex 1 with nitrogen, water, carbon dioxide, and carbon monoxide in presence of tert-butylethylene (the) at room temperature in an appropriate solution gave the dinitrogen complex, $[Ir{C-6H_3-2,6-(CH_2PBu_2^t)_2}]_2({\mu}-N_2)$ (2), the hydrido hydroxyl complex, $IrH(OH){C_6H_3-2,6-(CH_2PBu_2^t)_2}$ (3), the carbon dioxide complex, $Ir({\eta}^2-CO_2) {C_6H_3-2,6-(CH_2PBu_2^t)_2}$ (including the bicarbonate complex, $IrH({\kappa}^2-O_2COH){C_6H_3-2,6-(CH_2PBu_2^t)_2}\;(4))$, and the carbonyl complex, $Ir(CO) {C_6H_3-2,6-(CH_2PBu_2^t)_2}\;(5)$ (including the carboxyl complex, $IrH(C(O)OH) {C_6H_3-2,6-(CH_2PBu_2^t)_2}\;(6))$, in good yield, respectively. These P-C-P iridium complexes were isolated and characterized by $^1H,\;^{13}C,\;^{31}P\; NMR$, and IR spectroscopy. In addition, the complexes (1-6) were characterized by a single crystal X-ray crystallography. These complexes account for these small molecules' inhibition of dehydrogenation of alkanes catalyzed by the dihydrido complex 1.

Bis(imino)aryl Complex of Nickel(II): N,C,N-Pincer Type Complex, (2,6-(2,6-Et2PhN=CH)2C6H3)NiBr

  • Lee, Dong-Hwan;Hong, Sung-Won;Park, Soon-Heum
    • Bulletin of the Korean Chemical Society
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    • v.29 no.1
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    • pp.187-190
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    • 2008
  • The synthesis of a novel N,C,N-type pincer, bis(N-aryl)-2-bromoisophthalaldimine 2,6-(2,6-Et2PhN = CH)2C6H3Br (1) and Ni(1)Br (2) is described. They were characterized by elemental analysis and spectroscopic techniques (IR and 1H NMR). Attempted ethylene polymerization catalyzed by 2 has been futile, leading only to the formation of a small amount of oily oligomers.

Nickel Complexes Having (N-C-N) Tridentate Ligands ((N-C-N) 세자리 리간드를 가지는 니켈 착물)

  • Lee, Dong-Hwan;Park, Soon-Heum
    • Journal of the Korean Chemical Society
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    • v.51 no.6
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    • pp.499-505
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    • 2007
  • Monomeric complexes of nickel(II) having terdentate bis(imino)aryl ligands (N,C,N-pincer) are reported. New complexes (2,6-(ArN=CH)2C6H3)NiBr (Ar=2,6-dimethylphenyl (1), 2,6-diisopropylphenyl (2)) have been synthesized through oxidative addition of 1,3-(ArN=CH)2C6H3Br (bis(N-Ar)-2-bromoisophthalaldimine: Ar=Ph-2,6-Me2, Ph-2,6-iPr2) to Ni(COD)2 (COD=1,5-cyclooctadiene), in high yields. The development of a synthetic route to ligands and nickel complexes is outlined. The complexes were characterized by IR, 1H-NMR and elemental analysis. Full characterization of complexes 1 and 2 is discussed. An investigation into the catalytic activity of the complexes in ethylene polymerization was performed, resulting in no formation of polyethylenes but producing a small amount of oily oligomers. Preliminary results indicate that the pincer complexes were found to be inactive as catalysts in ethylene polymerization.

Palladium(II) Aryloxides of Pd(2,6-(CH2NMe2)2C6H3)(OC6H4-X-p) (X = Me, NO2): Synthesis, Property and Reactivity towards Diphenyliodium Chloride

  • Jung, Hyun-Sang;Park, Yun-Sik;Seul, Jung-Min;Kim, Jong-Sook;Lee, Ho-Jin;Park, Soon-Heum
    • Bulletin of the Korean Chemical Society
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    • v.32 no.8
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    • pp.2711-2716
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    • 2011
  • para-Substituted phenoxide derivatives of Pd(II) having an NCN pincer, Pd(NCN)($OC_6H_4$-p-X) (NCN = 2,6-$(CH_2NMe_2)_2C_6H_3$; X = $NO_2$ (1), Me (2)) were prepared by the reaction of Pd(NCN)($OSO_2CF_3$) with equi-molar amount of $NaOC_6H_4$-p-X. Treatment of Pd(NCN)($OSO_2CF_3$) with an excess amount of $NaOC_6H_4$-p-Me affords the hydrogen-bonding adduct complex 3 ($2{\cdot}HOC_6H_4$-p-Me). Complex 3 can also be obtained from benzene solution of 2 in the presence of free $HOC_6H_4$-p-Me. Complex 1 does not undergo adduct formation with $HOC_6H_4-p-NO_2$ neither from metathesis reaction of Pd(NCN)($OSO_2CF_3$) with an excess amount of $NaOC_6H_4-p-NO_2$ nor from treatment of 1 with free $HOC_6H_4-p-NO_2$. Complex 3 undergoes fast exchange of the coordinated p-cresolate with the hydrogen-bonding p-cresol. Complex 2 undergoes ${\sigma}$-ligand exchange reaction with $HOC_6H_4-p-NO_2$ to give 1. The exchange reaction, however, is irreversible as readily anticipated from their respective $pK_a$ values of the phenol derivatives. Reaction of 2 with diphenyliodium chloride quantitatively produced Pd(NCN)Cl and PhI along with liberation of O-phenylated product $PhOC_6H_4$-p-Me which was identified by GC/MS spectroscopy.

Amine and Olefin Complexes of Pt(II) Having a PCP-Pincer Ligand

  • Park, Soon-Heum
    • Bulletin of the Korean Chemical Society
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    • v.23 no.1
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    • pp.132-136
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    • 2002
  • $Pt(2,6-(Cy_2PCH_2)_2C_6H_3)(OTf)\;(OTf=CF_3SO_3^-)$ readily reacts with various amines to afford cationic amine complexes $[Pt(2,6-(Cy_2PCH_2)_2C_6H_3)(amine)](OTf)\;(amine=NH_3,\;NHMe_2,\;NHC_4H_8,\;NH_2Ph,\;NH_2(Tol-p))$ in high yields. These complexes have been fully characterized by IR, $^1H-,\;^{19}F{^1H}-,\;and\;^{31}P{^1H}-NMR$ spectroscopy, and elemental analyses. Reaction of $Pt(2,6-(Cy_2PCH_2)_2C_6H_3)(OTf)$ with acrylonitrile quantitatively produced the ${\pi}$-olefinic complex $Pt(2,6-(Cy_2PCH_2)_2C_6H_3)(CH_2=CHCN)](OTf)$ which is only stable in solution in the presence of acrylonitrile. Attempt at isolating this complex in the pure solid state was failed due to partial decomposition into $Pt(2,6-(Cy_2PCH_2)_2C_6H_3)(OTf)$ The equilibrium constants $(K_{eq}=[Pt(PCP)-(NH_2R)^+][CH_2=CHCN]/[Pt(PCP)(CH_2=CHCN)^+][NH_2R]:\;[Pt(2,6-(Cy_2PCH_2)_2C_6H_3)(CH_2=CHCN)]^++NH_2R{\rightleftarrows}[Pt(2,6-(Cy_2PCH_2)_2C_6H_3)(NH_2R)]^++CH_2=CHCN=Ph,\;p-tolyl)$ were calculated to be 0.28 (for R = Ph) and 3.1 (R = p-tolyl) at $21^{\circ}C$. The relative stability of the ${\sigma}$-donor amine versus the ${\pi}$-olefinic acrylonitrile complex has been found largely dependent upon the amine-basicity $(pK_b)$, implicating that acrylonitrile practically competes with amine in the platinum coordination sphere. On the contrary to the formation of the acrylonitrile complex, no reaction of $Pt(2,6-(Cy_2PCH_2)_2C_6H_3)(OTf)$ with other olefins such as ethylene, styrene and methyl acrylate was observed.