Complete assignments of NMR data of salens and their cobalt (III) complexes

Woo, Yoonkyung,Koh, Dongsoo,Lim, Yoongho John Wiley Sons, Ltd. 2009 Magnetic resonance in chemistry Vol.47 No.2

<P>Salens, derived from 1,2-ethylenediamine and salicylaldehydes, have been widely used as ligands for metal complexes which have been showing enormous potential in chemical properties of asymmetric catalysts as well as biological properties such as anticancer agents. Almost all of the salen–metal complexes with their corresponding metal (II)-complexes show the evidences of chelation of two oxygens in salens. However, several metal (II) complexes, especially cobalt (II) complexes, could not show NMR spectra due to their paramagnetism. Recently, it has been reported that one of the cobalt (III) complexes was used for NMR spectroscopy to evaluate its stereoselectivity as a catalyst. Even though many salen ligands are known, their NMR data are not assigned completely. It was possible that modification in northern part of salen with 2-hydroxyphenyl group afforded another oxygen chelation site in salen ligand. Here we report that synthesis and full NMR assignment of new salen ligands, which form meso 1,2-bis(2-hydroxyphenyl)ethylenediamine) and their cobalt (III) complexes. The assignments of <SUP>1</SUP>H and <SUP>13</SUP>C NMR data obtained in this experiment can help us to predict the NMR data of other salen ligands. Copyright © 2008 John Wiley & Sons, Ltd.</P> <B>Graphic Abstract</B> <P>Even though many salen ligands are known, their NMR data are not assigned completely. It was possible that modification in northern part of salen with 2-hydroxyphenyl group afforded another oxygen chelation site in salen ligand. Here we report synthesis and full NMR assignment of new salen ligands, which form meso 1,2-bis(2-hydroxyphenyl)ethylenediamine) and their cobalt (III) complexes. <img src='wiley_img/07491581-2009-47-2-MRC2372-gra001.gif' alt='wiley_img/07491581-2009-47-2-MRC2372-gra001'> </P>

Synthesis and Characterization of the Surface Modified SBA-15 with Dicobaltcarbonyl Complex

Sora Park,Yea-sel Jeon,Ki Won Jun,이윤조,한덕영,김형진,황광진 대한화학회 2014 Bulletin of the Korean Chemical Society Vol.35 No.7

Cobalt-immobilized SBA-15 6a-c was synthesized from alkyne-attached SBA 5a-c by the reaction with Co2(CO)8 in toluene. Alkyne group was introduced into amino SBA-15 (4) by imine-linkage or substitution with propargyl bromide to afford iminoalkyne 5a and aminoalkyne 5b, respectively. Meanwhile, alkyne 5c was prepared in one-step by reacting triethoxysilyl hexyne with SBA-15. Dicobalt-complexes 6a-c were characterized by means of FT-IR, solid-state NMR and elemental analysis.

Synthesis and Characterization of the Surface Modified SBA-15 with Dicobaltcarbonyl Complex

Park, Sora,Jeon, Yea-Sel,Jun, Ki-Won,Lee, Yun-Jo,Han, Doug-Young,Kim, Hyung Jin,Hwang, Kwang-Jin Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.7

Cobalt-immobilized SBA-15 6a-c was synthesized from alkyne-attached SBA 5a-c by the reaction with $Co_2(CO)_8$ in toluene. Alkyne group was introduced into amino SBA-15 (4) by imine-linkage or substitution with propargyl bromide to afford iminoalkyne 5a and aminoalkyne 5b, respectively. Meanwhile, alkyne 5c was prepared in one-step by reacting triethoxysilyl hexyne with SBA-15. Dicobalt-complexes 6a-c were characterized by means of FT-IR, solid-state NMR and elemental analysis.

First bistable monocobalt complex with six free nitrogen donors: 3,5-Di-tert-butylbenzoquinonatocobalt complex containing triethanolaminetriisonicotinate

Liang, H.,Cha, M.S.,Lee, Y.A.,Lee, S.S.,Jung, O.S. Elsevier 2007 INORGANIC CHEMISTRY COMMUNICATIONS Vol.10 No.1

A novel cobalt-benzoquinone complex containing triethanolaminetriisonicotinate as a coligand, [Co(3,5-dbq)<SUB>2</SUB>(tati)<SUB>2</SUB>] (3,5-dbq=3,5-di-tert-butyl-1,2-benzoquinone; tati=triethanolaminetriisonicotinate) is consisted of a valence tautomeric mixture of [Co<SUP>II</SUP>] and [Co<SUP>III</SUP>]. The tati coligand acts as a monodentate, resulting in the formation of discrete trans-[Co(3,5-dbq)<SUB>2</SUB>(tati)<SUB>2</SUB>] with six free nitrogen donors.

A Large Trans/cis Conversion Ratio In Redox-Conjugated Single-Light Reversible Isomerization of a Cobalt Complex with meta-Bipyridylazobenzene Ligands

Kume, Shoko,Kurihara, Masato,Nishihara, Hiroshi The Korean Electrochemical Society 2002 한국전기화학회지 Vol.5 No.4

Reversible trans-cis isomerization of meta-bipyridylazobenzene coordinated to cobalt was achieved by a combination of photoirradiation with a single UV light source and a Co(II)/Co(III) redox reaction. The trans/cis conversion performance was significantly improved in the meta-form compared with the meta-form ligated to cobalt.

Enantioselective Synthesis of β-Blockers via Hydrolytic Kinetic Resolution of Terminal Oxiranes by Using Bimetallic Chiral {{2,2′-[Cyclohexane-1,2-diylbis(nitrilomethylidyne)]bis[phenolato]}(2−)}cobalt([Co(salen)])-Type Complexes

Kawthekar, Rahul B.,Kim, Geon-Joong WILEY-VCH Verlag 2008 Helvetica chimica acta Vol.91 No.2

<P>The synthesis of chirally pure β-blockers was successfully achieved via hydrolytic kinetic resolution of butyl (±)-4-(oxiran-2-ylmethoxy)benzeneacetate ((±)-1) and (±)-4-(oxiran-2-ylmethoxy)benzeneacetonitrile ((±)-2) in the presence of bimetallic chiral [Co(salen)]-type complexes. The newly synthesized bimetallic chiral [Co(salen)]-type complexes exhibited excellent enantioselectivities of up to >98% ee in good yields (Tables 1–3).</P>

Pyridine 용액에서 산소 첨가된 네자리 Schiff base Cobalt(III) 착물들의 전기 분석화학적 연구

임채평,채희남,조기형,최용국,Rim, Chae-Pyeong,Chae, Hee-Nam,Chjo, Ki-Hyung,Choi, Yong-Kook 한국분석과학회 1995 분석과학 Vol.8 No.1

네 자리 Schiff base cobalt(II) 착물로서 $Co(II)_2-N$, N-bis(salicylidene)-m-phenylendiimine : [$Co(II)_2(SMPD)_2(H_2O)_4$] 및 $Co(II)_2-N$, N-bis(salicylidene)-p-phenylendiimine : [$Co(II)_2(SPPD)_2(H_2O)_4$]들을 합성하였다. Pyridine 용액에서 이와 같은 착물들에 산소를 가하여 산소 첨가된 생성착물로서 [$Co(III)_2O_2(SMPD)_2(Py)_2$] 및 [$Co(III)_2O_2(SPPD)_2(Py)_2$]들을 합성하였다. 원소분석과 금속정량, IR spectia 및 TGA를 측정한 결과로부터 pyridine과 산소가 중심금속에 6배위로 결합함을 밝혔다. 0.1M TEAP-pyridine 용액에서 순환 전압-전류법에 의한 산소 첨가 생성 착물들의 산화-환원 과정은 다음과 같이 5단계의 일전자 반응으로 진행됨을 알았다. $$[Co(III)_2-O_2-CO(III)]\rightarrow^{e^-}[Co(III)-O_2-Co(II)]\rightarrow^{e^-}[Co(II)-O_2-Co(II)]\rightleftarrows^{e^-}[Co(II)+Co(II)+O_2{\cdot}^-]\rightleftarrows^{e^-}[Co(II)+Co(I)+O_2{\cdot}^-]\rightleftarrows^{e^-}[Co(I)+Co(I)+O_2{\cdot}^-]$$. Tetradentate Schiff base cobalt(II) complexes such as $Co(II)_2-N$, N-bis(salicylidene)-m-phenylendiimine; [$Co(II)_2(SMPD)_2(H_2O)_4$] and $Co(II)_2-N$, N-bis(salicylidene)-p-phenylendiimine: [$Co(II)_2(SPPD)_2(H_2O)_4$], and oxygen adducted cobalt (III) complexes such as [$Co(III)_2O_2(SMPD)_2(Py)_2$] and [$Co(III)_2O_2(SPPD)_2(Py)_2$] in pyridine solutions were synthesized. It was identified that the oxygen adducted cobalt(III) complexes have hexacoordinated octahedral configuration with pyridine and oxygen from the measurement of elemental analysis, AA, IR spectra, and TGA. The redox processes were investigated for the oxygen adducted complexes in 0.1M TEAP-pyridine solution, using cyclic voltammetry on the glassy carbon electrode. The redox processes of oxygen adducted Co(III) complexes result in $$[Co(III)_2-O_2-CO(III)]\rightarrow^{e^-}[Co(III)-O_2-Co(II)]\rightarrow^{e^-}[Co(II)-O_2-Co(II)]\rightleftarrows^{e^-}[Co(II)+Co(II)+O_2{\cdot}^-]\rightleftarrows^{e^-}[Co(II)+Co(I)+O_2{\cdot}^-]\rightleftarrows^{e^-}[Co(I)+Co(I)+O_2{\cdot}^-]$$.

Highly active cobalt( II ) and copper( II ) complexes supported by aminomethylquinoline mediating stereoselective ring‐opening

이재영,Nayab Saira,Kumar Ameet,김동일,정혜원,이상호,조대흠,이효선 대한화학회 2024 Bulletin of the Korean Chemical Society Vol.45 No.4

Cobalt(II) and copper(II) complexes supported by 4‐(quinolin‐2‐ylmethyl)morpholine (L) were characterized, and their reactivity toward the ring‐opening polymerization (ROP) of rac ‐lactide ( rac ‐LA) was studied. The use of [LMCl 2 ]/LiO i Pr and [LMCl 2 ]/LiMe (M = Co, Cu) resulted in over 95% conversion within 10 min at 25 °C. The effect of the initiating group and geometry of the metal complexes steered the heterotactic enchainment of the resultant polylactide(PLA). The Co(II)/LiMe system represents the first example of the ROP of rac ‐LA with high heterotactic enchainment ( P r  = 0.92) with 98% conversion at 0 °C. Cobalt(II) and copper(II) complexes supported by 4-(quinolin-2-ylmethyl) morpholine (L) were characterized, and their reactivity toward the ringopening polymerization (ROP) of rac-lactide (rac-LA) was studied. The use of [LMCl2]/LiOiPr and [LMCl2]/LiMe (M = Co, Cu) resulted in over 95% conversion within 10 min at 25 C. The effect of the initiating group and geometry of the metal complexes steered the heterotactic enchainment of the resultant polylactide(PLA). The Co(II)/LiMe system represents the first example of the ROP of rac-LA with high heterotactic enchainment (Pr = 0.92) with 98% conversion at 0 C.

Synthesis and structural characterization of 5-coordinate cobalt(II), copper(II) and 4-coordinate zinc(II) complexes containing <i>N</i>′-cyclopentyl substituted <i>N</i>,<i>N</i>-bispyrazolylmethylamine

Shin, Sujin,Ahn, Seoung Hyun,Choi, Sunghye,Choi, Sang-Il,Nayab, Saira,Lee, Hyosun Elsevier 2016 Polyhedron Vol.110 No.-

<P><B>Abstract</B></P> <P>Novel [<B>L<SUB>n</SUB>MCl<SUB>2</SUB> </B>] complexes (L<SUB>n</SUB> =L<SUB>A</SUB>, L<SUB>B</SUB>; M=Co, Cu, Zn) containing the <I>N</I>,<I>N</I>-chelating ligands <I>N</I>,<I>N</I>-bis((1H-pyrazol-1-yl)methyl)cyclopentanamine (<B>L<SUB>A</SUB> </B>) and <I>N</I>,<I>N</I>-bis((3,5-dimethyl-1H-pyrazol-1-yl)methyl)cyclopentanamine (<B>L<SUB>B</SUB> </B>) have been synthesized and characterized. The X-ray crystal structures of the Co(II) and Cu(II) complexes revealed that the ligands are coordinated in an <I>N</I>,<I>N</I>,<I>N</I>-tridentate manner, resulting in distorted trigonal bipyramidal geometries through the coordinative interaction of the nitrogen atom of the cyclopentylamine moiety and the metal centers. [<B>L<SUB>A</SUB>ZnCl<SUB>2</SUB> </B>] showed a distorted tetrahedral geometry involving a non-coordinative interaction of the N<SUB>amine</SUB> atom and the Zn(II) center, resulting in the formation of an eight membered chelate ring. [<B>L<SUB>A</SUB>CoCl<SUB>2</SUB> </B>] exhibited the highest catalytic activity (7.67×10<SUP>4</SUP> gPMMA/molCoh) for the polymerization of MMA in the presence of MMAO at 60°C and yielded PMMA with a high molecular weight (<I>M</I> <SUB>w</SUB>) (11.2×10<SUP>5</SUP> g/mol) and narrower polydispersity index (PDI) 1.01 compared to its Cu(II) and Zn(II) analogs. Syndiotactic enriched PMMA was obtained with <I>T</I> <SUB>g</SUB> in the range 120–132°C. The introduction of bulky methyl substituents played an influential role on controlling the catalytic activities while the syndiotacticities remained unaffected.</P> <P><B>Graphical abstract</B></P> <P>Novel Co(II), Cu(II) and Zn(II) complexes ligated to <I>N</I>′-cyclopentyl substituted <I>N</I>,<I>N</I>-bispyrazolylmethylamine have been synthesized and characterized. These complexes polymerize methyl methacrylate in the presence of MMAO to yield syndiotactic poly(methylmethacrylate) at 60°C. The Co(II) complexes exhibited higher catalytic activity compared to the Cu(II) and Zn(II) analogs. The catalytic activities were affected by the steric encumbrance around the metal center.</P> <P>[DISPLAY OMISSION]</P>

Preparation and Characterization of Half-Sandwich Cobalt(III) Complexes of Cp Ligands with a Rigid Thioanisole Side-Chain

Sujith S,Bun Yeoul Lee*,한진욱 대한화학회 2007 Bulletin of the Korean Chemical Society Vol.28 No.8

New sulfur functionalized cyclopentadiene ligands, 1-[2-(thioanisole)]-2,5-dimethylcyclopentadiene (3), 1-[2-(thioanisole)]-2,3,5-trimethylcyclopentadiene (4), and 1-[2-(thioanisole)]-2,3,4,5-tetramethylcyclopentadiene (5), were prepared. In these ligands, the S-donor atom is connected to a cyclopentadiene ring by a rigid phenylene spacer. CpCo(III)-diiodo half-sandwich complexes (6-8) were obtained from reaction the ligands (3-5) with Co2(CO)8, followed by treatment of I2. Substitution reaction of CpCo(III)-diiodo complexes with MeLi yielded the corresponding CpCo(III)-dimethyl complexes (9-11). Further transformation to the corresponding cationic cobalt complexes (12-14) were achieved by reaction of the CpCo(III)-dimethyl complexes with HB(ArF)42Et2O and trapping with CD3CN. The new sulfur functionalized cyclopentadiene ligands having a rigid phenylene spacer and the corresponding cobalt complexes were characterized by 1H, 13C and 19F NMR spectroscopy. The diiodo Complex 6 was also characterized by a single crystal X-ray diffraction method.